The structures of two new bispyrroloiminoquinone alkaloids, tsitsikammamine A (1) and tsitsikammamine B (2) and two new pyrroloiminoquinone alkaloids 14-bromodiscorhabdin C (3) and 14-bromodihydrodiscorhabdin C (4) were determined spectroscopically. Compounds 1 and 2 are the first bispyrroloiminoquinone alkaloids to be isolated from a marine sponge while compounds 3 and 4 are the first reported discorhabdin metabolites with a C-14 substituent. All four compounds exhibit antimicrobial activity. Copyright (C) 1996 Elsevier Science Ltd