Sunday, November 12, 2006 - 4:00 PM

Analysis of Azadirachtin Levels in Aqueous Extracts of Neem Using High Performance Thin-Layer Chromatography (HPTLC).

Lisa Moore, Virginia Tech, 825 Walters Dr., Christianburg, VA 24073, United States of America

            Neem (Azadirachta indica) is a hardwood tree native to the Indian subcontinent and which has been introduced in several other countries worldwide, including Mali.  The leaves and seeds of the neem tree contain azadirachtin, a bioactive compound that has insecticidal properties.  Traditional farmers in Mali use aqueous extracts of neem leaves to protect their crops from insects.  The purpose of this study was to analyze the levels of azadirachtin present in aqueous neem extracts as prepared by traditional Malian methods, and to determine if azadirachtin levels can be increased during the extraction process by the addition of ingredients commonly available to Malian farmers.

            Aqueous extracts were prepared in the lab by the traditional Malian method of grinding neem leaves with a mortar and pestle, combining the ground leaf with water and a small quantity of soap, and steeping the mixture overnight.  One-microliter aliquots of the extract were applied to a silica-gel-coated glass plate alongside one-microliter aliquots of azadirachtin standards of known concentration and scanned using the ImageJ program to determine the quantity of azadirachtin present in the aqueous extracts.  In this study, comparative analyses were done of the azadirachtin content in the traditional aqueous extracts prepared from fresh and dried neem leaf, and of aqueous extracts prepared in the same manner to which shea butter or peanut oil was added during the leaf grinding process.  Because azadirachtin is not highly soluble in water, the purpose of adding shea butter or peanut oil was to determine if the inclusion of one of these lipids, both of which are commonly available to Malian farmers, would increase the amount of azadirachtin drawn from the leaf material during extraction and enhance the potency of the aqueous extract.