Assessment of the larvicidal potentials of thymol derivatives on anopheles mosquitoes

Abstract

Thymol, a major constituent of the south-eastern Nigeria variety of Ocimum gratissimum, popularly known as nchawu (scent leaf), was converted to its O-methyl, O-ethyl, acetate and benzyloxy derivatives that are characterized by their spectral data such as infra red, proton n.m.r. and mass spectra. Tests on their insecticidal potency show that, like the parent compound thymol, they also possess insecticidal properties in the decreasing order benzyloxy > acetate > O-ethyl > O-methyl. This order is explained partly by the electron withdrawing tendency of the benzyloxy and acetate groups and also because as the molecular weight of the derivatives increases their solubility decreases.