Studies on human fetal lens crystallins under oxidative stress and protective effects of tea polyphenols

To investigate the oxidative modification of water-soluble crystallins of human fetal lens with H2O2 and fourteen metal ions with or without EDTA. Tea-polyphenols (TP) was added to above solutions in order to testing their antioxidative abilities.

The experiments were performed at 37 degrees C with final concentration of 2.5 mg/ml protein, 0.1 mM metal ions, 0.3 mM EDTA and 1.0 mM H2O2. Then the TP was added to the solution with CuSO4 and H2O2, after 5 or 24 hours, the crystallins were analysed with SDS-PAGE and IEF.

There were marked oxidative modifications of lens protein in H2O2 and copper without EDTA. In SDS-PAGE patterns, we found an increase in those species above of bands higher than 30 kD and some diffuse bands from 30 to 17 kD after 5 hours. In IEF patterns, there were a general increase on acidity with loss of the more basic species. When the TP was added, there was not any difference with control group.

The results indicate that exposure of water-soluble protein to H2O2 and copper leads to covalent crosslinking and cleavage of polypeptides. After 24 hours, the development of the oxidative modifications of crystallins continues, comparison with the catalytic strength, copper ions stronger than the iron ions. On other hand, this work reported that the anti-oxidative action of TP is strong.