Julichrome Monomers from Marine Gastropod Mollusk-Associated Streptomyces and Stereochemical Revision of Julichromes Q_3.5 and Q_3.3

Two julichrome monomers, julichromes Q(11) (1) and Q(12) (2), along with five known julichromes (Q(10), Q(3).(5), Q(3).(3), Q(6).(6), Q(6), 3-7) and four known anthraquinones (chrysophanol, 4-acetylchrysophanol, islandicin, huanglongmycin A, 8-11), were isolated from the marine gastropod mollusk Batillaria zonalis-associated Streptomyces sampsonii SCSIO 054. This is the first report of julichromes isolated from a marine source. Extensive dissection of 1D and 2D NMR datasets combined with X-ray crystallography enabled rigorous elucidation of the previously reported configurations of julichrome Q(3).(5) (4) and related julichrome Q(3).(3) (5); both of the configuration at C(9) needs to be revised. In addition, julichrome Q(12) (2) was found to display antibacterial activity against Micrococcus luteus and Bacillus subtilis with MICs of 2.0 and 8.0 mu g mL(-1); four compounds (1, 3, 6, 7) also showed inhibitory activities against an array of methicillin-resistant Staphylococcus aureus, S. aureus and S. simulans AKA1 with MIC values ranging from 8 to 64 mu g mL(-1).