Biological activity and cytotoxicity studies on Hypericum montbretii Spach (Hypericaceae)

The genus Hypericum Tourn. ex L. is represented by 96 species and 116 taxa in Türkiye and is an important genus with an endemism rate of 40% [ 1 ]. In this study, antioxidant, antimicrobial, and cytotoxicity activities of methanol and ethyl acetate extracts prepared from aerial parts of Hypericum montbretii Spach were investigated. MIC values of extracts were analyzed by microdilution method. Ethyl acetate extracts were found to be effective against Pseudomonas aeruginosa , Staphylococcus aureus standard bacteria at a concentration of 3 μg/mL, Bacillus subtilis , Escherichia coli bacteria at 7 μg/mL and Candida albicans with Candida krusei yeasts at a concentration of 930 μg/mL. Methanol extracts were effective against Pseudomonas aeruginosa and Bacillus subtilis at a concentration of 541 μg/mL, Escherichia coli , and Staphylococcus aureus at a concentration of 1083 μg/mL, and also Candida albicans with Candida krusei yeasts at a concentration of 270 μg/mL. The cytotoxic activity of extracts was assessed using the MTT assay and NIH3T3 mouse embryonic fibroblast cells were used for the cytotoxicity test. The IC 50 value of the methanol extract (135.4±0.21 μg/mL) was found to be higher compared to ethyl acetate extract (>500 μg/mL). Antioxidant activity was evaluated using the DPPH method. Methanol extract showed 46% inhibition, while ethyl acetate showed 23% inhibition. Total phenol content was determined using the Folin-Ciocalteu method, revealing that the methanol extract (99.03±0.086 mg GAE/g) contained a higher phenolic content compared to the ethyl acetate extract (65.00±0.079 mg GAE/g). Publication History Article published online: 05 March 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany