Junichi Kuroyanagi

1,3-Benzoxazole-4-carbonitrile as a novel antifungal scaffold of β-1,6-glucan synthesis inhibitors.

Synthesis and in vitro antifungal evaluations of 1,3-benzoxazole-7-carbonitrile 3, 1,3-benzoxazole-4-carbonitrile 4, benzofuran 5, benzoxazine 7, and benzimidazole 8 were reported. Among them, 1,3-benzoxazole-4-carbonitrile was found to be a superior scaffold structure with moderate growth inhibition against Candida species. 1,3-Benzoxazole-4-carbonitrile 6 showed potent activity against Candida species compared to 5-desmethyl compound 4 and triazolopyridine 2. Compound 6 was efficiently prepared from versatile intermediate 24, which possessed six different substituents on the benzene ring. Conversion of benzene 24 into various 1,3-benzoxazole derivatives such as 2-aliphatic 34, 2-amino 35, and lactone 38 was demonstrated.

Novel antifungal agents: Triazolopyridines as inhibitors of β-1,6-glucan synthesis

Preparations and in vitro antifungal activities of triazolopyridines, imidazopyridines, and a pyrazolopyridine were reported. Among those scaffolds, triazolopyridine was found to be the specific inhibitor of the synthesis of beta-1,6-glucan, an essential component of the fungal cell wall, and to show potent antifungal activities against several Candida species.

Design, synthesis, and biological evaluations of novel 7-[7-amino-7-methyl-5-azaspiro[2.4]heptan-5-yl]-8-methoxyquinolines with potent antibacterial activity against respiratory pathogens.

Novel 7-[7-amino-7-methyl-5-azaspiro[2.4]heptan-5-yl]-6-fluoro-1-[(1R,2S)-2-fluorocyclopropyl]- 8-methoxy-1,4-dihydro-4-oxoquinoline-3-carboxylic acid 2a and 2b were designed and synthesized to obtain potent antibacterial drugs for the treatment of respiratory tract infections. Among these, compound 2a possessing (S)-configuration for the asymmetrical carbon on the pyrolidine moiety at the C-7 position of the quinolone scaffold exhibited potent in vitro antibacterial activity against respiratory pathogens including gram-positive (Streptococcus pneumoniae and Staphylococcus aureus), gram-negative (Haemophilus influenzae and Moraxcella catarrhalis), and atypical strains (Chalmydia pneumoniae and Mycoplasma pneumoniae), as well as multidrug-resistant Streptococcus pneumoniae and quinolone-resistant and methicillin-resistant Staphylococcus aureus). Furthermore, compound 2a showed excellent in vivo activity against the experimental murine pneumonia model due to multidrug resistant Streptococcus pneumoniae (MDRSP) and favorable profiles in preliminary toxicological and nonclinical pharmacokinetic studies.