Bioactive components of Azadirachta indica (neem) seed oil on some pathogenic bacteria isolates

Abstract

The purpose of this study was to evaluate the antibacterial efficacy of Azadirachta indica oil against several selected pathogenic bacteria. The oil was extracted with n-hexane, petroleum ether, and methanol. The results of the phytochemical screening revealed the presence of secondary metabolites such as steroids, terpenoids, cardiac glycosides, anthraquinones, flavonoids, and alkaloids. At P ≤ 0.05, there was a significant difference in antibacterial activity. The methanol extract showed the highest inhibitory effect against the test bacteria, followed by the n-hexane extract, while the petroleum ether oil had no effect against the test bacteria. Salmonella typhi was the most sensitive to the n-Hexane oil, with inhibition rates ranging from 6.83 ± 0.27 to 17.70 ± 0.17, followed by Escherichia coli at 2.17 ± 0.12–15.63 ± 0.32, Staphylococcus aureus at 1.50 ± 0.29–14.80 ± 0.20 and Bacillus subtilis was the least sensitive at 0.00 ± 0.00–9.97 ± 0.15. The S. typhi was the most inhibited by the methanolic oil extract, followed by E. coli, B. subtilis, and S. aureus. The results of the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) for n-Hexane oil showed that E. coli and S. aureus had MIC’s of 25%, B. subtilis 50% and S. typhi 12.5% with MBC’s of 50%, 100% and 25%, respectively. Similarly for the methanolic oil E. coli and S. typhi had MIC’s of 6.25%, S. aureus 25%, and B. subtilis 12.5%. The results obtained support the use of oil for the treatment of diseases.