Yukiko Hiraiwa

Metallo-β-lactamase inhibitory activity of phthalic acid derivatives

4-Butyl-3-methylphthalic acid was recognized as a metallo-beta-lactamase inhibitor. The structure-activity relationship study of substituted phthalic acids afforded 3-phenylphthalic acid derivatives as potent IMP-1 inhibitors. On the other hand, 3-substituted with 4-hydroxyphenyl phthalic acid derivative displayed a potent combination effect with biapenem (BIPM) against Pseudomonas aeruginosa that produce IMP-1.

X-ray crystallographic analysis of IMP-1 metallo-β-lactamase complexed with a 3-aminophthalic acid derivative, structure-based drug design, and synthesis of 3,6-disubstituted phthalic acid derivative inhibitors.

3-(4-Hydroxypiperidine-1-yl) phthalic acid 1 shows potent inhibitory activity against metallo-β-lactamase, which is known to inactivate β-lactam antibiotics such as carbapenems. Here, the structure of co-crystals of the metallo-β-lactamase IMP-1 and 1 was first analyzed by X-ray crystallography, and then used for structure-based drug design. Four novel compounds bearing substituents at the 6-position were synthesized to produce 3,6-disubstituted phthalic acid derivatives, and their IMP-1 inhibitory activity and synergistic effect with the carbapenem biapenem (BIPM) were evaluated. 3,6-Disubstituted phthalic acid derivatives showed potent IMP-1 inhibitory activity. In particular, compound 13 showed 10-fold higher IMP-1 inhibitory activity as compared with the parent derivative 1.

Design and synthesis of novel ring-expanded arbekacin analogues

Novel homologated aminoglycosides having a seven-membered ring were designed and synthesized by treatment of 5-keto arbekacin with diazomethane in CH 2 Cl 2 -Et 2 O. The ring-expanded arbekacin analogue showed good antibacterial activity against Staphylococcus aureus and Escherichia coli including aminoglycoside-resistant bacterial strain.

In vitro and in vivo antimicrobial activity of TS2037, a novel aminoglycoside antibiotic

To overcome serious methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa infections, we synthesized TS2037, 5,4″-diepi-arbekacin, a novel aminoglycoside antibiotic, and evaluated its biological properties. TS2037 showed broad-range, as well as robust antibacterial activities against Gram-positive and Gram-negative bacteria. The MIC50 and MIC90 of TS2037 against clinical isolates of MRSA (n = 54) were both 0.25 µg/mL, and no resistant strain was observed. The MIC50 and MIC90 of TS2037 against clinical isolates of P. aeruginosa (n = 54) were 1 and 4 µg/mL, respectively. TS2037 and arbekacin, anti-MRSA aminoglycoside, were more stable against AAC(6′)-APH(2″), aminoglycoside-6′-N-acetyltransferase and 2″-O-phosphotransferase, produced by resistant S. aureus than gentamicin. Therapeutic efficacies of TS2037 in the mouse models of systemic infection with MRSA were superior to those of arbekacin, vancomycin, and linezolid. The efficacy of TS2037 against systemic infection caused by P. aeruginosa producing AAC(6′)-II was superior to those of arbekacin and amikacin. In the nephrotoxicity risk screening, the release of free N-acetyl-β-d-glucosaminidase from the kidney epithelial cell line after treatment with TS2037 at 2.5 and 5.0 μM were 2.0 and 2.1 (U/L), respectively, which were about two times higher than those of arbekacin. In conclusion, TS2037 exhibited the most potent antibacterial activity among aminoglycosides tested against both MRSA and P. aeruginosa in vitro and in vivo, although its nephrotoxicity risk remains to be improved.

Chromium(II) chloride-mediated coupling reactions of Garner aldehyde with allyl bromides: facile asymmetric synthesis of (2R,3S)-3-hydroxy-2-hydroxymethylpyrrolidine

Chromium(II) chloride-mediated coupling reactions of 1,1-dimethylethyl (S)- and (R)-4-formyl-2,2-dimethyloxazolidine-3-carboxylates [(S)- and (R)-Garner aldehydes ] (1a,b) with allyl bromides 2a–c proceeded with moderate to good stereoselectivity to give the corresponding homoallyl alcohols 3a–d in good yields. The homoallyl alcohol 3b was easily transformed to (2R,3S)-3-hydroxy-2-hydroxymethylpyrrolidine 8.