Three new bis-indole alkaloids, topsentin-A (1), -B1 (2), and -B2 (3) have been isolated from the Mediterranean sponge Topsentiagenitrix and their structure determined by spectroscopic methods. These compounds are weakly toxic for fish and for dissociated cells of the freshwater sponge Ephydatiafluviatilis and thus might be partially responsible for the chemical defense of the sponge.

Chemotaxonomy of the genus AgelasBraekman, J.C.; Stoller, C.; van Soest, R.W.M. Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Download date: 09 May 2018Biochemical Systernatics and Ecology, Vol. 20. No. 5. pp, 417-431, 1992 Abstract--The secondary metabolite content of four different species of Agelas (Porifera) from the West Indies has been studied. All the compounds isolated are already known metabolites whose identification was confirmed by comparison of their spectral properties with those reported in the literature. They pertain to two different classes of compounds: terpenoids and pyrrole-2-carboxylic acid derivatives. The chemotaxonomic value of these secondary metabolites has been evaluated. Their distribution amongst the Porifera, as well as that of isocyanide derivatives, suggests a close relationship between the Agelasidae, the Axinellidae and the Halichondriidae.

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ring sponge TOp8mtM g e n i t r k , has been achieved starting from 3-acetylindole. The synthesis of topsentin-A, a bisindole alkaloid isolated from the ma- Recently, we reported the isolation from the marine sponge T o p e e n t i a g e n i t r kof three related basic compounds, topsentin-AU), -el(?) and -B2(2) pertaining to a new type of bisindole alkaloids. The structure determinations were based on their spectral properties and, in particular, on homo-and heterocorrelated 2D NWR experiments"). These derivatives are presumed to derive from the biocondensation of two tryptophan units. total synthesis of topsentin-A starting from 3-acetylindole. This synthesis is based on the rearrangement, reported by Koga et al.(283), of 1,1-dimethyl-1-phenacylhydrazinium bromide (1) into 12-phenyl-lH-imidazol-4yllphenylmethanone (2). of a N to N migration of the phenacyl to give l,l-dimethyl-2-phenacylhydrazine 2 OH H 3 OH Br --