A NEW TOPOISOMERASE-II INHIBITOR, BE-22179, PRODUCED BY A STREPTOMYCETE .1. PRODUCING STRAIN, FERMENTATION, ISOLATION AND BIOLOGICAL-ACTIVITY

A new topoisomerase II inhibitor, designated BE-22179, was isolated fr om the culture broth of Streptomyces sp. A22179, which resembles ''Str eptomyces gangtokensis''. The inhibitor was extracted from the mycelia l cake of the culture broth with organic solvent and successively puri fied by silica gel chromatography. BE-22179 inhibited topoisomerase II strongly but not topoisomerase I and showed potent antitumor activity against various tumor cell lines both and vitro and in vivo.