Investigation of Antimicrobial and Antioxidant Activity of Hypericum retusum Aucher Plant

Hypericum species have attracted considerable scientific interest due to their diverse phytochemical composition and pharmacological properties. Researchers worldwide are actively investigating the antimicrobial, antiviral, anti-inflammatory, antidiabetic, and antioxidant properties inherent in these botanicals. Given the escalating challenge of antibiotic resistance, identifying novel, plant-based antimicrobial solutions is now more crucial than ever. This research sought to assess the antimicrobial and antioxidant capabilities of both methanol and aqueous extracts derived specifically from the leaves of the Hypericum retusum Aucher plant.Our methodology included utilizing agar dilution and broth macrodilution techniques to test antimicrobial and antifungal efficacy, while the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay was employed to determine antioxidant activity. Total phenolic content was quantified using the Folin-Ciocalteu assay. The findings revealed that the methanol extract exhibited pronounced antimicrobial effectiveness, particularly against Gram-positive bacteria (including S. aureus, S. epidermidis, and B. cereus), achieving a minimum inhibitory concentration (MIC) of 6.51 µg/ml. B. subtilis was inhibited at 13.02 µg/ml. Notably, no activity was detected against any of the Gram-negative bacterial strains tested. In the antioxidant assessment, both methanol and aqueous extracts showed similar radical scavenging activities, with IC50 values determined as 46.18 ± 0.33 µg/mL and 40.86 ± 0.68 µg/mL, respectively. The total phenolic content was remarkably higher in the aqueous extract (424.41 ± 1.48 mg GAE/g dry extract). These findings suggest that H. retusum Aucher may be a potential source of bioactive compounds with antimicrobial activity against Gram-positive bacteria and antioxidant properties.