Abstract

This work describes the larvicidal activity of the ethanolic crude extract (EEB) as well as the hexanic (FH), chloroform (FCL), ethyl acetate (FAE) and remaining (FR) fractions obtained from Byrsonima intermedia leaves and bark against Aedes aegypti. Hexanic and remaining fractions from the leaves demonstrated larvicide activity against A. aegypti larvae on the 3rd stage, with LC₅₀ values of 250 and 125 μg/ml^-1, respectively, with less mortality as compared to the other fractions. Hexanic and remaining fraction from the leaves demonstrated larvicide acitivity against A. aegypti larvae on the 3rd stage, with LC₅₀ values of 250 and 125 μg/ml^-1, respectively, with less mortality as compared to the other fractions. Trypsin activities from gut of larvae treated with the extract or the fractions were significant (p < 0.05), and the major effects occurred with hexanic fraction (0.06 μmol min^-1) and remaining fraction (0.09 μmol min^-1) in the 1000 μg/ml^-1 concentration, respectively. The same fractions inhibited chymotrypsin activity in 0.06 μmol/ml^-1 (hexanic fraction) and 0.13 μmol/ml^-1 (remaining fraction) at 1000 μg/ml^-1. The inhibition was dose-dependent. The results show the inhibitory effects of the hexanic and remaining fractions from the leaves of B. intermedia on trypsin and chymotrypsin activity, which may be responsible for the deleterious effects on larvae mortality. The crude ethanolic extract and fractions of the bark does not inhibit the synthesis of trypsin compared to control. The results show the inhibitory effects of the hexanic and remaining fraction from the leaves of B. intermedia on trypsin and chymotrypsin activity, which may be responsible for the deleterious effects on larvae mortality.

Key words: Digestive system, dengue fever, larvicidal activity, natural products.