The chemistry of the burrowing sponge Aka coralliphagum was investigated to identify chemically labile secondary metabolites. The HPLC-MS analysis of the two growth forms typica and incrustans revealed different metabolites. The previously unknown sulfated compounds siphonodictyals B1 to B3 (6-8), corallidictyals C (9) and D (10), and siphonodictyal G (11) were isolated, and their structures were elucidated by NMR and MS experiments. The compounds were tested in a DPPH assay, in antimicrobial assays against bacteria, yeasts, and fungi, and in antiproliferation assays using cultures of mouse fibroblasts. The biological activity was linked to the presence of the ortho-hydroquinone moiety.

Previous studies have indicated that Caribbean reef sponges of the common genus Agelas are chemically defended from fish predators by brominated pyrrole alkaloids: Agelas clathrodes and A. wiedenmayeri by 4,5-dibromopyrrole-2-carboxylic acid (1) and oroidin (2), A. conifera by sceptrin (3). In this study, we expand our understanding of chemical defense in this sponge genus to include an extensive HPLC quantification analysis of the defensive metabolites in tissues of A. cerebrum, A. cervicornis, A. dilatata, A. dispar and A. sceptrum. A. cervicornis and A. dispar contained the same two major metabolites as A. clathrodes and A. wiedenmayeri, while A. cerebrum, A. dilatata and A. sceptrum contained a mixture of dimeric bromopyrrole alkaloids dominated by sceptrin, similar to A. conifera. At natural volumetric concentrations, both crude extracts and purified compounds from each species were unpalatable to a common generalist reef fish, Thalassoma bifasciatum, in aquarium assays, and inhibited attachment of the marine bacterium Vibrio harveyi in surface fouling assays. Brominated pyrrole alkaloids may play multiple ecological roles in protecting sponges of the genus Agelas.

Previous studies have indicated that Caribbean reef sponges of the common genus Agelas are chemically defended from fish predators by brominated pyrrole alkaloids: Agelas clathrodes and A. wiedenmayeri by 4,5-dibromopyrrole-2-carboxylic acid (1) and oroidin (2), A. conifera by sceptrin (3). In this study, we expand our understanding of chemical defense in this sponge genus to include an extensive HPLC quantification analysis of the defensive metabolites in tissues of A. cerebrum, A. cervicornis, A. dilatata, A. dispar and A. sceptrum. A. cervicornis and A. dispar contained the same two major metabolites as A. clathrodes and A. wiedenmayeri, while A. cerebrum, A. dilatata and A. sceptrum contained a mixture of dimeric bromopyrrole alkaloids dominated by sceptrin, similar to A. conifera. At natural volumetric concentrations, both crude extracts and purified compounds from each species were unpalatable to a common generalist reef fish, Thalassoma bifasciatum, in aquarium assays, and inhibited attachment of the marine bacterium Vibrio harveyi in surface fouling assays. Brominated pyrrole alkaloids may play multiple ecological roles in protecting sponges of the genus Agelas.

In this first report on the chemistry of the sponge Stylissa caribica, two known bromopyrrole metabolites and a new compound, N-methyldibromoisophakellin (1), were isolated and identified. The structure of 1 was determined using spectroscopic methods and the computer program COCON. N-Methyldibromoisophakellin (1) was shown to be the only secondary metabolite in Stylissa caribica that, at its natural concentration, is active as a feeding deterrent against a common omnivorous reef fish.

A detailed analysis of the chemical constituents of a specimen of Agelas wiedenmayeri (Alcolado, 1984) was performed. Four brominated alkaloids (1−4) were isolated and one was identified as a new bromopyrrole metabolite. The structure of the new compound, 1, was assigned using spectroscopic methods. Compounds 2 and 3, which are the major brominated metabolites, have been previously described from other Agelas sponges. The new compound, 1, may be a biosynthetic precursor for oroidin-like derivatives.

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Thomas Hassenklover1**, Sabine Predehl1**, Jyotsna Pili1**, Michael Assmann2 (*), Ulf Bickmeyer3* 1** Students of Biology/Zoology at the University of Hamburg, Germany 2 Alfred-Wegener-Institut fur Polarund Meeresforschung in der HelmholtzGemeinschaftAWI, Am Handelshafen 12, 27570 Bremerhaven, Germany 3 * Alfred-Wegener-Institut (AWI) fur Polarund Meeresforschung in der HelmholtzGemeinschaft, Biologische Anstalt Helgoland, Kurpromenade, 27498 Helgoland, Germany