Upregulation of erythrocyte ascorbate free radical reductase by tea catechins: Correlation with their antioxidant properties

摘要

Tea catechins have been shown to possess a variety of health promoting effects, most of these effects have been attributed to their strong antioxidant property. Ascorbate (ASC) is the primary antioxidant in plasma and human erythrocytes play a vital role in regereneration of ASC in blood plasma by reduction of ascorbate free radical (AFR) into ASC by AFR reductase, a transmembrane enzyme. In the present study we report that tea catechins; EGCG, ECG, EGC and EC driven activation of erythrocyte AFR reductase. The efficiency of tea catechins to activate AFR reductase has a significant positive correlation with the antioxidant activities of these compounds, measured by DPPH- scavenging and FRAP assays. Since AFR reductase along with other transmembrane oxidoreductases, is reported to act as compensatory/protective mechanism that operates to minimize the extent of oxidative stress, activation of this enzyme by tea catechins may be a mechanism for these compounds to elicit antioxidant effect in vivo.