Investigation of Antioxidant and Antimicrobial Effects of Methanolic Extracts of Berberis integerrima and Graminifolius tragopogon

Background and Objective: Medicinal plants contain a high level of antioxidant compounds such as flavonoids, phenolic, carotenoids, and tannins, which can be used to eliminate excess free radicals in the body. This study aimed to determine the total phenolic and flavonoid content and to investigate the antioxidant and antibacterial effects of Berberis integerrima and Graminifolius tragopogon methanolic extracts on some Gram-positive and Gram-negative microorganisms. Methods: In this descriptive-analytical study, methanolic extracts of B. integerrima and G. tragopogon were prepared using 80% methanol. Total phenol and flavonoid contents were determined by Folin–Ciocalteu and aluminum chloride colorimetric methods, respectively. The antioxidant capacity was assessed by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and reducing power methods. The antibacterial activity of the extracts of B. integerrima and G. tragopogon on Escherichia coli, Bacillus subtilis, Listeria monocytogenes, Staphylococcus aureus, and Salmonella typhimurium were determined by the disk diffusion method. Butylated hydroxytoluene and ciprofloxacin were used as positive controls for antioxidant activity and bacterial strains, respectively. Results: Total phenol and flavonoid compounds in the extracts of B. integerrima and G. tragopogon were 46.90±0.70 and 22.63±0.59 mg gallic acid per gram of extract and 5.61±0.01 and 46.74±0.81 mg quercetin per gram of extract, respectively. The extracts of B. integerrima and G. tragopogon showed significant antibacterial activity. B. subtilis and S. typhimurium showed the highest sensitivity and resistance to the extracts, respectively. Moreover, the extract of B. integerrima had the most potent inhibitory effect on the examined microorganisms. Conclusion: B. integerrima extract exhibits higher phenolic content, antioxidant properties, and antimicrobial activity than G. tragopogon extract