Evaluation of in Vitro Antimicrobial Effects of Aqueous Extract of Tribulus terrestris Against Oral Bacteria

Medicinal plants have long been considered as one of the most important pillars of traditional medicine. Existing challenges in the treatment of diseases, particularly infectious diseases, are major drivers for herbal medicine studies. Tribulus terrestris has been widely used in traditional medicine to treat various diseases. This study aimed to investigate in vitro antibacterial effect of the aqueous extract of T. terrestris on several oral bacteria.

In this experimental study, after preparing the aqueous extract of T. terrestris, minimum inhibitory and bactericidal concentrations (MIC and MBC) of the extract were determined against standard strains of Streptococcus mutans, Staphylococcus aureus, Klebsiella pneumoniae and Streptococcus pyogenes using the broth microdilution method. The experiments were repeated three times and the results were analyzed with SPSS 22 using the one-way analysis of variance (ANOVA) and LSD statistical tests with the significance level set at 0.05.

The aqueous extract of T. terrestris had the highest inhibitory effect on S. pyogenes and S. mutans, and the difference between the MIC and MBC values was significant (P <0.05). However, no such effect was observed against S. aureus and K. pneumonia at concentrations below 50 mg/ml when compared to ampicillin and chlorhexidine.

The aqueous extract of T. terrestris has significant antibacterial effects against S. pyogenes and S. mutans. Therefore, it can be incorporated into topical formulations such as toothpaste and mouthwash products after further in vivo and toxicity experiments.