Akira Nakagawa

Structure of virantmycin, a novel antiviral antibiotic

Abstract The structure of virantmycin, a novel antiviral antibiotic, isolated from Streptomyces , has been established by chemical and spectroscopic evidences.

Structure of herbimycin A new ansamycin antibiotic

Abstract Herbimycin is a new potent herbicidal antibiotic1) isolated from the cultured filtrate of Streptomyces (Sm.) hygroscopicus AM-3672. We assign structure 1 to herbimycin based on 1H- and 13C-nmr spectral analyses and biosynthetic means using 13C-labeled precursors.

Elasnin, a new human granulocyte elastase inhibitor produced by a strain of Streptomyces.

Elasnin, a new human granulocyte elastase inhibitor, has been isolated from Streptomycesnoboritoensis KM-2753. Elasnin is a neutral, lipophilic colorless and viscous oil (nD17=1.4983, [α]D18 −0.9°, λmaxEtOH 291 nm (e, 7760)). The molecular formula was C24H40O4 (M.W.: 392) as determined by its elemental analysis and mass spectrum. Elasnin inhibits markedly human granulocyte elastase, but is almost ineffective for pancreatic elastase, trypsin, chymotrypsin, thermolysin and papain.

The structures of diazaquinomycins a and b, new antibiotic metabolites

Abstract Novel substituted 1,8-diazaanthraquinone structures of diazaquinomycins A and B were determined by the application of nmr spectroscopy.

The structure of hitachimycin, a novel macrocyclic lactam involving β-phenylalanine

Abstract The structure of hitachimycin ( 1 ) has been determined by NMR spectrometry and chemical reactions. The antibiotic is a novel 19-membered macrocyclic lactam possessing a β-phenylalanine moiety.

Chemistry of leucomycin-X: Conformational studies on leucomycin

Abstract The conformation of leucomycin, a macrolide antibiotic with a 16-membered ring lactone, was examined in solution by IR, NMR and CD spectral analysis. The IR reveals that the five hydroxyls are all involved in intramolecular H-bonding. The NMR of the 16-membered ring lactone forming the aglycone shows that the acetyl-carbonyl at C-3, the allylic proton at C-11 and the aldehyde proton are in close proximity on the lactone ring. CD studies suggest that the conformation of the 16-membered ring lactone, especially around the lactone, is mobile and solvent dependent.