Publication Date:
2012-06-11
Description:
Background: It was observed that Medicago truncatula seed flour displayed a strong toxic activity towards the rice weevil Sitophilus oryzae (Coleoptera), a major pest of stored cereals. Results: The toxic molecule was purified, by solvent extraction and HPLC, and identified as a saponin, namely 3-GlcA-28-AraRhaxyl-medicagenate. Saponins are detergents, and the CMC of this molecule was found to be 0.65 mg per mL. Neither the worm Caenorhabditis elegans nor the bacteria E. coli were found to be sensitive to this saponin, but growth of the yeast Saccharomyces cerevisiae was inhibited at concentrations higher than 100 ug per mL. The purified molecule is toxic for rice weevils at concentrations down to 100 ug per g of food, but this does not apply to the others insects tested, including the Coleoptera Tribolium castaneum and the Sf9 insect cultured cells. Conclusions: This specificity for the weevil led us to investigate its potential for pest control and to propose the hypothesis that this saponin has a specific mode of action, rather than acting via its non-specific detergent properties.
Electronic ISSN:
1472-6769
Topics:
Biology
,
Chemistry and Pharmacology
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