Juliana Oliveira Abreu Narciso, Marco Antonio Soares de Souza, Mario Geraldo de Carvalho, Mário Sergio da Rocha Gomes, Marcelo Genestra, Marise Maleck de Oliveira Cabral

Journal of Natural Pharmaceuticals 2011 2(3):133-137

Background: Piptadenia rigida is a source of flavonoids such as isoliquiritigenin ( 1 ), 7,3',4'-trihydroxyflavone ( 2 ) and 7,8,3',4'-tetrahydroxyflavanone ( 3 ). Flavonoids influence on the feeding behavior of insects besides the inhibition of the insect larvae growth. Nitric oxide (NO) seems to be conserved in invertebrate innate immunity and the NO synthase (NOS) activity has been implicated in insect immunity. Therefore, the NOS expression can be evaluated to determine the inhibition of NADPH consumption. Material and Methods: three natural flavonoids, isolated from P. rigida whose structures were determined by 1 H and 13 C NMR spectral data analysis, were evaluated on the Oncopeltus fasciatus control by molting processes and NADPH consumption in the insect intestine following mortality. Results: The flavonoids treatment on O. fasciatus showed 50% mortality and 50% ecdysis ( 1 ), 30% mortality and 43% ecdysis ( 2 ), and topical treatment with th 3 resulted in 43% ecdysis but did not show high toxicity at 100μg/nymph. Intestine homogenates obtained from insects treated with flavonoids that were incubated with NADPH substrate showed percentage inhibitions of 72%, 78% and 80%, for the treatments 3, 1 and 2, respectively. Conclusion: The flavanone ( 3 ) was the most effective and least toxic to the insect, followed by 2 and then 1 .