Dynemicin O

New antibiotics, dynemicins O (3), P (4) and Q (5), were isolated from the culture broth of Micromonospora chersina M956-1, the dynemicin A (1)-producing strain. An ethyl acetate extract of a tank culture was roughly separated by a column of Diaion SP-800 and was further purified by combining a variety of column chromatographies to afford a few mg of compounds 3, 4 and 5. Their structures, analyzed from the spectral data, had a bridging phenylene group, a vic-diol and an oxo group in place of the respective 1,5-diyn-3-ene bridge, the epoxide ring and the carboxyl group in dynemicin A. Their biological activities were evaluated against bacteria and tumor cells.

Dynemicin A is a potent antibacterial and antitumor antibiotic having a striking hybrid structure of both anthraquinone as a DNA intercalator and diynene as a DNA strand breaker. We have investigated the DNA-binding property and cytotoxicity of non-diynene class of dynemicins (H, L, M, O and Q) and several related synthetic tri- and pentacyclic aza-anthraquinones 1a-3a (R = H) and 1b-3b (R = CH3). Among them, dynemicin H, L, M, O, Q, 1a, 1b and 2b exhibited DNA-binding property. All non-diynene class of dynemicins investigated exhibited intercalative binding activity, however, synthetic aza-anthraquinones 1a-3a did not show such ability. Dynemicin H, Q, 2a, 2b and 3b showed cytotoxicity against HL-60 and K-562 cell lines.