Isolation and characterization of a new pyrano[4',3':6,7]naphtho[1,2-b]xanthene antibiotic FD-594

During our screening of microbial metabolites for effective drugs against tumor cell lines, we discovered a new pyrano[4',3':6,7]naphtho[1,2-b]xanthene derivative, FD-594 from the fermentation broth of Streptomyces sp. TA-0256. FD-594 shows moderate activity against tumor cell lines, comparative to that of adriamycin, as well as antibacterial activity against some Gram-positive bacteria.