What it is
Methyl jasmonate, abbreviated MeJA, is a volatile organic compound derived from jasmonic acid. It is a natural cyclopentanone lipid belonging to the jasmonate family of plant oxylipin stress hormones. The (1R,2R) form, called (-)-methyl jasmonate, has the IUPAC name methyl 2-[(1R,2R)-3-oxo-2-[(Z)-pent-2-enyl]cyclopentyl]acetate.
Occurrence
It is a naturally occurring compound in floral scents such as jasmine, tuberose and magnolia.
Function in plants
Plants produce jasmonic acid and methyl jasmonate in response to many biotic and abiotic stresses, in particular herbivory and wounding. Unharmed plants absorb airborne methyl jasmonate through the stomata or by diffusion through the leaf cell cytoplasm. It can induce a plant to produce several types of defense chemicals, such as phytoalexins and protease inhibitors. Protease inhibitors interfere with the insect digestive process and discourage the insect from eating the plant again. An herbivorous attack makes a plant produce methyl jasmonate both for its own defense and as a signal to other plants.
Methyl jasmonate is also a plant hormone involved in tendril coiling, flowering, and seed and fruit maturation. Increased amounts of methyl jasmonate in plant roots have been shown to inhibit their growth. Applied to Norway spruce, it doubled the accumulation of monoterpene and sesquiterpene compounds in the needle tissues, a response normally triggered only by tissue damage.
Methyl jasmonate takes part in plant defense and in developmental pathways such as seed germination, root growth, flowering, fruit ripening and senescence. The growth inhibition in roots is predicted to come from higher amounts activating genes that were not expressed before. It induces ethylene-forming enzyme activity, which raises ethylene to the amount fruit maturation needs. A rise in the hormone affects flowering time, flower morphology and the number of open flowers. Sprayed on leaves, it prevented bacterial growth in plants, an effect thought to come from induced resistance.
Related materials
Methyl dihydrojasmonate is a synthetic relative of methyl jasmonate with an odour similar to that of jasmine. Some of its earliest syntheses rested on the selective hydrogenation of methyl jasmonate obtained from natural jasmine oil, until better routes were developed. Adding methyl dihydrojasmonate to a classically hesperidic fragrance construction is considered the beginning of a new trend in perfumery toward transparency and projection. Decarboxylation of jasmonic acid affords the related fragrance jasmone.
Research
In four human non-small-cell lung cancer cell lines, methyl jasmonate suppressed proliferation, with 1.6 mM giving up to 80% inhibition after 48 hours. It triggered apoptosis in these cells through the DDIT3-TNFRSF10B-CASP axis.
Regulation and safety
Methyl jasmonate has the FEMA number 3410. It has been assessed and approved by the FAO/WHO as a food additive. The US Environmental Protection Agency published an exemption from the requirement of a tolerance for it, and no toxicological endpoints were found through any route of exposure. It was described there as a naturally occurring plant hormone and a natural part of the human diet through commonly consumed fruits.
History
Jasmonic acid was first isolated in 1957, in the form of its methyl ester, by the Swiss chemist Édouard Demole and his colleagues. Methyl jasmonate isolated from the jasmine oil of Jasminum grandiflorum led to the discovery of the molecular structure of the jasmonate plant hormones. Its isolation and structure determination from jasmine oil were published in 1962.
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