Antibacterial Activity of Anacardium occidentale (Cashew) Stem Bark against Bacterial Isolates

Abstract

The aim of this study was to investigate the relative antibacterial activity and phytochemical properties of ethanolic and water extracts of Anacardium occidentale (cashew) stem bark. The phytochemicals were screened using qualitative methods. Qualitatively analyzed phytochemical constituents in the stem bark extracts includes carbohydrates, alkaloids, flavonoids, saponins, tannins, sterols, anthraquinone, terpens and phenol. The microorganisms assayed for the antibacterial activities using the agar well diffusion were Escherichia coli, Salmonella Typhi, Bacillus subtilis and Staphylococcus aureus, studies on the susceptibility pattern and the zones of inhibition exhibited by the extracts shows a certain degree of inhibitory effects against the test organisms. Ethanolic extract of A. occidentale stem bark was effective against B.subtilis at concentration of 100mg/ml and 50 mg/ml only, S. aureus and S. Typhi at concentration of 100 mg/ml only, and E. coli at concentration of 100 mg/ml only while in aqueous extract of A. occidentale stem bark, there was effect against S. aureus at concentration of 100 mg/ml and 50 mg/ml, followed by B. subtilis at concentration of 100 mg/ml and 50 mg/ml, S. Typhi and lastly E.coli both at the concentration of 100 mg/ml. Considering the diameter of the zone of inhibition, it was noticed that there was little or no difference between the diameters of both extracts. Although, these results suggest an important ethno-pharmaceutical potential of A. occidentaleas a source of compounds with broad-spectrum antimicrobial activity that can be used in the pharmaceutical industry its low activity may be due to low concentration of the extracts.