WO2020208093A1 - Cysteine derivatives for treatment and prevention of bacterial infections - Google Patents

Cysteine derivatives for treatment and prevention of bacterial infections Download PDF

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Publication number
WO2020208093A1
WO2020208093A1 PCT/EP2020/060066 EP2020060066W WO2020208093A1 WO 2020208093 A1 WO2020208093 A1 WO 2020208093A1 EP 2020060066 W EP2020060066 W EP 2020060066W WO 2020208093 A1 WO2020208093 A1 WO 2020208093A1
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compound
use according
group
agr
hours
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PCT/EP2020/060066
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French (fr)
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Christian Adam OLSEN
Bengt Herbert GLESS
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University Of Copenhagen
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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K45/00—Medicinal preparations containing active ingredients not provided for in groups A61K31/00 - A61K41/00
    • A61K45/06—Mixtures of active ingredients without chemical characterisation, e.g. antiphlogistics and cardiaca
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K31/00—Medicinal preparations containing organic active ingredients
    • A61K31/13—Amines
    • A61K31/145—Amines having sulfur, e.g. thiurams (>N—C(S)—S—C(S)—N< and >N—C(S)—S—S—C(S)—N<), Sulfinylamines (—N=SO), Sulfonylamines (—N=SO2)
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K31/00—Medicinal preparations containing organic active ingredients
    • A61K31/185—Acids; Anhydrides, halides or salts thereof, e.g. sulfur acids, imidic, hydrazonic or hydroximic acids
    • A61K31/19—Carboxylic acids, e.g. valproic acid
    • A61K31/195—Carboxylic acids, e.g. valproic acid having an amino group
    • A61K31/197—Carboxylic acids, e.g. valproic acid having an amino group the amino and the carboxyl groups being attached to the same acyclic carbon chain, e.g. gamma-aminobutyric acid [GABA], beta-alanine, epsilon-aminocaproic acid or pantothenic acid
    • A61K31/198—Alpha-amino acids, e.g. alanine or edetic acid [EDTA]
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K31/00—Medicinal preparations containing organic active ingredients
    • A61K31/21—Esters, e.g. nitroglycerine, selenocyanates
    • A61K31/215—Esters, e.g. nitroglycerine, selenocyanates of carboxylic acids
    • A61K31/22—Esters, e.g. nitroglycerine, selenocyanates of carboxylic acids of acyclic acids, e.g. pravastatin
    • A61K31/223—Esters, e.g. nitroglycerine, selenocyanates of carboxylic acids of acyclic acids, e.g. pravastatin of alpha-aminoacids
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L15/00—Chemical aspects of, or use of materials for, bandages, dressings or absorbent pads
    • A61L15/16—Bandages, dressings or absorbent pads for physiological fluids such as urine or blood, e.g. sanitary towels, tampons
    • A61L15/42—Use of materials characterised by their function or physical properties
    • A61L15/44—Medicaments
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L29/00—Materials for catheters, medical tubing, cannulae, or endoscopes or for coating catheters
    • A61L29/14—Materials characterised by their function or physical properties, e.g. lubricating compositions
    • A61L29/16—Biologically active materials, e.g. therapeutic substances
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
    • A61P31/00—Antiinfectives, i.e. antibiotics, antiseptics, chemotherapeutics
    • A61P31/04—Antibacterial agents
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L2300/00—Biologically active materials used in bandages, wound dressings, absorbent pads or medical devices
    • A61L2300/40—Biologically active materials used in bandages, wound dressings, absorbent pads or medical devices characterised by a specific therapeutic activity or mode of action
    • A61L2300/404—Biocides, antimicrobial agents, antiseptic agents

Definitions

  • the present invention relates to cysteine derivatives for use in the prevention and treatment of bacterial infections.
  • Staphylococcus aureus a member of the family Micrococcaceae, is a Gram-positive coccus whose cells tend to occur either singly or if dividing cells do not separate, form pairs, tetrads and distinctive irregular“grape-like” structures. Humans are commonly colonised by S. aureus on external skin surfaces and the upper respiratory tract, particularly the nasal passages. Healthy individuals are usually unaware of
  • S. aureus can cause more serious infections. Burns and surgical wound infections are commonly invaded by S. aureus, where the production of toxins by S. aureus can e.g. give rise to toxic shock syndrome leading to fever, sickness and in some cases death. Infections caused by S.
  • aureus include, pneumonia (inflammation of lungs), mastitis (infection of the mammary glands), infections of skin (impetigo, cellulitis and staphylococcal scalded skin syndrome), osteomyelitis (infection of bone), endocarditis (infection of the endothelial lining of the heart and valves) and bacteremia (bacteria present in blood). S.
  • aureus can also cause food poisoning, the result of enterotoxin production.
  • Treatment of S. aureus infections before the 1950s involved the administration of benzylpenicillin (penicillin G), but by the late 1950s S. aureus strains resistant to benzylpenicillin were causing increasing concern.
  • Resistant strains typically produced an enzyme, called a b-lactamase, which inactivated the b-lactam antibiotic.
  • Efforts were made to synthesise penicillin derivatives that were resistant to b-lactamase hydrolysis. This was achieved in 1959 with the synthesis of methicillin.
  • methicillin-resistant S. aureus (MRSA) strains emerged with resistance towards the action of methicillin.
  • MRSA methicillin-resistant S. aureus
  • bacterial infections may e.g. be treated by inhibiting or reducing bacterial biofilm formation and/or by inhibiting or reducing bacterial virulence.
  • Antibacterial agents that act through other mechanisms than by targeting bacterial growth and/or biofilm formation, may provide an effective treatment alternative to standard antibiotics.
  • cysteine and derivatives thereof bearing a free amine and a free thiol demonstrate significant inhibitory activity towards quorum sensing in Gram-positive bacteria. This effect is not seen for N-acetyl cysteine (NAC).
  • the present disclosure thus provides cysteine and derivatives thereof for use in the prevention or treatment of a bacterial infection, in particular bacterial infections caused by quorum sensing bacteria. It is an aspect to provide a compound according to the formula (I),
  • n 0 or 1 ;
  • z is 0 or 1 ;
  • Ri is selected from the group consisting of: H and alkyl
  • R 2 and R 3 are independently of each other selected from the group consisting of: hydrogen, halogen, and alkyl;
  • Y is selected from the group consisting of: -(CO)R 4 , -CO 2 R 4 , -0(CO)R 4 ,
  • R 4 , R 5 , and R 6 are independently of each other selected from the group consisting of: hydrogen, alkyl, aryl, and heteroaryl;
  • the compound for use according to the present disclosure is of formula
  • the compound for use according to the present disclosure is of formula
  • composition for use in the treatment or prevention of a bacterial infection in a subject, said composition comprising the compound as defined herein, and one or more excipients.
  • the present disclosure provides a method for treatment or prevention of a bacterial infection, the method comprising administering to a subject a compound or a composition as defined herein, and a further antimicrobial agent.
  • the present disclosure provides a method for preventing bacterial colonization of a wound, said method comprising administering a compound or a composition as defined herein to the wound of a subject.
  • the present disclosure provides a method for inhibiting or reducing bacterial virulence on the skin of a subject, said use comprising contacting a compound or a composition as defined herein with the skin of the subject.
  • the present disclosure provides a method for inhibiting quorum sensing of bacteria comprising contacting a compound or a composition as defined herein with the bacteria.
  • the present disclosure provides a method for treatment or prevention of bacterial damage or disease in a subject, comprising administering a compound or a composition as defined herein to the subject.
  • the present disclosure provides a method for decreasing the
  • pathogenicity of bacteria in or on a subject comprising administering a compound or a composition as defined herein to the subject.
  • the present disclosure provides a method for increasing the
  • the present disclosure provides a medical device comprising a compound or a composition as defined herein. In one aspect, the present disclosure provides a use of a compound or a composition as defined herein for the manufacture of a medicament for the treatment or prevention of a bacterial infection in a subject.
  • Fig. 1 Ring opening reaction of an autoinducing peptide (AIP) with cysteine methyl ester under relevant physiological pH value.
  • Fig. 2 Fluorescence YFP assay for inhibition of quorum sensing for S. aureus agr- 1. The bars represent the mean fluorescence value measured by flow cytometry after 7 hours of growth in the presence of various compounds.
  • the control inhibitor used is AIP-III D4A.
  • the tested amino-thiol compounds L-cysteine, L-cysteine methyl ester and D-cysteine showed strongly reduced fluorescence at a concentration of 10 mM compared to the negative inhibition control against S. aureus agr- 1 type after 7 hours of growth (Fig. 2).
  • L-cysteine methyl ester was able to fully inhibit the quorum sensing activity of S. aureus agr- 1 to the same extent as the inhibitor AIP-III D4A.
  • Fig. 3 Fluorescence YFP assay for inhibition of quorum sensing for S. aureus agr- II.
  • the bars represent the mean fluorescence value measured by flow cytometry after 7 hours of growth in the presence of various compounds.
  • the control inhibitor used is AIP-III D4A.
  • the tested amino-thiol compounds L-cysteine, L-cysteine methyl ester and D-cysteine showed strongly reduced fluorescence at a concentration of 10 mM compared to the negative inhibition control against S. aureus agr- II type after 7 hours of growth (Fig. 3).
  • Fig. 4 Fluorescence YFP assay for inhibition of quorum sensing for S. aureus agr-lll.
  • the bars represent the mean fluorescence value measured by flow cytometry after 7 hours of growth in the presence of various compounds.
  • the control inhibitor used is AIP-III D4A.
  • the tested amino-thiol compounds L-cysteine, L-cysteine methyl ester and D-cysteine showed strongly reduced fluorescence at a concentration of 10 mM compared to the negative inhibition control against S. aureus agr- III type after 7 hours of growth (Fig. 4).
  • L-cysteine methyl ester was able to fully inhibit the quorum sensing activity of S.
  • FIG. 5 Fluorescence YFP assay for inhibition of quorum sensing for S. aureus agr-IV. The bars represent the mean fluorescence value measured by flow cytometry after 7 hours of growth in the presence various compounds.
  • the control inhibitor used is AIP- III D4A.
  • the tested amino-thiol compounds L-cysteine, L-cysteine methyl ester and D- cysteine showed strongly reduced fluorescence at concentration of 10 mM compared to the negative inhibition control against S. aureus agr- IV type after 7 hours of growth (Fig. 5).
  • Fig. 6 Fluorescence YFP assay for inhibition of quorum sensing for S. aureus agr- 1 with comparative data between cysteine analogues and N-acetylated analogues. The bars represent the mean fluorescence value measured by flow cytometry after 8 hours of growth in the presence various compounds.
  • the control inhibitor used is AIP-III D4A.
  • Fig. 7 Bacterial growth of S. aureus agr- 1 during quorum sensing inhibition displayed by the optical density at 600 nm (OD600). The graph shows the bacterial growth in the presence of various compounds measured hourly over the course of 8 hours by the absorbance at 600 nm.
  • Fig. 8 Structures of tested amino-thiol compounds.
  • Fig. 9 UPLC assay for the determination of reaction rates for the ring opening of a synthetic AIP using amino-thiol compounds.
  • the bar graphs represent the conversion of an AIP to the linear ring opened peptide after 30 min and 60 min in the presence of 40 equivalents of an amino-thiol compound.
  • the structures of amino-thiol compounds are shown in Fig. 8.
  • Fig. 10 Fluorescence YFP 96-well plate assay for the inhibition of quorum sensing for S. aureus agr- 1.
  • the bars represent the agr quorum sensing activity derived from the fluorescence values measured after 20 h of incubation in the presence of amino-thiol compounds at concentrations of 10 mM and 5.0 mM.
  • Negative controls are wells containing no compounds and positive controls are wells containing the inhibitor AIP-III D4A at a concentration of 100 nM.
  • the structures of amino-thiol compounds are shown in Fig. 8.
  • Fig. 11 Fluorescence YFP 96-well plate assay for the inhibition of quorum sensing for S. aureus agr- II.
  • the bars represent the agr quorum sensing activity derived from the fluorescence values measured after 20 h of incubation in the presence of amino-thiol compounds at concentrations of 10 mM and 5.0 mM. Negative controls are wells containing no compounds and positive controls are wells containing the inhibitor AIP-III D4A at a concentration of 100 nM.
  • the structures of amino-thiol compounds are shown in Fig. 8.
  • Fig. 12 Fluorescence YFP 96-well plate assay for the inhibition of quorum sensing for S. aureus agr-lll.
  • the bars represent the agr quorum sensing activity derived from the fluorescence values measured after 24 h of incubation in the presence of amino-thiol compounds at concentrations of 10 mM and 5.0 mM.
  • Negative controls are wells containing no compounds and positive controls are wells containing the inhibitor AIP-III D4A at a concentration of 100 nM.
  • the structures of amino-thiol compounds are shown in Fig. 8.
  • Fig. 13 Fluorescence YFP 96-well plate assay for the inhibition of quorum sensing for S. aureus agr-IV.
  • the bars represent the agr quorum sensing activity derived from the fluorescence values measured after 20 h of incubation in the presence of amino-thiol compounds at concentrations of 10 mM and 5.0 mM.
  • Negative controls are wells containing no compounds and positive controls are wells containing the inhibitor AIP-III D4A at a concentration of 100 nM.
  • the structures of amino-thiol compounds are shown in Fig. 8. Fig.
  • treatment comprises any type of therapy, which aims at terminating, preventing, ameliorating and/or reducing the susceptibility to a clinical condition as described herein.
  • treatment relates to prophylactic treatment (i.e. a therapy to reduce the susceptibility of a bacterial infection as defined herein).
  • treatment refers to obtaining a desired effect, such as a biological, pharmacologic and/or physiologic effect, covering any treatment of a bacterial infection in a subject, such as a mammal, including a human.
  • the effect may be prophylactic in terms of completely or partially preventing a bacterial infection or symptom thereof and/or may be therapeutic in terms of a partial or complete cure for the bacterial infection and/or adverse effect attributable to the infection.
  • treatment includes (1) preventing the bacterial infection from occurring or recurring in a subject, (2) inhibiting the bacterial infection, such as arresting its development, (3) stopping, terminating or alleviating the bacterial infection or at least symptoms associated therewith, so that the subject no longer suffers from the disorder or clinical condition or its symptoms, such as causing regression of the bacterial infection or its symptoms, for example, by restoring or repairing a lost, missing or defective function, or stimulating an inefficient process, or (4) relieving, alleviating, or ameliorating the bacterial infection, or symptoms associated therewith, where ameliorating is used in a broad sense to refer to at least a reduction in the magnitude of a parameter, such as inflammation, pain, and/or immune deficiency.
  • a parameter such as inflammation, pain, and/or immune deficiency
  • prevent refers to a decrease in the occurrence of symptoms or characteristics of a bacterial infection.
  • the term is also used in the context of preventing dissemination of the bacterial infection.
  • the prevention may be complete.
  • the prevention may also be partial, such that for example the occurrence of symptoms or characteristics of a bacterial infection in a subject is less than that which would have occurred without the present invention.
  • Prevention also refers to reduced susceptibility to a bacterial infection.
  • antibiotic resistance refers to a bacterium, which has acquired resistance to an antibiotic that was once able to treat an infection by that bacterium. Antibiotic resistance may be dose dependent, meaning that higher doses of the antibiotic than usual are required to sufficiently treat the infection, or complete in that a certain antibiotic is without effect irrespective of dose.
  • the non-resistant bacteria may be referred to as antibiotic sensitive bacteria.
  • A“bacterial infection” according to the present disclosure may be caused by Gram positive bacteria, Gram-negative bacteria, Mycobacteria, or a combination thereof.
  • the term "pharmaceutically acceptable salt” refers to a salt used typically in the pharmaceutical field. Examples of
  • the pharmaceutically acceptable salt include sodium salts, hydrochloride salts, magnesium salts, calcium salts and potassium salts, but are not limited thereto.
  • n is 0 or 1 ;
  • z is 0 or 1 ;
  • Ri is selected from the group consisting of: H and alkyl
  • R 2 and R 3 are independently of each other selected from the group consisting of: hydrogen, halogen, and alkyl;
  • Y is selected from the group consisting of: -(CO)R 4 , -CO 2 R 4 , -0(CO)R 4 ,
  • R 4 , R 5 , and R 6 are independently of each other selected from the group consisting of: hydrogen, alkyl, aryl, and heteroaryl;
  • n 0 or 1 ;
  • z is 0 or 1 ;
  • Ri is selected from the group consisting of: H and alkyl
  • R 2 and R 3 are independently of each other selected from the group consisting of: hydrogen, halogen, and alkyl;
  • Y is selected from the group consisting of: -(CO)R 4 , -CO 2 R 4 , -0(C0)R 4 ,
  • R 4 , R 5 , and R 6 are independently of each other selected from the group consisting of: hydrogen, alkyl, aryl, and heteroaryl;
  • RiNH is covalently attached via nitrogen to the carbon to which Y is also attached.
  • HS is covalently attached via sulphur to the carbon to which R 2 and R 3 is attached.
  • Y is directly attached to its adjacent carbon atom as depicted in formula (I).
  • Y is“-aryl-RV, which should be understood as aryl covalently attached to the adjacent carbon of Y, wherein the aryl is also functionalized by a substituent R4.
  • Y should be interpreted as .
  • the bond from phenyl intersected by a wavy bond corresponds to of“-aryl” in the“-aryl-FV.
  • R4 may be connected by a covalent bond to any of the other positions of the aryl.
  • the expression“-heteroaryl-RV should be interpreted in a similar manner and is understood by a person of skilled in the art.
  • Y is“-CC-R4”, which shall be interpreted as
  • Ri is hydrogen or methyl, of the compound of formula (I) as defined herein. In one embodiment, Ri is hydrogen. In one embodiment, R2 and R3 are both methyl. In one embodiment, R2 and R3 are both hydrogen. In one embodiment, either R2 or R3 is a hydrogen. In one embodiment, either R2 or R3 is methyl.
  • R4 is selected from the group consisting of: alkyl, aryl, and heteroaryl. In one embodiment, R4 is a C1 to C6 alkyl. In one embodiment, R4 is methyl. In one embodiment, n is 0. In one embodiment, z is 0. In one embodiment, n is 0 and z is 0.
  • Y is selected from the group consisting of: -CO2R4 and -0(C0)R 4 , and R4 is as defined herein.
  • Y is a bond to the terminal carbon of R2, and R2 is a C3, C4, or C5 alkyl.
  • Y is a heteroaryl, such triazole.
  • the compound is not L-cysteine. In one embodiment the compound is selected from the group consisting of: L-cysteine methyl ester, D- penicillamine, and D-penicillamine methyl ester, preferably the compound is L-cysteine methyl ester.
  • the compound is of formula (la),
  • Ri is selected from the group consisting of: H and Ci- 8 alkyl
  • X is selected from the group consisting of:
  • R4 and R5 are independently of each other selected from the group consisting of: H, alkyl, aryl, and heteroaryl;
  • v is selected from the group consisting of: 1 , 2, 3, and 4.
  • R4 is selected from the group consisting of:
  • i is selected from the group consisting of 1 , 2, and 3;
  • Ar is aryl, such as C6-10 aryl substituted by one, two, or three substituents; and T is selected from the group consisting of: -(CO)R7, -CO2R7, -0(CO)R 7 ,
  • R 7 , R 8 , and Rg are independently of each other selected from the group consisting of: hydrogen, alkyl, aryl, and heteroaryl.
  • the compound of formula (la) is provided, wherein R4 is wherein i is 1 and Ar is C6-10 aryl substituted by one, two, or three substituents.
  • the compound of formula (la) as defined herein is used in the treatment or prevention of a bacterial infection caused by a Gram-positive bacterium, wherein the Gram-positive bacterium comprises an agr, optionally wherein the Gram- positive bacterium is selected from the group consisting of: staphylococci, listeria, and Clostridium.
  • the compound is selected from the group consisting of:
  • the compound is selected from the group consisting of:
  • the compound is cysteamine for use in the treatment or prevention of a bacterial infection caused by a Gram-positive bacterium, wherein the Gram-positive bacterium comprises an agr, optionally wherein the Gram-positive bacterium is selected from the group consisting of: staphylococci, listeria, and
  • the compound is not D-penicillamine.
  • the compound for use as defined herein is provided, wherein the compound is of formula (II),
  • the compound of formula (II) is defined by the following:
  • Ri is selected from the group consisting of: H and C 1-6 alkyl
  • R 2 and R 3 are independently of each other selected from the group consisting of:
  • R 4 is selected from the group consisting of: C 1-6 alkyl, benzyl, phenyl, naphthalenyl, furyl, thienyl, pyrrolyl, oxazolyl, thiazolyl, imidazolyl, pyrazolyl, isoxazolyl, isothiazolyl, oxadiazolyl, triazolyl, thiadiazolyl, pyridinyl, pyridazinyl, pyrimidinyl, pyrazinyl, indolyl, isoindolyl, benzofuryl, benzothienyl, indazolyl, benzimidazolyl, benzothiazolyl, benzoxazolyl, benzisoxazolyl, benzothiadiazolyl, benzotriazolyl, quinolinyl, isoquinolinyl and quinazolinyl.
  • the compound for use as defined herein is provided, wherein the compound is of formula (III),
  • R 4 is as defined herein, such as a C1-6 alkyl.
  • the compound as defined herein is selected from the group consisting of: L-cysteine methyl ester, L-cysteine, D-penicillamine, D-penicillamine methyl ester and D-cysteine, preferably the compound is L-cysteine methyl ester.
  • a composition for use is provided for the treatment or prevention of a bacterial infection in a subject, said composition comprising the compound as defined herein, and one or more excipients.
  • the compound for use as defined herein is provided, wherein the compound is administered prior to, simultaneously with, or subsequently to an antimicrobial agent.
  • the use of a compound as defined herein increases the susceptibility of bacteria to the antimicrobial agent.
  • quorum sensing a process termed quorum sensing (QS). This chemical signalling process effectively allows bacteria to “count” themselves and behave as a group at high cell number. While the specifics may vary between species, QS circuits share general organizing principles: bacteria produce, secrete, and detect signal molecules referred to as autoinducing peptides (AIPs) in staphylococci and other Gram-positive bacteria. At high population densities in a given environment, the AIPs will reach a sufficiently high concentration to bind and activate their cognate extracellular receptors.
  • AIPs autoinducing peptides
  • non-native ligands e.g., small molecule and peptides
  • targeting QS provides an alternative anti-infective therapy that does not place selective pressure on the bacterial population to develop resistance. This is especially important in the case of S. aureus, which rapidly develops resistance to antibiotics, including resistance to the once last-resort antibiotic vancomycin.
  • the staphylococcal QS system is named after its chromosomal locus accessory gene regulator (agr) and agr-like QS systems have been found in other Gram-positive bacteria such as Listeria, Clostridia and Lactobacilli.
  • the activation of the agr QS system leads to the expression of many virulence factors, which lead to the formation of skin abscesses and worst symptoms on the subject infected by the bacteria.
  • the secreted signalling peptides, the AIPs share a common chemical moiety, a thiolactone, which is necessary for structural integrity and activation of QS.
  • Staphylococcus aureus has four distinct agr systems (agr-l-l V) with unique Al P- receptor pairs. These specificity groups represent a challenge for inhibitor development due to the different binding profiles necessary for pan-group-inhibitors.
  • a compound is provided as defined herein for use in treatment or prevention of a bacterial infection, wherein the compound is capable of reacting with a bacterial autoinducing peptide (AIP) thereby inactivating the AIP and inhibiting quorum sensing.
  • AIP bacterial autoinducing peptide
  • the bacterial autoinducing peptide is one or more or all of AIP-I, AIP-II, AIP-III, and AIP-IV, such as one or more or all of S. aureus AIP-I, AIP-II, AIP-III, and AIP-IV.
  • the compound as defined herein inhibits accessory gene regulator (agr) mediated signaling of the bacteria.
  • the inhibition of agr mediated signalling is determined by a quorum sensing inhibition assay using one or more fluorescence reporter strains.
  • the bacterial infection treated or prevented by a compound as defined herein is caused by a Gram-positive bacterium.
  • the Gram-positive bacterium comprises an agr.
  • the compound of formula (I) as defined herein is a bacterial quorum sensing inhibitor.
  • a bacterial infection prevented or treated by a compound as defined herein is on the skin and/or a mucosal surface of a subject.
  • the mucosal surface is on an eye, an ear, inside the nose, inside the mouth, on the lip, vagina, the urethra, the bladder and/or the gastrointestinal tract, such as the oesophagus or the anus, of the subject.
  • the bacterial infection prevented or treated by a compound as defined herein is in a wound.
  • the compound for use as defined herein is provided for prevention or treatment of a bacterial infection by attenuation, inhibition or reduction of virulence in the bacteria.
  • the attenuation, inhibition or reduction of virulence in the bacteria is maintained for at least 30 min, such as at least 1 hour, such as at least 2 hours, such as at least 3 hours, such as at least 4 hours, such as at least 5 hours, such as at least 6 hours, such as at least 7 hours, such as at least 8 hours, such as at least 9 hours, such as at least 10 hours, such as at least 11 hours, such as at least 12 hours, such as at least 13 hours, such as at least 14 hours, such as at least 15 hours, such as at least 16 hours, such as at least 17, such as at least 18 hours, such as at least 19 hours, such as at least 20 hours, such as at least 21 hours, such as at least 22 hours, such as at least 23 hours, such as at least 24 hours, after administering a single dose of the compound to the subject.
  • the compound for use as defined herein decreases the
  • the prevention or treatment of the bacterial infection is by attenuation of virulence of the bacteria without significantly inhibiting bacterial growth.
  • the use of a compound as defined herein reduces or inhibits formation of abscesses on the skin. In one embodiment, the use reduces or inhibits dermo-necrosis in a subject.
  • the compound for use as defined herein does not significantly reduce, inhibit or degrade bacterial biofilm. In another embodiment, the compound also reduces, inhibits or degrades bacterial biofilm.
  • the bacterial infection treated or prevented by a compound as defined herein is caused by a Gram-positive bacterium.
  • the bacterial infection is caused by a bacterium selected from the group consisting of: staphylococci, listeria, and Clostridium.
  • the staphylococci are selected from the group consisting of: S. aureus, S. epidermidis, S. lugdunensis, S. haemolyticus, S. capitis, S. caprae, S. cohnii, S. pasteuri, S. pettenkoferi, S. schleiferi, S. sciuri, S. simulans, S. warneri, S. xylosus, S. hominis, S. argenteus, S. arlettae, S. auricularis, S. carnosus, S.
  • the staphylococci are selected from the group consisting of: S. aureus, S. epidermidis, S. lugdunensis, and S. saprophyticus.
  • the S. aureus comprises an accessory gene regulator (agr) type selected from the group consisting of: agr- 1, agr-ll, agr-lll, and agr-IV.
  • the S. epidermidis comprises an accessory gene regulator (agr) type selected from the group consisting of: agr- 1, agr-ll, and agr-lll.
  • the S. lugdunensis comprises an accessory gene regulator (agr) type selected from the group consisting of: agr- 1 and agr-ll.
  • the listeria are listeria monocytogenes.
  • the Clostridium is selected from the group consisting of:
  • Clostridium difficile Clostridium perfringens, Clostridium acetobutylicum, and
  • Clostridium butyricum In one embodiment, the Clostridium is selected from the group consisting of: Clostridium difficile and Clostridium perfringens.
  • the bacterial infection is caused by an antibiotic-resistant bacterium, such as a multi-resistant bacterium.
  • the antibiotic- resistant bacterium is selected from the group consisting of: S. aureus and Clostridium difficile.
  • the antibiotic-resistant bacterium is a methicillin resistant bacterium, such as methicillin resistant S. aureus (MRSA) or Vancomycin resistant S. aureus (VRSA). Methicillin-resistant Staphylococcus aureus (MRSA)
  • MRSA Methicillin-resistant Staphylococcus aureus
  • MRSA is a Gram-positive bacterium responsible for several types of infections in humans, which are d iff i cu It-to-treat.
  • MRSA comprise any strain of Staphylococcus aureus that has developed multiple drug resistance to b-lactam antibiotics. The strains may have gained drug resistance through horizontal gene transfer and natural selection b-lactam antibiotics are a broad spectrum group which includes some penams - penicillin derivatives such as methicillin and oxacillin, and cephems such as the cephalosporins.
  • MRSA have evolved from horizontal gene transfer of the mecA gene to at least five distinct S.
  • Beta-lactam antibiotics permanently inactivate penicillin-binding proteins (PBP’s), which are essential for bacterial life, by permanently binding to their active sites. Some forms of MRSA, however, express a PBP that will not allow the antibiotic into their active site. Acquisition of staphylococcal cassette chromosome (SCCmec) in methicillin-sensitive staphylococcus aureus (MSSA) gives rise to a number of genetically different MRSA lineages.
  • SCCmec staphylococcal cassette chromosome
  • MSSA methicillin-sensitive staphylococcus aureus
  • Staphylococcus aureus (S. aureus).
  • the term also includes any strain regardless of how it is acquired and thus includes HA-MRSA (healthcare-associated MRSA), CA- MRSA (community-associated MRSA) and LA-MRSA (livestock-associated MRSA).
  • HA-MRSA healthcare-associated MRSA
  • CA- MRSA community-associated MRSA
  • LA-MRSA livestock-associated MRSA
  • Several newly discovered strains of MRSA show antibiotic resistance even to vancomycin and teicoplanin.
  • These new evolutions of the MRSA bacterium are referred to as vancomycin intermediate-resistant Staphylococcus aureus (VISA).
  • VISA vancomycin intermediate-resistant Staphylococcus aureus
  • MRSA is generally obtained by touching the skin of another person who is colonized with MRSA, by a bacterial transfer by hand from the nose to an opening on the skin, or by touching a contaminated surface (such as a countertop, door handle, or phone).
  • MRSA Malignant suppression
  • MRSA may progress substantially within 24-48 hours of initial topical symptoms. After 72 hours, MRSA can take hold in human tissues and eventually become resistant to treatment.
  • the initial presentation of MRSA is small red bumps that resemble pimples, spider bites, or boils; they may be accompanied by fever and, occasionally, rashes. Within a few days, the bumps become larger and more painful; they eventually open into deep, pus-filled boils. About 75 percent of CA-MRSA infections are localized to skin and soft tissue. Infections can usually be treated effectively with conventional antibiotics.
  • CA-MRSA strains display enhanced virulence, spreading more rapidly and causing illness much more severe than traditional HA-MRSA infections, and they can affect vital organs and lead to widespread infection (sepsis), toxic shock syndrome, and necrotizing pneumonia. This is thought to be due to toxins carried by CA-MRSA strains, such as Panton-Valentine leukocidins (PVL) and phenol-soluble modulins (PSM), though PVL was recently found not to be a factor in a study by the National Institute of Allergy and Infectious Diseases at the National Institutes of Health. It is not known why some healthy people develop CA-MRSA skin infections that are treatable while others infected with the same strain develop severe infections or die.
  • PVL Panton-Valentine leukocidins
  • PSM phenol-soluble modulins
  • the methods of the present disclosure relate to treatment or prevention of a bacterial infection in or on a subject by the use of a compound as defined herein.
  • the compound is administered to the subject at least once a day, such as at least two times a day, such as at least three times a day. In one
  • the compound is administered every second day.
  • the compound for use as defined herein is administered by topical administration.
  • the topical administration is via a cream, a solution, a foam, a gel, a lotion, an ointment, a transdermal patch, a powder, a sponge, a tape, or a paste.
  • the compound is administered via a wound dressing or a catheter.
  • the compound may also be administered by application to the surface of a catheter.
  • the compound as defined herein may be applied to the wound dressing, which is applied to the subject on the wound to prevent or treat a bacterial infection.
  • the present disclosure provides a method for treatment or prevention of a bacterial infection, the method comprising administering to a subject a compound or a composition as defined herein, and a further antimicrobial agent.
  • the present disclosure provides a method for preventing bacterial colonization of a wound, said method comprising administering a compound or a composition as defined herein to the wound of a subject.
  • the present disclosure provides a method for inhibiting or reducing bacterial virulence on the skin of a subject, said use comprising contacting a compound or a composition as defined herein with the skin of the subject.
  • the present disclosure provides a method for inhibiting quorum sensing of bacteria comprising contacting a compound or a composition as defined herein with the bacteria.
  • the present disclosure provides a method for treatment or prevention of bacterial damage or disease in a subject, comprising administering a compound or a composition as defined herein to the subject.
  • the present disclosure provides a method for decreasing the pathogenicity of bacteria in or on a subject, comprising administering a compound or a composition as defined herein to the subject.
  • the present disclosure provides a method for increasing the susceptibility of bacteria in or on a subject to an antimicrobial agent.
  • the present disclosure provides use of a compound or a composition as defined herein for the manufacture of a medicament for the treatment or prevention of a bacterial infection in a subject.
  • halogen represents fluorine, chlorine, bromine or iodine.
  • an alkyl group designates a univalent saturated, straight or branched hydrocarbon chain.
  • the hydrocarbon chain preferably contain of from one to six carbon atoms (Ci- 6 -alkyl), including pentyl, isopentyl, neopentyl, tertiary pentyl, cyclopentyl, hexyl, cyclohexyl and isohexyl.
  • alkyl represents a Ci-4-alkyl group, including butyl, isobutyl, secondary butyl, cyclobutyl and tertiary butyl.
  • alkyl represents a Ci-3-alkyl group, which may in particular be methyl, ethyl, propyl, cyclopropyl or isopropyl.
  • aryl refers to an unsaturated, aromatic monocyclic or bicyclic ring of 6 to 10 carbon members i.e.“Ce-io aryl”. Examples of aryl rings include phenyl and
  • naphthalenyl An aryl ring may be substituted by one or more substituents.
  • heteroaryl refers to an aromatic monocyclic or bicyclic aromatic ring system having 5 to 10 ring members and which contains carbon atoms and from 1 to 4 heteroatoms independently selected from the group consisting of N, O, and S. Included within the term heteroaryl are aromatic rings of 5 or 6 members wherein the ring consists of carbon atoms and has at least one heteroatom member. Suitable heteroatoms include nitrogen, oxygen, and sulfur. In the case of 5 membered rings, the heteroaryl ring preferably contains one member of nitrogen, oxygen or sulfur and, in addition, up to 3 additional nitrogen atoms. In the case of 6 membered rings, the heteroaryl ring preferably contains from 1 to 3 nitrogen atoms. For the case wherein the 6 membered ring has 3 nitrogen atoms, at most 2 nitrogen atoms are adjacent.
  • heteroaryl groups include furyl, thienyl, pyrrolyl, oxazolyl, thiazolyl, imidazolyl, pyrazolyl, isoxazolyl, isothiazolyl, oxadiazolyl, triazolyl, thiadiazolyl, pyridinyl, pyridazinyl, pyrimidinyl, pyrazinyl, indolyl, isoindolyl, benzofuryl, benzothienyl, indazolyl, benzimidazolyl, benzothiazolyl, benzoxazolyl, benzisoxazolyl,
  • heteroaryl is attached to its pendant group at any heteroatom or carbon atom that results in a stable structure.
  • halogen refers to fluorine, chlorine, bromine and iodine atoms.
  • a subject which may be suitable for treatment of a bacterial infection as defined herein may be a vertebrate, such as a mammal.
  • the subject is a human being.
  • the subject may also be non human, such as a dog, a horse, a goat, a sheep or a pig.
  • the subject is a vertebrate such as a bird or a fish.
  • the bird is selected from the group consisting of: turkey, chicken, duck, hen, goose, guinea fowl and quail.
  • the fish is selected from the group consisting of: carp, tilapia, salmon, roho labeo, trout, milkfish, wuchang bream, northern snakehead and amur catfish.
  • a medical device comprising a compound or a composition as defined herein.
  • the medical device is selected from the group consisting of: a wound dressing and a catheter.
  • the compound is administered via a wound dressing or a catheter.
  • the compound as defined herein may be applied to the wound dressing, which is applied to the subject on the wound to prevent or treat a bacterial infection.
  • n is 0 or 1 ;
  • z is 0 or 1 ;
  • Ri is selected from the group consisting of: H and alkyl
  • R 2 and R 3 are independently of each other selected from the group consisting of: hydrogen, halogen, and alkyl;
  • Y is selected from the group consisting of: -(CO)R 4 , -CO 2 R 4 , -0(C0)R 4 ,
  • R 4 , R 5 , and R 6 are independently of each other selected from the group consisting of: hydrogen, alkyl, aryl, and heteroaryl;
  • n 0 or 1 ;
  • z is 0 or 1 ;
  • Ri is selected from the group consisting of: H and alkyl
  • R 2 and R 3 are independently of each other selected from the group consisting of: hydrogen, halogen, and alkyl;
  • Y is selected from the group consisting of: -(CO)R 4 , -CO 2 R 4 , -0(CO)R 4 ,
  • R 4 , R 5 , and R 6 are independently of each other selected from the group consisting of: hydrogen, alkyl, aryl, and heteroaryl;
  • the mucosal surface is on an eye, an ear, inside the nose, inside the mouth, on the lip, vagina, the urethra, the bladder and/or the gastrointestinal tract, such as the oesophagus, or the anus, of the subject.
  • AIP bacterial autoinducing peptide
  • the compound for use according to any one of the preceding items, wherein the bacterial autoinducing peptide is one or more or all of S. aureus AIP-I, AIP-II, AIP- III, and AIP-IV.
  • I-20 The compound for use according to any one of the preceding items, wherein the compound is administered to the subject at least once a
  • Gram-positive bacterium comprises an agr.
  • I-27 The compound for use according to any one of the preceding items, wherein the bacterial infection is caused by a bacterium selected from the group consisting of: staphylococci, listeria, and Clostridium.
  • staphylococci are selected from the group consisting of: S. aureus, S.
  • piscifermentans S. pulvereri, S. rostri, S. saccharolyticus, S. simiae, S.
  • stepanovicii and S. succinus. I-29.
  • staphylococci are selected from the group consisting of: S. aureus, S.
  • S. aureus comprises an accessory gene regulator (agr) type selected from the group consisting of: agr- 1, agr-ll, agr-lll, and agr-IV.
  • agr accessory gene regulator
  • S. epidermidis comprises an accessory gene regulator (agr) type selected from the group consisting of: agr- 1, agr-ll, and agr-lll.
  • agr accessory gene regulator
  • S. lugdunensis comprises an accessory gene regulator (agr) type selected from the group consisting of: agr- 1 and agr-ll.
  • agr accessory gene regulator
  • Clostridium is selected from the group consisting of: Clostridium difficile, Clostridium perfringens, Clostridium acetobutylicum, and Clostridium butyricum.
  • Clostridium difficile The compound for use according to any one of the preceding items, wherein the Clostridium is selected from the group consisting of: Clostridium difficile and
  • I-36 The compound for use according to any one of the preceding items, wherein the bacterial infection is caused by an antibiotic-resistant bacterium, such as a multi- resistant bacterium.
  • antibiotic-resistant bacterium is selected from the group consisting of: S. aureus and Clostridium difficile. I-38.
  • antibiotic-resistant bacterium is a methicillin resistant bacterium, such as methicillin resistant S. aureus (MRSA) or Vancomycin resistant S. aureus (VRSA).
  • Ri is selected from the group consisting of: H and C 1-6 alkyl
  • X is selected from the group consisting of: wherein
  • R4 and R5 are independently of each other selected from the group consisting of: H, alkyl, aryl, and heteroaryl;
  • v is selected from the group consisting of: 1 , 2, 3, and 4.
  • I-58 The compound for use according to any one of the preceding items, wherein the compound is of formula (la) and the bacterial infection is caused by a Grampositive bacterium, wherein the Gram-positive bacterium comprises an agr, optionally wherein the Gram-positive bacterium is selected from the group consisting of: staphylococci, listeria, and Clostridium.
  • I-59 The compound for use according to any one of the preceding items, wherein the compound is cysteamine for use in the treatment or prevention of a bacterial infection caused by a Gram-positive bacterium, wherein the Gram-positive bacterium comprises an agr, optionally wherein the Gram-positive bacterium is selected from the group consisting of: staphylococci, listeria, and Clostridium.
  • i is selected from the group consisting of 1 , 2, and 3;
  • Ar is aryl, such as C6-10 aryl substituted by one, two, or three substituents; and T is selected from the group consisting of: -(CO)R7, -CO2R7, -0(CO)R 7 ,
  • R 7 , R 8 , and Rg are independently of each other selected from the group consisting of: hydrogen, alkyl, aryl, and heteroaryl.
  • compositions for use in the treatment or prevention of a bacterial infection in a subject comprising the compound as defined in any one of the preceding items and one or more excipients.
  • a method for treatment or prevention of a bacterial infection the method
  • I-68 A method for preventing bacterial colonization of a wound, said method comprising administering a compound or a composition as defined in any one of the preceding items to the wound of a subject.
  • a method for inhibiting or reducing bacterial virulence on the skin of a subject said use comprising contacting a compound or a composition as defined in any one of the preceding items with the skin of the subject.
  • a method for inhibiting quorum sensing of bacteria comprising contacting a
  • a method for treatment or prevention of bacterial damage or disease in a subject comprising administering a compound or a composition as defined in any one of the preceding items to the subject.
  • I-74 A medical device comprising a compound or a composition as defined in any one of the preceding items.
  • I-75 The medical device according to any one of the preceding items, wherein the medical device is selected from the group consisting of: a wound dressing and a catheter.
  • n 0 or 1 ;
  • z is 0 or 1 ;
  • Ri is selected from the group consisting of: H and alkyl
  • R 2 and R 3 are independently of each other selected from the group consisting of: hydrogen, halogen, and alkyl;
  • Y is selected from the group consisting of: -(CO)R4, -CO2R4, -0(CO)R 4 ,
  • R 4 , R 5 , and R 6 are independently of each other selected from the group consisting of: hydrogen, alkyl, aryl, and heteroaryl;
  • Ri is selected from the group consisting of: H and C 1-6 alkyl
  • R 2 and R 3 are independently of each other selected from the group consisting of: hydrogen, halogen, and C 1-6 alkyl;
  • R 4 is selected from the group consisting of: C 1-6 alkyl, benzyl, phenyl, naphthalenyl, furyl, thienyl, pyrrolyl, oxazolyl, thiazolyl, imidazolyl, pyrazolyl, isoxazolyl, isothiazolyl, oxadiazolyl, triazolyl, thiadiazolyl, pyridinyl, pyridazinyl, pyrimidinyl, pyrazinyl, indolyl, isoindolyl, benzofuryl, benzothienyl, indazolyl, benzimidazolyl, benzothiazolyl, benzoxazolyl, benzisoxazolyl, benzothiadiazolyl, benzotriazolyl, quinolinyl, isoquinolinyl and quinazolinyl.
  • the compound for use according to any one of the preceding items wherein the compound is selected from the group consisting of: L-cysteine methyl ester, D- penicillamine, and D-penicillamine methyl ester, preferably wherein the compound is L-cysteine methyl ester.
  • the bacterial infection is on the skin and/or a mucosal surface, of the subject, optionally wherein the mucosal surface is on an eye, an ear, inside the nose, inside the mouth, on the lip, vagina, the urethra, the bladder and/or the gastrointestinal tract, such as the oesophagus, or the anus.
  • I-6 The compound for use according to any one of the preceding items, wherein the prevention or treatment is by attenuation, inhibition or reduction of virulence in the bacteria.
  • AIP bacterial autoinducing peptide
  • the compound inhibits accessory gene regulator (agr) mediated signaling of the bacteria.
  • a medical device comprising a compound of formula (II),
  • Ri is selected from the group consisting of: H and Ci-e alkyl
  • R 2 and R 3 are independently of each other selected from the group consisting of: hydrogen, halogen, and C 1-6 alkyl;
  • R 4 is selected from the group consisting of: C 1-6 alkyl, benzyl, phenyl,
  • a wound dressing selected from the group consisting of: a wound dressing and a catheter.
  • Example 1 Ring opening of an autoinducing peptide by L-cysteine methyl ester in aqueous buffer
  • Fig. 1 The reaction mixture was analyzed after 5 min and 6 hours using an ultra-high- performance liquid chromatography (UPLC) mass spectrometry (MS) instrument.
  • UPLC ultra-high- performance liquid chromatography
  • MS mass spectrometry
  • Fluorescent S. aureus reporter strains of agr types l-IV that express the yellow fluorescent protein (YFP) upon AIP induced quorum sensing activation are used for quorum sensing inhibition assays.
  • Fluorescent S. aureus reporter strains of agr type l-IV (P3 -yfp) were streaked on agar plates and grown over night at 37 °C. Single colonies of the individual reporter strains were then inoculated in 5.0 ml_ TSB medium containing chloramphenicol and grown overnight at 37 °C in an incubator with 200 rpm shaking. The overnight cultures (120 pl_) were diluted (1 :250) into fresh TSB medium (30 mL) containing chloramphenicol and grown for 1 hour at 37 °C in an incubator with 200 rpm shaking.
  • the individual bacterial samples were grown at 37 °C in an incubator with 200 rpm shaking to late stationary phase to allow for full agr induction (7-8 hours).
  • P3 promoter activity (quorum sensing activity) of the bacterial population was measured as accumulated YFP by flow cytometry on a BD AccuriTM C6 flow cytometer using the FL1 channel after 7-8 hours.
  • L-cysteine, L-cysteine methyl ester and D-cysteine showed strongly reduced fluorescence at a concentration of 10 mM compared to the negative inhibition control against S. aureus agr- 1 type after 7 hours of growth (Fig. 2).
  • L- cysteine methyl ester was able to fully inhibit the quorum sensing activity of S. aureus agr- 1 to the same extent as the inhibitor AIP-111 D4A.
  • the tested amino-thiol compounds L-cysteine, L-cysteine methyl ester and D-cysteine showed strongly reduced fluorescence at a concentration of 10 mM compared to the negative inhibition control against S. aureus agr- II type after 7 hours of growth (Fig. 3). All tested cysteine analogues were able to fully inhibit the quorum sensing activity of S. aureus agr- II to the same extent as the inhibitor AIP-III D4A.
  • L-cysteine, L-cysteine methyl ester and D-cysteine showed strongly reduced fluorescence at a concentration of 10 mM compared to the negative inhibition control against S. aureus agr- III type after 7 hours of growth (Fig. 4).
  • L-cysteine methyl ester was able to fully inhibit the quorum sensing activity of S. aureus agr- III to the same extent as the inhibitor AIP-III D4A.
  • the tested amino-thiol compounds L-cysteine, L-cysteine methyl ester and D-cysteine showed strongly reduced fluorescence at a concentration of 10 mM compared to the negative inhibition control against S. aureus agr- IV type after 7 hours of growth (Fig. 5).
  • amino-thiol containing cysteine analogues can inhibit agr-mediated quorum sensing of the four agr-l-IV types of S. aureus.
  • amino- thiol compounds of this type can inhibit quorum sensing regardless of the autoinducing peptide employed by the bacterial strains as long as it contains a thiolactone functionality.
  • L-cysteine methyl ester displayed a superior effect toward inhibition of quorum sensing in the bacteria tested. This effect may be generalized to further L-cysteine analogues, such as other L-cysteine alkyl esters.
  • the fluorescence quorum sensing inhibition assay was performed as described in example 2 using the S. aureus reporter strain of agr- 1 type (P3 -yfp) and the following cysteine analogues at a concentration of 10 mM: L-cysteine, L-cysteine methyl ester, N-acetyl L-cysteine and N-acetyl L-cysteine methyl ester.
  • the bacterial growth of individual bacterial samples was monitored hourly by measuring the optical density at a wavelength of 600 nm (OD600) using a UV meter.
  • N-acetylated compounds N-acetyl L-cysteine and N-acetyl L-cysteine methyl ester showed no reduction in fluorescence at a concentration of 10 mM, while the tested amino-thiol compounds L-cysteine and L-cysteine methyl ester showed strongly reduced fluorescence at a concentration of 10 mM compared to the negative inhibition control against S. aureus agr- 1 type after 8 hours of growth (Fig. 6).
  • the bacterial growth was not inhibited by any of the tested compounds at a
  • Example 4 Reaction rate for ring opening of an autoinducing peptide by various amino- thiol compounds determined by UPLC
  • acetonitrile 72 mI_
  • TCEP tris(2-carboxyethyl)phosphine
  • the bar graphs in Fig. 9 show conversions for the ring opening of the synthetic AIP in the range of 60-95% using 40 equivalents of the amino-thiol compounds 1 , 2, 3, 4 and 5 after 60 min incubation.
  • the negative control compound 8 N-acetyl cysteine
  • compound 9 D-penicillamine
  • AIP autoinducing peptides
  • cysteine analogue compound 3 (cysteamine)
  • cysteamine cysteine analogue
  • the requirement of a free N-terminal amine to irreversibly ring open and destroy an AIP is demonstrated by the inability of compound 8 (N-acetyl L-cysteine) to do so.
  • Compound 9 displays a reduced ability to react with AIPs and therefore represents a less effective inhibitor of staphylococcal virulence.
  • cysteine (1) and analogues thereof (2, 4, 5) as well as simple amino-thiol compounds (3) are effective in inhibiting virulence of staphylococci.
  • Example 5 Quorum sensing inhibition of Staphylococcus aureus by amino-thiol compounds using a 96-well plate fluorescence assay
  • Fluorescent S. aureus reporter strains of agr types l-IV that express the yellow fluorescent protein (YFP) upon AIP induced quorum sensing activation are used for quorum sensing inhibition assays.
  • the 96-well plate was incubated at 37 °C for 20-24 h under constant shaking at 282 rpm in a plate reader.
  • the tested amino-thiol compounds 1 , 2, 3, 5, 6 and 7 were able to fully inhibit the quorum sensing activity of S. aureus agr- 1 at a concentration of 10 mM over a time span of 20 h (Fig. 10). Further, compounds 3, 5 and 6 displayed equal inhibitory properties at a concentration of 5.0 mM.
  • Compound 8 N-acetyl L-cysteine
  • compound 9 D-penicillamine
  • the tested amino-thiol compounds 1 , 2, 3, 5, 6 and 7 were able to fully inhibit the quorum sensing activity of S. aureus agr- II at a concentration of 10 mM over a time span of 20 h (Fig. 11). Further, compounds 2, 3, 5 and 6 displayed equal inhibitory properties at a concentration of 5.0 mM. Compound 8 (N-acetyl L-cysteine) was not able to inhibit the quorum sensing activity of S. aureus agr- II, while compound 9 (D- penicillamine) displayed only reduced inhibitory properties.
  • the tested amino-thiol compounds 1 , 2, 4, 3, 5, 6 and 7 were able to fully inhibit the quorum sensing activity of S. aureus agr- III at a concentration of 10 mM over a time span of 24 h (Fig. 12). Further, compounds 1 , 2, 3, and 5 displayed equal inhibitory properties at a concentration of 5.0 mM. Compound 8 (N-acetyl L-cysteine) as well as compound 9 (D-penicillamine) were not able to inhibit the quorum sensing activity of S. aureus agr-lll.
  • the tested amino-thiol compounds 1 , 2, 3, 5, 6 and 7 were able to fully inhibit the quorum sensing activity of S. aureus agr- IV at a concentration of 10 mM over a time span of 20 h (Fig. 13). Further, compounds 2, 5 and 6 displayed equal inhibitory properties at a concentration of 5.0 mM. Compound 8 (N-acetyl L-cysteine) as well as compound 9 (D-penicillamine) were not able to inhibit the quorum sensing activity of S. aureus agr-IV.
  • amino-thiol compounds can effectively inhibit agr-mediated quorum sensing of the four agr-l-IV types of S. aureus.
  • amino- thiol compounds of this type can inhibit agr-mediated quorum sensing regardless of the autoinducing peptide employed by the bacterial strains as long as the peptide contains a thiolactone functionality.
  • compound 1 L-cysteine
  • compound 2 L-cysteine methyl ester
  • Example 6 Quorum sensing deactivation of a virulent Staphylococcus aureus agr- 1 fluorescent reporter strain by amino-thiol compounds using a 96-well plate
  • a fluorescent S. aureus reporter strain of agr type I that expresses the green fluorescent protein (GFP) upon inhibition of agr-mediated quorum sensing is used for quorum sensing deactivation assays.
  • the bacterial reporter strain represses the expression of GFP when agr-mediated quorum sensing is induced.
  • aureus AIP-I (50 nM) to induce quorum sensing activity.
  • Amino-thiol compound stock solutions (20 mI_) in 1 :2 serial dilution (final concentration 10 mM-5.0 mM) were added to each well of a 96-well plate followed by 180 mI_ of bacterial culture.
  • the 96-well plate was incubated at 37 °C for 20 h under constant shaking at 282 rpm in a plate reader.
  • amino-thiol compounds 3 and 5 are can effectively inhibit agr-mediated quorum sensing of an induced (virulent) S. aureus agr- 1.
  • amino-thiol compounds can not only be used to prevent bacteria from turning virulent but can effectively reverse virulence of induced cultures through inhibition of agr- mediated quorum sensing.
  • the example further demonstrates that a free amino-thiol functionality is required to observe the inhibitory effect.
  • compound 8 N-acetyl L-cysteine

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Abstract

The present invention relates to cysteine derivatives for use in the treatment or prevention of a bacterial infection by inhibiting bacterial quorum sensing. Bacterial infections of particular interest are bacterial infections caused by Gram-positive bacteria that employ thiolactone containing auto-inducing peptides (AIPs).

Description

Cysteine derivatives for treatment and prevention of bacterial infections
Technical field
The present invention relates to cysteine derivatives for use in the prevention and treatment of bacterial infections.
Background
The increase in antibiotic resistant bacteria poses a threat to the continued use of antibiotics to treat bacterial infections. The overuse and misuse of antibiotics has been identified as a significant driver in the emergence of resistance. Finding optimal treatment regimens is therefore critical in ensuring the prolonged effectiveness of these antibiotics. The impact of antibiotic resistance on society is at present already tangible in terms of increased morbidity, mortality and healthcare costs. A recent report commissioned by the British Government estimated that the global burden of antibiotic resistance could become 10 million additional deaths a year by 2050. This disturbing circumstance necessitates continuous development of new antibacterial therapeutics to combat the increasing problems of antibiotic resistance.
Staphylococcus aureus, a member of the family Micrococcaceae, is a Gram-positive coccus whose cells tend to occur either singly or if dividing cells do not separate, form pairs, tetrads and distinctive irregular“grape-like” structures. Humans are commonly colonised by S. aureus on external skin surfaces and the upper respiratory tract, particularly the nasal passages. Healthy individuals are usually unaware of
staphylococcal carriage but they may suffer from minor skin infections such as boils and abscesses. Given the right circumstances, S. aureus can cause more serious infections. Burns and surgical wound infections are commonly invaded by S. aureus, where the production of toxins by S. aureus can e.g. give rise to toxic shock syndrome leading to fever, sickness and in some cases death. Infections caused by S.
aureus include, pneumonia (inflammation of lungs), mastitis (infection of the mammary glands), infections of skin (impetigo, cellulitis and staphylococcal scalded skin syndrome), osteomyelitis (infection of bone), endocarditis (infection of the endothelial lining of the heart and valves) and bacteremia (bacteria present in blood). S.
aureus can also cause food poisoning, the result of enterotoxin production. Treatment of S. aureus infections before the 1950s involved the administration of benzylpenicillin (penicillin G), but by the late 1950s S. aureus strains resistant to benzylpenicillin were causing increasing concern. Resistant strains typically produced an enzyme, called a b-lactamase, which inactivated the b-lactam antibiotic. Efforts were made to synthesise penicillin derivatives that were resistant to b-lactamase hydrolysis. This was achieved in 1959 with the synthesis of methicillin. Unfortunately, as soon as methicillin was used clinically, methicillin-resistant S. aureus (MRSA) strains emerged with resistance towards the action of methicillin. The use of different types of antibiotics over the years has led to the emergence of multi-resistant MRSA strains.
Most of the antibiotics that have been approved in recent years and that are in clinical development are derivatives of existing classes of antibiotics, often relying on already exploited antibiotic mechanisms that have previously led to development of resistance.
Apart from targeting bacterial growth, bacterial infections may e.g. be treated by inhibiting or reducing bacterial biofilm formation and/or by inhibiting or reducing bacterial virulence. Antibacterial agents that act through other mechanisms than by targeting bacterial growth and/or biofilm formation, may provide an effective treatment alternative to standard antibiotics.
Hence, there is a need in the art for developing alternative treatments of bacterial infections, and in particular infections caused by bacteria resistant to commonly employed antibiotics, such as methicillin.
Summary
The present inventors have surprisingly discovered that cysteine and derivatives thereof bearing a free amine and a free thiol demonstrate significant inhibitory activity towards quorum sensing in Gram-positive bacteria. This effect is not seen for N-acetyl cysteine (NAC).
The present disclosure thus provides cysteine and derivatives thereof for use in the prevention or treatment of a bacterial infection, in particular bacterial infections caused by quorum sensing bacteria. It is an aspect to provide a compound according to the formula (I),
Figure imgf000004_0001
wherein n is 0 or 1 ;
z is 0 or 1 ;
Ri is selected from the group consisting of: H and alkyl;
R2 and R3 are independently of each other selected from the group consisting of: hydrogen, halogen, and alkyl;
Y is selected from the group consisting of: -(CO)R4, -CO2R4, -0(CO)R4,
-NR5(CO)R4, -(CO)N(R5)R4, -C(R5)=C(R4)Re, -CC-R4, -aryl-R4, -heteroaryl-R4, hydrogen, and a bond to R2; and
R4, R5, and R6 are independently of each other selected from the group consisting of: hydrogen, alkyl, aryl, and heteroaryl;
for use in the prevention or treatment of a bacterial infection in a subject.
In one aspect, the compound for use according to the present disclosure is of formula
(II),
Figure imgf000004_0002
wherein Ri, R2, R3 and R4 are as defined herein.
In one aspect, the compound for use according to the present disclosure is of formula
Figure imgf000004_0003
wherein R4 is as defined herein, such as a C1 to C6 alkyl. In one aspect, a composition is provided for use in the treatment or prevention of a bacterial infection in a subject, said composition comprising the compound as defined herein, and one or more excipients.
In one aspect, the present disclosure provides a method for treatment or prevention of a bacterial infection, the method comprising administering to a subject a compound or a composition as defined herein, and a further antimicrobial agent.
In one aspect, the present disclosure provides a method for preventing bacterial colonization of a wound, said method comprising administering a compound or a composition as defined herein to the wound of a subject.
In one aspect, the present disclosure provides a method for inhibiting or reducing bacterial virulence on the skin of a subject, said use comprising contacting a compound or a composition as defined herein with the skin of the subject.
In one aspect, the present disclosure provides a method for inhibiting quorum sensing of bacteria comprising contacting a compound or a composition as defined herein with the bacteria.
In one aspect, the present disclosure provides a method for treatment or prevention of bacterial damage or disease in a subject, comprising administering a compound or a composition as defined herein to the subject.
In one aspect, the present disclosure provides a method for decreasing the
pathogenicity of bacteria in or on a subject, comprising administering a compound or a composition as defined herein to the subject.
In one aspect, the present disclosure provides a method for increasing the
susceptibility of bacteria in or on a subject to an antimicrobial agent.
In one aspect, the present disclosure provides a medical device comprising a compound or a composition as defined herein. In one aspect, the present disclosure provides a use of a compound or a composition as defined herein for the manufacture of a medicament for the treatment or prevention of a bacterial infection in a subject. Description of Drawings
Fig. 1 : Ring opening reaction of an autoinducing peptide (AIP) with cysteine methyl ester under relevant physiological pH value. Fig. 2: Fluorescence YFP assay for inhibition of quorum sensing for S. aureus agr- 1. The bars represent the mean fluorescence value measured by flow cytometry after 7 hours of growth in the presence of various compounds. The control inhibitor used is AIP-III D4A. The tested amino-thiol compounds L-cysteine, L-cysteine methyl ester and D-cysteine showed strongly reduced fluorescence at a concentration of 10 mM compared to the negative inhibition control against S. aureus agr- 1 type after 7 hours of growth (Fig. 2). L-cysteine methyl ester was able to fully inhibit the quorum sensing activity of S. aureus agr- 1 to the same extent as the inhibitor AIP-III D4A.
Fig. 3: Fluorescence YFP assay for inhibition of quorum sensing for S. aureus agr- II. The bars represent the mean fluorescence value measured by flow cytometry after 7 hours of growth in the presence of various compounds. The control inhibitor used is AIP-III D4A. The tested amino-thiol compounds L-cysteine, L-cysteine methyl ester and D-cysteine showed strongly reduced fluorescence at a concentration of 10 mM compared to the negative inhibition control against S. aureus agr- II type after 7 hours of growth (Fig. 3).
Fig. 4: Fluorescence YFP assay for inhibition of quorum sensing for S. aureus agr-lll. The bars represent the mean fluorescence value measured by flow cytometry after 7 hours of growth in the presence of various compounds. The control inhibitor used is AIP-III D4A. The tested amino-thiol compounds L-cysteine, L-cysteine methyl ester and D-cysteine showed strongly reduced fluorescence at a concentration of 10 mM compared to the negative inhibition control against S. aureus agr- III type after 7 hours of growth (Fig. 4). L-cysteine methyl ester was able to fully inhibit the quorum sensing activity of S. aureus agr- III to the same extent as the inhibitor AIP-III D4A. Fig. 5: Fluorescence YFP assay for inhibition of quorum sensing for S. aureus agr-IV. The bars represent the mean fluorescence value measured by flow cytometry after 7 hours of growth in the presence various compounds. The control inhibitor used is AIP- III D4A. The tested amino-thiol compounds L-cysteine, L-cysteine methyl ester and D- cysteine showed strongly reduced fluorescence at concentration of 10 mM compared to the negative inhibition control against S. aureus agr- IV type after 7 hours of growth (Fig. 5).
Fig. 6: Fluorescence YFP assay for inhibition of quorum sensing for S. aureus agr- 1 with comparative data between cysteine analogues and N-acetylated analogues. The bars represent the mean fluorescence value measured by flow cytometry after 8 hours of growth in the presence various compounds. The control inhibitor used is AIP-III D4A.
Fig. 7: Bacterial growth of S. aureus agr- 1 during quorum sensing inhibition displayed by the optical density at 600 nm (OD600). The graph shows the bacterial growth in the presence of various compounds measured hourly over the course of 8 hours by the absorbance at 600 nm.
Fig. 8: Structures of tested amino-thiol compounds.
Fig. 9: UPLC assay for the determination of reaction rates for the ring opening of a synthetic AIP using amino-thiol compounds. The bar graphs represent the conversion of an AIP to the linear ring opened peptide after 30 min and 60 min in the presence of 40 equivalents of an amino-thiol compound. The structures of amino-thiol compounds are shown in Fig. 8.
Fig. 10: Fluorescence YFP 96-well plate assay for the inhibition of quorum sensing for S. aureus agr- 1. The bars represent the agr quorum sensing activity derived from the fluorescence values measured after 20 h of incubation in the presence of amino-thiol compounds at concentrations of 10 mM and 5.0 mM. Negative controls are wells containing no compounds and positive controls are wells containing the inhibitor AIP-III D4A at a concentration of 100 nM. The structures of amino-thiol compounds are shown in Fig. 8. Fig. 11 : Fluorescence YFP 96-well plate assay for the inhibition of quorum sensing for S. aureus agr- II. The bars represent the agr quorum sensing activity derived from the fluorescence values measured after 20 h of incubation in the presence of amino-thiol compounds at concentrations of 10 mM and 5.0 mM. Negative controls are wells containing no compounds and positive controls are wells containing the inhibitor AIP-III D4A at a concentration of 100 nM. The structures of amino-thiol compounds are shown in Fig. 8.
Fig. 12: Fluorescence YFP 96-well plate assay for the inhibition of quorum sensing for S. aureus agr-lll. The bars represent the agr quorum sensing activity derived from the fluorescence values measured after 24 h of incubation in the presence of amino-thiol compounds at concentrations of 10 mM and 5.0 mM. Negative controls are wells containing no compounds and positive controls are wells containing the inhibitor AIP-III D4A at a concentration of 100 nM. The structures of amino-thiol compounds are shown in Fig. 8.
Fig. 13: Fluorescence YFP 96-well plate assay for the inhibition of quorum sensing for S. aureus agr-IV. The bars represent the agr quorum sensing activity derived from the fluorescence values measured after 20 h of incubation in the presence of amino-thiol compounds at concentrations of 10 mM and 5.0 mM. Negative controls are wells containing no compounds and positive controls are wells containing the inhibitor AIP-III D4A at a concentration of 100 nM. The structures of amino-thiol compounds are shown in Fig. 8. Fig. 14: Fluorescence GFP 96-well plate assay for the deactivation of agr-mediated quorum sensing of an AIP-I induced (virulent) S. aureus agr- 1 reporter strain (spa::gfp). The bars represent the fluorescence values measured after 20 h of incubation in the presence of amino-thiol compounds. Increased fluorescence represents inhibition of agr-mediated quorum sensing activity since virulent S. aureus agr- 1 (spa::gfp) reporter strains repress the expression of GFP. Negative controls are wells containing no inhibitor and positive controls are wells containing the inhibitor AIP-III D4A at a concentration of 100 nM. The structures of amino-thiol compounds are shown in Fig. 8. Detailed description
Terms and definitions To facilitate the understanding of the following description, a number of definitions are presented in the following paragraphs.
The term "treatment", as used anywhere herein comprises any type of therapy, which aims at terminating, preventing, ameliorating and/or reducing the susceptibility to a clinical condition as described herein. In one embodiment, the term treatment relates to prophylactic treatment (i.e. a therapy to reduce the susceptibility of a bacterial infection as defined herein).
Thus, "treatment," "treating," and the like, as used herein, refer to obtaining a desired effect, such as a biological, pharmacologic and/or physiologic effect, covering any treatment of a bacterial infection in a subject, such as a mammal, including a human. The effect may be prophylactic in terms of completely or partially preventing a bacterial infection or symptom thereof and/or may be therapeutic in terms of a partial or complete cure for the bacterial infection and/or adverse effect attributable to the infection. That is, "treatment" includes (1) preventing the bacterial infection from occurring or recurring in a subject, (2) inhibiting the bacterial infection, such as arresting its development, (3) stopping, terminating or alleviating the bacterial infection or at least symptoms associated therewith, so that the subject no longer suffers from the disorder or clinical condition or its symptoms, such as causing regression of the bacterial infection or its symptoms, for example, by restoring or repairing a lost, missing or defective function, or stimulating an inefficient process, or (4) relieving, alleviating, or ameliorating the bacterial infection, or symptoms associated therewith, where ameliorating is used in a broad sense to refer to at least a reduction in the magnitude of a parameter, such as inflammation, pain, and/or immune deficiency.
The terms "prevent", "preventing," and "prevention", as used herein, refer to a decrease in the occurrence of symptoms or characteristics of a bacterial infection. The term is also used in the context of preventing dissemination of the bacterial infection. The prevention may be complete. The prevention may also be partial, such that for example the occurrence of symptoms or characteristics of a bacterial infection in a subject is less than that which would have occurred without the present invention. Prevention also refers to reduced susceptibility to a bacterial infection.
The term“antibiotic resistance” as used herein refers to a bacterium, which has acquired resistance to an antibiotic that was once able to treat an infection by that bacterium. Antibiotic resistance may be dose dependent, meaning that higher doses of the antibiotic than usual are required to sufficiently treat the infection, or complete in that a certain antibiotic is without effect irrespective of dose. The non-resistant bacteria may be referred to as antibiotic sensitive bacteria.
A“bacterial infection” according to the present disclosure may be caused by Gram positive bacteria, Gram-negative bacteria, Mycobacteria, or a combination thereof.
As used herein, the term "pharmaceutically acceptable salt" refers to a salt used typically in the pharmaceutical field. Examples of
the pharmaceutically acceptable salt include sodium salts, hydrochloride salts, magnesium salts, calcium salts and potassium salts, but are not limited thereto.
Preferred is a sodium salt or a hydrochloride salt. The term "substituent" as used herein, includes alkyl, substituted alkyl, aryl, substituted aryl, aralkyl, hydroxyl, alkoxyl, aryloxyl, aralkyloxyl, carboxyl, carbonyl, acyl, halo, nitro, alkoxycarbonyl, aryloxycarbonyl, aralkoxycarbonyl, acyloxyl, acylamino, aroylamino, carbamoyl, alkylcarbamoyl, dialkylcarbamoyl, arylthio, alkylthio, alkylene, and -NR'R", wherein R' and R" can each be independently hydrogen, alkyl, substituted alkyl, aryl, substituted aryl, and aralkyl.
Cysteine derivatives
It is an aspect of the disclosure to provide a compound according to the formula (I),
Figure imgf000010_0001
or a pharmaceutically acceptable salt thereof,
wherein n is 0 or 1 ; z is 0 or 1 ;
Ri is selected from the group consisting of: H and alkyl;
R2 and R3 are independently of each other selected from the group consisting of: hydrogen, halogen, and alkyl;
Y is selected from the group consisting of: -(CO)R4, -CO2R4, -0(CO)R4,
-NR5(CO)R4, -(CO)N(R5)R4, -C(R5)=C(R4)Re, -CC-R4, -aryl-R4, -heteroaryl-R4, hydrogen, and a bond to R2; and
R4, R5, and R6 are independently of each other selected from the group consisting of: hydrogen, alkyl, aryl, and heteroaryl;
for use in the prevention or treatment of a bacterial infection in a subject.
It is an aspect of the disclosure to provide a compound according to the formula (I),
Figure imgf000011_0001
wherein n is 0 or 1 ;
z is 0 or 1 ;
Ri is selected from the group consisting of: H and alkyl;
R2 and R3 are independently of each other selected from the group consisting of: hydrogen, halogen, and alkyl;
Y is selected from the group consisting of: -(CO)R4, -CO2R4, -0(C0)R4,
-NR5(CO)R4, -(CO)N(R5)R4, -C(R5)=C(R4)Re, -CC-R4, -aryl-R4, -heteroaryl-R4, hydrogen, and a bond to R2; and
R4, R5, and R6 are independently of each other selected from the group consisting of: hydrogen, alkyl, aryl, and heteroaryl;
for use in the prevention or treatment of a bacterial infection in a subject.
It should be understood by the skilled person that if z is 0, RiNH is covalently attached via nitrogen to the carbon to which Y is also attached. If n is 0, HS is covalently attached via sulphur to the carbon to which R2 and R3 is attached. Y is directly attached to its adjacent carbon atom as depicted in formula (I). In one embodiment, Y is“-aryl-RV, which should be understood as aryl covalently attached to the adjacent carbon of Y, wherein the aryl is also functionalized by a substituent R4. As an exemplary embodiment where the aryl is phenyl, Y should be interpreted as
Figure imgf000012_0001
. The bond from phenyl intersected by a wavy bond corresponds to of“-aryl” in the“-aryl-FV. R4 may be connected by a covalent bond to any of the other positions of the aryl. The expression“-heteroaryl-RV should be interpreted in a similar manner and is understood by a person of skilled in the art.
In one embodiment, Y is“-CC-R4”, which shall be interpreted as
Figure imgf000012_0002
wherein the akyne is directly attached to the carbon adjacent to Y.
In one embodiment, Ri is hydrogen or methyl, of the compound of formula (I) as defined herein. In one embodiment, Ri is hydrogen. In one embodiment, R2 and R3 are both methyl. In one embodiment, R2 and R3 are both hydrogen. In one embodiment, either R2 or R3 is a hydrogen. In one embodiment, either R2 or R3 is methyl.
In one embodiment, R4 is selected from the group consisting of: alkyl, aryl, and heteroaryl. In one embodiment, R4 is a C1 to C6 alkyl. In one embodiment, R4 is methyl. In one embodiment, n is 0. In one embodiment, z is 0. In one embodiment, n is 0 and z is 0.
In one embodiment, Y is selected from the group consisting of: -CO2R4 and -0(C0)R4, and R4 is as defined herein.
In one embodiment, Y is a bond to the terminal carbon of R2, and R2 is a C3, C4, or C5 alkyl.
In one embodiment, Y is a heteroaryl, such triazole.
In one embodiment, the compound is not L-cysteine. In one embodiment the compound is selected from the group consisting of: L-cysteine methyl ester, D- penicillamine, and D-penicillamine methyl ester, preferably the compound is L-cysteine methyl ester.
In one embodiment, the compound is of formula (la),
Figure imgf000013_0001
wherein Ri is selected from the group consisting of: H and Ci-8 alkyl,
X is selected from the group consisting of:
Figure imgf000013_0002
wherein
R4 and R5 are independently of each other selected from the group consisting of: H, alkyl, aryl, and heteroaryl; and
v is selected from the group consisting of: 1 , 2, 3, and 4.
In one embodiment, R4 is selected from the group consisting of:
Figure imgf000013_0003
wherein;
i is selected from the group consisting of 1 , 2, and 3;
Ar is aryl, such as C6-10 aryl substituted by one, two, or three substituents; and T is selected from the group consisting of: -(CO)R7, -CO2R7, -0(CO)R7,
-NR8(CO)R7, -(CO)N(RS)R7, -C(RS)=C(R7)R9, -CC-R7, -aryl-R7, -heteroaryl-R7, and hydrogen; wherein
R7, R8, and Rg are independently of each other selected from the group consisting of: hydrogen, alkyl, aryl, and heteroaryl.
In one embodiment, the compound of formula (la) is provided, wherein R4 is
Figure imgf000013_0004
wherein i is 1 and Ar is C6-10 aryl substituted by one, two, or three substituents. In one embodiment, the compound of formula (la) as defined herein is used in the treatment or prevention of a bacterial infection caused by a Gram-positive bacterium, wherein the Gram-positive bacterium comprises an agr, optionally wherein the Gram- positive bacterium is selected from the group consisting of: staphylococci, listeria, and Clostridium.
In one embodiment, the compound is selected from the group consisting of:
Figure imgf000014_0001
In one embodiment, the compound is selected from the group consisting of:
Figure imgf000014_0002
In a particular embodiment, the compound is cysteamine for use in the treatment or prevention of a bacterial infection caused by a Gram-positive bacterium, wherein the Gram-positive bacterium comprises an agr, optionally wherein the Gram-positive bacterium is selected from the group consisting of: staphylococci, listeria, and
Clostridium.
In one embodiment, the compound is not D-penicillamine.
In one embodiment, the compound for use as defined herein is provided, wherein the compound is of formula (II),
Figure imgf000015_0001
wherein Ri , R2, R3 and R4 are as defined herein.
In one embodiment, the compound of formula (II) is defined by the following:
Ri is selected from the group consisting of: H and C1-6 alkyl;
R2 and R3 are independently of each other selected from the group consisting of:
hydrogen, halogen, and C1-6 alkyl; and
R4 is selected from the group consisting of: C1-6 alkyl, benzyl, phenyl, naphthalenyl, furyl, thienyl, pyrrolyl, oxazolyl, thiazolyl, imidazolyl, pyrazolyl, isoxazolyl, isothiazolyl, oxadiazolyl, triazolyl, thiadiazolyl, pyridinyl, pyridazinyl, pyrimidinyl, pyrazinyl, indolyl, isoindolyl, benzofuryl, benzothienyl, indazolyl, benzimidazolyl, benzothiazolyl, benzoxazolyl, benzisoxazolyl, benzothiadiazolyl, benzotriazolyl, quinolinyl, isoquinolinyl and quinazolinyl.
In one embodiment, the compound for use as defined herein is provided, wherein the compound is of formula (III),
Figure imgf000015_0002
wherein R4 is as defined herein, such as a C1-6 alkyl. In one embodiment, the compound as defined herein is selected from the group consisting of: L-cysteine methyl ester, L-cysteine, D-penicillamine, D-penicillamine methyl ester and D-cysteine, preferably the compound is L-cysteine methyl ester. In one embodiment, a composition for use is provided for the treatment or prevention of a bacterial infection in a subject, said composition comprising the compound as defined herein, and one or more excipients.
In one embodiment, the compound for use as defined herein is provided, wherein the compound is administered prior to, simultaneously with, or subsequently to an antimicrobial agent. In one embodiment, the use of a compound as defined herein increases the susceptibility of bacteria to the antimicrobial agent.
Quorum sensing
Many bacteria utilize small molecule (Gram-negative bacteria) or peptidic signals (Gram-positive bacteria) to assess their local population densities in a process termed quorum sensing (QS). This chemical signalling process effectively allows bacteria to “count” themselves and behave as a group at high cell number. While the specifics may vary between species, QS circuits share general organizing principles: bacteria produce, secrete, and detect signal molecules referred to as autoinducing peptides (AIPs) in staphylococci and other Gram-positive bacteria. At high population densities in a given environment, the AIPs will reach a sufficiently high concentration to bind and activate their cognate extracellular receptors. Signal-receptor binding then alters the expression of genes involved in bacterial group behaviours, such as swarming, sporulation, bioluminescence, conjugation, biofilm formation, and virulence factor production. These phenotypes can have widespread and sometimes devastating effects on human health, agriculture, and the environment. For example, pathogenic bacteria utilize QS to launch synchronized attacks on their hosts only after they have achieved a high cell density, thereby overwhelming the defence mechanisms of the host. As several prevalent human pathogens (e.g., Staphylococcus aureus) use QS to control virulence, QS has received considerable recent attention as a new anti-infective target. There has been significant interest in the development of non-native ligands (e.g., small molecule and peptides) capable of blocking QS pathways. In contrast to antibiotics, which target bacterial pathways that are essential for survival, targeting QS provides an alternative anti-infective therapy that does not place selective pressure on the bacterial population to develop resistance. This is especially important in the case of S. aureus, which rapidly develops resistance to antibiotics, including resistance to the once last-resort antibiotic vancomycin.
The staphylococcal QS system is named after its chromosomal locus accessory gene regulator (agr) and agr-like QS systems have been found in other Gram-positive bacteria such as Listeria, Clostridia and Lactobacilli. The activation of the agr QS system leads to the expression of many virulence factors, which lead to the formation of skin abscesses and worst symptoms on the subject infected by the bacteria. The secreted signalling peptides, the AIPs, share a common chemical moiety, a thiolactone, which is necessary for structural integrity and activation of QS. Most agents targeting the QS system to reduce bacterial virulence are structural mimetics of the AIPs that bind to the QS receptors without activating them, thereby preventing binding of AIPs. Staphylococcus aureus has four distinct agr systems (agr-l-l V) with unique Al P- receptor pairs. These specificity groups represent a challenge for inhibitor development due to the different binding profiles necessary for pan-group-inhibitors.
The present inventors have found that simple 1 -amino, 2-mercapto- (amino-thiols) containing molecules readily react with quorum sensing thiolactone peptides to destroy their activity. This novel way of preventing QS activation/virulence does not rely on competitive inhibition with the native AIP for receptor binding and is applicable to all Gram-positive bacteria that secrete thiolactone based quorum sensing signalling molecules. In one embodiment, a compound is provided as defined herein for use in treatment or prevention of a bacterial infection, wherein the compound is capable of reacting with a bacterial autoinducing peptide (AIP) thereby inactivating the AIP and inhibiting quorum sensing. In one embodiment, the bacterial autoinducing peptide is one or more or all of AIP-I, AIP-II, AIP-III, and AIP-IV, such as one or more or all of S. aureus AIP-I, AIP-II, AIP-III, and AIP-IV.
In one embodiment, the compound as defined herein inhibits accessory gene regulator (agr) mediated signaling of the bacteria. In one embodiment, the inhibition of agr mediated signalling is determined by a quorum sensing inhibition assay using one or more fluorescence reporter strains. In one embodiment, the bacterial infection treated or prevented by a compound as defined herein is caused by a Gram-positive bacterium. In one embodiment, the Gram-positive bacterium comprises an agr.
In one embodiment, the compound of formula (I) as defined herein is a bacterial quorum sensing inhibitor.
Bacterial infections and treatment thereof
In one embodiment, a bacterial infection prevented or treated by a compound as defined herein, is on the skin and/or a mucosal surface of a subject.
In one embodiment, the mucosal surface is on an eye, an ear, inside the nose, inside the mouth, on the lip, vagina, the urethra, the bladder and/or the gastrointestinal tract, such as the oesophagus or the anus, of the subject.
In one embodiment, the bacterial infection prevented or treated by a compound as defined herein, is in a wound.
In one embodiment, the compound for use as defined herein is provided for prevention or treatment of a bacterial infection by attenuation, inhibition or reduction of virulence in the bacteria. In one embodiment, the attenuation, inhibition or reduction of virulence in the bacteria is maintained for at least 30 min, such as at least 1 hour, such as at least 2 hours, such as at least 3 hours, such as at least 4 hours, such as at least 5 hours, such as at least 6 hours, such as at least 7 hours, such as at least 8 hours, such as at least 9 hours, such as at least 10 hours, such as at least 11 hours, such as at least 12 hours, such as at least 13 hours, such as at least 14 hours, such as at least 15 hours, such as at least 16 hours, such as at least 17, such as at least 18 hours, such as at least 19 hours, such as at least 20 hours, such as at least 21 hours, such as at least 22 hours, such as at least 23 hours, such as at least 24 hours, after administering a single dose of the compound to the subject.
In one embodiment, the compound for use as defined herein decreases the
pathogenicity of the bacteria. In one embodiment, the prevention or treatment of the bacterial infection is by attenuation of virulence of the bacteria without significantly inhibiting bacterial growth.
In one embodiment, the use of a compound as defined herein reduces or inhibits formation of abscesses on the skin. In one embodiment, the use reduces or inhibits dermo-necrosis in a subject.
In one embodiment, the compound for use as defined herein does not significantly reduce, inhibit or degrade bacterial biofilm. In another embodiment, the compound also reduces, inhibits or degrades bacterial biofilm.
In one embodiment, the bacterial infection treated or prevented by a compound as defined herein is caused by a Gram-positive bacterium.
In one embodiment, the bacterial infection is caused by a bacterium selected from the group consisting of: staphylococci, listeria, and Clostridium.
In one embodiment, the staphylococci are selected from the group consisting of: S. aureus, S. epidermidis, S. lugdunensis, S. haemolyticus, S. capitis, S. caprae, S. cohnii, S. pasteuri, S. pettenkoferi, S. schleiferi, S. sciuri, S. simulans, S. warneri, S. xylosus, S. hominis, S. argenteus, S. arlettae, S. auricularis, S. carnosus, S.
chromogenes, S. hyicus, S. jettensis, S. lentus, S. saprophyticus, S. schweitzeri, S. vitulinus, S. agnetis, S. argensis, S. caseolyticus, S. condimenti, S. devriesei, S.
edaphicus, S. equorum, S. felis, S. fleuretti, S. gallinarum, S. kioosii, S. lutrae, S. massiliensis, S. microti, S. muscuae, S. nepalensis, S. petrasii, S. piscifermentans, S. pulvereri, S. rostri, S. saccharolyticus, S. simiae, S. stepanovicii, and S. succinus.
In one embodiment, the staphylococci are selected from the group consisting of: S. aureus, S. epidermidis, S. lugdunensis, and S. saprophyticus.
In one embodiment, the S. aureus comprises an accessory gene regulator (agr) type selected from the group consisting of: agr- 1, agr-ll, agr-lll, and agr-IV. In one embodiment, the S. epidermidis comprises an accessory gene regulator (agr) type selected from the group consisting of: agr- 1, agr-ll, and agr-lll. In one embodiment, the S. lugdunensis comprises an accessory gene regulator (agr) type selected from the group consisting of: agr- 1 and agr-ll.
In one embodiment, the listeria are listeria monocytogenes.
In one embodiment, the Clostridium is selected from the group consisting of:
Clostridium difficile, Clostridium perfringens, Clostridium acetobutylicum, and
Clostridium butyricum. In one embodiment, the Clostridium is selected from the group consisting of: Clostridium difficile and Clostridium perfringens.
In one embodiment, the bacterial infection is caused by an antibiotic-resistant bacterium, such as a multi-resistant bacterium. In one embodiment, the antibiotic- resistant bacterium is selected from the group consisting of: S. aureus and Clostridium difficile.
In one embodiment, the antibiotic-resistant bacterium is a methicillin resistant bacterium, such as methicillin resistant S. aureus (MRSA) or Vancomycin resistant S. aureus (VRSA). Methicillin-resistant Staphylococcus aureus (MRSA)
Methicillin-resistant Staphylococcus aureus (MRSA) is a Gram-positive bacterium responsible for several types of infections in humans, which are d iff i cu It-to-treat. MRSA comprise any strain of Staphylococcus aureus that has developed multiple drug resistance to b-lactam antibiotics. The strains may have gained drug resistance through horizontal gene transfer and natural selection b-lactam antibiotics are a broad spectrum group which includes some penams - penicillin derivatives such as methicillin and oxacillin, and cephems such as the cephalosporins. MRSA have evolved from horizontal gene transfer of the mecA gene to at least five distinct S.
aureus lineages.
Beta-lactam antibiotics permanently inactivate penicillin-binding proteins (PBP’s), which are essential for bacterial life, by permanently binding to their active sites. Some forms of MRSA, however, express a PBP that will not allow the antibiotic into their active site. Acquisition of staphylococcal cassette chromosome (SCCmec) in methicillin-sensitive staphylococcus aureus (MSSA) gives rise to a number of genetically different MRSA lineages. The term“MRSA” as used herein includes any Methicillin-resistant strain of
Staphylococcus aureus (S. aureus). The term also includes any strain regardless of how it is acquired and thus includes HA-MRSA (healthcare-associated MRSA), CA- MRSA (community-associated MRSA) and LA-MRSA (livestock-associated MRSA). Several newly discovered strains of MRSA show antibiotic resistance even to vancomycin and teicoplanin. These new evolutions of the MRSA bacterium are referred to as vancomycin intermediate-resistant Staphylococcus aureus (VISA). Thus, in one embodiment of the present disclosure, MRSA also includes VISA strains.
MRSA is generally obtained by touching the skin of another person who is colonized with MRSA, by a bacterial transfer by hand from the nose to an opening on the skin, or by touching a contaminated surface (such as a countertop, door handle, or phone).
You can develop an infection from MRSA if your skin is colonized and the bacteria enter an opening (e.g. a cut, scrape, or wound) in the skin. Infection is most commonly seen under the nostrils. The rest of the respiratory tract, open wounds, intravenous catheters, and the urinary tract are also potential sites for infection. Healthy individuals may carry MRSA asymptomatically for periods ranging from a few weeks to many years. People with compromised immune systems are at a significantly greater risk of symptomatic secondary infection. MRSA can usually be detected by swabbing the nostrils and isolating the bacteria found inside the nostrils. Combined with extra sanitary measures for those in contact with infected people, swab screening people admitted to hospitals has been found to be effective in minimizing the spread of MRSA in hospitals in the United States, Denmark, Finland, and the Netherlands. MRSA may progress substantially within 24-48 hours of initial topical symptoms. After 72 hours, MRSA can take hold in human tissues and eventually become resistant to treatment. The initial presentation of MRSA is small red bumps that resemble pimples, spider bites, or boils; they may be accompanied by fever and, occasionally, rashes. Within a few days, the bumps become larger and more painful; they eventually open into deep, pus-filled boils. About 75 percent of CA-MRSA infections are localized to skin and soft tissue. Infections can usually be treated effectively with conventional antibiotics. Some CA-MRSA strains display enhanced virulence, spreading more rapidly and causing illness much more severe than traditional HA-MRSA infections, and they can affect vital organs and lead to widespread infection (sepsis), toxic shock syndrome, and necrotizing pneumonia. This is thought to be due to toxins carried by CA-MRSA strains, such as Panton-Valentine leukocidins (PVL) and phenol-soluble modulins (PSM), though PVL was recently found not to be a factor in a study by the National Institute of Allergy and Infectious Diseases at the National Institutes of Health. It is not known why some healthy people develop CA-MRSA skin infections that are treatable while others infected with the same strain develop severe infections or die.
Methods
The methods of the present disclosure relate to treatment or prevention of a bacterial infection in or on a subject by the use of a compound as defined herein.
In one embodiment, the compound is administered to the subject at least once a day, such as at least two times a day, such as at least three times a day. In one
embodiment, the compound is administered every second day.
In one embodiment, the compound for use as defined herein is administered by topical administration. In one embodiment, the topical administration is via a cream, a solution, a foam, a gel, a lotion, an ointment, a transdermal patch, a powder, a sponge, a tape, or a paste.
In one embodiment, the compound is administered via a wound dressing or a catheter. The compound may also be administered by application to the surface of a catheter. The compound as defined herein may be applied to the wound dressing, which is applied to the subject on the wound to prevent or treat a bacterial infection.
In one embodiment, the present disclosure provides a method for treatment or prevention of a bacterial infection, the method comprising administering to a subject a compound or a composition as defined herein, and a further antimicrobial agent. In one embodiment, the present disclosure provides a method for preventing bacterial colonization of a wound, said method comprising administering a compound or a composition as defined herein to the wound of a subject.
In one embodiment, the present disclosure provides a method for inhibiting or reducing bacterial virulence on the skin of a subject, said use comprising contacting a compound or a composition as defined herein with the skin of the subject.
In one embodiment, the present disclosure provides a method for inhibiting quorum sensing of bacteria comprising contacting a compound or a composition as defined herein with the bacteria.
In one embodiment, the present disclosure provides a method for treatment or prevention of bacterial damage or disease in a subject, comprising administering a compound or a composition as defined herein to the subject.
In one embodiment, the present disclosure provides a method for decreasing the pathogenicity of bacteria in or on a subject, comprising administering a compound or a composition as defined herein to the subject.
In one embodiment, the present disclosure provides a method for increasing the susceptibility of bacteria in or on a subject to an antimicrobial agent.
In one embodiment, the present disclosure provides use of a compound or a composition as defined herein for the manufacture of a medicament for the treatment or prevention of a bacterial infection in a subject.
Definition of Substituents
In the context of the present disclosure halogen represents fluorine, chlorine, bromine or iodine.
In the context of present disclosure an alkyl group designates a univalent saturated, straight or branched hydrocarbon chain. The hydrocarbon chain preferably contain of from one to six carbon atoms (Ci-6-alkyl), including pentyl, isopentyl, neopentyl, tertiary pentyl, cyclopentyl, hexyl, cyclohexyl and isohexyl. In one embodiment alkyl represents a Ci-4-alkyl group, including butyl, isobutyl, secondary butyl, cyclobutyl and tertiary butyl. In another embodiment of this invention alkyl represents a Ci-3-alkyl group, which may in particular be methyl, ethyl, propyl, cyclopropyl or isopropyl.
The term "aryl" refers to an unsaturated, aromatic monocyclic or bicyclic ring of 6 to 10 carbon members i.e.“Ce-io aryl”. Examples of aryl rings include phenyl and
naphthalenyl. An aryl ring may be substituted by one or more substituents.
The term "heteroaryl" refers to an aromatic monocyclic or bicyclic aromatic ring system having 5 to 10 ring members and which contains carbon atoms and from 1 to 4 heteroatoms independently selected from the group consisting of N, O, and S. Included within the term heteroaryl are aromatic rings of 5 or 6 members wherein the ring consists of carbon atoms and has at least one heteroatom member. Suitable heteroatoms include nitrogen, oxygen, and sulfur. In the case of 5 membered rings, the heteroaryl ring preferably contains one member of nitrogen, oxygen or sulfur and, in addition, up to 3 additional nitrogen atoms. In the case of 6 membered rings, the heteroaryl ring preferably contains from 1 to 3 nitrogen atoms. For the case wherein the 6 membered ring has 3 nitrogen atoms, at most 2 nitrogen atoms are adjacent.
Examples of heteroaryl groups include furyl, thienyl, pyrrolyl, oxazolyl, thiazolyl, imidazolyl, pyrazolyl, isoxazolyl, isothiazolyl, oxadiazolyl, triazolyl, thiadiazolyl, pyridinyl, pyridazinyl, pyrimidinyl, pyrazinyl, indolyl, isoindolyl, benzofuryl, benzothienyl, indazolyl, benzimidazolyl, benzothiazolyl, benzoxazolyl, benzisoxazolyl,
benzothiadiazolyl, benzotriazolyl, quinolinyl, isoquinolinyl and quinazolinyl. Unless otherwise noted, the heteroaryl is attached to its pendant group at any heteroatom or carbon atom that results in a stable structure.
The term "halogen" or "halo" refers to fluorine, chlorine, bromine and iodine atoms.
It is understood that substituents and substitution patterns on the compounds of the present invention can be selected by one of ordinary skill in the art to provide compounds that are chemically stable and that can be readily synthesized by techniques known in the art as well as those methods set forth herein. Subjects
A subject which may be suitable for treatment of a bacterial infection as defined herein, may be a vertebrate, such as a mammal.
In one embodiment, the subject is a human being. The subject may also be non human, such as a dog, a horse, a goat, a sheep or a pig.
In one embodiment, the subject is a vertebrate such as a bird or a fish. In one embodiment, the bird is selected from the group consisting of: turkey, chicken, duck, hen, goose, guinea fowl and quail. In one embodiment, the fish is selected from the group consisting of: carp, tilapia, salmon, roho labeo, trout, milkfish, wuchang bream, northern snakehead and amur catfish.
Wound care
It is an aspect of the present disclosure to provide a compound that may be used in prevention or treatment of a bacterial infection of a wound.
In one embodiment, a medical device is provided comprising a compound or a composition as defined herein. In one embodiment, the medical device is selected from the group consisting of: a wound dressing and a catheter. In one embodiment, the compound is administered via a wound dressing or a catheter. The compound as defined herein may be applied to the wound dressing, which is applied to the subject on the wound to prevent or treat a bacterial infection.
Items
1-1. A compound according to the formula (I),
Figure imgf000025_0001
or a pharmaceutically acceptable salt thereof,
wherein n is 0 or 1 ; z is 0 or 1 ;
Ri is selected from the group consisting of: H and alkyl;
R2 and R3 are independently of each other selected from the group consisting of: hydrogen, halogen, and alkyl;
Y is selected from the group consisting of: -(CO)R4, -CO2R4, -0(C0)R4,
-NR5(CO)R4, -(CO)N(R5)R4, -C(R5)=C(R4)Re, -CC-R4, -aryl-R4, -heteroaryl-R4, hydrogen, and a bond to R2; and
R4, R5, and R6 are independently of each other selected from the group consisting of: hydrogen, alkyl, aryl, and heteroaryl;
for use in the prevention or treatment of a bacterial infection in a subject.
I-2. A compound according to the formula (I),
Figure imgf000026_0001
wherein n is 0 or 1 ;
z is 0 or 1 ;
Ri is selected from the group consisting of: H and alkyl;
R2 and R3 are independently of each other selected from the group consisting of: hydrogen, halogen, and alkyl;
Y is selected from the group consisting of: -(CO)R4, -CO2R4, -0(CO)R4,
-NR5(CO)R4, -(CO)N(R5)R4, -C(R5)=C(R4)Re, -CC-R4, -aryl-R4, -heteroaryl-R4, hydrogen, and a bond to R2; and
R4, R5, and R6 are independently of each other selected from the group consisting of: hydrogen, alkyl, aryl, and heteroaryl;
for use in the prevention or treatment of a bacterial infection in a subject.
I-3. The compound for use according to any one of the preceding items, wherein the bacterial infection is on the skin and/or a mucosal surface.
I-4. The compound for use according to any one of the preceding items, wherein the mucosal surface is on an eye, an ear, inside the nose, inside the mouth, on the lip, vagina, the urethra, the bladder and/or the gastrointestinal tract, such as the oesophagus, or the anus, of the subject.
I-5. The compound for use according to any one of the preceding items, wherein the bacterial infection is in a wound.
1-6. The compound for use according to any one of the preceding items, wherein the prevention or treatment is by attenuation, inhibition or reduction of virulence in the bacteria.
1-7. The compound for use according to any one of the preceding items, wherein the use decreases the pathogenicity of the bacteria.
1-8. The compound for use according to any one of the preceding items, wherein the compound is administered prior to, simultaneously with, or subsequently to an antimicrobial agent.
I-9. The compound for use according to any one of the preceding items, wherein the use increases the susceptibility of the bacteria to the antimicrobial agent.
1-10. The compound for use according to any one of the preceding items, wherein the prevention or treatment is by attenuation of virulence of the bacteria without significantly inhibiting bacterial growth. 1-11. The compound for use according to any one of the preceding items, wherein the use reduces or inhibits formation of abscesses on the skin.
1-12. The compound for use according to any one of the preceding items, wherein the use reduces or inhibits dermo-necrosis.
1-13. The compound for use according to any one of the preceding items, wherein the compound does not significantly reduce, inhibit or degrade bacterial biofilm.
1-14. The compound for use according to any one of the preceding items, wherein the compound reduces, inhibits or degrades bacterial biofilm. 1-15. The compound for use according to any one of the preceding items, wherein the compound is capable of reacting with a bacterial autoinducing peptide (AIP) thereby inactivating the AIP and inhibiting quorum sensing.
1-16. The compound for use according to any one of the preceding items, wherein the bacterial autoinducing peptide is one or more or all of S. aureus AIP-I, AIP-II, AIP- III, and AIP-IV.
1-17. The compound for use according to any one of the preceding items, wherein the compound inhibits accessory gene regulator (agr) mediated signaling of the bacteria.
1-18. The compound for use according to any one of the preceding items, wherein the inhibition of agr mediated signalling is determined by a quorum sensing inhibition assay using one or more fluorescence reporter strains.
1-19. The compound for use according to any one of the preceding items, wherein the attenuation, inhibition or reduction of virulence in the bacteria is maintained for at least 30 min, such as at least 1 hour, such as at least 2 hours, such as at least 3 hours, such as at least 4 hours, such as at least 5 hours, such as at least 6 hours, such as at least 7 hours, such as at least 8 hours, such as at least 9 hours, such as at least 10 hours, such as at least 11 hours, such as at least 12 hours, such as at least 13 hours, such as at least 14 hours, such as at least 15 hours, such as at least 16 hours, such as at least 17, such as at least 18 hours, such as at least 19 hours, such as at least 20 hours, such as at least 21 hours, such as at least 22 hours, such as at least 23 hours, such as at least 24 hours, after administering a single dose of the compound to the subject. I-20. The compound for use according to any one of the preceding items, wherein the compound is administered to the subject at least once a day, such as at least two times a day, such as at least three times a day.
1-21. The compound for use according to any one of the preceding items, wherein the compound is administered every second day. I-22. The compound for use according to any one of the preceding items, wherein the compound is administered by topical administration. 1-23. The compound for use according to any one of the preceding items, wherein the topical administration is via a cream, a solution, a foam, a gel, a lotion, an ointment, a transdermal patch, a powder, a sponge, a tape, or a paste.
1-24. The compound for use according to any one of the preceding items, wherein the compound is administered via a wound dressing or a catheter.
I-25. The compound for use according to any one of the preceding items, wherein the bacterial infection is caused by a Gram-positive bacterium. I-26. The compound for use according to any one of the preceding items, wherein the
Gram-positive bacterium comprises an agr.
I-27. The compound for use according to any one of the preceding items, wherein the bacterial infection is caused by a bacterium selected from the group consisting of: staphylococci, listeria, and Clostridium.
I-28. The compound for use according to any one of the preceding items, wherein the staphylococci are selected from the group consisting of: S. aureus, S.
epidermidis, S. lugdunensis, S. haemolyticus, S. capitis, S. caprae, S. cohnii, S. pasteuri, S. pettenkoferi, S. schleiferi, S. sciuri, S. simulans, S. warneri, S.
xylosus, S. hominis, S. argenteus, S. arlettae, S. auricularis, S. carnosus, S. chromogenes, S. hyicus, S. jettensis, S. lentus, S. saprophyticus, S. schweitzeri, S. vitulinus, S. agnetis, S. argensis, S. caseolyticus, S. condimenti, S. devriesei, S. edaphicus, S. equorum, S. felis, S. fleuretti, S. gallinarum, S. kioosii, S. lutrae, S. massiliensis, S. microti, S. muscuae, S. nepalensis, S. petrasii, S.
piscifermentans, S. pulvereri, S. rostri, S. saccharolyticus, S. simiae, S.
stepanovicii, and S. succinus. I-29. The compound for use according to any one of the preceding items, wherein the staphylococci are selected from the group consisting of: S. aureus, S.
epidermidis, S. lugdunensis, and S. saprophyticus. I-30. The compound for use according to any one of the preceding items, wherein the
S. aureus comprises an accessory gene regulator (agr) type selected from the group consisting of: agr- 1, agr-ll, agr-lll, and agr-IV.
1-31. The compound for use according to any one of the preceding items, wherein the S. epidermidis comprises an accessory gene regulator (agr) type selected from the group consisting of: agr- 1, agr-ll, and agr-lll.
I-32. The compound for use according to any one of the preceding items, wherein the S. lugdunensis comprises an accessory gene regulator (agr) type selected from the group consisting of: agr- 1 and agr-ll.
I-33. The compound for use according to any one of the preceding items, wherein the listeria are listeria monocytogenes. I-34. The compound for use according to any one of the preceding items, wherein the
Clostridium is selected from the group consisting of: Clostridium difficile, Clostridium perfringens, Clostridium acetobutylicum, and Clostridium butyricum.
I-35. The compound for use according to any one of the preceding items, wherein the Clostridium is selected from the group consisting of: Clostridium difficile and
Clostridium perfringens.
I-36. The compound for use according to any one of the preceding items, wherein the bacterial infection is caused by an antibiotic-resistant bacterium, such as a multi- resistant bacterium.
I-37. The compound for use according to any one of the preceding items, wherein the antibiotic-resistant bacterium is selected from the group consisting of: S. aureus and Clostridium difficile. I-38. The compound for use according to any one of the preceding items, wherein antibiotic-resistant bacterium is a methicillin resistant bacterium, such as methicillin resistant S. aureus (MRSA) or Vancomycin resistant S. aureus (VRSA).
I-39. The compound for use according to any one of the preceding items, wherein the subject is a vertebrate, such as a mammal.
1-40. The compound for use according to any one of the preceding items, wherein the mammal is a human being.
1-41. The compound for use according to any one of the preceding items, wherein the mammal is a dog, a horse, a goat, a sheep or a pig. I-42. The compound for use according to any one of the preceding items, wherein the compound of formula (I) is a bacterial quorum sensing inhibitor.
I-43. The compound for use according to any one of the preceding items, wherein Ri is hydrogen or methyl.
I-44. The compound for use according to any one of the preceding items, wherein Ri is hydrogen.
I-45. The compound for use according to any one of the preceding items, wherein R2 and R3 both are methyl.
I-46. The compound for use according to any one of the preceding items, wherein R2 and R3 both are hydrogen. I-47. The compound for use according to any one of the preceding items, wherein R2 or R3 is hydrogen.
I-48. The compound for use according to any one of the preceding items, wherein R2 or R3 is methyl. I-49. The compound for use according to any one of the preceding items, wherein R4 is selected from the group consisting of: alkyl, aryl, and heteroaryl.
1-50. The compound for use according to any one of the preceding items, wherein R4 is a C1 to C6 alkyl.
1-51. The compound for use according to any one of the preceding items, wherein R4 is methyl.
I-52. The compound for use according to any one of the preceding items, wherein n is 0.
I-53. The compound for use according to any one of the preceding items, wherein z is 0.
I-54. The compound for use according to any one of the preceding items, wherein Y is selected from the group consisting of: -CO2R4 and -0(CO)R4, and wherein R4 is as defined in any one of the preceding items. I-55. The compound for use according to any one of the preceding items, wherein Y is a bond to the terminal carbon of R2, and R2 is a C3, C4, or C5 alkyl.
I-56. The compound for use according to any one of the preceding items, wherein Y is heteroaryl, such triazole.
I-57. The compound for use according to any one of the preceding items, wherein the compound is of formula (la),
Figure imgf000032_0001
wherein Ri is selected from the group consisting of: H and C1-6 alkyl,
X is selected from the group consisting of: wherein
R4 and R5 are independently of each other selected from the group consisting of: H, alkyl, aryl, and heteroaryl; and
v is selected from the group consisting of: 1 , 2, 3, and 4.
I-58. The compound for use according to any one of the preceding items, wherein the compound is of formula (la) and the bacterial infection is caused by a Grampositive bacterium, wherein the Gram-positive bacterium comprises an agr, optionally wherein the Gram-positive bacterium is selected from the group consisting of: staphylococci, listeria, and Clostridium.
I-59. The compound for use according to any one of the preceding items, wherein the compound is cysteamine for use in the treatment or prevention of a bacterial infection caused by a Gram-positive bacterium, wherein the Gram-positive bacterium comprises an agr, optionally wherein the Gram-positive bacterium is selected from the group consisting of: staphylococci, listeria, and Clostridium.
I-60. The compound for use according to any one of the preceding items, wherein the compound is of formula (II),
Figure imgf000033_0001
wherein Ri, R2, R3 and R4 are as defined in any one of the preceding items.
1-61. The compound for use according to any one of the preceding items, wherein the compound is of formula (III), wherein R4 is as defined in any one of the preceding items.
I-62. The compound for use according to any one of the preceding items, wherein R4 is selected from the group consisting of:
Figure imgf000034_0001
wherein;
i is selected from the group consisting of 1 , 2, and 3;
Ar is aryl, such as C6-10 aryl substituted by one, two, or three substituents; and T is selected from the group consisting of: -(CO)R7, -CO2R7, -0(CO)R7,
-NR8(CO)R7, -(CO)N(RS)R7, -C(RS)=C(R7)R9, -CC-R7, -aryl-R7, -heteroaryl-R7, and hydrogen; wherein
R7, R8, and Rg are independently of each other selected from the group consisting of: hydrogen, alkyl, aryl, and heteroaryl.
I-63. The compound for use according to any one of the preceding items, wherein the compound is selected from the group consisting of: L-cysteine methyl ester, L- cysteine, D-penicillamine, D-penicillamine methyl ester and D-cysteine, preferably L-cysteine methyl ester.
I-64. The compound for use according to any one of the preceding items, wherein the compound is selected from the group consisting of:
1-65. The compound for use according to any one of the preceding items, wherein the compound is selected from the group consisting of:
Figure imgf000035_0001
I-66. A composition for use in the treatment or prevention of a bacterial infection in a subject, said composition comprising the compound as defined in any one of the preceding items and one or more excipients.
1-67. A method for treatment or prevention of a bacterial infection, the method
comprising administering to a subject a compound or a composition as defined in any one of the preceding items, and a further antimicrobial agent. I-68. A method for preventing bacterial colonization of a wound, said method comprising administering a compound or a composition as defined in any one of the preceding items to the wound of a subject. 1-69. A method for inhibiting or reducing bacterial virulence on the skin of a subject, said use comprising contacting a compound or a composition as defined in any one of the preceding items with the skin of the subject.
1-70. A method for inhibiting quorum sensing of bacteria comprising contacting a
compound or a composition as defined in any one of the preceding items with the bacteria.
1-71. A method for treatment or prevention of bacterial damage or disease in a subject, comprising administering a compound or a composition as defined in any one of the preceding items to the subject.
I-72. A method for decreasing the pathogenicity of bacteria in or on a subject,
comprising administering a compound or a composition as defined in any one of the preceding items to the subject.
I-73. A method for increasing the susceptibility of bacteria in or on a subject to an
antimicrobial agent.
I-74. A medical device comprising a compound or a composition as defined in any one of the preceding items.
I-75. The medical device according to any one of the preceding items, wherein the medical device is selected from the group consisting of: a wound dressing and a catheter.
I-76. Use of a compound or a composition as defined in any one of the preceding
items for the manufacture of a medicament for the treatment or prevention of a bacterial infection in a subject. Items II
1 1 A compound according to the formula (I),
Figure imgf000037_0001
wherein n is 0 or 1 ;
z is 0 or 1 ;
Ri is selected from the group consisting of: H and alkyl;
R2 and R3 are independently of each other selected from the group consisting of: hydrogen, halogen, and alkyl;
Y is selected from the group consisting of: -(CO)R4, -CO2R4, -0(CO)R4,
-NR5(CO)R4, -(CO)N(R5)R4, -C(R5)=C(R4)Re, -CC-R4, -aryl-R4, -heteroaryl-R4, hydrogen, and a bond to R2; and
R4, R5, and R6 are independently of each other selected from the group consisting of: hydrogen, alkyl, aryl, and heteroaryl;
for use in the prevention or treatment of a bacterial infection in a subject.
I-2. The compound for use according to item 1 , wherein the compound is of formula
(II),
Figure imgf000037_0002
wherein:
Ri is selected from the group consisting of: H and C1-6 alkyl;
R2 and R3 are independently of each other selected from the group consisting of: hydrogen, halogen, and C1-6 alkyl; and
R4 is selected from the group consisting of: C1-6 alkyl, benzyl, phenyl, naphthalenyl, furyl, thienyl, pyrrolyl, oxazolyl, thiazolyl, imidazolyl, pyrazolyl, isoxazolyl, isothiazolyl, oxadiazolyl, triazolyl, thiadiazolyl, pyridinyl, pyridazinyl, pyrimidinyl, pyrazinyl, indolyl, isoindolyl, benzofuryl, benzothienyl, indazolyl, benzimidazolyl, benzothiazolyl, benzoxazolyl, benzisoxazolyl, benzothiadiazolyl, benzotriazolyl, quinolinyl, isoquinolinyl and quinazolinyl. 1-3. The compound for use according to any one of the preceding items, wherein the compound is selected from the group consisting of: L-cysteine methyl ester, D- penicillamine, and D-penicillamine methyl ester, preferably wherein the compound is L-cysteine methyl ester. I-4. The compound for use according to any one of the preceding items, wherein the bacterial infection is on the skin and/or a mucosal surface, of the subject, optionally wherein the mucosal surface is on an eye, an ear, inside the nose, inside the mouth, on the lip, vagina, the urethra, the bladder and/or the gastrointestinal tract, such as the oesophagus, or the anus.
I-5. The compound for use according to any one of the preceding items, wherein the bacterial infection is in a wound.
I-6. The compound for use according to any one of the preceding items, wherein the prevention or treatment is by attenuation, inhibition or reduction of virulence in the bacteria.
1-7. The compound for use according to any one of the preceding items, wherein the compound: a. decreases the pathogenicity of the bacteria;
b. reduces or inhibits formation of abscesses on the skin;
c. prevents bacterial colonization of a wound;
d. inhibits quorum sensing of the bacteria;
e. prevents or treats bacterial damage on the skin;
f. increases susceptibility to a further antimicrobial agent; and/or
g. reduces or inhibits dermo-necrosis.
I-8. The compound for use according to any one of the preceding items, wherein the compound is administered prior to, simultaneously with, or subsequently to an antimicrobial agent, optionally wherein the use increases the susceptibility of the bacteria to the antimicrobial agent.
I-9. The compound for use according to any one of the preceding items, wherein the compound is capable of reacting with a bacterial autoinducing peptide (AIP) thereby inactivating the AIP and inhibiting quorum sensing, optionally wherein the bacterial autoinducing peptide is one or more or all of S. aureus AIP-I, AIP-II, AIP- III, and AIP-IV. 1-10. The compound for use according to any one of the preceding items, wherein the compound inhibits accessory gene regulator (agr) mediated signaling of the bacteria.
1-11. The compound for use according to any one of the preceding items, wherein the compound is administered by topical administration, such as via a cream, a solution, a foam, a gel, a lotion, an ointment, a transdermal patch, a powder, a sponge, a tape, or a paste.
1-12. The compound for use according to any one of the preceding items, wherein the bacterial infection is caused by a Gram-positive bacterium, wherein the Gram positive bacterium comprises an agr, optionally wherein the Gram-positive bacterium is selected from the group consisting of: staphylococci, listeria, and Clostridium. 1-13. The compound for use according to any one of the preceding items, wherein the bacterial infection is caused by an antibiotic-resistant bacterium, such as a multi- resistant bacterium.
1-14. A medical device comprising a compound of formula (II),
Figure imgf000039_0001
wherein:
Ri is selected from the group consisting of: H and Ci-e alkyl;
R2 and R3 are independently of each other selected from the group consisting of: hydrogen, halogen, and C1-6 alkyl; and
R4 is selected from the group consisting of: C1-6 alkyl, benzyl, phenyl,
naphthalenyl, furyl, thienyl, pyrrolyl, oxazolyl, thiazolyl, imidazolyl, pyrazolyl, isoxazolyl, isothiazolyl, oxadiazolyl, triazolyl, thiadiazolyl, pyridinyl, pyridazinyl, pyrimidinyl, pyrazinyl, indolyl, isoindolyl, benzofuryl, benzothienyl, indazolyl, benzimidazolyl, benzothiazolyl, benzoxazolyl, benzisoxazolyl, benzothiadiazolyl, benzotriazolyl, quinolinyl, isoquinolinyl and quinazolinyl.
1-15. The medical device according to item 1-15, wherein the medical device is
selected from the group consisting of: a wound dressing and a catheter.
Examples
Example 1 : Ring opening of an autoinducing peptide by L-cysteine methyl ester in aqueous buffer
Procedure for the ring opening reaction
A synthetic autoinducing peptide (AIP) containing a thiolactone functionality was incubated at a concentration of 0.2 mM in an aqueous phosphate buffered solution (0.1 M, pH = 7.4) in 50% acetonitrile containing tris(2-carboxyethyl)phosphine (TCEP, 30 mM) and L-cysteine methyl ester (10.0 mM, 50 equivalents) for 6 hours at 37 °C
(Fig. 1). The reaction mixture was analyzed after 5 min and 6 hours using an ultra-high- performance liquid chromatography (UPLC) mass spectrometry (MS) instrument.
Results
The UV traces and corresponding m/z displays after 5 minutes (Fig. 1 left panel) and 6 hours (Fig. 1 right panel) reaction time show full conversion of the synthetic AIP m/z of [M+H]+ = 991.4 to the opened AIP m/z of [M+H]+ = 1126.5 through reaction of the thiolactone functionality with the amino-thiol functionality of L-cysteine methyl ester.
Conclusion The example demonstrates that autoinducing peptides (AIP) containing a thiolactone functionality readily react under relevant physiological pH = 7.4 with cysteine analogues that contain an amino thiol functionality to form a linear peptide that is not able to activate the staphylococcal quorum sensing system and to induce virulence. Thus, L-cysteine methyl ester is effective in inhibiting virulence of staphylococci.
Example 2: Quorum sensing inhibition of Staphylococcus aureus by cysteine analogues
Bacterial reporter strains
Fluorescent S. aureus reporter strains of agr types l-IV that express the yellow fluorescent protein (YFP) upon AIP induced quorum sensing activation are used for quorum sensing inhibition assays.
Figure imgf000041_0001
General procedure of quorum sensing inhibition assay using fluorescence reporter strains
Fluorescent S. aureus reporter strains of agr type l-IV (P3 -yfp) were streaked on agar plates and grown over night at 37 °C. Single colonies of the individual reporter strains were then inoculated in 5.0 ml_ TSB medium containing chloramphenicol and grown overnight at 37 °C in an incubator with 200 rpm shaking. The overnight cultures (120 pl_) were diluted (1 :250) into fresh TSB medium (30 mL) containing chloramphenicol and grown for 1 hour at 37 °C in an incubator with 200 rpm shaking. 200 mI_ of 100 mM cysteine analogues solutions in TSB medium (prepared from 1.0 M stock solutions in H2O) were added to 10 mL centrifugal tubes followed by 1.8 mL of individual reporter strain broth (grown for 1 hour). For negative inhibition control experiments 200 pL of TSB medium without inhibitor were added followed by 1.8 mL bacterial broth. For positive inhibition control experiments 200 pL of a 1.0 pM solution of the inhibitor AIP-III D4A (Tal-Gan et al., 2013) in TSB medium were added followed by 1.8 mL bacterial broth. The individual bacterial samples were grown at 37 °C in an incubator with 200 rpm shaking to late stationary phase to allow for full agr induction (7-8 hours). P3 promoter activity (quorum sensing activity) of the bacterial population was measured as accumulated YFP by flow cytometry on a BD AccuriTM C6 flow cytometer using the FL1 channel after 7-8 hours.
Results
S. aureus agr- 1
The tested amino-thiol compounds L-cysteine, L-cysteine methyl ester and D-cysteine showed strongly reduced fluorescence at a concentration of 10 mM compared to the negative inhibition control against S. aureus agr- 1 type after 7 hours of growth (Fig. 2). L- cysteine methyl ester was able to fully inhibit the quorum sensing activity of S. aureus agr- 1 to the same extent as the inhibitor AIP-111 D4A.
S. aureus agr- II
The tested amino-thiol compounds L-cysteine, L-cysteine methyl ester and D-cysteine showed strongly reduced fluorescence at a concentration of 10 mM compared to the negative inhibition control against S. aureus agr- II type after 7 hours of growth (Fig. 3). All tested cysteine analogues were able to fully inhibit the quorum sensing activity of S. aureus agr- II to the same extent as the inhibitor AIP-III D4A.
S. aureus agr- III
The tested amino-thiol compounds L-cysteine, L-cysteine methyl ester and D-cysteine showed strongly reduced fluorescence at a concentration of 10 mM compared to the negative inhibition control against S. aureus agr- III type after 7 hours of growth (Fig. 4). L-cysteine methyl ester was able to fully inhibit the quorum sensing activity of S. aureus agr- III to the same extent as the inhibitor AIP-III D4A.
S. aureus agr- IV
The tested amino-thiol compounds L-cysteine, L-cysteine methyl ester and D-cysteine showed strongly reduced fluorescence at a concentration of 10 mM compared to the negative inhibition control against S. aureus agr- IV type after 7 hours of growth (Fig. 5).
Conclusions
This example demonstrates that amino-thiol containing cysteine analogues can inhibit agr-mediated quorum sensing of the four agr-l-IV types of S. aureus. Hence, amino- thiol compounds of this type can inhibit quorum sensing regardless of the autoinducing peptide employed by the bacterial strains as long as it contains a thiolactone functionality. In particular, L-cysteine methyl ester displayed a superior effect toward inhibition of quorum sensing in the bacteria tested. This effect may be generalized to further L-cysteine analogues, such as other L-cysteine alkyl esters. The vast majority of staphylococcal pathogens as well as other Gram-positive bacteria such as Listeria, Lactobacilli and Clostridia utilize thiolactone containing autoinducing peptides and hence, can be inhibited by amino-thiol chemotypes.
Example 3: Comparative inhibition data for N-acetyl cysteine analogues
Procedure for quorum sending inhibition using N-acetyl cysteine analogues
The fluorescence quorum sensing inhibition assay was performed as described in example 2 using the S. aureus reporter strain of agr- 1 type (P3 -yfp) and the following cysteine analogues at a concentration of 10 mM: L-cysteine, L-cysteine methyl ester, N-acetyl L-cysteine and N-acetyl L-cysteine methyl ester.
The bacterial growth of individual bacterial samples was monitored hourly by measuring the optical density at a wavelength of 600 nm (OD600) using a UV meter.
Results
The tested N-acetylated compounds, N-acetyl L-cysteine and N-acetyl L-cysteine methyl ester showed no reduction in fluorescence at a concentration of 10 mM, while the tested amino-thiol compounds L-cysteine and L-cysteine methyl ester showed strongly reduced fluorescence at a concentration of 10 mM compared to the negative inhibition control against S. aureus agr- 1 type after 8 hours of growth (Fig. 6).
The bacterial growth was not inhibited by any of the tested compounds at a
concentration of 10 mM compared to the negative inhibition control (Fig. 7).
Conclusion
This example demonstrates that a free amino-thiol functionality is required to observe the inhibitory effect. Hence, N-acetyl L-cysteine does not produce any inhibitory effect on quorum sensing. Further, none of the compounds studied had any significant, direct effect on bacterial growth, which is important for circumventing evolutionary pressure on the bacterium to develop resistance toward the compound.
Example 4: Reaction rate for ring opening of an autoinducing peptide by various amino- thiol compounds determined by UPLC
Procedure for reaction rate UPLC assay
To a solution of aqueous phosphate buffer (108 mI_, 90.0 mM, pH = 7.4) and acetonitrile (72 mI_) at 37 °C, was added an aqueous solution of tris(2-carboxyethyl)phosphine (TCEP) (8.0 mI_, 250 mM, pH = 7.0) and a solution of an amino-thiol compound in aqueous phosphate buffer (100 mM, pH = 7.4) (10.0 mI_, 100 mM, 40 equiv). Finally, a solution of synthetic autoinducing peptide (AIP) in dimethylsulfoxid (DMSO) (2.5 mI_, 10 mM) was added and the reaction was stirred at 37 °C. After 30 min and 60 min, 100 mI_ aliquots were taken and treated with a hydrazine monohydrate solution (5.0 mI_, 50- 60% v/v) for 2.0 min and subsequently acidified by adding an aqueous solution of trifluoroacetic acid (TFA) (20.0 mI_, 50% v/v). The samples were analyzed by ultra-high- performance liquid chromatography (UPLC) and the conversion of the AIP with an amino-thiol compound was determined by integration of the peaks for the linear hydrazide peptide and the ring opened linear peptide.
Amino-thiol compounds
Figure imgf000044_0001
Figure imgf000045_0001
Results
The bar graphs in Fig. 9 show conversions for the ring opening of the synthetic AIP in the range of 60-95% using 40 equivalents of the amino-thiol compounds 1 , 2, 3, 4 and 5 after 60 min incubation. The negative control compound 8 (N-acetyl cysteine) shows no conversion and compound 9 (D-penicillamine) shows only traces of ring-opened peptide.
Conclusion
The example demonstrates that autoinducing peptides (AIP) containing a thiolactone functionality readily react under relevant physiological pH = 7.4 with various amino-thiol compounds to form a linear peptide that is not able to activate the staphylococcal quorum sensing system and to induce virulence. Even the simplest cysteine analogue, compound 3 (cysteamine), can effectively react with autoinducing peptides. The requirement of a free N-terminal amine to irreversibly ring open and destroy an AIP is demonstrated by the inability of compound 8 (N-acetyl L-cysteine) to do so. Compound 9 displays a reduced ability to react with AIPs and therefore represents a less effective inhibitor of staphylococcal virulence. Thus, cysteine (1) and analogues thereof (2, 4, 5) as well as simple amino-thiol compounds (3) are effective in inhibiting virulence of staphylococci.
Example 5: Quorum sensing inhibition of Staphylococcus aureus by amino-thiol compounds using a 96-well plate fluorescence assay
Bacterial reporter strains
Fluorescent S. aureus reporter strains of agr types l-IV that express the yellow fluorescent protein (YFP) upon AIP induced quorum sensing activation are used for quorum sensing inhibition assays.
Figure imgf000046_0001
General procedure of quorum sensing inhibition assay using fluorescence reporter strains Stock solutions of amino-thiol compounds were prepared with a concentration of 100 mM in phosphate buffer (0.1 M, pH = 7.4) for free base compounds and in phosphate buffer (0.1 M, pH = 8.0) for hydrochloride salts. The assays were performed in black 96-well microtiter plates with clear bottom. Fluorescent S. aureus reporter strains of agr type l-IV (P3 -yfp) were streaked on agar plates and grown over night at 37 °C. Single colonies of the individual reporter strains were then inoculated in 20 ml_ TSB medium containing chloramphenicol and grown at 37 °C in an incubator with 200 rpm shaking to early exponential phase (optical density at a wavelength of 600 nm (OD600) = 0.35). Amino-thiol compound stock solutions (20 mI_) in 1 :2 serial dilution (final concentration = 10 mM-5.0 mM) were added to each well of a 96-well plate followed by 180 mI_ of bacterial culture. Positive inhibition controls were wells replacing the amino-thiol compound with the control inhibitor AIP-III D4A (Tal-Gan et al., 2013) (20 mI_ of 1.0 mM stock, final concentration = 100 nM) and negative inhibition controls were wells replacing the amino-thiol compound with phosphate buffer (20 mI_, 0.1 M, pH = 7.4). The 96-well plate was incubated at 37 °C for 20-24 h under constant shaking at 282 rpm in a plate reader. P3 promoter activity (quorum sensing activity) of the bacterial population was measured by fluorescence (extinction = 513 nm, emission = 527 nm) as well as bacterial growth was measured by OD600 of each well every 30 min.
Results
S. aureus agr- 1
The tested amino-thiol compounds 1 , 2, 3, 5, 6 and 7 were able to fully inhibit the quorum sensing activity of S. aureus agr- 1 at a concentration of 10 mM over a time span of 20 h (Fig. 10). Further, compounds 3, 5 and 6 displayed equal inhibitory properties at a concentration of 5.0 mM. Compound 8 (N-acetyl L-cysteine) as well as compound 9 (D-penicillamine) were not able to inhibit the quorum sensing activity of S. aureus agr- 1.
S. aureus agr- II
The tested amino-thiol compounds 1 , 2, 3, 5, 6 and 7 were able to fully inhibit the quorum sensing activity of S. aureus agr- II at a concentration of 10 mM over a time span of 20 h (Fig. 11). Further, compounds 2, 3, 5 and 6 displayed equal inhibitory properties at a concentration of 5.0 mM. Compound 8 (N-acetyl L-cysteine) was not able to inhibit the quorum sensing activity of S. aureus agr- II, while compound 9 (D- penicillamine) displayed only reduced inhibitory properties.
S. aureus agr- III
The tested amino-thiol compounds 1 , 2, 4, 3, 5, 6 and 7 were able to fully inhibit the quorum sensing activity of S. aureus agr- III at a concentration of 10 mM over a time span of 24 h (Fig. 12). Further, compounds 1 , 2, 3, and 5 displayed equal inhibitory properties at a concentration of 5.0 mM. Compound 8 (N-acetyl L-cysteine) as well as compound 9 (D-penicillamine) were not able to inhibit the quorum sensing activity of S. aureus agr-lll.
S. aureus agr- IV
The tested amino-thiol compounds 1 , 2, 3, 5, 6 and 7 were able to fully inhibit the quorum sensing activity of S. aureus agr- IV at a concentration of 10 mM over a time span of 20 h (Fig. 13). Further, compounds 2, 5 and 6 displayed equal inhibitory properties at a concentration of 5.0 mM. Compound 8 (N-acetyl L-cysteine) as well as compound 9 (D-penicillamine) were not able to inhibit the quorum sensing activity of S. aureus agr-IV.
Conclusions
This example demonstrates that various amino-thiol compounds can effectively inhibit agr-mediated quorum sensing of the four agr-l-IV types of S. aureus. Hence, amino- thiol compounds of this type can inhibit agr-mediated quorum sensing regardless of the autoinducing peptide employed by the bacterial strains as long as the peptide contains a thiolactone functionality. Even though compound 1 (L-cysteine) strongly inhibits agr- mediated quorum sensing, compound 2 (L-cysteine methyl ester) compound 3
(cysteamine), compound 5 (L-cysteine benzyl amide) and compound 6 (L-cysteine piperidyl amide) displayed a superior effect toward inhibition of quorum sensing in the bacteria tested. In contrary, compound 9 (D-penicillamine) shows no to very reduced inhibition of agr-mediated quorum sensing. The example further demonstrates that a free amino-thiol functionality is required to observe the inhibitory effect. Hence, compound 8 (N-acetyl L-cysteine) does not produce any inhibitory effect on agr- mediated quorum sensing. The vast majority of staphylococcal pathogens as well as other Gram-positive bacteria such as Listeria, Lactobacilli and Clostridia utilize thiolactone containing autoinducing peptides and hence, can be inhibited by amino- thiol chemotypes.
Example 6: Quorum sensing deactivation of a virulent Staphylococcus aureus agr- 1 fluorescent reporter strain by amino-thiol compounds using a 96-well plate
fluorescence assay
Bacterial reporter strain
A fluorescent S. aureus reporter strain of agr type I that expresses the green fluorescent protein (GFP) upon inhibition of agr-mediated quorum sensing is used for quorum sensing deactivation assays. The bacterial reporter strain represses the expression of GFP when agr-mediated quorum sensing is induced.
Figure imgf000048_0001
General procedure of quorum sensing deactivation assay of induced cultures using a spa::gfp fluorescence reporter strain Stock solutions of amino-thiol compounds were prepared with a concentration of 100 mM in phosphate buffer (0.1 M, pH = 7.4) for free base compounds and in phosphate buffer (0.1 M, pH = 8.0) for hydrochloride salts. The assays were performed in black 96-well microtiter plates with clear bottom. The fluorescent S. aureus reporter strain of agr type I ( spa::gfp ) was streaked on agar plates and grown over night at 37 °C. A single colony of the reporter strain was then inoculated in 20 ml_ TSB medium containing chloramphenicol and synthetic S. aureus AIP-I (50 nM) to induce quorum sensing activity. The induced culture was grown at 37 °C in an incubator with 200 rpm shaking to early exponential phase (optical density at a wavelength of 600 nm (OD600) = 0.35). Amino-thiol compound stock solutions (20 mI_) in 1 :2 serial dilution (final concentration = 10 mM-5.0 mM) were added to each well of a 96-well plate followed by 180 mI_ of bacterial culture. Positive inhibition controls were wells replacing the amino- thiol compound with the control inhibitor AIP-III D4A (Tal-Gan et al., 2013) (20 mI_ of 1.0 mM stock, final concentration = 100 nM) and negative inhibition controls were wells replacing the amino-thiol compound with phosphate buffer (20 mI_, 0.1 M, pH = 7.4).
The 96-well plate was incubated at 37 °C for 20 h under constant shaking at 282 rpm in a plate reader. P3 promoter activity (quorum sensing activity) of the bacterial population was measured by fluorescence (extinction = 488 nm, emission = 509 nm) as well as bacterial growth was measured by OD600 of each well every 30 min.
Results
The tested amino-thiol compounds 3 (concentration = 10 mM) and 5 (concentration = 5.0 mM) were able to inhibit agr-mediated quorum sensing of induced (virulent) bacterial cultures of S. aureus agr- 1 to same extent as the control inhibitor AIP-III D4A (Fig. 14) over a time span of 20 h. Compound 1 (concentration = 10 mM) showed less efficient inhibition and compound 8 (concentration = 10 mM) had no effect on agr- mediated quorum sensing of induced (virulent) bacterial cultures of S. aureus agr- 1.
Conclusion
This example demonstrates that amino-thiol compounds 3 and 5 are can effectively inhibit agr-mediated quorum sensing of an induced (virulent) S. aureus agr- 1. Hence, amino-thiol compounds can not only be used to prevent bacteria from turning virulent but can effectively reverse virulence of induced cultures through inhibition of agr- mediated quorum sensing. The example further demonstrates that a free amino-thiol functionality is required to observe the inhibitory effect. Hence, compound 8 (N-acetyl L-cysteine) has no effect on agr-mediated quorum sensing of virulent cultures of S. aureus agr- 1.

Claims

Claims
1. A compound according to the formula (I),
Figure imgf000051_0001
or a pharmaceutically acceptable salt thereof,
wherein n is 0 or 1 ;
z is 0 or 1 ;
Ri is selected from the group consisting of: H and alkyl;
R2 and R3 are independently of each other selected from the group consisting of: hydrogen, halogen, and alkyl;
Y is selected from the group consisting of: -(CO)R4, -CO2R4, -0(CO)R4,
-NR5(CO)R4, -(CO)N(R5)R4, -C(R5)=C(R4)Re, -CC-R4, -aryl-R4, -heteroaryl-R4, hydrogen, and a bond to R2; and
R4, R5, and R6 are independently of each other selected from the group consisting of: hydrogen, alkyl, aryl, and heteroaryl;
for use in the prevention or treatment of a bacterial infection in a subject.
2. The compound for use according to claim 1 , wherein the bacterial infection is on the skin and/or a mucosal surface.
3. The compound for use according to claim 2, wherein the mucosal surface is on an eye, an ear, inside the nose, inside the mouth, on the lip, vagina, the urethra, the bladder and/or the gastrointestinal tract, such as the oesophagus, or the anus, of the subject.
4. The compound for use according to any one of the preceding claims, wherein the bacterial infection is in a wound.
5. The compound for use according to any one of the preceding claims, wherein the prevention or treatment is by attenuation, inhibition or reduction of virulence in the bacteria.
6. The compound for use according to any one of the preceding claims, wherein the use decreases the pathogenicity of the bacteria.
7. The compound for use according to any one of the preceding claims, wherein the compound is administered prior to, simultaneously with, or subsequently to an antimicrobial agent.
8. The compound for use according to claim 7, wherein the use increases the
susceptibility of the bacteria to the antimicrobial agent.
9. The compound for use according to any one of the preceding claims, wherein the prevention or treatment is by attenuation of virulence of the bacteria without significantly inhibiting bacterial growth.
10. The compound for use according to any one of the preceding claims, wherein the use reduces or inhibits formation of abscesses on the skin.
11. The compound for use according to any one of the preceding claims, wherein the use reduces or inhibits dermo-necrosis.
12. The compound for use according to any one of the preceding claims, wherein the compound does not significantly reduce, inhibit or degrade bacterial biofilm.
13. The compound for use according to any one of the preceding claims, wherein the compound reduces, inhibits or degrades bacterial biofilm.
14. The compound for use according to any one of the preceding claims, wherein the compound is capable of reacting with a bacterial autoinducing peptide (AIP) thereby inactivating the AIP and inhibiting quorum sensing.
15. The compound for use according to any one of the preceding claims, wherein the bacterial autoinducing peptide is one or more or all of S. aureus AIP-I, AIP-II, AIP-III, and AIP-IV.
16. The compound for use according to any one of the preceding claims, wherein the compound inhibits accessory gene regulator (agr) mediated signaling of the bacteria.
17. The compound for use according to claim 161-16, wherein the inhibition of agr mediated signalling is determined by a quorum sensing inhibition assay using one or more fluorescence reporter strains.
18. The compound for use according to any one of the preceding claims, wherein the attenuation, inhibition or reduction of virulence in the bacteria is maintained for at least 30 min, such as at least 1 hour, such as at least 2 hours, such as at least 3 hours, such as at least 4 hours, such as at least 5 hours, such as at least 6 hours, such as at least 7 hours, such as at least 8 hours, such as at least 9 hours, such as at least 10 hours, such as at least 11 hours, such as at least 12 hours, such as at least 13 hours, such as at least 14 hours, such as at least 15 hours, such as at least 16 hours, such as at least 17, such as at least 18 hours, such as at least 19 hours, such as at least 20 hours, such as at least 21 hours, such as at least 22 hours, such as at least 23 hours, such as at least 24 hours, after administering a single dose of the compound to the subject.
19. The compound for use according to any one of the preceding claims, wherein the compound is administered to the subject at least once a day, such as at least two times a day, such as at least three times a day.
20. The compound for use according to any one of the preceding claims, wherein the compound is administered every second day.
21. The compound for use according to any one of the preceding claims, wherein the compound is administered by topical administration.
22. The compound for use according to claim 21 , wherein the topical administration is via a cream, a solution, a foam, a gel, a lotion, an ointment, a transdermal patch, a powder, a sponge, a tape, or a paste.
23. The compound for use according to any one of the preceding claims, wherein the compound is administered via a wound dressing or a catheter.
24. The compound for use according to any one of the preceding claims, wherein the bacterial infection is caused by a Gram-positive bacterium.
25. The compound for use according to claim 24, wherein the Gram-positive bacterium comprises an agr.
26. The compound for use according to any one of the preceding claims, wherein the bacterial infection is caused by a bacterium selected from the group consisting of: staphylococci, listeria, and Clostridium.
27. The compound for use according to claim 26, wherein the staphylococci are
selected from the group consisting of: S. aureus, S. epidermidis, S. lugdunensis, S. haemolyticus, S. capitis, S. caprae, S. cohnii, S. pasteuri, S. pettenkoferi, S.
schleiferi, S. sciuri, S. simulans, S. warneri, S. xylosus, S. hominis, S. argenteus, S. arlettae, S. auricularis, S. carnosus, S. chromogenes, S. hyicus, S. jettensis, S. lentus, S. saprophyticus, S. schweitzeri, S. vitulinus, S. agnetis, S. argensis, S. caseolyticus, S. condimenti, S. devriesei, S. edaphicus, S. equorum, S. felis, S. fleuretti, S. gallinarum, S. kioosii, S. lutrae, S. massiliensis, S. microti, S. muscuae, S. nepalensis, S. petrasii, S. piscifermentans, S. pulvereri, S. rostri, S.
saccharolyticus, S. simiae, S. stepanovicii, and S. succinus.
28. The compound for use according to any one of claims 26-27, wherein the
staphylococci are selected from the group consisting of: S. aureus, S. epidermidis, S. lugdunensis, and S. saprophyticus.
29. The compound for use according to claim 28, wherein the S. aureus comprises an accessory gene regulator (agr) type selected from the group consisting of: agr- 1, agr-ll, agr-lll, and agr-IV.
30. The compound for use according to claim 28, wherein the S. epidermidis comprises an accessory gene regulator (agr) type selected from the group consisting of: agr- 1, agr-ll, and agr-lll.
31. The compound for use according to claim 28, wherein the S. lugdunensis comprises an accessory gene regulator (agr) type selected from the group consisting of: agr- 1 and agr-ll.
32. The compound for use according to claim 26, wherein the listeria are listeria
monocytogenes.
33. The compound for use according to claim 26, wherein the Clostridium is selected from the group consisting of: Clostridium difficile, Clostridium perfringens,
Clostridium acetobutylicum, and Clostridium butyricum.
34. The compound for use according to claim 26, wherein the Clostridium is selected from the group consisting of: Clostridium difficile and Clostridium perfringens.
35. The compound for use according to any one of the preceding claims, wherein the bacterial infection is caused by an antibiotic-resistant bacterium, such as a multi- resistant bacterium.
36. The compound for use according to claim 35, wherein the antibiotic-resistant
bacterium is selected from the group consisting of: S. aureus and Clostridium difficile.
37. The compound for use according to claim 35, wherein the antibiotic-resistant
bacterium is a methicillin resistant bacterium, such as methicillin resistant S. aureus (MRSA) or Vancomycin resistant S. aureus (VRSA).
38. The compound for use according to any one of the preceding claims, wherein the subject is a vertebrate, such as a mammal.
39. The compound for use according to claim 38, wherein the mammal is a human being.
40. The compound for use according to claim 38, wherein the mammal is a dog, a horse, a goat, a sheep or a pig.
41. The compound for use according to any one of the preceding claims, wherein the compound of formula (I) is a bacterial quorum sensing inhibitor.
42. The compound for use according to any one of the preceding claims, wherein Ri is hydrogen or methyl.
43. The compound for use according to any one of the preceding claims, wherein Ri is hydrogen.
44. The compound for use according to any one of the preceding claims, wherein R2 and R3 both are methyl.
45. The compound for use according to any one of claims 1-43, wherein R2 and R3 both are hydrogen.
46. The compound for use according to any one of claims 1-43, wherein R2 or R3 is hydrogen.
47. The compound for use according to any one of claims 1-43, wherein R2 or R3 is methyl.
48. The compound for use according to any one of the preceding claims, wherein R4 is selected from the group consisting of: alkyl, aryl, and heteroaryl.
49. The compound for use according to any one of the preceding claims, wherein R4 is a C1 to C6 alkyl.
50. The compound for use according to any one of the preceding claims, wherein R4 is methyl.
51. The compound for use according to any one of the preceding claims, wherein n is 0.
52. The compound for use according to any one of the preceding claims, wherein z is 0.
53. The compound for use according to any one of the preceding claims, wherein Y is selected from the group consisting of: -CO2R4 and -0(C0)R4, and wherein R4 is as defined in any one of the preceding claims.
54. The compound for use according to any one of claims 1-53, wherein Y is a bond to the terminal carbon of R2, and R2 is a C3, C4, or C5 alkyl.
55. The compound for use according to any one of claims 1-53, wherein Y is
heteroaryl, such triazole.
56. The compound for use according to any one of claims 1-41 , wherein the compound is of formula (la),
Figure imgf000057_0001
wherein Ri is selected from the group consisting of: H and C1 -6 alkyl,
X is selected from the group consisting of:
Figure imgf000057_0002
wherein
R4 and R5 are independently of each other selected from the group consisting of: H, alkyl, aryl, and heteroaryl; and
v is selected from the group consisting of: 1 , 2, 3, and 4.
57. The compound for use according to claims 56, wherein the compound is of formula (la) and the bacterial infection is caused by a Gram-positive bacterium, wherein the Gram-positive bacterium comprises an agr, optionally wherein the Gram-positive bacterium is selected from the group consisting of: staphylococci, listeria, and Clostridium.
58. The compound for use according to any one of claims 1-41 , wherein the compound is cysteamine for use in the treatment or prevention of a bacterial infection caused by a Gram-positive bacterium, wherein the Gram-positive bacterium comprises an agr, optionally wherein the Gram-positive bacterium is selected from the group consisting of: staphylococci, listeria, and Clostridium.
59. The compound for use according to any one of the preceding claims 1-50, wherein the compound is of formula (II),
Figure imgf000058_0001
wherein Ri , R2, R3 and R4 are as defined in any one of the preceding claims.
60. The compound for use according to claim 59, wherein the compound is of formula
(HI),
Figure imgf000058_0002
wherein R4 is as defined in any one of the preceding claims.
61. The compound for use according to any one of the preceding claims, wherein R4 is selected from the group consisting of:
Figure imgf000058_0003
wherein;
i is selected from the group consisting of 1 , 2, and 3;
Ar is aryl, such as C6-10 aryl substituted by one, two, or three substituents; and T is selected from the group consisting of: -(CO)R7, -CO2R7, -0(CO)R7,
-NR8(CO)R7, -(CO)N(RS)R7, -C(RS)=C(R7)R9, -CC-R7, -aryl-R7, -heteroaryl-R7, and hydrogen; wherein
R7, Re, and Rg are independently of each other selected from the group consisting of: hydrogen, alkyl, aryl, and heteroaryl.
62. The compound for use according to any one of claims 1-41 , wherein the compound is selected from the group consisting of: L-cysteine methyl ester, L-cysteine, and D- cysteine, preferably L-cysteine methyl ester.
63. The compound for use according to any one of claims 1-41 , wherein the compound is selected from the group consisting of:
Figure imgf000059_0001
64. The compound for use according to any one of claims 1-41 , wherein the compound is selected from the group consisting of:
Figure imgf000059_0002
65. A composition for use in the treatment or prevention of a bacterial infection in a subject, said composition comprising the compound as defined in any one of the preceding claims and one or more excipients.
66. A method for treatment or prevention of a bacterial infection, the method
comprising administering to a subject a compound or a composition as defined in any one of the preceding claims, and a further antimicrobial agent.
67. A method for preventing bacterial colonization of a wound, said method comprising administering a compound or a composition as defined in any one of the preceding claims to the wound of a subject.
68. A method for inhibiting or reducing bacterial virulence on the skin of a subject, said use comprising contacting a compound or a composition as defined in any one of the preceding claims with the skin of the subject.
69. A method for inhibiting quorum sensing of bacteria comprising contacting a
compound or a composition as defined in any one of the preceding claims with the bacteria.
70. A method for treatment or prevention of bacterial damage or disease in a subject, comprising administering a compound or a composition as defined in any one of the preceding claims to the subject.
71. A method for decreasing the pathogenicity of bacteria in or on a subject, comprising administering a compound or a composition as defined in any one of the preceding claims to the subject.
72. A method for increasing the susceptibility of bacteria in or on a subject to an
antimicrobial agent.
73. A medical device comprising a compound or a composition as defined in any one of the preceding claims.
74. The medical device according to claim 73, wherein the medical device is selected from the group consisting of: a wound dressing and a catheter.
75. Use of a compound or a composition as defined in any one of the preceding claims for the manufacture of a medicament for the treatment or prevention of a bacterial infection in a subject.
PCT/EP2020/060066 2019-04-12 2020-04-08 Cysteine derivatives for treatment and prevention of bacterial infections WO2020208093A1 (en)

Applications Claiming Priority (4)

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