In addition to three known sex lure components [(Z)-11-hexadecenyl acetate, (Z)-11-hexadecenal, and (Z)-11-hexadecenol], (Z)-9-tetradecenyl acetate was field-proven as a trace coattractant for malePlutella xylostella, with an optimal content below 0.01% in blends. This potent four-component lure for diamondback males also attractedCrymodes devastator males, and in this respect is not different in its attractancy from virgin diamondback females. Replacement of (Z)-9-tetradecenyl acetate in the four component lure with (Z)-9-tetradecen-1-ol, at the level of 10% of the total lure mixture, did not alter its attractancy for diamondback males, but it did inhibit attraction ofCrymodes devastator. The status of biologically active components as possible sex pheromones or para-pheromones is discussed.
A method for the characterization of sub-milligram quantities of plant coumarins has been devised. Each compound was purified by gas-liquid chromatography, and the collected material analyzed by a combination of ultraviolet absorption and nuclear magnetic resonance spectroscopy. The procedures developed were tested successfully on several plant extracts. Limettin and bergapten were identified in lime peel; angelicin, psoralen, and xanthotoxin in parsnips; and angelicin, xanthotoxin, and bergapten in Angelica leaves. Isopimpinellin was found in all three plant materials.
Labelling experiments with 14C and 3H have shown that linear furanocoumarins of Ammi majus, Angelica archangelica, Heracleum lanatum (Umbelliferae), and Ruta graveolens (Rutaceae) are formed from umbelliferone via the dihydrofuranocoumarin, marmesin. The unsubstituted furanocoumarin psoralen is formed first, and hydroxylation and O-methylation then lead to methoxy-substituted derivatives, with other alkylated psoralens assumed to be formed analogously. No evidence was obtained for oxygenation of the coumarin nucleus before attachment of a side chain, since oxygenated umbelliferones were poorly utilized for furanocoumarin biosynthesis. A detailed biosynthetic route to linear furanocoumarins, consistent with known stereochemistry, is proposed.A separation of furanocoumarins by column partition chromatography on formamide-impregnated silica, and syntheses of [3-14C]umbelliferone, [2-14C]- and [3-14C]skimmin, [3-14C]daphnetin, [2-14C]-7-hydroxy-8-methoxycoumarin, and [2-14C]5-methoxy-7-hydroxycoumarin are described.
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