Antioxidant activity and phenolic components of sea buckthorn (Hippophae rhamnoides) seed extracts

Antioxidant-rich fractions were extracted from sea buckthorn (Hippophae rhamnoides) seeds using various solvents, including acetone, methanol, ethanol, ethyl acetate, water and mixtures of different solvents, and analyzed for their phenolic components. The antioxidant activity of the extracts was evaluated using a copper-catalyzed lecithin liposome oxidation assay. At 250 μg/mL concentration, the sea buckthorn seed extracts inhibited formation of conjugated diene hydroperoxides and thiobarbituric acid reactive substance (TBARS) by 0-90% and 0-88.6%, respectively. 70% acetone extract showed the highest antioxidant activity. The extract also showed good reducing power and DPPH radical scavenging capacity. Proanthocyanidins were the predominating polyphenols while hydroxycinnamates and flavonols represent minor components in all extracts. Positive correlations were found between proanthocyanidin content and antioxidant activities of sea buckthorn seed extracts.