Antibacterial efficacy of neem oil fractions on clinical isolates of endometritic Cows

Abstract

The objective of this study was to assess in vitro antibacterial activity of neem oil (Azadirachta indica) and its fractions and neem seed aqueous extract on microflora of cervico-vaginal mucus (CVM) collected from cows with endometritis. The CVM samples were obtained from 12 cows during 40-50 days postpartum and were subjected to bacterial isolation and identification. Neem oil was fractionated by 2 approaches, viz. by solvent extraction and by column chromatography using a silica gel column. Neem seed aqueous extract was prepared from dried neem seeds. Isolates (20) were identified, comprising mostly facultative anaerobic bacteria. Non-lactose fermenting (NLF) bacteria belonging to Enterobacteriaceae family was the most frequently isolated bacteria (25%) followed by Escherichia coli (20%), Corynebacterium sp. and Streptococcus sp. (15% each). Extraction of neem oil with organic solvents, viz. methanol and hexane yielded 4 fractions, which were termed methanol miscible (F1), methanol-immiscible emulsion (F2), hexane miscible (F3) and hexane-immiscible emulsion (F4). Column chromatography yielded 3 fractions, viz. F5 (first fraction), F6 (second fraction) and F7 (third fraction). The F1 (methanolic) fraction showed the highest antibacterial activity with a sensitivity pattern of 95% followed by F2 and F3 (85% each), F4 (65%), F6 and F7 (40% each). Moreover, the neem seed aqueous extract did not possess any antibacterial activity.