In addition to aplysinopsin (1), the anthozoan Astroides calycularis produces 6-bromoaplysinopsin (6) and smaller amounts of propionyl derivatives of 1 (7) and 6 (8). Aplysinopsin (1), a yellow tryptophan derivative that showed cytotoxic activity against some cancer cell lines, has been isolated from three different marine sponges [Thorecta sp. (1), Verongia spengelii (2), and Dercitus sp. (3)]. The last organism also produces 2'-de-N-methylaplysinopsin (2) and 6-bromo-2'-de-N-methylaplysinopsin (3). More recently (4), the marine sponge Smerospongia aurea was shown to contain the closely related bromo compound 4. In addition, the N-methylaplysinopsin (5) has also been isolated from a marine sponge (5). This compound is an interesting antidepressant, acting as a competitive inhibitor of monoamine oxidase. We report that metabolites of this type, which until now seemed to be produced by Porifera only, are also present in the Mediterranean anthozoan Astroides calycularis Pallas which, in addition to 1, elaborates the newly discovered 6-bromoaplysinopsin (6). In the extracts of this organism, we have also found smaller amounts of their N-propionyl derivatives 7 and 8, from which possibly 1 and 6 could have been generated during the extraction procedure.