Identification and Antimicrobial Activity of Combined Extract from Azadirachta indica and Ocimum sanctum

Abstract

The chemical constituents of decoction (individual) and concoction (mixed) of ethanolic leaf extracts from Azadirachta indica (neem) and Ocimum sanctum (tulsi) were analyzed by gas chromatography-­mass spectro-­ photometery (GC-­MS). Decoctions of A. indica and O. sanctum had 24 and 33 constituents, respectively. Mixed together, 26 compounds were identified. Four major (high percentage) compounds were identified in A. indica: n-­hexadecanoic acid (14.34%), phytol (19.96%), 9,12,15-­octa-­ decatrienoic acid, (Z,Z,Z)-­ (18.57%), and vitamin E (11.37%). Three major compounds were identified in O. sanctum: phenol,2-­methoxy-­3-­(2-­ propenyl) (15.32%), 9,12,15-­octadecatrienoic acid,(Z,Z,Z)-­ (16.94%), and 9,12,15-­octadecatrienoic acid, methyl ester,(Z,Z,Z)-­ (22.05%). Three major compounds were identified in the mixed extract: n-­hexadecanoic acid (16.58%), phenol,2-­methoxy-­3-­(2-­propenyl) (20.62%), and 9,12,15-­ octadecatrienoic acid,(Z,Z,Z) (25.98%). Four of the compounds in the mixed extract were new: eudesma-­4(14),11-­diene (0.18%), 6-­ azabicyclo[3.2.1]octane (0.51%), cyclohexane,1-­ethyl-­1-­methyl-­2,4-­ bis(1-­methylenyl)-­,[1S-­␣␣␣␣␣␣␣␣␣␣␣-­␣-­Elemen (0.77%), and globulol (1.45%). The mixed extract had a high level of antimicrobial activity against fish pathogens as indicated by zone of inhibition, minimum inhibitory concentration, and minimum bactericidal concentration.