A new antitumour ansamitocin from Actinosynnema pretiosum.

A new compound of ansamitocin was isolated from the extracts of fermentation medium of mutant strain HGF052 derived from Actinosynnema pretiosum ssp. aurantium ATCC 31565, and identified as N-demethyl-desepoxy-9-methoxy-maytansinol (1) on the basis of extensive spectroscopic methods. Bioassay results showed that compound 1 had cytotoxic activity against HL-60 and BEL-7402 cell lines.