| The present paper describes the protective effect of TP(Tea polyphenols) on the injury induced by Ionizing Radiation and its mechanisms.cyto-toxicity of (-)epigallocatechin-3-gallate(EGCG) and cytomorphological and, biochemical changes induced by X-ray at molecular and cell level were observed means of MTT assay, fluoromicrographs, DNA electrophoresis and flow cytometer .Tea polyphenols were orally administered to normal mice, tumor-bearing mice and rats prior to or after radiation treatment . The weight of immunnological organ, hemogram, hematopoietic cells, cell micronuclease rate, and some other biochemical indices were investigated in these three models. Further-more, clinical observation of tea polyphenols mixed with Se and Vc was also carried out. The results are as follows:1. MTT assay showed that both TP and EGCG at concentrations of less than 125Hg/ml had comparatively low inhibition effect on cell growth, IC5n values of TP and EGCG against WI-38 and SPC was almost at a same level, i. e. IC50 against WI-3S for TP was (578Hg/ml), for EGCG was (574Hg/ml), and against SPC, IC50 for TP was (695Hg/ml) , and for EGCG was (694 g/ml) .2. Morphological observation showed that EGCG induced a little amount of apoptosis. whereas X-ray at dosage of 10Gy showed lager apoptosis for WI-38 However, when cells treated with EGCG before radiation showed obviously less apoptosis than that of only treated with radiation. This means that EGCG improves ability of normal cell against radiation , Cell of SPC showed greater apoptosis after radiation, while when treated with EGCG before radiation it showed increased mount of necrosis. This means that EGCG increasd radiation sensitivity of the cancer cells.3. In DNA electrophoresis, WI-38 showed typical "ladder-like" pattern of degraded DNA products after radiation, and no degraded DNA products in the group treated with EGCG. DNA degredation group treated with EGCG before radiation decreased apparently.This shows that EGCG can lessen degraded DNA fragments induced by radiationin normal cells. However, EGCG increased radiation sensitivity of cancer cell therefore induced more necrosis of cancer cell during radiation4.In FACS, EGCG could increase radiation resistance of normal cells, which was shown by a lower apoptosis peak.WI-38 showed 12.24% apoptosis by radiation, 5. 35% with EGCG before radiation. In cancer cell , SPC showed 8. 33% apoptosis by radiation , and 13. 22% with EGCG before radiation. It suggests that EGCG can increase radiation sensitivity of cancer cells. Also , EGCG would be a potential therapeutic agent to protect normal cell from apoptosis induced by radiation and to sensitize the tumor cells to the damage effect of ionizing radiation.5.In the animal experiments, Tea polyphenols' administration demonstrated a visible protective and theraputic action against radiation damage to immunnological organs and hemogram. TP inhibited the increasing number of cell micronucleas induced by radiation, promoted the GSH-Px and SOD activities, and LF levels in animal serum and liver. The protective activity of tea polyphenols was stronger than that of the control medicine, for example , fauric acid. A visible improvement in the immunological organs and hemogram was also observed in tumor-bearing mice following radiation treatment, administered TP mixed with Se and Vc could remarkably increase the effect. The results showed that oral administration of tea polyphenols prior to or after radiation treatment could increase leukocytes in tumor-bearing mice. The combination of TP with Vc and Se showed interactive effect to cancer cell, therefore, it will be helpful to peservere continuous radiation treatment, and be good for cancer therapy.
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