Evaluation of antibiotic potential of alkaloids of Tribulus terrestris L. against some pathogenic microorganisms

Abstract

Context: Antibiotic resistance has become a global concern. There has been an increasing incidence of multiple resistances in human pathogenic microorganisms in recent years, largely due to indiscriminate use of commercial antimicrobial drugs commonly employed in the treatment of infectious diseases. Tribulus terrestris (Family: Zygophyllaceae) is a well‑known medicinal plant and has been used world‑wide for the treatment of infectious diseases. Alkaloids are group of naturally occurring chemical compounds, which are known to have antimicrobial properties. Aim: The present study is designed to evaluate the antimicrobial potential of alkaloids of T. terrestris L. Materials and Methods: Alkaloids extracted from different parts (root, stem, leaf and fruits) of T. terrestris were screened by Disc diffusion assay against three bacterial strains: gram positive (Staphylococcus aureus), gram negative (Escherichia coli and Proteus mirabilis) and two fungal strains: Aspergillus flavus and Aspergillus niger. Minimum inhibitory concentration of the extracts was evaluated by micro broth dilution method while minimum bactericidal/fungicidal concentration was determined by sub culturing the relevant samples. Total activity of the extracts against each sensitive test pathogens was also calculated. Statistical Analysis: Mean value and standard error mean were calculated for the results of disc diffusion assay and data were analysed by one‑way analysis of variance and P values were considered significant at P < 0.05. Results: The alkaloid extracts of T. terrestris showed significant antibacterial potential as all test extracts were found active against both the gram positive and negative bacteria, but were inactive against the tested fungi. Conclusion: The present study indicates the broad spectrum antibacterial potential of the alkaloids of T. terrestris, hence may be exploited for future antibacterial drugs. Key words: Alkaloids, antimicrobial properties, total activity, Tribulus terrestris