Unprecedented oxylipins from the marine green alga Acrosiphonia coalita.

The Oregon marine chlorophyte Acrosiphonia coalita produces an assortment of oxidized polyunsaturated fatty acids, or oxylipins. The smallest of these was a 10-carbon conjugated trienal 1 with antimicrobial properties. Related to 1 were three novel branched-chain conjugated trienals 4, 5, and 9 in which the aldehyde was present as a branch on a 17-carbon fatty acid chain. Additionally, two novel conjugated unbranched trienone octadecanoids 8 and 10 were also isolated and characterized. Finally, a family of related epoxy-alcohols (11, 12, 15, and 17) was obtained from A. coalita. Structures were determined by spectroscopic methods in combination with formation of various degradation products and derivatives. The absolute stereochemistry of several of these metabolites was determined by application of exciton chirality circular dichroic spectroscopy on benzoate derivatives.