Comparison of the antioxidant activities and major constituents of three Hypericum species (H. perforatum, H. scabrum and H. origanifolium) from Turkey

Total phenolic content, antioxidant activity, and the main constituents of three Hypericum species (H. perforatum, H. scabrum, and H. origanifolium) from Turkey had been investigated in this study. The quantification of main constituents (hypericin, and pseudohypericin) was performed by HPLC. The aerial parts of the plant extracts were screened in terms of their total phenolic content (TPC) and antioxidant activity tests including DPPH (2,2 diphenyl 1- picrylhdrazyl) radical scavenging activity, trolox equivalent antioxidant capacity (TEAC), ferric cyanide reducing (FRAP) antioxidant power assay, and total antioxidant activity by ferricthiocyanate (FTC). The highest TPC value (148.31 ± 4.57 mg GAE/g DW) was obtained for H. scabrum (HS) while H. perforatum (HP) extract had the highest hypericin (9.57 ± 0.07 µg/mL), and pseudohypericin (7.82 ± 0.05 µg/mL) amount. All Hypericum species demonstrated stronger DPPH activities than the standard compounds butylated hydroxytoluene (BHT) and ascorbic acid (AA) with the values of IC50 < 3.8 µg/mL. The highest trolox equivalent antioxidant capacity (TEAC) value (11.28 ± 0.28) was achieved with HO. Considerable values were obtained for HS (90.25 ± 0.05), HP (90.20 ± 0.07), and HO (88.42 ± 0.02) by total antioxidant determination using ferricthiocyanate (FTC) method with 2 days incubation. This study reveals that all Hypericum species are good sources of natural antioxidants with high TPC and major constituent contents.