The oxidation profile at C-18 of furanocembranolides may provide a taxonomical marker for several genera of octocorals

Abstract

The furanocembranolides 1-3 along with the known compounds pukalide, pukalidealdehyde, epoxypukalide, and leptolide were isolated from Leptogorgia spp. and their structures were determined by spectroscopic evidences. An NMR-based method using Pirkle's reagent at low temperature allowed us to determine the absolute configuration at C-10 of a g-butenolide unit embedded in a flexible furanocembranolide network. The C-18 of furanocembranolides undergoes an oxidation cascade leading from a methyl group to a carboxylic acid/ ester that appears to be genus specific.We introduce the concept genus-specific oxidation, a feature that provides a chemotaxonomical marker for several genera of octocorals. This concept also allowed us to propose a biogenetic pathway for these compounds. 2007 Elsevier Ltd. All rights reserved.