Brasiliquinones A, B and C, new benz[alpha]anthraquinone antibiotics from Nocardia brasiliensis. I. Producing strain, isolation and biological activities of the antibiotics.

New benz[alpha]anthraquinone antibiotics (brasiliquinones A, B and C) with an ethyl group at C-3 were isolated. The producer was identified as Nocardia brasiliensis. The antibiotics were active against Gram-positive bacteria including Mycobacterium sp., but not active against Gram-negative bacteria or fungi. They were also active against multiple drug-resistant P388/ADR tumor cells.