Evaluation of in vitro biological activities of three Hypericum species (H. calycinum, H. confertum, and H. perforatum) from Turkey

Hypericum species have been used since ancient times for medicinal purposes due to their important pharmacological properties. As the most abundant species of the genus Hypericum, Hypericum perforatum is unquestionably one of the best-known and most consumed medicinal plants in the world. The aim of this current study is to evaluate antioxidant, anticholinesterase, and antiurease activities of the methanol extracts of flowering aerial parts of Hypericum calycinum L. Hypericum confertum Choisy, and Hypericum perforatum L. from Turkey. In this study, total phenolic and total flavonoid contents were determined as pyrocatechol and quercetin equivalents, respectively. Antioxidant activities of the species were carried out by using DPPH free radical scavenging, ABTS cation radical scavenging, metal chelate, and CUPRAC activity methods.Among the species that were investigated, it was determined that H. calycinum had the highest total phenolic content (141.12±2.40 μg PEs/mg), whereas H. confertum had the highest total flavonoid content (70.61±0.51 μg QEs/mg). The biochemical results in this study showed that all three species exerted strong antioxidant activity. H. calycinum appeared the most active in all antioxidant activity assays which is mainly due to its rich phenolic content. Additionally, H. calycinum showed the highest acetylcholinesterase inhibitory activity, while H. perforatum had the best inhibition towards butyrylcholinesterase. According to the urease inhibitory activity assay results, only H. calycinum showed low antiurease activity, whereas the other species did not show any activity against urease. The obtained results suggest that the studied three Hypericum species, especially H. calycinum could be promising sources for the treatment of several diseases because of their antioxidant and anticholinesterase properties.