Antimicrobial Activity of Stem Bark of Faidherbia albida

This study was aimed at evaluating the antimicrobial activity of stem bark extract of Faidherbia albida on E. Coli, Salmonella typhi and Shigella sp. The study was conducted in laboratory of Biochemistry department of Modibbo Adama University of Technology, Yola, Adamawa, Nigeria, between July and October, 2012. The antimicrobial activity was carried out using agar disc diffusion method and the crude extract was separated using column chromatography. The phytochemical analysis of the crude methanolic stem bark extract of Faidherbia albida revealed the presence of tannins, saponins and alkaloids. The in vitro antimicrobial activity of the crude methanolic extract of the stem bark showed highest activity on Salmonella typhi with zone of inhibition of 12.0 ± 0.17mm compared to E. coli and Shigella sp. Column chromatography of the crude extract eluted with benzene/methanol, acetic acid/methanol and ethylacetate/methanol gave three fractions designated: I, II and III; of which fraction III showed highest activity against the test organisms. Minimum inhibitory concentration of the most active fraction is 60mg/ml on E. coli and Salmonella typhi and 80mg/ml on Shigella sp.The in vitro antimicrobial activity of the crude methanolic stem bark extract of Faidherbia albida was also compared to some standard antibiotics. The results showed that azithromycin had highest activity ranging from 17.0 ± 0.11mm to 23.0 ± 0.12mm against the test organisms with no significance difference (P<0.05) compared to the activity of fraction III. There was also no significant (p<0.05) difference between the effect of the crude methanolic stem bark extract and that of cirprofloxacin with zone of inhibition ranging between 12.0±0.08mm to 20.0± 0.15.mm These results reveal the antibacterial nature of the stem bark of Faidherbia albida and suggest that it could be exploited in the management of diseases caused by the tested organisms in human.