Unprecedented pathogen-inducible complex oxylipins from flax--linolipins A and B.

Oxylipins constitute a large family of bioregulators, biosynthesized via unsaturated fatty acid oxidation. This study reports the detection of an unprecedented family of complex oxylipins from flax leaves. Two major members of this family, compounds 1 and 2, were isolated and purified. Their structures were evaluated using NMR and MS analyses. Both compounds were identified as monogalactosyldiacylglycerol species. Compound 1 contains one alpha-linolenoyl residue and one residue of (9Z,11E,1'Z,3'Z)-12-(1',3'-hexadienyloxy)-9,11-dodecadienoic, (omega5Z)-etherolenic acid at positions sn-1 and sn-2, respectively. Compound 2 possesses (omega5Z)-etherolenic acid residues at both position sn-1 and position sn-2. We suggest the trivial names linolipin A and linolipin B for compounds 1 and 2, respectively, and the collective name linolipins for this new family of complex oxylipins. The linolipin content of flax leaves increased significantly in response to pathogenesis. Thus, accumulation of esterified antimicrobial divinyl ethers may be of relevance to plant defense.