Systemic evaluation of antibacterial activity of Anacardium occidentale

Abstract

Background: Evaluation of antibacterial activity of different parts of two varieties of Anacardium occidentale L. tree {red fruited variety (RFV) and yellow fruited variety (YFV)}, namely, the fruit, leaf, stem bark and root extracts on human pathogens (Staphylococcus aureus, Eschericjia coli, Pseudomonas aeroginosa, Salmonella typhi, Proteus mirabilis and Klebsella spp) was carried out in vitro. Materials and Methods: Phytochemical screening and preparation of the extracts was by standard methods. Antibacterial activity was measured by the agar diffusion methods, which ascertained the diameter of inhibition halos around wells after 24 h incubation at 37°C. Results: Alkaloids, saponins, flavonoids, tannins, HCN, phenols and anthocyanin were present in leaf and stem bark extracts of the RFV and YFV. HCN was absent in the fruit and root of both varieties. Aqueous fruit extract of the RFV did not exhibit antibacterial effect on P. aeroginosa, S. typhi, P. mirabilis and Klebsella spp. Likewise, ethanolic fruit extract of the RFV did not inhibit bacterial activity of S. typhi and P. mirabilis, whereas S. aureus, E. coli, P. aeroginosa and Klebsella spp were inhibited by ethanolic red fruit extract in the following corresponding order: E. coli = 65.11% > P. aeroginosa = 64.30% > S. aureus = 53.01% > Klebsella spp = 46.76%. The zone of inhibition (ZOI) of aqueous leaf extract of the RFV was between 10.50 ± 0.05 mm and 14.50 ± 0.01 mm halos. Generally, antibacterial activities of aqueous and ethanolic stem bark, leaf and root extracts of the RFV and YFV were identical. Conclusion: The results offered precise reference information on comparative antibacterial activities of various parts of A. occidentale L. tree for possible optimum exploitation and usage.