ISOLATION OF THE MURICINS. EVIDENCE OF A CHEMICAL ADAPTATION AGAINST FOULING IN THE MARINE OCTOCORAL MURICEA FRUTICOSA (GORGONACEA)

Article abstract of DOI:10.1016/S0040-4020(01)96473-7

Chemical comparisons of the closely-related Pacific gorgonians Muricea californica and M. fruticosa have shown that the much less fouled M. fruticosa contains four new esterified aminogalactose saponins assigned as the muricins-1 through -4 (1-4).The structures of these new saponins were defined by chemical degradation yielding the aglycone pregna-5,20-dien-3β-ol, and by extensive 1H and 13C NMR investigations.Muricins-2, -3 and -4 were found to possess 2-acetamidogalactopyranose components with unprecedented n-butyrate ester functionalities in the C-4', C-6' and the C-4' and C-6' positions, respectively.At approximately natural concentrations, the muricins were found to inhibit growth of the marine diatom Phaeodactylum tricornutum.The muricins did not, however, possess the ichthyotoxic, cytotoxic, or antimicrobial effects reported for numerous marine-derived saponins.The potential role of these compounds in contributing to the reduced fouling of M. fruticosa is discussed.