The polysaccharide from Tamarindus indica, (TS-polysaccharide) protects cultured corneal-derived cells (SIRC cells) from ultraviolet rays

The aim of this work was to investigate the possible protective effect of a new viscosising agent, TS-polysaccharide, on corneal-derived cells (SIRC) exposed to ultraviolet-B rays. To verify this, SIRC cells were first exposed, in the absence or in the presence of TS-polysaccharide (1% w/v), for 9 s at the UV-B source and then post-incubated for 45 min at 37degreesC. After this period the hydrogen peroxide (H2O2) accumulated in the medium and the concentration of 8-hydroxy-2'-deoxy-guanosine (8-OHdG) in cell DNA was measured. In addition, the amount of H-3-methyl-thymidine incorporated in cellular DNA was evaluated after 18 h from irradiation. Our results show that cells exposed to UV-B rays accumulate H2O2, and have higher levels of 8OHdG and a lower amount of H-3-methyl-thymidine incorporated in DNA than control cells. In the presence of TS-polysaccharide, the H2O2 and 8-OHdG accumulation, and the H-3-methyl-thymidine incorporation were significantly reduced with respect to the values measured in cells exposed in the absence of the polysaccharicle. We propose a protective role of the polysaccharicle in reducing UV-B derived DNA damage to eye cells. This finding could be of some clinical importance when the polysaccharicle is used as a delivery system for ophthalmic preparations.