Extraction of natural insecticide azadirachtin from neem (Azadirachta indica A. Juss) seed kernels using pressurized hot solvent

Abstract

Plant-derived pesticides are gaining popularity on account of the increasing sustainable farming practices and also due to the environmental and health hazards resulting from excessive usage of their synthetic counterparts. The neem (Azadirachta indica A. Juss) tree, belonging to the Meliaceae family, is a storehouse of insecticidal azadirachtin, which possess antifeedant, growth disrupting and larvicidal properties against an array of agricultural insect pests. Pressurized Hot Solvent Extraction (PHSE) is fast emerging as an efficient means for recovering valuable active ingredients from natural plant matrices at an accelerated rate and with a reduced solvent consumption. The technique employing heated organic solvents at elevated pressures is a potential green substitute for conventional solvent extractions. The present study deals with the extraction of azadirachtin from defatted neem seed kernels (NSK) using pressurized methanol. Important operating variables like temperature, pressure, extraction time, solvent flow rate and particle size influencing the extraction efficiency were investigated in detail. The azadirachtin content in the extracts was determined by HPLC. The optimum conditions for maximizing azadirachtin yield were found to be 50°C temperature, 50bar pressure, −60+80 mesh particle size and 5mL/min extractant flow rate. Under optimal conditions, 210.93mg azadirachtin was extracted per 100g defatted NSK within an extraction time of 100min. Moreover, the proposed method resulted in 1.5 fold reduction in solvent consumption as compared to conventional maceration.