ANTIMICROBIAL INDOLEQUINONES FROM THE MID-INTESTINAL GLAND OF THE MURICID GASTROPOD DRUPELLA-FRAGUM

Three new indolequinones, 6-merhoxyindole-4,7-quinone (1), 5-methoxyin dole-4,7-quinone (2) and 5-methylindole-4,7-quinone (3) were isolated from the mid-intestinal gland of the muricid gastropod Drupella fragum . The structures of 1 and 2 were established by spectroscopic methods and total synthesis, whereas the structure of 3 was elucidated mainly by NMR spectroscopic analyses. Compounds 1 3 exhibited moderate antimi crobial activities against Staphylococcus aureus, Bacillus subtilis, a nd Escherichia coli with MIC = 6.25 similar to 50 mu g/mL. (C) 1998 El sevier Science Ltd. All rights reserved.