Evaluation of phytochemical and antibacterial properties of Terminalia avicennioides crude extract against selected bacteria from diarrhoeic patients

Abstract

Phytochemical screening of aqueous and ethanol crude extracts of the different plant parts of Terminalia avicennioides was carried out using standard chemical evaluation methods. The antibacterial effects of aqueous and ethanol crude extracts of Terminalia avicennioides against E.coli and S.typhimurium clinical and reference isolates from diarrhoeic patients were also evaluated using agar-well diffusion method. The minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of aqueous and ethanol crude extracts were evaluated by broth dilution techniques. The result revealed the presence of carbohydrates, alkaloids, tannins, flavonoids saponins, triterpens and glycosides. All bacteria were found to be susceptible to the extracts which were indicated by the various zones of inhibition. The activity of extracts was concentration dependent. The reference strains were less susceptible to all extracts at low concentrations of 12.5mg/ml, but highly susceptible to extracts at varied concentrations of 25, 50 and 100mg/ml. However, all test bacteria were more susceptible to the ethanol extracts compared to the aqueous extracts with mean zones of inhibition ranging between 0.68 + 2.54 mm to 22.08 + 1.75 mm on E. coli clinical isolates, 0.0 + 0.0 mm to 20.00+0.mm on E. coli reference isolate, 3.08 + 6.0 mm to 21.50 + 0.00 mm on S. typhimurium clinical isolates and 0.00 + 0.mm to 20.00 + 0.0 mm on S. typhimurium reference isolate. The ethanol crude extracts exhibited lower MICs (12.5 to 25mg/ml) and MBCs (25 to 50mg/ml) values indicating higher efficacy of ethanol extracts, with the leaf extract demonstrating the highest activity against all the bacterial isolates. The important bioactive compounds present in the plant may be responsible for the observed antibacterial activity of the plant and hence its potential use as an antibacterial agent.

Keywords: Phytochemical, Antibacterial effect, Terminalia avicennioides, diarrhoeaic patients.