Effects Of Catechins On The Growth Of Endothelial Cells And Their Complex With Cu～(2+)

Tumor is the most common and the most serious disease, the incidence and mortality of tumour appear to be in the preceding in the world. In 1971, Folkman first reported that the growth and metastatic spread of solid tumors are dependent on angiogenesis, and the chemical signal from tumor tissues is able to activate the resting vascular endothelial cells. Of the numerous promoters of angiogenesis that have been identified, one of the most importance is vascular endothelial growth factor(VEGF). Many studies found that cathechins have inhibitory effects on angiogenesis, the mechanisms of angiogenic activity were the following three aspects: inhibition of the vascular endothelial cell proliferation, inhibition of cell adhesion molecule expression and suppression of basement membrance degradation. Hypoxia activates can increase the levels of endogenetic VEGF(Vascular endothelial growth factor) in the endothelial cells, which is a recently discovered mitogen for endothelial cells in vitro and a potent angiogenesis-promoting factor in vivo. This is the acute responsion under hypoxic environment for cells, however, endogenetic VEGF couldn't change the excessive apoptosis of the endothelial cells. Hypoxia activates can accelerate the apoptosis of the endothelial cells,which bring to the function of endothelial cells unconventionality and participate in the process of series of clinical pathology.By employing techniques of cell culture, the effects of four tea catechins, EGCG, ECG, EC and C were studied on the proliferation and migration of ECV304 in this paper. The result demonstrated that EGCG was the most effective in cell viability among the four catechins tested. Viability of ECV304 were significantly different in the case of the concentrations of EGCG ,which was ranged from 50 to 150 μ mol/L. The IC50 of EGCG was 75~150 μ mol/L ; EGCG was also effective in cell migration in a dose dependent manner, the IC50 was 150 μmol/L . EGCG can inhibit angiogensis, which may be related to the decreased migration of endothelial cell. The IC50 was at 390 μ mol/L and 370 μ mol/L in 36-hour-disposal and 48-hour-disposal of ECG respectively.The viability of ECV304 disposed by C and EC were above 80%. It was indicated that catechins showed little inhibitory effect on normal cell growthand migration at the concentration of lower than 75 μ mol/L.By employing anoxia injury model using Na2S2O4 and MTT assay ,the effects of EGCG for the anoxia injury to ECV304 cells,the Viability of RF/6A and the anoxia injury to RF/6A were studied in this paper. The result demonstrated that anoxia injury in the case of the concentrations and appropriate time of Na2S2O4 can significantly effect the cell viability of ECV304 cells, but EGCG was significantly protective effective for the anoxia injury in a dose and time dependent manner. Meantime, the result showed that 24-hour-disposal of EGCG was the most effective to the viability of RF/6A and the IC50 of EGCG was 125 μ mol/L; Anoxia injury in the case of the concentrations and appropriate time of Na2S2O4 can significantly effect the cell viability of RF/6A, and EGCG was significantly protective effective for the anoxia injury in the low Concentration.Copper ion is necessary for the normal growth of mankind. After exceeding or lacking of copper ion in the body, it could result in many kinds of diseases including tumor. Tea cathechins, one of the most effective bioactive constituent of tea, have lots of pharmacological functions. Molecular of tea polyphenols(including catechins) has many hydroxyl groups, and can complex with many kind of metal ion. Many studies found that cathechins could complex with metal ions and formed stable metal complexes, which had special pharmacological activities, copper ions easily complex with ligand and acting as the central ion. EGCG((-)Epigallocatechin gallate ), one of the catechins in tea, is the most active natural polyphenol in the products and being a polyligand, can complex with Cu2+. The complex can inhibit the excessive expression of free radicles, and inhibit the occurrence of tumors.In the present paper, the reaction condition for EGCG to complex with Cu2+ was investigated. The results showed that pH value and the ratio of EGCG to Cu2+ were the main affecting factors. Under the condition of strong acidity (pH^4.0), it was difficult for EGCG to complex with Cu2+; at 9.0>pH>4.0, EGCG could complex with Cu2+; at pH>9.0, catechol-hydroxyl groups interacted with Na+ to form catechol- Na+. Presence of Cu2+ strongly promoted the autoxidative activity of EGCG, so that Cu2+ was oxidized to Cu+. In the meantime we found that in acetic acid buffer solution of...