Chemical defenses against fish predation in three Brazilian octocorals: 11beta, 12 beta-epoxypukalide as a feeding deterrent in Phyllogorgia dilatata

The feeding-deterrence properties of crude extracts of three Brazilian octo coral species, Neospongodes atlantica Kukenthal (Alcyonacea, Nephtheidae), Plexaurella regia Castro (Gorgonacea, Plexauridae), and Phyllogorgia dilata ta Esper (Gorgonacea, Gorgoniidae), were investigated. All the extracts wer e incorporated into food strips at the concentrations occurring in the livi ng organisms. Crude extract and its ethyl acetate fraction obtained from P. dilatata collected in Armacao dos Buzios (Rio de Janeiro State), when inco rporated into artificial diets and tested in the habitat of origin, reduced consumption of food strips by fishes, relative to controls. Crude extracts from two octocoral species collected at the National Marine Park of Abrolh os (Bahia State), N. atlantica and P. regia, had no apparent feeding-deterr ence properties; in fact, they seemed to stimulate feeding. Bioassay-guided fractionation of the bioactive P. dilatata crude extract revealed that the deterrent property was restricted to a medium polarity fraction. Field pal atability experiments with two pure compounds isolated from this fraction r evealed that the furanocembranolide 11 beta,12 beta-epoxypukalide is a pote nt feeding deterrent produced by P. dilatata against fish. Apparently, fura nocembranolides are a particular class of compounds with feeding deterrent properties, protecting some octocorals from potential fish predator species in both tropical and temperate environments.