Bioactive Metabolites from the Caribbean Sponge Aka coralliphagum

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. The burrowing sponge Aka coralliphagum ()Siphonodictyon coralliphagum) is a bright yellow colored sponge that burrows into corals. Four distinct morphological growth forms have been described for Aka coralliphagum from the Caribbean: forma typica, f. tubulosa, f. obruta, and f. incrustans.1 Several bioactive sesquit-erpene hydroquinones, such as the siphonodictyals (B, 1) and siphonodictyols,2 were obtained from the forms tubulosa and typica. Although the isolation of labile compounds such as siphonodictyols G (2) and H (3) suggested the existence of additional sulfate