TOXICITY OF ALKALOIDS OF Erythrina americana ON LARVAE OF MOSQUITO Culex quinquefasciatus

Abstract

This work describes the effect of several alkaloid fractions obtained from the seeds of Erythrina americana (Fabaceae); these fractions allowed to evaluate their in vivo toxicity for the mosquito Culex quinquefasciatus larvae. The fraction of liberated alkaloids in the methanolic extract did not show any activity; however, the fraction of free alkaloids showed high toxicity (88 % of mortality) on larvae. By gas chromatography-mass spectrometry and ¹H-NMR the presence of dienoic alkaloids erysopine, erysovine and erysodine was detected in the free alkaloids fraction. Also in the free alkaloid fraction, two lactonic alkaloids, α and β-erythroidine, were identified. Two of the main alkaloids were chosen for the insecticide test, β-erythroidine and erysovine. Both alkaloids, showed a 60% mortality on the insect model and their LC₅₀ were 225 and 394 mg L^-1, respectively. The results show than β-erythroidine was more toxic that erysovine.