Borrero_2019_Comp.Biochem.Physiol.C.Toxicol.Pharmacol__108664

New compounds having insecticidal activity are needed to control of Aedes aegypti, and plants are a source of this type of molecules. A principal component analysis was carried out to determine the criterion to select metabolites for evaluation. The larvicidal activity of the seven selected metabolites was evaluated by determining their lethal concentrations 50 (LC50) by probit analysis. Six of the seven evaluated molecules presented LC50 values<100ppm. The effects of these six molecules on acetylcholinesterase and the respiratory chain complexes of the mitochondrial of Ae. aegypti were evaluated. The four metabolites presenting the highest percentages of inhibition on different targets were mixed in 11 different combinations, and the percentage of mortality of each mixture on Ae. aegypti larvae was determined. Secondary metabolites geranyl acetate, alpha-humulene, beta-caryophyllene, geraniol, nerol, and n-octanol presented LC50 values under 100ppm (44, 41, 48, 84, 87, and 98ppm, respectively), whereas 1,8-cineole presented a LC50 value of 183ppm. Geranyl acetate inhibited acetylcholinesterase by 38%; alpha-humulene inhibited respiratory chain complexes II, III, and IV by 38, 35, and 30%, respectively; beta-caryophyllene inhibited complexes II and III by 30 and 36%, respectively, and geraniol inhibited complexes I and II by 27 and 29%, respectively. Nerol and n-octanol inhibited complex II significantly, by 41 and 25%, respectively. The evaluation of the different mixtures revealed a synergistic effect between geranyl acetate and geraniol, and an antagonistic effect was observed between alpha-humulene and beta-caryophyllene compounds.