Black tea extract protects against γ-radiation-induced membrane damage of human erythrocytes

The membrane integrity of circulating red blood cells (RBCs) is compromised by the deleterious actions of gamma-radiation in humans. Tea is the most widely consumed popular, inexpensive and non-toxic beverage rich in antioxidants. Here, we explored the radioprotective actions of black tea against the gamma-radiation-induced membrane permeability of human erythrocytes. The phytochemical analysis of tea revealed the total polyphenol content to be 114.89 +/- 6.03 mg gallic acid equivalent/g dry wt. and flavonoid content, 34 +/- 0.11 mg catechin equivalent/g dry wt. of the extractable solid in the commercially available tea bags. Tea extracts showed potential scavenging of H2O2 and NO, appreciable extent of total antioxidant capacity and effective anti-hemolytic action. Tea extracts (15 mu g/mL) significantly ameliorated the gamma-radiation induced increase of the levels of thiobarbituric acid-reactive substances (TBARS, an index of lipid peroxidation) in the RBC membrane ghosts. Stored blood showed higher levels of K+ ion as compared to the normal blood which was elevated by 7 radiation. Membrane ATPase was inhibited by the exposure to gamma-radiation. Treatment of RBCs with the tea extracts (15 mu g/ml) prior to the exposure of gamma-radiation significantly mitigated these changes in the erythrocyte membranes caused by the lower dose of radiation (4 Gy) as compared to that induced by the higher dose of gamma-radiation.