Chemical Examination of the Leaves of AZADIRACHTA INDICA A. JUSS. (NEEM) for Insect Anti-Feedants.
The chemistry of the extractives from the leaves of Azadirachta indica and its closely related species, Melia azedarach is reviewed. Cold methylated spirit was resolved into four fractions on the basis of their solubilities in the non-polar solvent hexane and in aqueous alkali. Each of these fractions was tested for repellent activity on the bean seed weevil; Callosobruchus maculatus. three of the fractions inhibited the emergence of the bean seed weevils and were therefore considered to possess the expected insect repellent activity. From one of these fractions, thick oil was isolated after purification using idolumn and thin layer chromatographic methods. Spectroscopic studies of this thick oil revealed the presence of one major compound whose molecule contained an ester group and a C=C in conjugation with another Pi electron system.