Abstract
In the present work we carried out a phytochemical and biological investigation on three endemic Hypericum species, i.e.Hypericum thymbrifolium (H. thymbrifolium), Hypericum spectabile (H. spectabile) and Hypericum pseudolaeve (H. pseudolaeve) from Anatolia in order to discover new sources of natural compounds for the treatment of inflammatory and neurodegenerative disorders. HPLC-DAD analysis indicated that two naphthodianthrones (pseudohypericin and hypericin) together with chlorogenic acid, rutin, hyperoside, isoquercitrin, kaempferol, quercitrin, quercetin, amentoflavone, and hyperforin are the main compounds present in the methanol extracts. After chemical characterization, all extracts were in-vitro biologically assayed for antioxidant potential by lipid peroxidation inhibitory activity, DPPH, FRAP assays, and superoxide radical scavenging activity, for AChE inhibitory activity by Ellman's method, for COX inhibitory activity by using enzyme immunoassay (EIA) kit, for cytotoxic activity on HeLa and NRK-52E cell lines by MTT assay. The superoxide radical scavenging activity and lipid peroxidation inhibitory activity of H. spectabile (EC50 = 0.430 mg/mL) were more remarkable than that of H. thymbrifolium and H. pseudolaeve. The extracts showed moderate inhibitory activity on AChE (from 49.37% to 63.41%). The best inhibitory activity against COX-1 (71.77% and 77.04%, respectively) and COX-2 ( 64.14% and 72.23%, respectively) were shown by H. thymbrifolium and H. spectabile, which may be due to their richest chlorogenic acid content (0.29576% and 0.23567%, respectively). Cytotoxicity screening results showed that the extracts did not demonstrate significant cytotoxic activity. It was concluded that the most promising extract with antioxidant, anti-inflammatory, and AChE inhibition potential is H. spectabile.