Chemical compounds of a native Jatropha curcas seed oil from Mexico and their antifungal effect on Fusarium oxysporum f. sp. gladioli

Application of plant derivatives, including Jatropha curcas seed oil, is among the newest alternative methods for controlling Fusarium oxysporum f. sp. gladioli, one of the most widespread and destructive gladiolus fungi. Phorbol esters are considered the main toxic compounds in J. curcas seeds; therefore, knowing the amount of these compounds for the possible application of the oil as fungicide is of utmost importance, including the identification and evaluation of the fungicidal effect of its compounds. In this study, phorbol ester content in the seed oil of a native J. curcas species from the state of Chiapas, Mexico, was almost negligible (0.15mgg ^-1 ). The result of the fractionation indicates that triacylglycerides were the dominant lipids. Further methanolysis of J. curcas seed oil and its fractions gave 49% oleic acid. Antifungal assays showed that the seed oil of J. curcas at 2.5mgmL ^-1 inhibited the growth rate of F. oxysporum f. sp. gladioli to about 0.77cmday ^-1 , while the effect of the G1-G9 fractions, obtained by column chromatography, tested on this parameter was variable. The best inhibitory concentration for G3-G9 fractions was 200mgL ^-1 . In G4 fraction at a similar concentration, the lowest percentage germination (about 57%) was observed. From the active compounds and commercial triacylglycerides tested, no pattern was associated with concentration-inhibition in the growth rate assay, while the lowest percentage germination was with the commercial triolein at 500mgL ^-1 (30% approximately).