Phytochemical and Antimicrobial Evaluation of Tribulus terrestris L. (Zygophyllaceae) Growing in Nigeria

The methanolic leaf extract of Tribulus terrestris L. (Zygophyllaceae) growing in Nigeria was subjected to preliminary phytochemical screening and in vitro antimicrobial tests. The phytochemical tests was conducted using standard methods of analyses and the extract revealed the presence of alkaloids, tannins, saponins and cardiac glycosides. The antimicrobial activity of the plant extract was assayed using the agar plate disc diffusion and nutrient broth dilution techniques. Test micro-organisms were Escherichia coli, Klebsiella sp., Pseudomonas aeruginosa, Salmonella typhi, Staphylococcus aureus and Candida albicans; all the organisms were laboratory isolates. The extract inhibited all the test organisms at various concentrations. It showed a minimum inhibitory concentration of 3.125 mg mL 1 against Salmonella typhi while against Escherichia coli, Klebsiella sp., Pseudomonas aeruginosa and Candida albicans was 6.250 mg mL 1. The minimal bactericidal concentration against Escherichia coli, Klebsiella sp., Pseudomonas aeruginosa and Candida albicans was found to be 1.563 mg mL 1 while against Salmonella typhi was 3.125 mg mL 1. This study laid credence to the use of this plant as a remedy for stomachic and urinary tract infections in folk medicine the world over, whose causative agents are some of the organisms used in this study.