Study the antimicrobial effects of methanolic extract of Hypericum perforatum on foodborne bacteria

Hypericum perforatum is a medicinal plant of the genus Hypercasia that has phenolic and flavonoid compounds with high antimicrobial and antioxidant properties. The present study was performed to evaluate the antimicrobial effects of the methanolic extract of Hypericum perforatum on food-borne bacteria. Aerial part of Hypericum perforatum was prepared from the research farm, and after approval by experts, it was dried and powdered and used to prepare methanolic extract. The diameter of the growth inhibition zone of Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus was assessed using disk diffusion and compared with antibiotics. Minimum inhibitory concentration (MIC) and Minimum Bacterial Concentration (MBC) of methanolic extract of Hypericum perforatum were evaluated on the target bacteria using ELISA plate. The diameter of the growth inhibition zone of bacteria against the methanolic extract of Hypericum perforatum ranged from 9.33±0.45 to 15.28±0.60 mm. Application of 100 mg/ml concentration of methanolic extract of Hypericum perforatum caused the highest diameter of the growth inhibition zone of Pseudomonas aeruginosa (12.27±0.53 mm), Escherichia coli (13.20±0.59 mm) and Staphylococcus aureus (15.28±0.60 mm). The antimicrobial effects of methanolic extract of fenugreek were dose-dependent (P <0.05). The lowest and highest levels of MIC and MBC of methanolic extract of Hypericum perforatum were obtained for Staphylococcus aureus (0.0010 and 0.0019, respectively) and Escherichia coli (0.50 and 1.00, respectively). The diameter of the growth inhibition zone of bacteria treated with methanolic extract of Hypericum perforatum was higher compared to some antibiotic discs.