Antioxidative activity of rooibos tea (Aspalathus linearis)

Abstract

The antioxidative activity of the rooibos tea was examined by using linoleic acid autoxidation, rabbit erythrocyte membrane, rat liver microsome and rat liver homogenate systems. Both freshly brewed rooibos tea and freeze-dried rooibos tea extract had antioxidative activity in linoleic acid system, and rooibos tea extract showed synergistic antioxidative effect with citric acid. In the rabbit erythrocyte membrane and rat liver microsome systems, rooibos tea extract exhibited strong antioxidative activity in a dose dependent manner. In the rat liver homogenate system, freshly brewed rooibos tea exhibited strong antioxidative activity. Several purified flavonoids contained in rooibos tea were examined in the rat liver microsome system and luteolin and quercetin showed strongest activity. These results suggest that the rooibos tea may play an important role in the prevention of lipid peroxidation of cell membranes induced by active oxygen radicals in living systems as dietary antioxidants after ingestion.