Variation of azadirachtin content during growth and storage of neem (Azadirachta indica) seeds.

Abstract

Variation of azadirachtin content during the growth and storage of neem seeds has been studied by reversed-phase high-performance liquid chromatography using anisole as internal standard. Samples were collected every fortnight from the initial stage of buds to ripened fruit stage and analyzed using an efficient sample preparation protocol developed for this purpose. Results indicated that azadirachtin appears only after the 9th week, gradually reaches the maximum of 0.38 +/- 0.06% (w/w, on a dry weight basis) around the 17th week, and decreases to 0.29 +/- 0.03% (w/w) by the 19th week. Thus, the fruits can be profitably harvested in the 17th week of development (when the neem fruit turns from green to yellow) for better yield of azadirachtin. Application of the method for storage studies of neem seeds indicated that azadirachtin was unstable under normal conditions of storage of the seeds, with azadirachtin content reducing to about 68% of the original level in a period of 4 months in the dark and to 55% in daylight.