Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D401/00—Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, at least one ring being a six-membered ring with only one nitrogen atom
  • C07D401/02—Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, at least one ring being a six-membered ring with only one nitrogen atom containing two hetero rings
  • C07D401/12—Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, at least one ring being a six-membered ring with only one nitrogen atom containing two hetero rings linked by a chain containing hetero atoms as chain links
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D219/00—Heterocyclic compounds containing acridine or hydrogenated acridine ring systems
  • C07D219/04—Heterocyclic compounds containing acridine or hydrogenated acridine ring systems with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to carbon atoms of the ring system
  • C07D219/06—Oxygen atoms
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D417/00—Heterocyclic compounds containing two or more hetero rings, at least one ring having nitrogen and sulfur atoms as the only ring hetero atoms, not provided for by group C07D415/00
  • C07D417/02—Heterocyclic compounds containing two or more hetero rings, at least one ring having nitrogen and sulfur atoms as the only ring hetero atoms, not provided for by group C07D415/00 containing two hetero rings
  • C07D417/04—Heterocyclic compounds containing two or more hetero rings, at least one ring having nitrogen and sulfur atoms as the only ring hetero atoms, not provided for by group C07D415/00 containing two hetero rings directly linked by a ring-member-to-ring-member bond
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D417/00—Heterocyclic compounds containing two or more hetero rings, at least one ring having nitrogen and sulfur atoms as the only ring hetero atoms, not provided for by group C07D415/00
  • C07D417/14—Heterocyclic compounds containing two or more hetero rings, at least one ring having nitrogen and sulfur atoms as the only ring hetero atoms, not provided for by group C07D415/00 containing three or more hetero rings
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12Q—MEASURING OR TESTING PROCESSES INVOLVING ENZYMES, NUCLEIC ACIDS OR MICROORGANISMS; COMPOSITIONS OR TEST PAPERS THEREFOR; PROCESSES OF PREPARING SUCH COMPOSITIONS; CONDITION-RESPONSIVE CONTROL IN MICROBIOLOGICAL OR ENZYMOLOGICAL PROCESSES
  • C12Q1/00—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions
  • C12Q1/26—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions involving oxidoreductase
  • C12Q1/28—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions involving oxidoreductase involving peroxidase
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
  • G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
  • G01N33/50—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing
  • G01N33/53—Immunoassay; Biospecific binding assay; Materials therefor
  • G01N33/531—Production of immunochemical test materials
  • G01N33/532—Production of labelled immunochemicals
  • G01N33/533—Production of labelled immunochemicals with fluorescent label
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
  • G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
  • G01N33/50—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing
  • G01N33/58—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing involving labelled substances
  • G01N33/582—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing involving labelled substances with fluorescent label
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S435/00—Chemistry: molecular biology and microbiology
  • Y10S435/968—High energy substrates, e.g. fluorescent, chemiluminescent, radioactive
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S436/00—Chemistry: analytical and immunological testing
  • Y10S436/80—Fluorescent dyes, e.g. rhodamine
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S436/00—Chemistry: analytical and immunological testing
  • Y10S436/904—Oxidation - reduction indicators

Definitions

• the present invention relates to a chemical compound comprising a light emitting moiety precursor and a precursor of a leaving group, bound to each other by an amide or by an ester bond and characterized in that the leaving group precursor upon oxidation is converted into the leaving group.
• the invention also relates to compounds additionally comprising a coupling group to the use of such compounds for labeling of biomolecules and more generally to the use of such compounds in chemiluminescence detection procedures.
• the specific detection and quantitation of biological molecules has been accomplished with excellent sensitivity for example by the use of radio-labeled reporter molecules.
• the first radio immunoassays developed in the end of the 1950's have matured into the most important tools of in vitro diagnostics, especially in medicine, using a broad variety of different detection or reporter systems.
• Well-known examples of reporter molecules are enzymes, labeled latex beads, fluorescent dyes and especially chemiluminescent dyes. Reviews describing the theory and practice of specific binding assays are available.
• luminophores have in many applications replaced isotopic labels. Some of the new luminescent labels facilitate analyte detection at extremely low levels of sensitivity. Therefore such labels also commercially are very interesting.
• Luminescent labels may be subdivided into the group of fluorescent labels and the group of luminescent labels. Whereas fluorescent labels require irradiation of a sample with excitation light in order to detect and measure the fluorescent label present, the chemiluminescent systems do not require an extra source of light. Well known chemiluminescent based systems make use of labels comprising amongst others the following categories, the combination of luciferins with corresponding luciferases, cyclic arylhydrazides, acridinium derivatives, stable dioxetanes, and oxalic acid derivatives.
• Acridinium esters represent a very important class of compounds used in chemiluminescence.
• An essential feature of such an acridinium ester is that the ester function has been substituted to carry a suitable leaving group. Suitable leaving groups are designed to match as good as possible two essential requirements: stability and high quantum yield.
• the leaving group of an acridinium esters must be as active as possible, i.e., leaving quite readily under measurement conditions, to allow for a sensitive detection and high quantum yield.
• This high activity goes to the expense of instability towards hydrolysis.
• Such instabilities are even more critical if such chemiluminescent labels are used for conjugation to biomolecules.
• the goal to achieve a high chemiluminescent yield and in addition a high stability of the labeled reagent equals to a fine balance act always ending in a compromise between light yield and stability.
• N-sulfonamides e.g., described in US 5,669,819, thioesters as described in DE 3 645 292, hydroxamic acid esters described in WO 98/56765, imidazolides as described by Waldrop III, A. A., et al., Luminescence 15 (2000) 169-182, and pyridinium amides (WO 95/19976).
• Some chemicals comprising an acridinium or an acridan dye and a phenol or hydroxy- phenol group bound by ester bond are known from a different field of research. These acridinium or acridan ester have been used as enzyme substrates or the phenol group has been described to modulate the hydrolytic stability or lability, respectively, of the ester bond (WO 97/33884; WO 01/09372; EP 625 510).
• compounds can be synthesized comprising a light emitting moiety precursor and a precursor of a leaving group which help to overcome problems known in the art.
• These novel compounds comprise a stable amide bond between a nitrogen atom of the leaving group precursor and a carbonyl group of a light emitting moiety precursor, wherein this nitrogen atom is part of a redox system or they comprise a stable ester bond between an oxygen atom of the leaving group precursor and a carbonyl group of the light emitting group precursor, wherein this oxygen is part of a redox system.
• the amide bond or the ester bond becomes activated and the light emitting group precursor is ready to generate chemiluminescence after reaction with peroxide.
• the present invention relates to a chemical compound comprising a light emitting moiety precursor and a precursor of a leaving group, wherein a carbonyl group of said light emitting moiety precursor is linked via amide bond or via ester bond to the leaving group precursor, characterized in that said leaving group precursor upon oxidation is converted into a leaving group.
• the invention also relates to compounds comprising a light emitting moiety precursor, a precursor of a leaving group and a coupling group.
• the compounds according to the present invention encompass both storage stability, as well as sensitive detection in chemiluminescent procedures they are also used to label biomolecules and the resulting conjugates with great advantage can be applied in appropriate specific binding assays for detection of an analyte in a sample.
• novel compounds can be used in the detection of peroxide as well as in the detection of peroxidase.
• the invention also relates to a method of performing a chemiluminescence measurement using a novel compound as described in which method the leaving group precursor first is oxidized, the light emitting group precursor becomes reactive, energy in form of light is generated according to standard procedures and the emitted light is measured as usual.
• the present invention relates to a chemical compound comprising a light emitting moiety precursor and a precursor of a leaving group, wherein a carbonyl group or a chemically equivalent group of said light emitting moiety precursor is linked via amide bond to a nitrogen atom of the leaving group precursor which is characterized in that said leaving group precursor upon oxidation is converted into the leaving group.
• the present invention also relates to a chemical compound comprising luciferin as a light emitting moiety precursor and a precursor of a leaving group, wherein a carbonyl group or a chemically equivalent group of said luciferin is linked via ester bond to an oxygen atom of the leaving group precursor, characterized in that said leaving group precursor upon oxidation is converted into the leaving group.
• the chemical compounds according to the present invention comprise a light emitting moiety precursor and a precursor of a leaving group. These two chemical entities are linked together via an amide or an ester bond. This amide or this ester bond, respectively, is stable thus ensuring the stability of the overall chemical structure. This rather stable bond, e.g., is not hydrolyzed under physiological conditions or under routine storage conditions.
• the chemical compound according to the present invention may also be described as a derivative of a light emitting moiety. These novel derivatives of a light emitting moiety can be easily handled, e.g., during conjugation to biomolecules or under long-term storage conditions, e.g. as required for many commercial applications.
• a "light emitting moiety precursor" in the sense of the present invention comprises such chemical moieties, which upon appropriate activation can be used and measured in an analysis system based on the detection of chemiluminescence.
• Well-known classes of chemical compounds used in chemiluminescent labeling comprise amongst others luciferins in combination with the corresponding luciferases, cyclic arylhydrazides, acridinium derivatives, stable dioxetanes, and oxalic acid derivatives.
• the light emitting moiety precursor of the present invention must carry a carbonyl group or a chemically equivalent group.
• the light emitting moiety precursor in a compound according to the present invention, is not present as a free light emitting group precursor but rather it comprises an amide or ester of the leaving group precursor.
• the light emitting moiety precursor in the compounds described has to be understood as the carboxylic acid part of an ester or amide of the free light emitting group precursor.
• the characteristic and important function of the carbonyl group is that nucleophils, like H 2 O 2 , can attack the sp 2 carbon atom. It is well-known that groups like thiocarbonyls or cyanimino residues bring about similar chemical properties. Amongst these groups carbonyl groups are preferred. In order to avoid linguistic redundancies, in the following in most cases simply the term carbonyl group is used. It has to be understood, however, that appropriate functional equivalents may as well be used.
• the leaving group precursor is converted into the leaving group, and as the term indicates, leaves after reaction of the carbonyl group with peroxide.
• the carbonyl group which is part of the stable amide or ester bond is the same carbonyl function which (after the leaving group has been formed) upon attack by peroxide and accompanied by emission of light is cleaved off from the light emitting moiety precursor.
• chemiluminescence labels are the acridinium compounds. Their mechanism of chemiluminescence has been extensively studied and is nicely summarized in a review article published in "Angewandte Chem. Intern. Ed. Engl.”, by Mayer, A. and Neuenhofer, S. (1994) 1044-1072, Weinheim, VCH Verlagsgesellschaft mbH.
• the carbonyl group (which has been part of the amide or ester bond) by attack of H 2 O 2 becomes part of a dioxetanone moiety.
• Spontaneous decomposition of the dioxetanone moiety is accompanied by light emission and yields a heterocyclic ketone and CO 2 in case of a carbonyl group, or in more general chemical terms a heterocumulene in case functional equivalents of the carbonyl group had been present.
• the light reaction (LR) and the dark processes (DP) both are dependent on the properties of the leaving group Z.
• a precursor of a leaving group is present.
• the term "precursor of a leaving group" is used to indicate that without farther chemical modification, according to the present invention oxidation, the leaving group precursor will not function as leaving group or at least is rather a poor leaving group and no light emitting moiety precursor will be set free. Without oxidation of the aromatic system of the leaving group precursor the amide bond between the light emitting moiety precursor and the leaving group precursor is stable towards hydrolysis.
• precursors of a leaving group are used instead of a leaving group, precursors, which are characterized in that they contain an "oxidizable" nitrogen within an amide bond which is also part of an aromatic system or an "oxidizable” oxygen atom of an ester bond.
• the nitrogen or oxygen atom is part of the reduced form of a two step donor-pi-donor redox system, also known as reversible two step redox system, as described by Huenig (Huenig S., Pure Appl Chem, 62 (1990) 395-406).
• Oxidizable nitrogen atoms of appropriate aromatic systems are well-known in the art.
• the most popular oxidizable aromatic systems are leuko-dyes, which upon oxidation are converted into dyes.
• the electron-rich nitrogen of the leuko-dye upon oxidation is converted into an electron poor nitrogen. This oxidation renders the amide bond highly unstable and the oxidized form of such leaving group precursor now efficiently works as leaving group.
• the chemical compound according to the present invention is a compound according to formula 1.
• R -NR 3 R 4 , -OR 5 , -SR 6 , -NR 7 NR 3 R 4
• R 2 H, R 1 , (C ⁇ -C ⁇ o)-alkyl, C 2 - do alkenyl, C 2 -C ⁇ o alkynyl, C 6 -C 22 aryl, SO 3 " ,-COOH, -halogen, nitro, anellated benzene ,
• R 3 to R 7 H, (C ⁇ -C ⁇ o)-alkyl, C 2 - C ]0 alkenyl, C 2 -C 10 alkynyl, C 6 -C 22 aryl; wherein any alkyl, alkenyl, alkynyl or aryl can be substituted by one or more moieties selected from the group consisting of -halogen, a coupling group, -OPO 3 2" , -PO 3 2" , -SO 3 " ,
• LEGP stands for light emitting group precursor.
• R 1 is -NR 3 R 4 or -OR 5 , wherein R 3 to R 5 independently is H, (d-C 10 )-alkyl or an (d-C ⁇ o)-alkyl substituted by a coupling group.
• Rl is -N(-ethyl) 2 , -O-ethyl, N(-methyl) 2 , O-methyl or one of these residues substituted by a coupling group.
• R 2 preferably is H or -methyl.
• the compound according to the present invention is represented by Formula 2.
• Ri and Ri' independently are residues as defined above for R 1 ,
• R 2 and R 2 ' are independently residues as defined above for R 2
• LEGP is the light emitting group precursor.
• the leaving group precursor comprises the structural elements as summarized in formula 3.
• Ri and Ri' independently are residues as defined above for R 1 , R 2 and R 2 ' are independently residues as defined above for R 2 , LEGP is the light emitting group precursor, and Z represents S, O, or N-R 8 , and wherein R 8 is H, ( C ⁇ -C ⁇ o)-alkyl, C 2 - C ⁇ _ alkenyl, C 2 -C ⁇ o alkynyl, C 6 -C 22 aryl.
• the nitrogen atom is part of a redox system, preferably of an oxidizable aromatic system.
• This structural feature i.e., the nitrogen atom of the leaving group precursor being part of redox system represents a preferred embodiment according to the present invention.
• the nitrogen of the leaving group precursor is oxidized as part of this redox system.
• the amide bond between the light emitting group precursor and the oxidized nitrogen is chemically very unstable and the light emitting group precursor is readily released upon reaction with H 2 O 2 .
• the leaving group precursor is a leuko-dye. More preferred such leuko-dye can be represented by structures comprised in formula 3. It is preferred to select the leaving group from the leuko-dyes corresponding to the classes of chemical substances consisting of resorufine, oxazine and methylene blue.
• the light emitting moiety precursor comprises a chemiluminogenic heterocycle.
• chemiluminogenic heterocycles are well- known in the art and e.g. summarized in the review article by Mayer, A. and Neuenhofer, S. in "Angewandte Chem. Intern. Ed. Engl.” (1994) 1044-1072, Weinheim, VCH Verlagsgesellschaft mbH.
• the light emitting moiety precursor is selected from compounds containing a carbonyl group or a chemically equivalent functional group to which the leaving group precursor is bound by amide bond.
• the light emitting moiety (or group) precursor is selected from the following categories of chemiluminescent compounds: 4Hbenzo[e] [ 1,3] oxazine, 4,5-dihydrothiazole, luciferin, acridan and acridinium dyes.
• the signal or light emitting moiety precursor according to the invention is not restricted to the dyes themselves but also includes chemiluminescent derivatives thereof.
• the light emitting group precursor preferably is a chemiluminogenic heterocycle, which is selected from the group consisting of luciferin, acridinium and acridan.
• the present invention relates to a chemical compound comprising luciferin or an analogue thereof as a light emitting moiety precursor and a precursor of a leaving group, wherein a carbonyl group or a chemically equivalent group of said luciferin is linked via amide bond to a nitrogen atom of the leaving group precursor, characterized in that said leaving group precursor upon oxidation is converted into the leaving group.
• the light emitting precursor and the leaving group precursor are linked by an ester bond.
• LEGP is the light emitting group precursor.
• the oxygen atom of this ester bond is part of a redox system.
• Appropriate groups rendering the oxygen atom oxidizable are electron donating groups like -OR 5 , -SR 6 , -NR 3 R 4 or -NR 7 -NR 3 R 4 (wherein R 3 to R 7 are as defined above) in ortho- or para- position of the phenol residue.
• the ester bond becomes highly unstable. With other words, the leaving group precursor is converted into the leaving group.
• the leaving group precursor which is bound to the light emitting moiety precursor by ester bond is selected from the group comprising phenoles substituted with an electron donor group in ortho- or para- position.
• Most preferred electron donors are - NR 3 R 4 or -O-R 5 , wherein R preferably is -H or Ci to C 5 alkyl.
• the light emitting group precursor, in formula 4 and formula 5 is a luciferin (Formula 6) or an analogue thereto (e.g., Formula 7 or Formula 8).
• Formula 6 is a luciferin (Formula 6) or an analogue thereto (e.g., Formula 7 or Formula 8).
• X N-alkyl N-alkyl- 2-(4 hydroxyphenyl) 4,5 dihydro imidazol 5,5 dimetbyl-4- carboxylic acid.
• the present invention therefore relates to a chemical compound comprising luciferin as a light emitting moiety precursor and a precursor of a leaving group, wherein a carbonyl group or a chemically equivalent group of said luciferin is linked via ester bond to an oxygen atom of the leaving group precursor, characterized in that said leaving group precursor upon oxidation is converted into the leaving group.
• said leaving group precursor is selected from the group consisting of leuko-resorufin, and a phenol group substituted with an electron donor group in ortho- or para-position.
• the leaving group is a phenol group substituted with an electron donor group in ortho- or para-position.
• the chemical compound according to the present invention comprises two light emitting group precursors.
• the LEGP may be identical, however, it is also possible to use two different LEGPs.
• Each of these light emitting group precursors is linked to a leaving group precursor by a stable but oxidizable amide or ester bond.
• Preferably both bonds between the leaving group precursor and the light emitting group precursors are of the same type.
• structures comprising two different types of bond, e.g., an ester bond or an amide bond may be advantageous.
• the leaving group precursor preferably is a substituted phenol group. Most preferred the two light emitting group precursors are attached to this phenol group in para-position.
• R 2 and R 3 represent residues as defined above and LEGP is a light emitting group precursor
• the compounds according to the present invention comprising a light emitting moiety precursor and a precursor of a leaving group represent very attractive labels, e.g., for labeling of biomolecules.
• the methods used for coupling of labels to biomolecules have significantly matured during the past years and an excellent overview is given in "Bioconjugation” Aslam, M. and Dent, A. (1998) 216-363, London, McMillan Reference and in the chapter “Macromolecule conjugation” in “Practice and theory of enzyme immunoassays” Tijssen (1990) , Elsevier, Amsterdam.
• the chemical compound according to the present invention preferably is designed and synthesized to comprise a coupling group which matches the coupling chemistry appropriate for the biomolecule under investigation.
• the chemical compound according to the present invention comprises a light emitting moiety precursor, a precursor of a leaving group and a coupling group, wherein a carbonyl group or a chemically equivalent group of said light emitting moiety precursor is linked via amide bond to a nitrogen atom of the leaving group precursor, characterized in that said leaving group precursor upon oxidation is converted into the leaving group.
• the chemical compound comprises luciferin or an analogue thereto as a light emitting moiety precursor, a precursor of a leaving group and a coupling group, wherein a carbonyl group or a chemically equivalent group of said light emitting moiety precursor is linked via ester bond to an oxygen atom of the leaving group precursor, characterized in that said leaving group precursor upon oxidation is converted into the leaving group.
• the chemical compound according to the present invention thus preferably also contains a coupling group, which may be termed Y.
• the coupling group Y is a reactive group or activated group which is used for chemically coupling of the compound to a biomolecule.
• the group Y preferably is an activated carboxylic acid group such as a carboxylic acid halogenide, a carboxylic acid anhydride, a carboxylic acid hydrazide, a carboxylic acid azide or an active ester e.g.
• N-hydroxy-succinimide an N-hydroxy-succinimide, a p-nitrophenyl, pentafluorophenyl, imidazolyl or N-hydroxybenzotriazolyl ester, an amine, a maleimide, a thiol, a para- aminobenzoyl group or a photoactivatable group e.g. an azide.
• Y is an N- hydroxy-succinimide ester.
• the coupling group Y is selected to match the chemical function on the biomolecule to which coupling shall be performed.
• Amino groups of biomolecules can be used for chemical coupling of a marker group thereto based on "amino chemistry".
• Amino chemistry comprise amongst others the reaction of amino groups with so-called activated groups, like NHS-esters, other activated esters, acid chlorides and azides.
• Carboxyl groups on biomolecules are used for chemical coupling based on “carboxy chemistry”.
• carboxy chemistry comprise amongst others the activation of these of carboxy groups to carry the above mentioned activated groups. Coupling to e.g., amino groups on the marker is then easily performed.
• sulfhydryl groups on biomolecules are used for chemical coupling based on "sulfhydryl chemistry".
• sulfhydryl chemistry comprise amongst others the reaction of -SH groups with maleimido groups, or alkylation with ⁇ - halogen carboxylic group or by thioethers.
• the hydroxyl group of tyrosine residues or the imidazol group of histidine also may be used to covalent link compounds according to the present invention to a biomolecule by aid, e.g., of diazonium groups.
• the coupling group may be either part of the light emitting group precursor or of the leaving group precursor. It is generally accepted that large biomolecules may interfere with the luminescence light emitted by the chemiluminescent group if both the chemiluminescent group and biomolecule are in close proximity. It is therefore preferred that the coupling group is part of the leaving group precursor and to preferably use such compound for coupling to a biomolecule. In this case upon oxidation of the precursor of the leaving group the light emitting moiety precursor is released from the biomolecule and both molecules no longer are in close proximity. This is advantageous in an assay for detection of an analyte in a sample.
• compounds according to the invention are synthesized by reacting an activated form of the light emitting precursor, preferably an acid chloride, with the leaving group precursor in its reduced form.
• Chemical substances suitable as leaving group precursors like substituted anilines or phenols are commercially available or can be synthesized according to standard procedures.
• Leuko-dyes, i.e., leaving group precursors can be obtained from commercially available dyes by reduction, preferably by reduction with sodium- dithionit.
• Dye compounds already comprising a coupling group are suitable partners for synthesis of the inventive compounds in case the coupling group shall be attached to the leaving group precursor.
• NHS-ester of oxazine dyes are commercially available (e.g., Evoblue) or described in the literature (EP 0 510 668)
• Biomolecule comprises molecules and substances of interest in a therapeutic or a diagnostic field.
• Biomolecule in the sense of the present invention may be any naturally occurring or synthetically produced molecule composed of biological molecules like amino acids, nucleotides, nucleosides, lipids, and/or sugars. Non-naturally occurring derivatives thereof like artificial amino acids or artificial nucleotides or nucleic acids analogs may also be used to substitute for the biomolecule.
• biomolecule is selected from the group consisting of polypeptides, nucleic acids, and low molecular weight drugs.
• a conjugate between a biomolecule and a chemical compound comprising a light emitting moiety precursor and a precursor of a leaving group with the characteristics according to the present invention represents a further preferred embodiment. It will be readily appreciated by the skilled artisan that conjugates between a biomolecule and the chemical compounds described in the present invention is of great advantage in a specific binding assay for detection of an analyte in a sample.
• Specific binding assays in general are based on the specific interaction of two members of a bioaffiine binding pair.
• suitable binding partners in such binding pairs are hapten or antigen and an antibody reactive thereto, biotin or biotin- analogs such as amino, biotin, iminobiotin, or desthiobiotin which binds to biotin or streptavidin, sugar and lectin nucleic acid or nucleic acid analogs and complementary nucleic acid, receptor and ligand for example steroid hormone receptor and steroid hormone, and enzymes and their substrates.
• nucleic acids or nucleic acid analogs
• nucleic acids complementary thereto in assays based on detection of hybridization between nucleic acid stands and the specific interaction of antibodies with their respective antigen on which the broad range of immunoassays is based, represent the most preferred binding pairs.
• the chemical compounds as described herein have the striking feature that the amide or ester bond between a light emitting moiety precursor and a precursor of a leaving group becomes unstable upon oxidation of the leaving group precursor. Light generation i.e. chemiluminescence thus is dependent on the presence of oxidants and peroxide. It therefore is evident that the chemical compounds described can be used both in assays for detection of peroxide on the one hand as well as in assays for detection of peroxidase on the other hand. In a preferred embodiment the compounds according to the present invention are used in a method for detection of peroxide.
• Peroxidase may be used to oxidize the leaving group precursor which after oxidation functions as leaving group. Under appropriate assay conditions the presence of peroxidase thus can be detected upon measurement of chemiluminescent light emitted.
• the chemical compounds according to the present invention are used in a detection method based on the activity of peroxidase. Most preferred the novel compounds are used for detection of peroxidase.
• the present invention relates to a method of performing a luminescence measurement based on the use of a compound according to the present invention.
• the method is characterized in that in the presence of peroxide the leaving group precursor is oxidized, the light emitting group precursor is activated, energy is emitted and measured.
• the chemical compounds according to the present invention do not comprise an active leaving group.
• the leaving group precursor has to be oxidized and its oxidized form works as a leaving group. Oxidation refers to the oxidative step transforming the leaving group precursor into the leaving group. In case of donor-pi-donor leaving groups this means that redox processes according to the Wurster or Weitz type occur ( Huenig, supra).
• the oxidation is performed using a peroxidase.
• Typical chemical oxidants include per-borate, per-sulfate, DDQ (dicyano dichloro quinone), diluted HNO 3 , Br0 4 -, H 2 O 2 , or cerammonium IV nitrate.
• oxidation is performed by electrochemical means.
• the light emitting moiety precursor is readily set free after oxidation of the leaving group precursor.
• peroxide or a reactive oxygen species like the oxygen radical anion
• the precursor of the light emitting moiety according to the mechanism illustrated in Figure 1 most likely forms a dioxetane intermediate which is decarboxylated to generate an electronically excited emitter.
• the energy (light) which is thereby emitted is measured according to standard procedures and with routine equipment.
• H 2 O 2 or a reactive oxygen species like the oxygen radical anion has to be present to form the intermediate dioxetanone.
• H 2 O 2 can be added directly or generated indirectly e.g. by enzymatic reaction (glucose oxidase/glucose).
• Reactive oxygen species are generated during the chemiluminescent reaction from oxygen or H O 2 .
• a reactive oxygen species can be generated intentionally e.g. by the oxygen initiated C- C coupling ( indoxyl-phosphate, US 5,589,328).
• the light emitting group precursor is oxidized during the light generating reaction, e.g, acridan is oxidized to acridinium.
• acridan is oxidized to acridinium.
• the oxidation conditions must be chosen that no destruction of the light emitting molecule occurs.
• the reagent used for oxidation of the LEGP is the same as the one used to transform the leaving group precursor to the leaving group. Most preferred oxidation is performed and light is generated by use of H 2 O 2 in presence of peroxidase.
• the mentioned oxidation steps e.g., catalyzed by enzymes like POD can also be accelerated by the use of mediators or enhancers.
• Mediators are redox-active compounds which facilitate the oxidation of a compound by accelerating electron transfer processes.
• the mediator is oxidized by the oxidant and oxidizes then the compounds according to the invention, whereby the mediator is reduced again.
• Typical mediators are hexocyanoferrate (II) and metal complexes like ferrocene.
• Other enhancers which are used in chemiluminescense reactions include chemicals like iodo-phenol or phenyl boronic acid.
• the oxidation preferably is performed in the presence of an appropriate detergent, which creates a hydrophobic microenvironment around the light emitting heterocyclic ketone. This results in an increase of the chemiluminescence quantum yield since quenching due to interaction with water molecules is reduced.
• an appropriate fluorophor like fluorescein can be attached covalent to the detergent or alternatively a fluorophor can be added to the reaction mixture in order to get an energy transfer from the excited heterocyclic ketone to this fluorophor.
• FIG. 1 Acridinium ester: Postulated reaction mechanisms Both possible pathways are depicted.
• LR light creating reaction
• DP dark reaction pathway
• Figure 2 Schematic of an acridi__ium-9-(N-sulfonyl) carboxamide label
• Example 1 Synthesis of a compound comprising an acridinium- (9-carboxylic acid) as light emitting group precursor and an oxazine as a leaving group precursor a) Synthesis of acridinium- (9- carboxylic acid) chloride
• Example 2 Evaluation of an acridinium oxazine: Kinetics, sensitivity, quantum yield
• Trigger 1 brings about the oxidation of the leaving group precursor
• trigger 2 promotes chemiluminescense.
• Trigger 1 300 ⁇ l, 0.5% H2O2, 0.1M HNO3
• Trigger 2 300 ⁇ l, 0.25M NaOH
• Acridinium-oxazine according to example 1 was diluted to lxlO "8 Mol/1 in PBS-buffer containing 0.1% Thesit. lOO ⁇ l sample was dispensed into a 5 ml-Sarstedt tube and set into the instrument. Trigger 1 was added in position -1, trigger 2 in the measuring position of the instrument. Measurement was performed for lOsec.
• Example 3 Synthesis of D-luciferin-oxazine (compound 7 in Figure 41 (3.7-bis- cUethylaminophenoxazine-10-yl)-[4.5-dihvdro-2-(6-hydroxybenzothiazole-2-y thiazole- 4- yl] -methanone a) Synthesis of 2-(6- tert.- butyldimethylsilyloxybenzothiazole-2-yl)- 4,5 dihydro thiazole- 4-yl carboxylic acid chloride (compound 3 in Figure 4)
• the product is eluted with petrol ether/ethyl acetate 4/1 (v/v), the appropriate fractions are collected and pooled. The solvent is removed and about 760 mg enriched product is obtained, which is rechromatographed on the same system.
• the highly viscous residue is dissolved in a small volume of methylene chloride and applied to a silica gel column (Kieselgel H 60, 1.5 x 35 cm). Separation of desired product from co- forming thiazole (8 in Fig. 4) (slightly behind) is performed with petrol ether/ethyl acetate 1/1 (v/v). Product containing fractions are pooled and evaporated. The pure conjugate (7 in Fig. 4) remains as viscous, nearly colorless oil after drying at low pressure.
• Example 4 Synthesis of (3,7-bis-diethylaminophenoxazine-10-yl ' )-[4.5-d-hydro-2-( ' 6- hydroxybenzothiazole-2-yl ' l-5.5-dimethylthiazole-4-yll -methanone (structure 8 in Figure 61 a) Preparation of dimethylluciferin, (4,5-dihydro-2-(6-hydroxybenzothiazole-2-yl)-5,5- dimethylthiazole-4-yl carboxylic acid) (structure 3 in Figure 6)
• the organic layer (containing leuko-oxazine (structure 7 in Figure 6) is transferred via thin rubber tube (standard HPLC equipment) into the second flask using high argon- pressure. The resulting reaction mixture is stirred overnight at ambient temperature to give a blue green solution.
• the product is dissolved in 8 ml acetonitrile/ ethyl acetate 1/1 (v/v) and purified by preparative reversed phase HPLC (Waters Delta Pak C-18 column, 100 A, 15 ⁇ m, 50 x 300 mm). The product is eluted with an acetonitril/ distilled water gradient (0-60 % acetonitrile; 0.1 % trifluoro acetic acid). The appropriate fractions are collected and pooled. Finally the solvent is removed by lyophilisation to obtain 1.8 mg slightly green product (8 in Fig. 6).
• O-protected anilide (3 in Fig. 7) are dissolved in 3 ml dry THF and 26.15 mg (0.1 mmol) tetrabutylammonium fluoride monohydrate (TBAF; Aldrich, no. 24,151-2) in 1 ml THF added to the clear orange solution while stirring under Argon atmosphere. The color changes to a deep red and after 10 min 20 ml of dichloromethane are added. The reaction mixture is washed with 2 x 10 ml 5% ammoniumchloride and 2 x saturated bicarbonate. The organic solution is dried with a small amount of anhydrous sodium sulfat, and subsequently the solvent is removed at a rotavapor.
• TBAF tetrabutylammonium fluoride monohydrate
• the product is isolated from the deep brownish mixture by preparative HPLC (Waters Delta-Pak C-18; 100 A; 50x300 mm; 15 ⁇ m; Eluent A : 80 % H 2 O/20% Acetonitril + 0,1 % TFA; eluent B : 100 % Acetonitril + 0,1 % TFA; 0 ->80% B in 80 min).

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