WO2014182839A1 - Macrocyclic peptidomimetics with nanomolar antifungal and antimicrobial activity - Google Patents

Abstract

Enantiopure cyclic peptidomimetic antimicrobials compounds that contain S-cysteine ester units and at least one pyridine unit within the macrocyclic ring have been prepared that show exceptional antifungal and antibacterial activity. These 17- or 18-membered macrocyclic compounds display MIC values as antifungal agents as low as 7.5 nm/mL and MIC values as antibacterial agents as low as 0.2 nm/mL. All the macrocyclic peptidomimetic compounds are isolated as crystalline solids in good yield.

Description

DESCRIPTION

MACROCYCLIC PEPTIDOMIMETICS WITH NANOMOLAR ANTIFUNGAL AND

ANTIMICROBIAL ACTIVITY

RELATED APPLICATIONS

This application claims the benefit of and priority to U.S. Provisional Patent

Application No. 61/820,832 filed May 8, 2013, the contents of which are incorporated herein by reference.

BACKGROUND OF INVENTION

Infectious diseases are the second leading cause of death worldwide even though many anti-infection drugs have been commercialized. Unfortunately, bacteria and fungi develop drug resistance rather quickly by producing metabolizing enzymes for the drug's degradation, modifying the drug's targets, and/or expressing high level of efflux proteins to 'pump' drug from the organism. Overcoming drug resistance requires innovative agents that provide different modes of action so that cross-resistance to present pharmaceuticals does not occur. An urgent need exists for new chemotherapeutic agents that overcome resistance and ideally shorten the duration of therapy.

Humans are naturally well protected against most fungi, because their body temperature is generally higher than that where fungi readily grow. However, fungal infections are very dangerous to those with compromised immune systems due to HIV, transplantations, steroid therapies, or other stresses. Candidiasis is a very common fungal infection and is especially problematic when associated with bloodstream and catheter-related infections. Fusarium, Aspergillus, and Trichosporon species are other pathogens that can emerge in suppressed immune systems.

The main classes of antifungal agents are macrocyclic polyenes, echinocandins, and azoles. Macrocyclic polyenes primarily target ergosterol, a component of fungi- and yeast- cell membranes, to compromise membrane integrity to promote the leakage of cations. Amphotericin B and nystatin are typical macrocyclic polyene antimicotics. Echinocandins include micafungin and caspofungin, whose mode of action appears to be due to the inhibition of l,3-/?-glucan synthase needed for the /?-glucans building blocks of cell wall membranes. Azole antifungal agents interfere with ergosterol functions by suppression of its synthesis from lanosterol via inhibition of the fungal cytochrome P450 enzyme, lanosterol 14oc-demethylase. Many of these antifungal drugs display problems including high toxicity, growing drug resistance, and severe side-effects, which has encouraged the development of new antifungal agents by synthetic efforts or by discovery of effective natural compounds.

Chiral macrocyclic ligands have wide applications in asymmetric synthesis and enantiomeric recognition. The incorporation of amino acids into abiotic anion receptors can lead to systems that mimic the anion coordination properties of anion binding proteins. Haridas et al. , /. Am. Chem. Soc. 1998, 120, 2696-2702, disclose that inclusion of cysteine subunits into a macrocycle facilitates receptor synthesis and can control the orientation of chains attached to a cysteine residue. Most cysteine-based anion receptors contain aromatic subunits that are amphi-receptors, able to interact with both cations and anions.

Antimicrobial peptides as antibiotics are attractive based on their high antibacterial and bactericidal effectiveness, their display of a broad spectrum of action, their high structural diversity, and their potential to be lower resistance-inducing than conventional antibiotics. The potential shortcomings of antimicrobial peptides use include restriction to topical applications because of liability to proteolysis and a high production cost, which is five to twenty times higher than that of conventional antibiotics. To this end, antimicrobial compounds that can be readily prepared at reasonable costs, yet demonstrate the favorable features of antimicrobial peptides, are desirable.

BRIEF SUMMARY

Embodiments of the invention are directed to antimicrobial compounds that are macrocyclic peptidomimetics comprising two ^-cysteine units and at least one pyridine unit.

, the macrocyclic peptidomimetic has the structure:

where: R

C1-C4 alkyl, benzyl, or H; and R² is hydrogen, C1-C4 alkyl, trifluoromethyl, C1-C4 alkoxy, nitrile, or nitro.

In an embodiment of the invention, the macrocyclic peptidomimetic comprises methyl or ethyl esters of cysteine. In another embodiment of the invention, the cysteine portions are in the acid form, where R¹ is hydrogen.

The antimicrobial compounds can be included with a pharmaceutically acceptable carrier in antifungal and/or antibacterial compositions, according to embodiments of the invention. The compositions can be in the form of a solution, a suspension, or a solid. The macrocyclic peptidomimetic of antifungal compositions, according to an embodiment of the invention, provides a minimum inhibitory concentration (MIC) as low as 0.0075 μg/mL toward Candida albicans. In antibacterial compositions, a macrocyclic peptidomimetic, according to an embodiment of the invention, can display a MIC toward a gram positive S. aureus as low as 0.0005 μg/mL and to a gram negative P. vulgaris as low as 0.008 μg/mL. In antibacterial compositions, the macrocyclic peptidomimetic can display a MIC toward gram negative positive S. aureus as low as 0.0005 μg/mL.

BRIEF DESCRIPTION OF DRAWINGS

Figure 1 shows structures for peptidomimetic compounds 4 and 5, according to embodiments of the invention.

Figure 2 shows reactions schemes for the preparation of peptidomimetic compound 4, according to embodiments of the invention.

Figure 3 shows reactions schemes for the preparation of peptidomimetic compound 5, according to embodiments of the invention.

Figure 4 shows schemes for the preparation of s-(lH-benzo[d][l,2,3]triazol-l- yl)methanone) substituted R compound 2.

Figure 5 shows the preparation of pyridine dicysteine ester hydrochlorides 3a or 3b. Figure 6 shows the preparation of a pyridine dicysteine 3c.

DETAILED DISCLOSURE

An embodiment of the invention is directed to enantiopure cyclic peptidomimetic antimicrobials compounds that contain ^-cysteine ester units and at least one pyridine unit within the macrocyclic ring. The peptidomimetics, according to an embodiment of the invention, have the structure:

= C1-C4 alkyl or benzyl for 4 or H for 5; and R² is hydrogen, C1-C4 alkyl, trifluoromethyl, Ci- C₄ alkoxy, nitrile, or nitro. Figure 1 shows various structures of peptidomimetics 4, and 5 that demonstrate antifungal and antibacterial activity, according to an embodiment of the invention.

The peptidomimetic 4 is prepared by the microwave assisted macrocyclic condensation of a pyridine dicysteine ester hydrochloride 3 and a bis-(lH- benzo[d][l,2,3]triazol-l-yl)methanone substituted R compound 2, where R is 4-substituted or unsubstituted 2,6-pyridine, 5-substituted or unsubstituted 1,3-benzene, 1,2-benzene, sym- neopentane, s_ym-dimethylsulfide, s_ym-dimethylether, or 1 ,2-ethane, as illustrated in Figure 2.

The peptidomimetic 5 is prepared by the macrocyclic condensation of a pyridine dicysteine 3c and a Ws-(lH-benzo[d][l,2,3]triazol-l-yl)methanone substituted R compound 2, where R is 4-substituted or unsubstituted 2,6-pyridine, 5-substituted or unsubstituted 1,3- benzene, 1,2-benzene, s_ym-neopentane, s_ym-dimethylsulfide, s_ym-dimethylether, or 1 ,2- ethane, as illustrated in Figure 3. The macrocyclic condensation involves an S- to N-acyl migration of 3 in the presence of a tertiary amine, triethylamine, and the subsequent reaction in situ with 2.

The Ws-(lH-benzo[d][l,2,3]triazol-l-yl)methanone substituted R compound 2 is prepared by the treatment of dicarboxylic acids, HO2C-R-CO2H with thionyl chloride followed by lH-benzotriazole (BtH), according to the procedure of Berhanu et al. , Beilstein J. Org. Chem. 2012, 8, 1146-60, supporting information, incorporated herein by reference. Alternatively, compound 2 can be prepared in the manner taught in Katritzky et al., Rev. Soc. Quim. Mex. 2004, 48, 275-278, incorporated herein by reference. The synthesis of compound 2 that differs by the R units is shown in Figure 3. The syntheses of the pyridine dicysteine ester hydrochlorides 3a and 3b from pyridine-2,6-diyl- s-(lH-benzo[d][l,2,3]triazol-l- yl)methanone is shown in Figure 5, and the synthesis of pyridine dicysteine 3c is shown in Figure 6.

According to an embodiment of the invention, the cyclic peptidomimetic antimicrobial compounds 4 or 5 are employed in antifungal or antibacterial compositions for use as medicaments for the treatment of fungal or bacterial infections. The medicament, or dosage form, can be for ingestion, injection, or for use as a topical preparation. The dosage form can be in the form of a solution, a suspension, or a solid. The dosage form can include one or more other known antimicrobial compounds. The dosage form can be adapted for various routes of administration, including, but not limited to, parenteral, intravenous, intramuscular, topical, and subcutaneous, where administration is carried out once, at distinct intervals, or continuously, in a manner readily determined by a person of ordinary skill in the art. Formulations of the medicament include, for example: aqueous sterile injection solutions, which may contain antioxidants, buffers, bacteriostats, and solutes that render the formulation isotonic with the blood of the intended recipient; aqueous and nonaqueous sterile suspensions, which may include suspending agents and thickening agents; or in an edible vehicle with an assimilable edible carrier.

Pharmaceutically acceptable carriers used in formulations with 4 or 5, include, but are not limited to, inert diluents and vehicles such as: one or more excipients, buccal tablets, troches, capsules, elixirs, suspensions, syrups, wafers, and aerosol sprays. Tablets, troches, pills, capsules, and the like may, but do not necessarily, contain binders, such as gum tragacanth, acacia, corn starch or gelatin; excipients, such as dicalcium phosphate; a disintegrating agent, such as corn starch, potato starch, or alginic acid; a lubricant, such as magnesium stearate; a sweetening agent, such as sucrose, fructose, lactose or aspartame; flavoring agent, such as peppermint, oil of wintergreen, or cherry flavoring; a liquid carrier, such as a vegetable oil or a polyethylene glycol; and/or solid carriers; such as finely divided solids such as talc, clay, microcrystalline cellulose, silica, or alumina. Any material used in preparing the dosage form should be pharmaceutically acceptable and substantially non-toxic in the amounts employed. The dosage form may be a sustained-release preparation. Other dosage forms can include surfactants, fragrances, or other adjuvants. Liquid compositions for topical use can be applied from absorbent pads or be impregnated on bandages and other dressings. Thickeners, such as synthetic polymers, fatty acids, fatty acid salts and esters, fatty alcohols, modified celluloses or modified mineral materials, can be employed with liquid carriers to form spreadable pastes, gels, or ointment.

Antifungal bioassays on the enantiopure cyclic peptidomimetic antimicrobials compounds 4a-41. 5a-b, and 5i, conducted by the standard technique using Candida albicans demonstrate that all possess extraordinary antifungal activity. The experimental minimum inhibition constants (MIC) for these compounds and that of a reference, Amphotericin B (AmpB), are given in Table 4, below. The observed antifungal activities of compounds 4a-41 are more than an order of magnitude higher than that of AmpB. This high level of inhibition evidences that macrocyclic peptidomimetics 4a-41 are highly potent antifungal agents. Compounds 4a and 4k possess an extraordinary nanogram level activity of 7.5 ng/mL. Common features of 4a and 4k are: (i) they are methyl esters and (ii) both have an electronegative atom in the dicarboxythiolate moiety. Structure-activity relationships deduced from these structural features can be visualized by comparing structures 4a (methyl ester) vs. 4b (ethyl ester), 4a (pyridine nitrogen) vs. 4c (phenyl carbon), 4k (oxygen) vs. 4i (sulfur), and 4k (methyl ester) vs. 41 (ethyl ester).

A surprising dichotomy was found for the antibacterial action of the title peptidomimetics, all, with the exception of 5b exhibited a low activity against Gram-positive Staphylococcus aureus and a high activity against Gram-negative Klebsiella pneumoniae, Proteus vulgaris, and Pseudomonas aeruginosa. As seen in Table 1, activity against K. pneumoniae was extremely high, with an MIC higher than for ciprofloxacin (Cip) against C. albicans. Although not to be bound by the mechanism, the sharp difference in activity against Gram-negative and Gram-positive bacteria may be due to a thinner peptidoglycan layer in Gram-negative compared to Gram-positive bacteria, which may infer that membrane disruption is the mechanism of activity.

Table 1. Experimental antifungal and antibacterial activities of compounds 4a-l, 5a, 5b, and 5i.

MIC in μg/mL

ID C. albicans S. aureus K. pneumonia P. vulgaris P. aeruginosa

4a 0.0075 16 0.001 0.06 0.12

4b 0.030 16 0.002 16 32

4c 0.015 16 0.001 0.06 1024

4d 0.015 64 0.008 0.06 0.12

4e 0.015 16 0.001 0.06 0.12

4f 0.030 16 0.0005 0.06 0.12 4g 0.030 16 0.0005 0.06 0.12

4h 0.030 64 0.03 0.06 0.12

4i 0.030 64 0.0005 0.06 0.12

4j 0.030 16 0.001 0.06 0.12

4k 0.0075 16 0.0005 0.06 0.12

41 0.030 16 0.0002 0.06 0.12

5a 0.030 2 0.03 0.015 1024

5b 0.030 0.0005 0.001 0.008 0.03

5i 0.030 0.52 0.03 0.06 1024

AmpB 0.390 - - - -

Cip 0.39 1.5 1.5 3.1

The cyclic peptidomimetics 4a-r and 5a-i have a significantly different structure than those of known macrocyclic and acyclic antimicrobial peptides. The cyclic peptidomimetics 4 and 5, according to embodiments of the invention, lack azole groups or long hydrophobic chains as do known active macrocyclic and acyclic antimicrobial peptides, but posses a 2,6- pyridine dicarboxamide fragment and dicarboxythiolate fragments.

Mechanistically, antimicrobial peptides can be divided into two classes, those that are membrane disruptive and those that are not non-membrane disruptive, having intracellular targets. The mechanism of AmpB's antifungal action involves binding of its -mycosamine sugar group to ergosterol, which is the ubiquitous component of fungi cell walls. The reason for the excellent antifungal activity, though not to be bound by a mechanism, may result because 4 and 5 compounds are effective at binding ergosterol. A cavity formed by the amide hydrogen atoms and the pyridine nitrogen appears to be the most probable structural feature for binding to ergosterol, with a resulting fungal cell malfunction. These highly symmetric 4 and 5 compounds are macrocycles with the capacity to form cavities that are sufficiently large for encapsulation of small organic molecules. Alternatively or additionally, a possible mechanism of activity, may be similar to that of pyridine-2,6-bisthiocarboxylic acid, which is a structural fragment of compounds 4a, 4b, and 5a or a possible metabolite therefrom. Pyridine-2,6-bisthiocarboxylic acid is a siderophore, a chelating agent with high affinity to essential transition metals, especially iron. As transition metals often function as cof actors for enzymes involved in redox or hydrolytic reactions, the action of the 4 and 5 compounds may target the hem-containing enzyme, Cytochrome P450, as do azole antifungal agents. Based on the structural features of compounds 4 and 5, which have antifungal activity at even nanomolar concentrations, the activity may be multimodal, including membrane disruptive and penetrative mechanisms and the formation of complexes with polyanions (DNA) and vital enzymes (P450). Peptidomimetics compounds 4 and 5 have distinct chemical structures that differ from existing antimicrobial peptides. These antimicrobial peptidomimetic compounds, according to an embodiment of the invention, are inexpensive to synthesize, yet are effective at even nanomolar level.

METHODS AND MATERIALS

Melting points were determined on a capillary point apparatus equipped with a digital thermometer. NMR spectra were recorded in CDCI₃, or CD₃OD on Mercury or Gemini NMR spectrometers operating at 300 MHz for ¹H (with TMS as an internal standard) and 75 MHz for ¹³ C. Elemental analyses were performed on a Carlo Erba-EA1108 instrument. All microwave assisted reactions were carried out with a single mode cavity Discover Microwave Synthesizer (CEM Corporation, NC). The reaction mixtures were transferred into a 10 mL glass pressure microwave tube equipped with a magnetic stirrer bar. The tube was closed with a silicon septum and the reaction mixture was subjected to microwave irradiation (Discover mode; run time: 60 sec; PowerMax-cooling mode).

General procedure for preparation of N-acyl benzotriazole derivatives

Thionyl chloride (0.95 mL, 13.17 mmol) was added to a solution of benzotriazole (5701 mg, 47.90 mmol) in dichloromethane (100 mL) and the solution was stirred at room temperature for 20 min. Dicarboxylic acids la-f (6 mmol) were added to the mixture which was stirred at room temperature for 12 h. The precipitate was filtered off and the filtrate was extracted with saturated sodium carbonate solution (3 x 100 mL). The organic layer was dried over anhydrous sodium sulfate, filtered and evaporated under vacuum to give compounds 2a- f.

Table 2. Preparation of N-acylbisbenzotriazoles 2a-f

Product Yield (%) MP (°C) Lit MP (°C)

2a 54 226-228 Novel

2b 68 231-233 231-233^a

2c 59 167-169 167-169³

2d 72 98-100 98-100^a

2e 85 152-154 150-160^a

2f 83 142-144 142-144^a

a Katritzky et al, Rev. Soc. Quim. Mex. 2004, 48, 275-278

Pyridine-2,6-diylbis((lH-benzo[d][l,2,3]triazol-l-yl)methanone) (2a) White microcrystals. *H NMR (DMSO-i¾ δ 7.70-7.88 (br s, 2H), 7.89-8.00 (br s, 2H), 8.33-8.49 (br s, 4H), 8.50-8.80 (br s, 3H). ¹³C NMR (DMSO-i¾ δ 114.2, 120.2, 127.0, 128.9, 131.1, 131.3, 138.4, 145.2, 149.7, 164.2. Anal. Calcd for C19H11N7O2: C, 61.79; H, 3.00; N, 26.55. Found: C, 61.41; H, 2.94; N, 26.22.

lH-l,2,3-Benzotriazol-l-yl[3-(lH-l,2,3-benzotriazol-l- ylcarbonyl)phenyl]methanone (2b) *H NMR (CDC13, 300 MHz) δ 7.59 (dd, / = 8.2, 6.9 Hz, 2H), 7.76 (dd, / = 8.3, 6.9 Hz, 2H), 7.84 (t, / = 7.8 Hz, 1H), 8.19 (d, / = 8.2 Hz, 2H), 8.44 (d, / = 8.3 Hz, 2H), 8.56 (dd, / = 7.8, 1.7 Hz, 2H), 9.07 (br s, 1H); ¹³C NMR (CDC13, 75 MHz) δ 114.8, 120.3, 126.6, 128.7, 130.7, 132.0, 132.2, 135.0, 136.2, 145.8, 165.5.

lH-l,2,3-Benzotriazol-l-yl[2-(lH-l,2,3-benzotriazol-l- ylcarbonyl)phenyl]methanone (2c) White micro crystals; ^!H NMR (CDC13, 300 MHz) δ 7.49 (ddd, J = 8.4, 6.9, 0.9 Hz, 2H), 7.63 (ddd, J = 8.2, 6.9, 0.9 Hz, 2H), 7.82-7.88 (m, 2H), 8.07 (d, J = 8.2 Hz, 2H), 8.12-8.17 (m, 2H), 8.22 (d, J = 8.2 Hz, 2H); ¹³C NMR (CDC13, 75 MHz) δ 114.5, 120.3, 126.5, 130.6, 131.5, 131.6, 132.1, 133.9, 145.9, 166.4.

l,5-Di(lH-l,2,3-benzotriazol-l-yl)-3,3-dimethyl-l,5-pentanedione (2d)

Colorless prisms; *H NMR (CDC13, 300 MHz) δ 1.42 (s, 6H), 3.84 (s, 4H), 7.50 (dd, / = 8.4, 6.9 Hz, 2H), 7.64 (dd, / = 7.8, 7.5 Hz, 2H), 8.11 (d, / = 8.4 Hz, 2H), 8.27 (d, / = 8.4 Hz, 2H); ¹³C NMR (CDC13, 75 MHz) δ 28.6, 34.1, 44.4, 114.6, 120.2, 126.2, 130.4, 131.1, 146.3, 171.0. Anal. Calcd for C19H18N602 requires C, 62.97; H, 5.01; N, 23.19. Found: C, 63.01 ; H, 5.03; N, 23.37 %.

l-(lH-l,2,3-Benzotriazol-l-yl)-2-{[2-(lH-l,2,3-benzotriazol- l-yl)-2-oxoethyl]sulfanyl}- 1-ethanone (2e) Pale yellow prisms; *H NMR (CDC13, 300 MHz) δ 4.58 (s, 4H), 7.54 (dd, J = 8.1, 6.9 Hz, 2H), 7.68 (dd, / = 8.1, 6.9 Hz, 2H), 8.13 (d, / = 8.1 Hz, 2H), 8.23 (d, / = 8.1 Hz, 2H); ¹³C NMR (CDC13, 75 MHz) δ 34.8, 114.5, 120.6, 126.7, 131.0, 131.3, 146.5, 167.9. Anal. Calcd for C16H12N602S requires C, 54.54; H, 3.43; N, 23.85. Found: C, 54.75; H, 3.30; N, 23.78 %.

l-(lH-l,2,3-Benzotriazol-l-yl)-2-[2-(lH-l,2,3-benzotriazol-l-yl)-2-oxoethoxy]-l- ethanone (2f) Colorless plates; *H NMR (CDC13, 300 MHz) δ 5.56 (s, 4H), 7.54 (dd, J = 8.1, 6.9 Hz, 2H), 7.70 (dd, / = 8.1, 6.9 Hz, 2H), 8.13 (d, / = 8.1 Hz, 2H), 8.29 (d, / = 8.1 Hz, 2H); ¹³C NMR (CDC13, 75 MHz) δ 70.3, 114.2, 120.6, 126.8, 131.0, 131.1, 146.0, 168.2. Anal. Calcd for C16H12N603 requires C, 57.14; H, 3.60; N, 24.99. Found: C, 57.45; H, 3.49; N, 25.00 %.

General procedure for preparation of N-acyl benzotriazole derivatives (2g-i) Thionyl chloride (1.5 mL, 20 mmol) was added to a solution of benzotriazole (9.6 g, 80 mmol) in THF (100 mL) and the solution was stirred at room temperature for 30 min. Dicarboxylic acids lg-i (10 mmol) in THF (50 mL) were added to the mixture which was stirred at room temperature for 24-48 hours. The precipitate was filtered and washed with THF (50 mL). The solvent was removed under vacuum from the combined filtrate. To the residue, CHC13 (150 mL) was added; the mixture was washed with water (30 ml) and saturated Na2C03 (3 x 30 mL). The organic layer was dried over anhydrous Na2S04, then it was filtered and the solvent was evaporated under vacuum to obtain a solid, which was recrystallized from an appropriate solvent or solvent mixture to obtain the pure compounds 2g-i.

(5-Methylbenzene-l,3-diyl)bis(lH-benzotriazol-l-ylmethanone) (2g)

White microcrystals; yield: 70%; mp 183-185 °C. *H NMR (300 MHz, CDC13): δ = 8.82 (br s, 1 H), 8.38 (d, / = 8.4 Hz, 2 H), 8.31 (br s, 2 H), 8.14 (d, / = 8.4 Hz, 2 H), 7.71 (t, J = 7.7 Hz, 2 H), 7.54 (t, / = 7.8 Hz, 2 H), 2.60 (s, 3 H). ¹³C NMR (75 MHz, CDC13): δ =

165.9, 146.0, 139.2, 136.9, 32.5, 132.4, 132.1, 130.8, 126.8, 120.5, 115.0, 21.7. Anal. Calcd for 21H14N602: C, 65.96; H, 3.69; N, 21.98. Found: C, 65.64; H, 3.66; N, 21.96.

(5-Nitrobenzene-l,3-diyl)bis(lH-benzotriazol-l-ylmethanone) (2h)

White microcrystals; yield: 68%; mp 200-202 °C. *H NMR (300 MHz, CDC13): δ = 9.41- 9.40 (m, 1 H), 9.38 (d, / = 1.5 Hz, 2 H), 8.44 (d, / = 8.1 Hz, 2 H), 8.22 (d, / = 8.4 Hz, 2 H), 7.80 (t, J = 7.7 Hz, 2 H), 7.63 (t, J = 7.7 Hz, 2 H). ¹³C NMR (75 MHz, CDC13): δ = 163.7, 146.1, 139.8, 133.9, 132.1, 132.0, 131.5, 130.6, 127.4, 120.9, 115.0. Anal. Calcd for

C20H11N7O4: C, 58.11 ; H, 2.68; N, 23.72. Found: C, 58.08; H, 2.36; N, 23.60.

l,4-Di(lH-benzo[rf][l,2,3]triazol-l-yl)butane-l,4-dione (2i)

White microcrystals; yield: 37%; mp 235-237 °C; *H NMR (DMSO- 6) δ 4.02 (br s,

4H), 7.63 (t, / = 8.0 Hz, 2H), 7.80 (t, / = 7.5 Hz, 2H), 8.24 (d, / = 8.1 Hz, 2H), 8.29 (d, / = 8.4 Hz, 2H); Anal, calcd for C16H12N602: C, 60.00; H, 3.78; N, 26.24; found: C, 59.73; H, 3.73; N, 26.24.

General procedure for preparation of pyridine dicysteine hydrochloric salt (3a,b) To a solution of 2a (1000 mg, 2.710 mmol) in tetrahydrofuran (250 mL), a solution of cysteine methyl or ethyl ester hydrochloric salt (5.962 mmol) in water (10 mL) was added. The heterogeneous mixture was stirred at room temperature for 2 h. The solid was filtered, washed with diethyl ether (3 X 30 mL), and dried under vacuum to give compounds 3a,b. Dimethyl 2,2'-((pyridine-2,6-dicarbonyl)bis(azanediyl))bis(3- mercaptopropanoate) hydrochloric salt (3a) White microcrystals (92%). mp 218-220 °C; *H NMR (D₂0) £ 3.60-3.77 (m, 4H), 3.88 (s, 6H), 4.54-4.60 (m, 2H), 8.13-8.18 (m, 3H). ¹³C NMR (D₂0) £29.3, 54.2, 55.5, 126.9, 141.8, 151.0, 170.1, 194.8. C15H21CI2N3O6S2: C, 37.98; H, 4.46; N, 8.86. Found: C, 37.74; H, 4.57; N, 8.83.

Diethyl 2,2'-((pyridine-2,6-dicarbonyl)bis(azanediyl))bis(3-mercaptopropanoate) hydrochloric salt (3b) White microcrystals (88%).mp 224-226 °C; *H NMR (D₂0) £ 1.28- 1.36 (m, 6H), 3.62-3.79 (m, 4H), 4.31-4.39 (m, 4H), 4.53-4.58 (m, 2H), 8.17-8.21 (m, 3H).¹³C NMR (D₂0) £ 14.6, 29.1, 54.2, 65.4, 126.6, 141.6, 150.8, 169.4, 194.2. Ci7H₂₅Cl₂N₃06S₂: C, 40.46; H, 5.02; N, 8.36. Found: C, 41.00; H, 5.37; N, 8.45.

(25,2'5)-3,3'-[(pyridine-2,6-dicarbonyl)bis(sulfanediyl)]bis(2-aminopropanoic acid) (3c). L-Cysteine (290 mg, 2.39 mmol) was added to a solution of compound 2a (400 mg, 1.05 mmol) in acetonitrile (25 mL) and water (6 mL). The mixture was stirred at room temperature for 12 hours. The solid precipitate was filtered and washed with diethyl ether (2 x 50 mL). The white solid was dried under vacuum to complete dryness to give compound 3c (260 mg, 0.70 mmol) as microcrystals in 64% yield. Mp 236 °C; 1H NMR (TFA-d) £ 3.63 (dd, J = 1.1, 5.0 Hz, 1H), 3.68 (dd, J = 1.1, 4.7 Hz, 1H), 3.85-3.97 (m, 2H), 4.69-4.79 (m, 2H), 8.05-8.21 (m, 3H); 13C NMR (TFA-d) £30.3, 57.2, 128.0, 142.5, 152.3, 173.5, 197.9; Anal, calcd for C13H15N306S2: C, 41.82; H, 4.05; N, 11.25; found: C, 41.50; H, 4.07; N, 11.08.

General procedure for preparation of the macrocycles 4

A mixture of 2a-i (0.316 mmol), compound 3a,b (0.316 mmol) and triethylamine (1.265 mmol) in DMF (5 mL) was irradiated in microwave at 50 °C and 20 watt for 20 min. The solution was poured on to crushed ice and the compound was extracted with ethylacetate (3 x 50 mL). The organic layer was washed with saturated solution of Na₂CC>3 then dried over anhydrous sodium sulfate, filtered, evaporated until complete dryness to give compounds 4a-l.

Dimethyl 2,7,13,18-tetraoxo-3,17-dithia-6,14,23,24-tetraazatricyclo[17.3.1.1⁸'¹²] tetracosa-l(23),8(24),9,ll,19,21-hexaene-5,15-dicarboxylate (4a) White microcrystals (83%). mp 275-277 °C; *H NMR (CDC1₃) £ 3.38 (dd, / = 14.0, 5.8 Hz, 2H), 3.77 (s, 6H), 4.17 (dd, / = 14.0, 2.3 Hz, 2H), 5.17-5.22 (m, 2H), 8.03-8.05 (m, 2H), 8.34 (t, / = 4.5, 2H), 8.90 (d, / = 9.3 Hz, 2H) .¹³C NMR (CDC1₃) £ 31.2, 50.4, 53.2, 123.1, 126.7, 139.6, 148.9, 149.8, 162.9, 170.1, 190.1. HRMS m/z for C22H21N4O₈S2 [M+H]⁺ calcd. 533.0792, found 533.0722.

Diethyl 2,7,13,18-tetraoxo-3,17-dithia-6,14,23,24-tetraazatricyclo[17.3.1.1⁸'¹²] tetracosa-l(23),8(24),9,ll,19,21-hexaene-5,15-dicarboxylate (4b) White microcrystals (77%). mp 296-298 °C;^lU NMR (CDC1₃) £ 1.29 (t, J = 7.2 Hz, 6H), 3.41(dd, / = 19.5, 5.6 Hz, 2H), 4.12-4.26 (m, 6H), 5.17-5.23 (m, 2H), 8.01-8.08 (m, 4H). 8.33-8.36 (m, 2H), 8.88 (d, / = 9.6 Hz, 2H).¹³C NMR (CDC1₃) £ 14.3, 31.3, 50.6, 62.3, 123.0, 125.8, 126.6, 139.5, 149.0, 156.3, 162.9, 169.6, 190.2. HRMS m/z for C24H25N4O₈S2 [M+H]⁺ calcd. 561.1108, found 561.1121.

Dimethyl 2,7,13,18-tetraoxo-6,14-dithia-3,17,23- triazatricyclo[17.3.1.1^{8 12}]tetracosa-l(23),8(24),9,ll,19,21-hexaene-4,16-dicarboxylate (4c) White microcrystals (55%). mp 158-160 "C'H NMR (DMSO-rf₆) £ 3.47 (dd, J = 13.7, 9.3 Hz, 2H), 3.62-3.76 (m, 8H), 4.62-4.69 (m, 2H), 7.52 (t, J = 7.8 Hz, 1H), 7.97 (dd, J = 7.9, 1.9 Hz, 2H ), 8.09-8.23 (m, 4H), 9.69 (d, / = 7.8Hz, 2H).¹³C NMR (DMSO-rf₆) £29.6, 51.9, 52.5, 124.5, 124.9, 130.0, 131.7, 136.5, 139.9, 147.7, 163.2, 170.2, 189.9. HRMS m/z for C2₃H22N₃O₈S2 [M+H]⁺ calcd. 532.0843, found 532.0861.

Diethyl 2,7,13,18-tetraoxo-6,14-dithia-3,17,23-triazatricyclo[17.3.1.1^{8 12}]tetracosa- l(23),8(24),9,ll,19,21-hexaene-4,16-dicarboxylate (4d) White microcrystals (54%). mp 210-212 "C^H NMR (CDC1₃) £ 1.10-1.32 (m, 6H), 3.42-3.45 (m, 1H), 3.58-3.78 (m, 3H), 4.06 - 4.29 (m, 4H), 4.87-5.01 (m, 2H), 7.38-7.49 (m, 1H), 7.87-8.09 (m, 2H), 8.20-8.45 (m, 4H), 8.78-9.08 (m, 2H).¹³C NMR (CDC1₃) £ 14.3, 30.8, 53.4, 62.2, 125.7, 129.5, 132.3, 137.0, 139.1, 148.3, 148.4, 163.9, 169.8, 191.0. C₂₅H₂₅N₃0₈S₂: C, 53.66; H, 4.50; N, 7.51. Found: C, 53.54; H, 4.74; N, 7.24.

Dimethyl l,6,12,17-tetraoxo-l,3,4,5,6,12,13,14,15,17-decahydro-7,ll-epiazeno- 2,16,5,13-benzodithiadiazacyclononadecine-4,14-dicarboxylate (4e) White microcrystals (71%). mp 132-134 °C; *H NMR (CDC1₃) £3.62-3.76 (m, 4H), 3.81 (s, 6H), 4.44-4.49 (m, 2H), 7.54 (dd, / = 5.9, 3.2 Hz, 2H), 7.73 (dd, J = 5.7, 3.2 Hz, 2H), 7.98 (t, J = 7.6 Hz, 1H), 8.27 (d, / = 7.8 Hz, 2H), 9.06 (d, / = 6.9 Hz, 2H).¹³C NMR (CDC1₃) £30.5, 53.0, 53.7, 125.2, 125.7, 129.1, 132.3, 135.4, 139.1, 148.2, 164.0, 170.0, 193.5. HRMS m/z for C₂₃H₂₂N₃0₈S₂ [M+H]⁺ calcd. 532.0843, found 532.0820.

Diethyl l,6,12,17-tetraoxo-l,3,4,5,6,12,13,14,15,17-decahydro-7,ll-epiazeno- 2,16,5,13-benzodithiadiazacyclononadecine-4,14-dicarboxylate (4f) White microcrystals (73%). mp 186-188 °C; ^!H NMR (CDC1₃) £ 1.33 (t, / = 7.2 Hz, 6H), 3.68 (dd, / = 14.8, 7.9 Hz, 2H), 3.82 (dd, / = 14.7, 3.4 Hz, 2H), 4.31 (q, / = 14.2 Hz, 4H), 4.95-5.01 (m, 2H), 7.58 (dd, J = 5.7, 3.2 Hz, 2H), 7.75 (dd, J = 5.7, 3.2 Hz, 2H), 8.00 (t, J = 7.8 Hz, 1H), 8.30 (d, J = 7.5 Hz, 2H), 9.10 (d, / = 6.6 Hz, 2H). ¹³C NMR (CDC1₃) £ 14.4, 30.4, 53.7, 62.1, 125.1, 129.0, 132.3, 135.3, 139.0, 148.1, 164.0, 169.3, 193.4. HRMS m/z for C₂₃H₂₂N₃0₈S₂ [M+H]⁺ calcd. 560.1156, found 560.1168.

Dimethyl 9,9-dimethyl-2,7,ll,16-tetraoxo-6,12-dithia-3,15,21- triazabicyclo[15.3.1] henicosa-l(21),17,19-triene-4,14-dicarboxylate (4g) White microcrystals (48%). mp 145-147 °C; *H NMR (CDC1₃) £ 1.09 (s, 6H), 2.47 (d, / = 15.2 Hz, 2H), 2.91 (d, / = 15.2 Hz, 2H), 3.33 (dd, J = 14.5, 4.5 Hz, 2H), 3.72-3.79 (m, 2H), 3.82 (s, 6H), 4.96-5.03 (m, 2H), 8.04 (t, J = 7.6 Hz, 1H), 8.34 (d, J = 7.7 Hz, 2H), 8.62 (d, J = 8.2 Hz, 2H).¹³C NMR (CDC1₃) £ 29.5, 31.3, 34.7, 52.0, 52.3, 53.0, 125.7, 139.2, 148.5, 163.6, 170.5, 198.1. HRMS m/z for C22H2₈N₃O₈S2 [M+H]⁺ calcd. 526.1312, found 526.1320.

Diethyl 9,9-dimethyl-2,7,ll,16-tetraoxo-6,12-dithia-3,15,21-triazabicyclo[15.3.1] henicosa-l(21),17,19-triene-4,14-dicarboxylate (4h) White microcrystals (45%). mp 103— 105 °C; *H NMR (CDC1₃) £ 1.04 (s, 6H), 1.29 (t, / = 7.0 Hz, 6H), 2.43 (d, / = 15.2 Hz, 2H ), 2.83 (d, J = 15.2 Hz, 2H ), 3.30 (dd, J = 14.5, 4.5 Hz, 2H ), 3.70 (dd, J = 14.5, 6.4 Hz, 2H), 4.18 - 4.26 (q, 4H), 4.88-4.94 (m, 2H), 7.99 (t, J = 7.8 Hz, 1H), 8.29 (d, J = 7.8 Hz, 2H), 8.54 (d, / = 8.2 Hz, 2H).¹³C NMR (CDC1₃) £ 14.3, 29.5, 31.2, 34.7, 52.1, 52.2, 62.1, 125.6, 139.0, 148.5, 163.6, 169.9, 198.0. HRMS m/z for C₂₄H₃₂N₃0₈S₂ [M+H]⁺ calcd. 554.1625, found 554.1621.

Dimethyl 2,7,ll,16-tetraoxo-6,9,12-trithia-3,15,21-triazabicyclo[15.3.1]henicosa- l(21),17,19-triene-4,14-dicarboxylate (4i) Oil (51%); ^!H NMR (CDC1₃) £ 3.37-3.50 (m, 4H), 3.78-3.92 (m, 10H), 5.11- 5.15 (m, 2H), 8.06 (t, / = 7.5 Hz, 1H), 8.32 (d, / = 7.6 Hz, 2H ), 8.80 (d, J = 8.6 Hz, 2H).¹³C NMR (CDC1₃) £ 32.5, 40.9, 51.2, 53.2, 125.5, 139.4, 148.3, 163.2, 170.4, 195.4. HRMS m/z for C19H22N₃O₈S₃ [M+H]⁺ calcd. 516.0564, found. 516.0570.

Diethyl 2,7,ll,16-tetraoxo-6,9,12-trithia-3,15,21-triazabicyclo[15.3.1]henicosa- l(21),17,19-triene-4,14-dicarboxylate (4j) White microcrystals (53%). mp 135-137 °C; *H NMR (CDCI₃) £ 1.37 (t, / = 7.1 Hz, 6H), 3.41 (dd, / = 14.3, 5.5 Hz, 4H), 3.83 (dd, / = 15.1, 5.1 Hz, 4H), 4.24-4.34 (m, 4H), 5.06-5.14 ( m, 4H),8.05 (t, / = 8.1 Hz, 1H), 8.32 (d, J = 7.8 Hz, 2H), 8.79 (d, J = 8.8 Hz, 2H). ¹³C NMR (CDC1₃) £ 14.3, 32.5, 40.8, 51.3, 62.5, 125.4, 139.3, 148.4, 163.2, 170.0, 195.3. HRMS m/z for CiiHieNsOsSs-IM+Nar calcd.566.0696, found. 566.0718.

Dimethyl 2,7,ll,16-tetraoxo-9-oxa-6,12-dithia-3,15,21- triazabicyclo[15.3.1]henicosa-l(21),17,19-triene-4,14-dicarboxylate (4k) Oil (50%); *H NMR (CDC1₃) 3.49 (dd, / = 14.4, 4.8 Hz, 2H), 3.74-3.84 (m, 8H), 4.16-4.40 (m, 4H), 5.16-5.21 (m, 2H), 8.00-8.05 (m, 1H), 8.31-8.38 (m, 4H). ¹³C NMR (CDC1₃) £ 30.1, 50.9, 53.2, 75.5, 125.8, 139.3, 148.4, 163.4, 170.4, 197.4. HRMS m/z for

[M+H]⁺ calcd. 522.0611, found. 522.0632.

Diethyl 2,7,ll,16-tetraoxo-9-oxa-6,12-dithia-3,15,21- triazabicyclo[15.3.1]henicosa-l(21),17,19-triene-4,14-dicarboxylate (41) Oil (52%); *H NMR (CDCI₃) £ 1.34 (t, / = 7.2Hz, 6H), 3.52 (dd, / = 14.2, 7.4 Hz, 2H), 3.80 (dd, / = 14.3, 3.3 Hz, 2H), 4.17-4.37 (m, 8H), 5.15-5.21 (m, 2H), 8.05 (t, / = 7.9 Hz, 1H), 8.34 (d, / = 7.9 Hz, 2H), 8.39 (d, / = 8.6 Hz, 2H). ¹³C NMR (CDC1₃) £ 14.3, 30.0, 51.0, 62.4, 125.8, 139.3, 148.5, 163.4, 169.9. 197.3. HRMS m/z for C21H26N₃O9S2 [M+H]⁺ calcd. 528.1105, found. 528.1103.

General Procedure for the preparation of the macrocycles 5

A solution of compound 3c (200 mg, 0.54 mmol) and triethylamine (0.30 mL, 2.15 mmol) in water (20 mL) was added dropwise to a solution of compound 2a-i (0.54 mmol) in tetrahydrofuran (100 mL). The solution was stirred at room temperature for 3 hours. The organic solvent was evaporated under reduced pressure and the aqueous layer was washed with 2 N HCl and extracted with ethyl acetate (3 x 50 mL). The organic layer was dried over anhydrous sodium sulfate, filtered, and evaporated until complete dryness to give compounds 5a, b, and i.

2,7,13,18-Tetraoxo-3,17-dithia-6,14,23,24-tetraazatricyclo[17.3.1.18,12]tetracosa- l(23),8(24),9,ll,19,21-hexaene-5,15-dicarboxyxlic acid (5a) Yield : 81%; white microcrystals; mp 256-258 °C; *H NMR (DMSO- 6) £3.53 (dd, J = 13.5, 5.4 Hz, 2H), 3.68 (dd, J = 13.5, 6.6 Hz, 2H), 4.80-4.87 (m, 2H), 8.13-8.31 (m, 6H), 9.36 (d, / = 8.1 Hz, 2H); ¹³C NMR (DMSO- 6) £ 29.3, 51.2, 123.5, 124.9, 139.7, 141.0, 149.2, 149.5, 163.7, 170.9, 191.4; Anal, calcd for C20H16N4O8S8-H2O: C, 45.97; H, 3.09; N, 10.72; found: C, 45.70; H, 3.29; N, 10.23.

2,7,13,18-tetraoxo-6,14-dithia-3,17,23-triazatricyclo[17.3.1.18,12]tetracosa- l(23),8(24),9,ll,19,21-hexaene-4,16-dicarboxylic acid (5b) Yield: 81%; white microcrystals; mp 230 °C; *H NMR (CD30D) J3.66 (dd, J = 14.3, 7.1 Hz, 2H), 3.88 (dd, J = 14.4, 4.5 Hz, 2H), 4.82-5.16 (m, 2H), 7.53-7.63 (m, 1H), 7.92-7.96 (m, 1H), 8.09-8.28 (m, 4H), 8.64-8.70 (m, 1H); ¹³C NMR (CD30D) £32.1, 53.0, 126.5, 130.9, 131.6, 131.9, 139.8, 140.4, 150.9, 166.2, 172.9, 193.2; Anal, calcd for C21H17N308S2- 3H20: C, 45.24; H, 4.16; N, 7.54; found: C, 44.69; H, 4.00; N, 7.23.

2,7,10,15-tetraoxo-6,ll-dithia-3,14,20-triazabicyclo[14.3.1]icosa-l(20),16,18- triene-4,13-dicarboxylic acid (5c) Yield: 82%; white microcrystals; mp 83-85 °C; ^!H NMR (DMSO- 6) J2.78-2.87 (m, 2H), 3.03-3.16 (m, 2H), 3.37 (dd, / = 14.1, 3.3 Hz, 2H), 3.58 (dd, / = 14.1, 9.9 Hz, 2H), 4.51-4.59 (m, 2H), 8.10-8.30 (m, 3H), 9.33-9.41 (m, 2H), 12.95 (br s, 2H); ¹³C NMR (DMSO- 6) 629.5, 39.1, 52.9, 125.1, 140.0, 148.8, 163.8, 171.8, 197.6; Anal, calcd for C17H17N308S2- H20: C, 43.12; H, 4.04; N, 8.87; found: C, 42.85 ; H, 4.23; N, 8.32.

Experimental details of bioassay.

Antifungal Assay

Antifungal activity screening of the synthesized compounds was determined by the minimum inhibitory concentration (MIC) as recommended by the Clinical and Laboratory Standard Institute (CLSI). A pure culture of a single microorganism {Candida albicans) "local isolate" was grown in Mueller-Hinton broth. The culture size was standardized to be 1.5 X 10⁸ cells per milliliter. The synthesized compounds were two-fold serially diluted in DMSO. After the tested compounds had been diluted, a volume of the standardized inoculum equal to the volume of the diluted compounds was added to each dilution in microti tre plates. These plates were incubated at 37° C for 18 - 24 hours. After incubation, the plates were observed for microbial growth, and the spot with the lowest concentration of compound showing no growth was defined as the minimum inhibitory concentration (MIC).

Antibacterial Assay

Antibacterial activity screening of the synthesized compounds 4a-l and 5a, 5b, and 5i was determined by the agar dilution technique standard method recommended by the Clinical and Laboratory Standard Institute (CLSI), in a methodology similar to that for antifungal bioassay. The tested compounds were dissolved in dimethylsulfoxide (DMSO). An inoculum of about 1.5 X 108 colony forming units (CFU) per spot was applied to the surfaces of Mueller-Hinton (in case of both Gram-positive and Gram-negative bacterial strains) agar plates containing graded concentrations of the respective compounds. Plates were incubated at 37 °C for 18 h (in case of Gram-positive and Gram- negative bacterial strains). The spot with the lowest concentration of compound showing no growth was defined as the minimum inhibitory concentration (MIC). All organisms used in this study were standard strains obtained from American Type Culture Collection (ATCC). The organisms included representatives of Gram-positive bacteria (Staphylococcus aureus ATCC 25923) and Gram- negative bacteria (Klebsiella pneumoniae ATCC 33495, Proteus vulgaris ATCC 13315 and Pseudomonas aeruginosa ATCC 27853). The MIC of Ciprofloxacin was determined concurrently as a reference standard for antibacterial activities (Table 4). Control DMSO was carried out with each experiment.

All patents, patent applications, provisional applications, and publications referred to or cited herein are incorporated by reference in their entirety, including all figures and tables, to the extent they are not inconsistent with the explicit teachings of this specification.

It should be understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested to persons skilled in the art and are to be included within the spirit and purview of this application.

Claims

CLAIMS We claim:

1. An antimicrobial compound, comprising a macrocyclic peptidomimetic comprising two S- cysteine units and at least one pyridine unit.

2. The antimicrobial compound of claim 1, wherein the macrocyclic peptidomimetic has the structure:

CrC₄ alkyl, benzyl, or H; and R is hydrogen, CrC₄ alkyl, trifluoromethyl, CrC₄ alkoxy, nitrile, or nitro.

3. The antimicrobial compound of claim 2, wherein R¹ is methyl or ethyl.

4. The antimicrobial compound of claim 2, wherein R¹ is hydrogen.

5. The antimicrobial compound of claim 2, wherein R is 2,6-pyridine, 1,3-benzene, 1,2-benzene, s m-neopentane, s m-dimethylsulfide, s m-dimethylether, or 1,2-ethane.

6. An antifungal composition, comprising:

an antimicrobial compound according to claim 1 ; and a pharmaceutically acceptable carrier, wherein the antifungal composition can be a solution or a suspension of the antimicrobial compound or a solid.

7. The antifungal composition of claim 6, wherein the macrocyclic peptidomimetic has the structure:

where: R

CrC₄ alkyl, benzyl, or H; and R is hydrogen, CrC₄ alkyl, trifluoromethyl, CrC₄ alkoxy, nitrile, or nitro.

8. The antifungal composition of claim 7, wherein R is methyl or ethyl.

9. The antifungal composition of claim 7, wherein R is hydrogen.

10. The antifungal composition of claim 7, wherein R is 2,6-pyridine, 1,3-benzene, 1,2-benzene, s m-neopentane, s m-dimethylsulfide, s m-dimethylether, or 1,2-ethane.

11. The antifungal composition of claim 6, wherein the pharmaceutically acceptable carrier is an aqueous solution.

12. The antifungal composition of claim 6, further comprising one or more of an antioxidant, buffer, bacteriostat, suspending agent, thickening agent, binder, excipients, disintegrating agent, lubricant, sweetening agent, and flavoring agent.

13. The antifungal composition of claim 6, wherein the antimicrobial compound has a minimum inhibitory concentration (MIC) of 0.030 μg/mL or less toward Candida albicans as determined by the recommended method of the Clinical and Laboratory Standard Institute (CLSI).

14. The antifungal composition of claim 6, further comprising a second antifungal agent.

15. An antibacterial composition, comprising:

an antimicrobial compound according to claim 1 ; and

a pharmaceutically acceptable carrier, wherein the antifungal composition can be a solution or a suspension of the antimicrobial compound or a solid.

16. The antibacterial composition of claim 15, wherein the macrocyclic peptidomimetic has the structure:

where: R is

, N— . or j R' z C C₄ alkyl, benzyl, or H; and R is hydrogen, C C₄ alkyl, trifluoromethyl, Q-C4 alkoxy, nitrile, or nitro.

17. The antibacterial composition of claim 16, wherein R is methyl or ethyl.

18. The antibacterial composition of claim 16, wherein R is hydrogen.

19. The antibacterial composition of claim 16, wherein R is 2,6-pyridine, 1,3-benzene, 1,2- benzene, s m-neopentane, s m-dimethylsulfide, s m-dimethylether, or 1,2-ethane.

20. The antibacterial composition of claim 16, wherein R¹ is hydrogen and R is 2,6-pyridine, 1,3-benzene, or 2,6-pyridine, 1,3-benzene, and wherein the antimicrobial compound has a minimum inhibitory concentration (MIC) of 2 μg/mL or less toward S. aureus as determined by the recommended method of the Clinical and Laboratory Standard Institute (CLSI).

21. The antibacterial composition of claim 15, wherein the pharmaceutically acceptable carrier is an aqueous solution.

22. The antibacterial composition of claim 15, further comprising one or more of an antioxidant, buffer, bacteriostat, suspending agent, thickening agent, binder, excipients, disintegrating agent, lubricant, sweetening agent, and flavoring agent.

23. The antibacterial composition of claim 15, wherein the antimicrobial compound has a minimum inhibitory concentration (MIC) of 0.03 μg/mL or less toward K. pneumoniae as determined by the recommended method of the Clinical and Laboratory Standard Institute (CLSI).

24. The antibacterial composition of claim 15, wherein the antimicrobial compound has a minimum inhibitory concentration (MIC) of 0.06 μg/mL or less toward P. vulgaris as determined by the recommended method of the Clinical and Laboratory Standard Institute (CLSI).

25. The antibacterial composition of claim 15, wherein the antimicrobial compound has a minimum inhibitory concentration (MIC) of 0.12 μg/mL or less toward P. aeruginosa as determined by the recommended method of the Clinical and Laboratory Standard Institute (CLSI).

6. The antifungal composition of claim 15, further comprising a second antibacterial agent.