MEPS 329:307-310 (2007)  -  doi:10.3354/meps329307

Antipredatory secosterols from the octocoral Pseudopterogorgia americana

Rosângela de A. Epifanio1,*, Lenize F. Maia1,4, Joseph R. Pawlik2, William Fenical3

1Instituto de Química, Universidade Federal Fluminense, Campus do Valonguinho, 24020-005, Niterói, Rio de Janeiro, Brazil
2Center for Marine Science, University of North Carolina Wilmington, Wilmington, North Carolina 28409, USA
3Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 92093-0204, USA
4Present address: Departamento de Bioquímica Médica, ICB, CNRMN, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-590, Brazil

ABSTRACT: The chemical defense of the Caribbean octocoral Pseudopterogorgia americana was investigated using feeding assays performed in aquaria and in situ with a natural assemblage of predatory fishes. Using a bioassay-guided scheme, crude extracts, fractions and pure compounds were incorporated into palatable foods and tested. Only the secosterol fraction deterred fish feeding. Two secosterols were identified from the bioactive fraction by spectroscopic methods and comparison with literature data: 9,11-secogorgosterol (Compound 1) and 9,11-secodinosterol (Compound 2), both of which have been previously described from Pseudopterogorgia spp. Our results suggest that symbiont-produced gorgosterol and dinosterol are oxidized by the coral host to C-ring secosterols, which then provide a chemical defense to both coral and alga.

KEY WORDS: Gorgonaceae · Octocorallia · Pseudopterogorgia americana · Secosterols · Feeding deterrents · Chemical defense

Full text in pdf format