Abstract

The antibacterial effect of the leaf, bark and leaf and bark combined of Alstonia boonei on bacterial pathogens, Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Streptococcus pneumonia, Proteus mirabilis, Klebsiella pneumonia, Shigella dysenteriae and Salmonella typhimurium was determined using agar diffusion technique to investigate their efficacy as anti-bacterial agent. The phytochemical components of the leaf and bark were studied. The phytochemical screening of the ethanolic leaf extract indicated the presence of tannins, phlobatannins, alkaloids, and cardiac glycosides, reducing sugar, saponins, anthraquinones and steroids, while the bark contains alkaloids, flavonoids, saponins, phlobatannins, anthraquinones, steroids and reducing sugars. The extracts showed varying inhibitory effect against P. aeruginosa and K. pneumonia. S. typhimurium (13±0.27 mm at 100 mg/ml for the leaf extract) being the most susceptible at all concentrations, 12±0.21 and 12±0.62 mm at concentrations 100 and 50 mg/ml respectively for bark extract and similarly for the leaf + bark extract. The result of the study suggests that the extracts of the different component parts of the plant can be used for the treatment of infections caused by the test organisms.

Key words:  In vitro, antibacterial, Alstonia boonei, extracts, agar diffusion.