Structural requirements for biologically active jasmonates: Induction of protease inhibitors and cotyledon senescence

Methyl jasmonate and jasmonate isomers were resolved for studies in stereoselectivity of biological action. Chemical modifications included fluorination at the chiral C7 carbon, trifluorination at the C12 of the pentenyl sidechain, shortening of this pentenyl to a butenyl moiety, and synthesis of the (+) and (-)-epi-methyl jasmonates. The effects of these modifications and stereospecificity were monitored using three assays: proteinase inhibitor II promoter driving the reporter β-glucuronidase; endogenous trypsin proteinase inhibitor induction; and sunflower cotyledon senescence induction. The methyl esters were more active than the corresponding acids, the R absolute configuration at C3 was most effective in all assays, fluorination at C7 abolished activity in the proteinase inhibitor assays, and the trifluorination at C12 or shortening to a butenyl did not alter activity relative to the active (-)- methyl jasmonate, but both of these latter modifications revealed a delayed response in the senescence conductivity measures.[PUBLICATION ABSTRACT]