Abstract

---

The use of plant parts and extracts in traditional medicine has proved to be a good lead for the discovery of a potential plant derived antimicrobial agent. To this end we conducted in vitro screening of aqueous and alcoholic extracts of the bark of Anogeissus leiocarpus for antibacterial activity against clinical isolates of Salmonella Typhi, Staphylococcus aureus, Pseudomonas aeruginosa, Shigella dysentriae, Klebsiella pnuemoniae and Streptococcus pyogenes following standard microbiological procedure. The bark extracts showing inhibitory activity on the test bacteria were partially purified using solvent-solvent purification and the different fractions were tested for antibacterial activity. Results of phytochemical screening of the bark extracts of A. leiocarpus revealed the presence of saponins, alkaloids, phenols, tannins and glycosides. Antibacterial studies of the extracts revealed that the plant showed strong antibacterial activity against all the test organisms at 25 mg/ml concentration. The solvent- solvent purification of extracts revealed that ethyl acetate and butanol fractions contained the highest concentration of the bioactive component as revealed by the diameter of the zone of inhibition (11- 25 mm) but no inhibitory activity was observed with the chloroform fraction and residue. The minimum inhibitory concentration of the purified fractions ranges between 0.625 mg/ml (acetone extracts) for Pseudomonas aeruginosa, Klebsiella pnuemoniae and Streptococcus pyogenes to 2.5 mg/ml (aqueous extracts) for all test organisms. The minimum bactericidal concentration is in the range 0.625 mg/ml to 5 mg/ml. The findings showed that the extracts had appreciable in vitro activity against the test organisms and this plant is a potential source of leads for development of antibacterial agents.

Keywords: Antibacterial, Fractions, Susceptibility, A. leiocarpus,