In vitro Antimicrobial Activity of Crude Tannins Isolated from the Stem Bark of Annona senegalensis

The aim of this study is to determine the antimicrobial activity of crude tannins from the stem bark of Annona senegalensis on some diarrhoea causing bacteria strains. 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 analysis revealed the presence of tannins, alkaloids, saponins, cardiac glycosides, steroids, tarpenoids and phenols. Quantitatively, crude tannins of 170.16mg were found to be present in 500mg of the extract which makes up a percentage composition of 34.03%. The extracted crude tannins were used to test for antimicrobial effect against Escherichia coli, Salmonella typhi, and Staphylococcus aureus and were only effective on Staphylococcus aureus with 19mm as the inhibition zone using the concentration of 100mg/ml. The Minimum Inhibitory Concentration (MIC) of the extracted crude tannins was observed at 12.5mg/ml on Staphylococcus aureus. This suggests that the isolated crude tannins have an antistaphylococci activity and can be used to treat infections caused by the organism.