ABSTRACT
This study was aimed at evaluating the antimicrobial effect of tannin isolated from the leaf of Annona senegalensis on Shigella dysenteriae, Escherichia coli and Salmonella typhi. The study was carried out in the laboratory of Biochemistry department, Modibbo Adama University of Technology, Yola, Adamawa State, Nigeria, between July and October, 2013.The antimicrobial activity was carried out using agar disc diffusion method. The phytochemical screening of the leaf of the plant revealed the presence of tannins, alkaloids, saponins, flavonoids, terpenoids, cardiac glycosides and anthraquinones while phenols and steroids were absent. Quantitatively, tannins were found to be 24% in the leaf of the plant. Isolated tannin exhibited antibacterial activities against all the tested bacteria; Shigella dysenteriae gave the zone of inhibition (18.6mm), Escherichia coli (13.9mm) and Salmonella typhi (10.6mm). Minimum Inhibitory concentration of the crude tannins on the test organisms ranged from 6.25mg/ml to 12.5mg/ml. These findings confirmed the basis of traditional use of the leaf of Annona senegalensis in the treatment of diseases such as dysentery and diarrhea.