Tetracenoquinocin and 5-iminoaranciamycin from a sponge-derived Streptomyces sp. Sp080513GE-26.

Two new anthracyclines, tetracenoquinocin (1) and 5-iminoaranciamycin (2), together with the known compounds aranciamycin (3) and antibiotic SM 173B were isolated from the culture of Streptomyces sp. Sp080513GE-26 associated with a marine sponge, Haliclona sp. The structures of 1 and 2 were established on the basis of extensive NMR and MS analyses along with (13)C-labeling experiments. The compounds 1-3 were evaluated for cytotoxicity against two cancer cell lines.