Phenylpropanstoffwechsel

Two new amide-linked conjugates of jasmonic acid, N-[(3R,7R)-(−)-jasmonoyl]-(S)-dopa (3) and N-[(3R,7R)-(−)-jasmonoyl]-dopamine (5), were isolated in addition to the known compound N-[(3R,7R)-(−)-jasmonoyl]-(S)-tyrosine (2) from the methanolic extract of flowers of broad bean (Vicia faba). Their structures were proposed on the basis of spectroscopic data (LC-MS/MS) and chromatographic properties on reversed and chiral phases and confirmed by partial syntheses. Furthermore, tyrosine conjugates of two cucurbic acid isomers (7, 8) were detected and characterized by LC-MS. Crude enzyme preparations from flowers of V. faba hydroxylated both (±)-2 and N-[(3R,7R/3S,7S)-(−)-jasmonoyl]tyramine [(±)-4] to (±)-3 and (±)-5, respectively, suggesting a possible biosynthetic relationship. In addition, a commercial tyrosinase (mushroom) and a tyrosinase-containing extract from hairy roots of red beet exhibited the same catalytic properties, but with different substrate specificities. The conjugates (±)-2, (±)-3, (±)-4, and (±)-5 exhibited in a bioassay low activity to elicit alkaloid formation in comparison to free (±)-jasmonic acid [(±)-1].