A new antitumor antibiotic, kazusamycin

A new antibiotic kazusamycin, was isolated from the culture broth of Streptomyces sp. No. 81-484, which shows antitumor activity against experimental murine tumors. This antibiotic did not possess antibacterial activity against Gram-positive and Gram-negative bacteria, but showed strong cytotoxic activity against HeLa cells in vitro. The chemical and physico-chemical properties of kazusamycin suggest that the molecular formula of this antibiotic is C33H48O7 (MW 556).