Antibacterial Activity and Total Phenolic Content of the Onopordon acanthium L. Seeds

Background: Onopordon acanthium L. is an important medicinal plant which has been used in Iranian medicine. In the present study, total phenolic content (TPC) was evaluated and antibacterial properties of n-hexane and methanol extracts of O. acanthium L. seeds were screened. Methods: TPC was determined by Folin–Ciocalteu reagent method. Antibacterial activities of O. acanthium were investigated using disc diffusion method, minimum inhibitory concentration (MIC) and resazurin microtiter assay against some gram-positive bacteria including Staphylococcus aureus, Staphylococcus epidermidis, Micrococcus loteus as well as gram-negative ones Escherichia coli and Klebsiella pneumonia. Results: The TPC was found to be 168.56 ± 4.89 mg of gallic acid/g of extract. Plant methanol extract showed significant antibacterial activity against gram-positive bacteria; Staphylococcus epidermidis and Micrococcus luteus (with MIC= 0.612 mg/ml), while n-hexane extract demonstrated negligible to no inhibitory activity against gram-negative and gram-positive bacteria. Conclusion: The results of the present study suggested the effect of O. acanthium methanol extract against the tested bacteria in vitro, may contribute to the in vivo efficacy of this extract