Tea polysaccharides as food antioxidants: an old woman's tale?

The crude polysaccharides from tea leaves (TPS) looks like have good antioxidant activities. However, whether or not the antioxidant abilities of crude TPS depend on tea polyphenols in the crude TPS is not understand. Herein, TPS fractions were isolated from crude TPS and their antioxidant activities were compared. The crude TPS showed stronger antioxidant activities than that of TPS fractions. However, EGCG (6.15 μg/mL) significantly enhanced DPPH radical scavenging potential of TPS fractions for each dose. Moreover, EGCG (8.0 μg/mL) significantly improved the reducing power of TPS fractions. EGCG causes a synergistic increase in the antioxidant activities of TPS fractions. The antioxidant activities of dextrans in the absence and presence of EGCG were investigated to illustrate that the antioxidant activities of TPS is similar to dextrans. These results illustrated that TPS fractions hardly exhibited antioxidant activities and tea polyphenols are the major antioxidant in the crude TPS. TPS as food antioxidants is an old woman's tale.