Abstract:
The present investigation was carried out to identify the components present in the headspace volatiles of neem seed and cake as these have been found to exert insect repellant action on many pests of horticultural crops. The composition of volatiles emitted by neem seed (Azadirachta indica L.) and its cake obtained after extraction of oil was analyzed by headspace solid-phase micro extraction (HS-SPME) combined with gas chromatography and gas chromatography- mass spectrometry (GC-MS). Major differences were found in the volatile composition of seed and cake. A total of 71 and 101 volatile compounds representing 83.47 % and 85.62 % of the total quantum of volatiles present in seed and cake, respectively, could be identified. These compounds were found distributed in several chemical classes namely, alcohols, carbonyl compounds (ketones, aldehydes, and esters), fatty acids, terpenes, nitrogenous and sulphur compounds among others. Of the various classes of compounds identified, fatty acids constituted the major group accounting for 24.82 % and 16.97 % of the total volatile concentration followed by aldehydes and ketones representing 26.49 % and 17.53 % and sulfur compounds contributing 12.94 % and 9.32 % of seed and cake volatiles, respectively. The most abundant volatile components were (Z)-9,7-octadecadienal and palmitic acid, a medium chain fatty acid comprising 25.47 % and 14.97 % of the total in seed and cake respectively.
