Protective effects of tea polyphenols against oxidative damage to red blood cells.


Grinberg LN, Newmark H, Kitrossky N




Biochem Pharmacol


Tea polyphenols (TPP) from black and green teas were evaluated for their antioxidant effects on normal red blood cells (RBC) and beta- thalassemic RBC membranes challenged with exogenous oxidants in vitro. The TPP of both types protected RBC against primaquine-induced lysis; they also protected the whole cells and the membranes against H2O2-induced lipid peroxidation so that about 80% protection was reached at [TPP] = 10 microg/mL. TPP from black tea at the same concentration protected normal RBC from morphological alterations caused by the peroxide treatment. The mechanism of the effects of TPP was investigated using a chemical system generating .OH (iron + ascorbic acid). TPP from both black and green teas inhibited the .OH fluxes in a concentration-dependent manner, indicating the possibility of iron chelation by TPP. Spectrophotometric titration revealed that TPP could stoichiometrically bind ferric iron to form a redox-inactive Fe-TPP complex. Quantitative analysis suggests that one or more major catechins from the TPP preparations are the likely iron-binding compounds accounting for the antioxidant effects of TPP on RBC.