Isolation and structure elucidation of linolipins C and D, complex oxylipins from flax leaves

Two previously unknown stress-inducible complex oxylipins, digalactosyldiacylglycerol species containing (ω5Z)-etherolenic acid residues, were isolated from flax leaves. Their structures were elucidated using UV, MS and NMR analyses. •Two complex oxylipins, linolipins C and D, were isolated from flax leaves.•The structures of linolipins were elucidated by NMR and mass spectrometry.•Inoculation of plants with Pectobacterium atrosepticum induces linolipin synthesis.•Rapid formation of linolipins also occurs in the freeze–thaw injured flax leaves. Two complex oxylipins (linolipins C and D) were isolated from the leaves of flax plants inoculated with phytopathogenic bacteria Pectobacterium atrosepticum. Their structures were elucidated based on UV, MS and NMR spectroscopic data. Both oxylipins were identified as digalactosyldiacylglycerol (DGDG) molecular species. Linolipin C contains one residue of divinyl ether (ω5Z)-etherolenic acid and one α-linolenate residue at sn-1 and sn-2 positions, respectively. Linolipin D possesses two (ω5Z)-etherolenic acid residues at both sn-1 and sn-2 positions. The rapid formation (2–30min) of linolipins C and D alongside with linolipins A and B occurred in the flax leaves upon their damage by freezing–thawing.