Structure and biosynthesis of marine algal oxylipins.

Diverse marine life, including algae, sponges, molluscs, corals, tunicates, and bacteria, have been found to possess a variety of structurally unique oxylipins. The algae are the best characterized of these organisms for their oxylipins, which have now been described from more than 30 species representing the three major groups of macrophytic algae (Rhodophyta = reds, Chlorophyta = greens, and Phaeophyceae = browns). A number of recent studies have sought to understand the biosynthetic origin and mechanistic chemistry which leads to the formation of these unique marine substances. In general, the red algae metabolize C20 acids via 12-lipoxygenase-initiated pathways, green algae metabolize C18 acids at C-9 and C-13, and brown algae metabolize both C18 and C20 acids, principally by lipoxygenases with n-6 specificity. This review updates the records of new oxylipins from marine algae and describes thoughts on their biogenesis as well as specific experiments aimed at probing these hypotheses.