Grace A. Hesler

Korkormicins, novel depsipeptide antitumor antibiotics fromMicromonospora sp C39500: Fermentation, precursor directed biosynthesis and biological activities

Micromonospora sp C39500, isolated in our laboratory from a soil sample, produced a complex of seven novel depsipeptide antitumor antibiotics, designated korkormicins. The major component of the complex, korkormicin A, has a MW of 1452 and a molecular formula of C66H84N16O22. Korkormicin A exhibits potentin vivo antitumor activity against P388 leukemia and M109 lung carcinoma implanted intraperitoneally (ip) in mice, with effective doses of 0.05–0.20 mg kg−1 injection−1, for five or three ip injections, respectively. It is also active against Gram-positive bacteria but inactive against Gram-negative bacteria. The production of korkormicin A was enhanced by 3-fold when 0.1%l-valine was added to the production culture at 48h. A titer of 401.0 μg ml−1 was achieved in the fermenter culture supplemented with 0.1%l-valine.