In vitro cytotoxic and antioxidant activity of some Hypericum species belonging to drosanthe section

The Hypericum genus of Hypericaceae is represented in Turkey by 100 taxa, 45 of which are endemic. Total phenolic compounds and total flavonoid contents in methanolic extracts of the flowering aerial parts of three of the endemic species of Turkey, namely, H. spectabile (HSM), H. pseudolaeve (HPSM) and H. thymbrifolium (HTM), were determined and compared to H. perforatum (HPM). The antioxidant activities of these extracts were determined by using biochemical assays, namely, the liposome peroxidation activity, superoxide radical scavenging activity, DPPH radical scavenging activity and reducing power. The activities correlated well with total phenolic and flavonoid contents. The cytotoxic activity of these extracts were also determined by using MTT cell cytotoxicity and WST-1 cell viability screening assay on HeLa cells. Concerning the antioxidant activities of the extracts, it may be concluded that HSM, HTM and HPM, containing the highest amounts of total phenolics showed the strongest antioxidant properties whereas HPSM, containing the least phenolics, were weakest in activity. The cytotoxic activity results showed that, all extracts except HPSM exhibited low cytotoxic properties against HeLa cell line. It was concluded that the extracts might be a potential sources of antioxidant phytochemicals with associated health benefits.