Muraminomicins, novel ester derivatives: in vitro and in vivo antistaphylococcal activity.

Novel muraminomicin derivatives with antimicrobial activity against methicillin-resistant Staphylococcus aureus (MRSA) were synthesized by esterification of the hydroxy group on the diazepanone ring of muraminomicin Z1. Compound 1b (DS14450354) possessed a diheptoxybenzyl-ß-Alanyl-ß-Alanyl group and exhibited minimum inhibitory concentrations (MICs) against MRSA comparable to those against methicillin-susceptible S. aureus (MSSA). The MICs that inhibited 50 and 90% of the strains were 1 and 2 µg/mL, respectively. Compound 1a (DS60182922) possessed an aminoethylbenzoyldodecylglycyl moiety and showed bactericidal activity against MSSA Smith. The bactericidal activity of 1a against MRSA 10925 was comparatively lower, whilst 1b exhibited dose-dependent bactericidal activity against MRSA 10925. The mutation frequency of 1b was lower than that of 1a. An amino acid substitution (F226I) was observed in MraY mutants isolated from culture plates containing 1a or 1b. Subcutaneous 1a and 1b administration showed good therapeutic efficacy in murine systemic infection models with MSSA Smith and MRSA 10925, comparable to that of vancomycin, suggesting that the novel muraminomicin derivatives may be effective therapeutic agents against MRSA that warrant further investigation. A scheme for the formulation of the key ester intermediate, requiring no HPLC preparation, was also established.

Muraminomicins, new lipo-nucleoside antibiotics from Streptosporangium sp. SANK 60501-structure elucidations of muraminomicins and supply of the core component for derivatization.

We screened for bacterial phospho-N-acetylmuramyl-pentapeptide-translocase (MraY: EC 2.7.8.13) inhibitors with the aim of discovering novel antibiotics and observed inhibitory activity in the culture broth of an actinomycete, SANK 60501. The active compounds, muraminomicins A, B, C, D, E1, E2, F, G, H, and I exhibited strong inhibitory activity against MraY with IC50 values of 0.0105, 0.0068, 0.0104, 0.0099, 0.0115, 0.0109, 0.0089, 0.0134, 0.0186, and 0.0094 µg ml-1, respectively. Although muraminomicin F exhibited favorable antibacterial activity against drug-resistant Gram-positive bacteria, this activity was reduced with the addition of serum. To efficiently supply the core component for chemical modification studies, production was carried out in a controlled trial by adding myristic acid to the medium, and a purification method suitable for large-scale production was successfully developed.

Design, synthesis and antifungal activity of the novel water-soluble prodrug of antifungal triazole CS-758.

CS-758 was selected as a candidate for clinical trials, but since its water-solubility was insufficient for an injectable formulation, phosphoryl ester prodrugs were designed. In this study, the synthesis and evaluation of these injectable prodrugs are described. Phosphoryl ester 17 h was soluble in water, and was stable in both water and in a solid state. 17 h was converted to CS-758 in human liver microsome and was also converted to CS-758 in rats after intravenous (i.v.) administration with good conversion speed and efficiency. 17 h (i.v.) reduced the viable cell counts in kidneys in a murine hematogenous Candida albicans infection model and in lungs in a murine pulmonary Aspergillus fumigatus infection model, wherein the effects were comparable to or slightly superior to that of CS-758 (per os).

Synthesis, cleavage, and antifungal activity of a number of novel, water-soluble ester prodrugs of antifungal triazole CS-758.

In this study, the synthesis and evaluation of a number of esters of CS-758 as injectable prodrugs are described. Phosphoryl ester 1a was soluble in water (>30mg/mL) and was converted to CS-758 in human liver microsome. It was also converted to CS-758 in rats after iv administration, wherein the bioavailability of CS-758 was 53%. Compound 1a (iv) reduced the viable cell counts in kidneys in a murine systemic Candida albicans infection model, wherein the effect was comparable to or slightly superior to that of CS-758 (po). The prodrug 1a proved to be a promising injectable antifungal agent whose further evaluation is warranted.

Amide analogs of antifungal dioxane-triazole derivatives: synthesis and in vitro activities.

A new series of triazole compounds possessing an amide-part were efficiently synthesized and their in vitro antifungal activities were investigated. The amide analogs showed excellent in vitro activity against Candida, Cryptococcus and Aspergillus species. The MICs of compound 23d against C. albicans ATCC24433, C. neoformans TIMM1855 and A. fumigatus ATCC26430 were 0.008, 0.031 and 0.031 microg/mL, respectively, (MICs of fluconazole: 0.5, >4 and >4 microg/mL; MICs of itraconazole: 0.125, 0.25, 0.25 microg/mL). Furthermore, compound 23d was stable under acidic conditions.

Carbon analogs of antifungal dioxane-triazole derivatives: synthesis and in vitro activities.

A new series of triazole compounds possessing a carbon atom in place of a sulfur atom were efficiently synthesized and their in vitro antifungal activities were investigated. The carbon analogs showed excellent in vitro activity against Candida, Cryptococcus, and Aspergillus species. The MICs of compound 1c against C. albicans ATCC24433, C. neoformans TIMM1855, and A. fumigatus ATCC26430 were 0.016, 0.016, and 0.125 microg/mL, respectively (MICs of fluconazole: 0.5, >4, and >4 microg/mL; MICs of itraconazole: 0.125, 0.25, and 0.25 microg/mL).

Synthesis and evaluation of novel pyrrolidinyl sordaricin derivatives as antifungal agents.

N-Benzyl pyrrolidinyl sordaricin derivatives have been synthesized from cis-4-hydroxy-D-proline in a stereocontrolled manner. These compounds maintained moderate antifungal activity against several pathogenic fungal strains. Their MIC values against Candida albicans were in the range of 0.25-2 microg/mL.

Synthesis and evaluation of N-substituted 1,4-oxazepanyl Sordaricins as selective fungal EF-2 inhibitors.

Sordaricin analogues possessing 6-methoxy-7-methyl-1,4-oxazepane moiety instead of the sugar part were synthesized and evaluated. It was found that N-substituents on the oxazepane ring had influence on biological activity. In particular, N-(2-methylpropenyl) derivative 12p exhibited potent in vitro antifungal activity. Furthermore, 12p maintained significant activity (MIC 0.25 microg/mL) against Candida albicans SANK51486 even in the presence of 20% horse serum.

Synthesis of Sordaricin analogues as potent antifungal agents against Candida albicans.

Sordaricin derivatives possessing a cyclohexane ring appendage attached via an ether, thioether, amine, oxime, ester or amide linkage were synthesized and their antifungal activity was evaluated in vitro. Compounds containing a thioether bond or an oxime bond as a linkage exhibited potent MICs (< or = 0.125 microg/mL) against four Candida albicans strains including azole-low-susceptible strains. They were also active (MIC < or = 0.125 microg/mL) against Candida glabrata. Their in vivo efficacy was confirmed in a murine intravenous infection model with Candida albicans.