Aya Shimizu

Dicationic dithiocarbamate carbapenems with anti-MRSA activity.

A new class of 1 beta-methylcarbapenems bearing a doubly quaternarized 1,4-diazabicyclooctane (DABCO) substituted dithiocarbamate moiety at the C-2 side chain was prepared, and the biological profiles of the compounds, including in vitro and in vivo anti-MRSA activity and DHP-I susceptibility, were evaluated to identify a carbapenem derivative that was superior to BO-3482 (1). As a result, we discovered a 1 beta-methyl-2-[4-(4-carbamoylmethyl-1,4-diazabicyclo[2,2,2]octanediium-1-yl)methyl-1,2,3,6-tetrahydropyridinylthiocarbonylthio]carbapenem, 14a showing greater than 2-fold better anti-MRSA activity in a mouse infection model and 3-fold better DHP-I susceptibility as compared with BO-3482 (1).

Stereoselective Synthesis of a Broad Spectrum 1β-Methylcarbapenem, J-114,870

Abstract An ultra-broad spectrum carbapenem, J-114,870 (1), was synthesized from the corresponding C-2 side chain and 1β-methylcarbapenem enolphosphate. Synthesis of the C-2 side chain was accomplished by installation of the benzene part to (4R)-hydroxy-2-pyrrolidone 3, affording 2-phenylpyrrolidine 8a, and asymmetric Michael addition of chiral amine to α,β-unsaturated ester derived from 8a.

Structure–Activity Relationships of 1β-Methyl-2-(5-phenylpyrrolidin-3-ylthio)carbapenems

Structure--activity relationship studies of 1beta-methyl-2-[(3S,5R)-5-(4-aminomethylphenyl)pyrrolidin-3-ylthio]carbapenems, especially those pertaining to the relationship between antibacterial activity and side-chain structure were conducted. These studies suggested that the trans-(3S,5R)-5-phenylpyrrolidin-3-ylthio side-chain and the aminomethyl group at the 4-position of the phenyl ring play a key role in enhancing the antibacterial activity against the MRSA and Pseudomonas aeruginosa strains. In particular, the basicity of a substituent at the 4-position of the phenyl ring were shown to greatly contribute to the antibacterial activity against MRSA and methicillin-resistant Staphyloccocus epidermidis strains. In contrast, the amidine group was shown to lead to potent antibacterial activity against P. aeruginosa strains comparable to that of imipenem, however, a good correlation between the basicity of the 4-substituent and antipseudomonal activity was not observed. In conclusion, the 4-aminomethyl or methylaminomethyl group on the phenyl ring was the best substituent for antipseudomonal activity.

Lipase-catalyzed kinetic resolution of ethyl 3-aryl-3-hydroxypropionate: preparation of the side chain of a novel carbapenem, J-114,870

Abstract An optically active 3-aryl-3-hydroxypropionate 3a was prepared by lipase-catalyzed kinetic hydrolysis of a diastereomeric mixture of 3-aryl-3-(α-chloroacetoxy)propionate 6 in good conversion yield with adequate purity (>95% de). This enzymatic reaction proceeded with great efficiency as measured by reaction rate, chemical yield and stereoselectivity. The compound 3a was converted to J-114,870 1a, a novel ultra-broad spectrum carbapenem, without significant epimerization.

Discovery of novel trans-3,5-disubstituted pyrrolidinylthio-1β-methylcarbapenems

Novel trans-3,5-disubstituted pyrrolidinylthio-1beta-methylcarbapenems were designed and synthesized to provide J-111,347 (1a) as the first example of an exceptionally broad-spectrum antibiotic, showing activity against methicillin-resistant Staphyloccocus aureus (MRSA) as well as Pseudomonas aeruginosa. Further derivation of 1a afforded J-111,225 (2a), J-114,870 (3a), and J-114,871 (3b). which showed improved safety profiles and retained broad-spectrum antibacterial activities.

Structure–activity relationships of trans-3,5-disubstituted pyrrolidinylthio-1β-methylcarbapenems. Part 2: J-111,225, J-114,870, J-114,871 and related compounds

Through further derivatization of J-111,347 (1a), a trans-3,5-disubstituted pyrrolidinylthio-1β-methylcarbapenem, undesired epileptogenicity in a rat intracerebroventricular assay (200 μg/rat) could be eliminated to afford J-111,225 (2a), J-114,870 (3a) and J-114,871 (3b) which preserved comparable broad antimicrobial activity.

Actinoplanes rishiriensis sp. nov., a novel motile actinomycete isolated by rehydration and centrifugation method

The motile actinomycete strain RI50-RCA114T was isolated using rehydration and centrifugation method from a soil sample obtained from Rishiri Island in Japan. The taxonomic status of this organism was established using a polyphasic approach. Cells of strain RI50-RCA114T were Gram positive, aerobic, motile and formed irregular sporangia. The strain grew in the presence of 0–2% (w/v) NaCl, between pH 5 and 8, and over a temperature range of 20–37°C, with optimal growth at 30°C. Whole-cell hydrolysates of the strain contained meso-diaminopimelic acid, galactose, glucose and mannose, in addition to one unidentified O-methyl-hexose. The predominant menaquinone was MK-9(H4), and the major polar lipids comprised phosphatidylethanolamine, diphosphatidylglycerol and phosphatidyl-N-methylethylethanolamine. The major cellular fatty acids were iso-C16:0, iso-C15:0 and anteiso-C17:0. Comparative 16S ribosomal RNA gene sequence analysis revealed that strain RI50-RCA114T had the closest sequence similarity with Actinoplanes globisporus JCM 3186T (97.6%). However, DNA–DNA hybridization assays as well as physiological and biochemical analyses differentiated strain RI50-RCA114T from its closest phylogenetic relative. On the basis of these data, we propose that strain RI50-RCA114T (=NBRC 108556T=BCC 49184T) be classified as the type strain of a novel Actinoplanes species and named Actinoplanes rishiriensis sp. nov.

Novel dithiocarbamate carbapenems1 with anti-MRSA activity

Abstract A new series of carbapenems, in which disubstituted-aminothiocarbonylthio moiety, directly attached to the C-2 position, were prepared and evaluated for their antibacterial potency. These analogs showed potent activity against high-level MRSA. Among them, 9e and 9i were found to exhibit good in vivo efficacy comparable to that of vancomycin, for mouse septicemia model with high-level MRSA.