In vitro study of Antibacterial Property and Cytotoxic Effects of Aqueous, Ethanolic, Methanolic, and Hydroalcoholic Extracts of Fenugreek seed

Background: Fenugreek (Trigonella Foenum-graecum) seed is reported to have anti-diabetic, anti-microbial, antiparasitic, and hypocholesterolemic effects. Aim: To evaluate the antibacterial activity and cytotoxic effect of aqueous, ethanolic, methanolic, and hydroalcoholic extracts of fenugreek seed in-vitro. Methods: Aqueous, ethanolic, methanolic, and hydroalcoholic extracts of fenugreek seed were prepared by maceration method. In this study, six standard bacterial strains were selected including; Salmonella Typhi, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus aureus and Streptococcus pyogenes. The antibacterial effect of fenugreek extracts was determined, using well diffusion agar and broth microdilution method. Cytotoxicity was determined on Vero cells by MTT (thiazolyl blue tetrazolium dye) assay. Results: In well diffusion agar method, none of the extracts showed inhibition zone on the bacterial strains. In the broth micro-dilution method, the MIC of the hydroalcoholic extract was determined 100, 100, 50, 100, and 100mg/mL for Escherichia coli, Pseudomonas aeruginosa, Salmonella Typhi, Streptococcus pyogenes and Staphylococcus aureus, respectively. Also, MIC of the methanolic extract on Streptococcus pyogenes was 100mg/mL. Minimum inhibitory concentration (MIC) could not be determined for other extracts. Conclusion: Our results showed that although fenugreek seed extracts might have antibacterial activity in concentration of 50-100 mg/mL, in safe and non-toxic concentrations have no in-vitro antibacterial effect on the studied bacteria.