Chrymutasin B

Chrymutasins A, B and C are glycosidic antibiotics produced by a mutant of the chartreusin producer-organism Streptomyces chartreusis. We report here the structure elucidation of these compounds. The sugar moieties involved were determined by comparison with the related chartreusins. The structure of the aglycone, the same in all three compounds, was elucidated by NMR, incorporation studies of labeled compounds and synthesis of derivatives. The chrymutasin aglycone differs from that of chartreusin by a single carbon and an amino group.

Three novel antibiotics, named chrymutasins A, B and C, were isolated from the fermentation products of a mutant strain obtained by NTG (N-methyl-N'-nitro-N-nitrosoguanidine) treatment. The mutant strain produced the chrymutasins, which differed in the aglycone moiety from chartreusin, and related compounds. The production of these compounds needed a characteristically long fermentation period. The antitumor activity of chrymutasin A is better in vivo than that of chartreusin, the cytotoxic activity against cell lines in vitro is equivalent, and the antimicrobial spectrum is narrower.