Chemical Composition of the Essential Oil of Neem (Azadirachta indica A. Juss. ) Seeds Harvested in Senegal

Abstract

Objective: To make better understanding of the neem seed composition (Azadirachta indica A. Juss.) particularly in Senegal by the extraction, the proportioning and the determination of the composition of its essential oil. Methods: The extraction of essential oil from neem seeds is carried out by hydro-distillation. The Gas Chromatography (GC) and Mass Spectrometry (MS) were used for analysis and identification of components. Findings: The yield of essential oil from dry neem seeds (95.7% dry matter) is 0.076%. The major compounds identified are 5,6-dihydro-2,4,6-triethyl- (4H) 1-3,5-dithiazine (39.1%), cis 1,2,4-Trithiolane, 3, 5-diethyl (7.9%), 1-H-indole 2,3-dione (7.9%), trans 1,2,4-Trithiolane, 3,5-diethyl (6.2%), and ethyl thioisobutyrate (4%). The classification of compounds reveals that the essential oil of neem seeds is composed of sulfur and nitrogen compounds (40.1%), sulfur compounds (25.3%), and nitrogen compounds (15.1%), sesquiterpenes (7.4%), Fatty Acid Esters (FAE) (1.5%) and hydrocarbons (0.4%). This composition reveals that neem essential oil is mainly composed of non-terpene compounds. Novelty: The method of analysis by GC-MS although being the most widely implemented in the quantification and identification of volatile compounds is not applied in the case of neem seeds of African origin. Keywords: Chemical Composition; Essential Oil; Neem; Azadirachta indica; Seeds