Synthesis and structure-activity relationships of novel parenteral carbapenems, CS-023 (R-115685) and related compounds containing an amidine moiety.

In order to design a new parenteral 1beta-methylcarbapenem antibiotic which has a broad antibacterial spectrum and improved plasma half-life, a series of 1beta-methylcarbapenems with 5-substituted pyrrolidine-3-ylthio groups including an amidine moiety at the C-2 position have been synthesized and structure-activity relationships were investigated. Among those carbapenem derivatives, CS-023 (R-115685) showed a broad spectrum and excellent antibacterial activity against Gram-positive and Gram-negative bacteria. This compound also showed sufficient dehydropeptidase-I (DHP-I) stability and high urinary recovery in animals after subcutaneous administration without cilastatin, a DHP-I inhibitor. Based on these characteristics, CS-023 was selected for further study.

Physicochemical analyses of phase transition and dehydration processes of a new oral 1beta-methylcarbapenem antibiotic agent, CS-834.

The characterizations of the anhydrate (A-form), monohydrate (B1-form), and dihydrate (B2-form) of CS-834 were investigated by powder X-ray diffraction, differential scanning calorimetry (DSC), thermogravimetry-differential thermal analysis (TG-DTA), infrared spectroscopy, and Karl Fischer moisture titration. The typical DSC curve of the B2-form showed five endothermic peaks at 35.0, 46.4, 56.2, 99.2, and 190.4 degrees C and an exothermic peak at 123.4 degrees C. In TG-DTA analysis, the three peaks at 35.0, 46.4, and 56.2 degrees C had a total weight loss of 7.3%, corresponding to the release of two water molecules. From morphological observation under thermomicroscopy, the endothermic peak at 99.2 degrees C was attributed to the melting of the dehydrous crystals (B0-form) and the exothermic peak at 123.4 degrees C to the recrystallization to the A-form crystals. The endothermic peak at 190.4 degrees C was due to the melting of the A-form crystals. After incubation for 6.0 h at 35, 50, 60, and 80 degrees C, the powder X-ray diffraction patterns of the B2-form indicated that it was converted into the A-form via the B1-form and B0-form. Thus CS-834 exists in homologous hydrous crystal forms in multiple-phase transformations with the dehydration of two water molecules.

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.