Comparative Analysis of Phenolic Compounds in Seven Hypericum Species and Their Antioxidant Properties

Abstract

A comparative analysis of the phenolic compounds in the 70% EtOH extracts of Hypericum acutum, H. androsaemum, H. barbatum, H hirsutum, H maculatum, and H richeri has been carried out using high-performance liquid chromatography coupled with photodiode array UV detection and high resolution TOF mass spectrometry. Quercetin, astilbin, I3,II8-biapigenin, orientin, 2"-O-acetylorientin, three phenolcarboxylic acids, and eight flavonols 3-O-glycosides were identified in the extracts on the basis of their on-line UV spectra, accurate mass spectral data, and in comparison of retention times with those from the standards. Fingerprint analysis of the extracts revealed significant differences in the qualitative and quantitative chemical composition of the studied species. Antioxidant assays with various reaction mechanisms were used including ferric reducing antioxidant power (FRAP) assay, DPPH, ABTS, superoxide anion radical scavenging capacity and inhibition of liposome peroxidation induced by Fe2+. The most potent were extracts of H acutum and H maculatum indicating this Hypericum species interesting for further research aimed as a potentially new source of biologically active compounds.