Microbial transformation of antibiotics II. Additional transformation products of maridomycin III

Streptomyces sp. strain No. K-245 was found to transform maridomycin III into four derivatives (A1, A2, A3 and A4) in addition to the transformation products reported previously. Isolation of the main product A1 was carried out by column chromatography on silica gel developed with CHCl3-MeOH (19:1). From the partial investigation of the structure of A1, it proved to have a C-18-aldehyde group and C 4''-propionyl group but no antimicrobial activity. The relationships between A group's derivatives and known derivatives of maridomycin III are also discussed.