Antifouling substances against larvae of the barnacle Balanus amphitrite from the marine sponge, Acanthella cavernosa

A total of 118 Japanese marine invertebrates were extracted with methanol, and their chloroform-soluble materials tested for antifouling activity as well as toxicity against barnacle (Balanus amphitrite) larvae. Among 86 species that showed more than 80% larval settlement inhibition, 13 species, including 8 sponges were weakly toxic to the barnacle larvae. The sponge Acanthella cavernosa, which showed most promising activity was extracted with ethanol and fractionated by solvent partitioning, silica gel column chromatography, gel filtration, and ODS HPLC to give two active compounds which on the basis of spectral data and chemical transformation were identified as a new compound, 10-formamido-4-cadinene and a known compound, T-cadinol, They inhibited larval settlement at concentrations of 0.5 mug ml(-1).