The kapurimycins, new antitumor antibiotics produced by Streptomyces. Producing organism, fermentation, isolation and biological activities.

As a result of screening for antitumor agents from actinomycetes, the kepurimycins were isolated from Streptomyces sp. DO-115. The antibiotics were produced in a fermentation medium supplemented with high porous polymer resin which adsorbs antibiotics and results in an increase of titer. The active complex was isolated from the polymer resin by a solvent extraction procedure and was separated by column chromatography, into two minor and one major component, named A1, A2 and A3. The kepurimycins were active against bacteria, particularly Gram-positive organisms, and were cytotoxic to HeLa S3 human cerivical cancer cells and T24 human bladder carcinoma cells in vitro. Among the individual components of the kapurimycins, kapurimycin A3 exhibited the strongest antibacterial and cytotoxic activities. It showed a potent antitumor activity against murine leukemia P388 in vivo.