Antioxidant activity and bioactive components of the aerial parts of Hypericum perforatum L. from Epirus, Greece

The aerial parts of Hypericum perforatum L. were studied to assess their composition in basic categories of bioactive compounds and their antioxidant activity, employing commonly accepted assays. The results reveal that floral buds, during the development stage, bear the highest concentrations of hyperforin followed by the flowers of the plant and comparable concentrations of hypericin and pseudohypericin. Among the various plant fractions, shoots and branches show significant antioxidant activity, a fact which may be accounted for by the high phenolic content. The measurement of DPPH antioxidant activity of extracts by an on-line HPLC-DPPH antioxidant activity measurement set-up, delineated the pivotal contribution of hyperforin, adhyperforin and their analogues to this antioxidant property. The role of phenolic compounds on the total DPPH scavenging activity was minor except chlorogenic acid and its derivatives. No encouraging results were obtained as regards the inhibition of the oxidative damage of proteins. All the extracts promote the damage of proteins exhibiting a functional pro-oxidant role.