Protective Effects Of Tea Extracts Against6-OHDA-induced Cell Injury In Sh-SY5Y Cells

Parkinson’s disease is a kind of neurodegenerative disease that has a influence on activity ability of the patients, which occurs in elderly people. So far, there are many thorough study on pathological of Parkinson’s disease; but there is no radical treatment. Hot-water soluble extracts and tea extracts have no/low toxicity, and are easy to get, especially in tea infusion. Tea infusion can be ingested through drinking daily, and non-PD people can also prevent thenselves by drinking tea daily.In this study, we choose6-OHDA-induced SH-SY5Y cells as PD model in vitro. On the basis of the protective effect of six kinds of tea extracts(EGCG, caffeine, L-theanine, polyphenols, theaflavins and pigments) on6-OHDA-induced SH-SY5Y cells, EGCG nanoparticles were prepared and investigated the cytotoxicity on SH-SY5Y cells and the protective effect on6-OHDA-induced SH-SY5Y cells and compared with the EGCG in the same concentration. We use western blot to detect related protein expression on6-OHDA-induced SH-SY5Y cells, to explore the etiology and pathogenesis of PD, and to reveal protective mechanism of tea extracts and EGCG nanoparticles on6-OHDA-induced SH-SY5Y cells. On this basis, we study the protective effect of tea infusion on6-OHDA-induced SH-SY5Y cells. The results obtained are as follows:First,6-OHDA-induced SH-SY5Y cells were chosen as PD model in vitro to determine the appropriate concentration of6-OHDA in reference to previous data base to facilitate conduct follow-up studies. When SH-SY5Y cells was treated with a concentration of100μmol/L of6-OHDA, cell viability was62.37±4.41%. So choose the concentration of100μmol/L as the appropriate concentration of6-OHDA we need.Second, methylene blue method was used to study the effect of tea extracts and EGCG nanoparticles on SH-SY5Y cells cytotoxicity assay and viability activity. The results show that within safe concentrations, the above eight kinds of samples were observed protective effects of different degrees on6-OHDA-induced SH-SY5Y cells. EGCG, theaflavins and EGCG-(FA+PEG)-NPs-1, EGCG-(FA+PEG)-NPs-2showed the best effect against6-OHDA-induced cell death. And the protectvie effects toward6-OHDA-induced SH-SY5Y cells in vitro was increased significantly by nanoparticles which FA and PEG modified together when compare to EGCG.Third, western blot were used to detect the expression of Akt、Bcl-2and Bax in6-OHDA-induced SH-SY5Y cells which were treated with EGCG, theaflavins and EGCG nanoparticles. Western blot analysis revealed that EGCG, theaflavins and EGCG nanoparticles prevented both the6-OHDA-induced expression of Bax, and the decrease in Akt and Bcl-2.Fourth, water soluble extracts were extracted with boiled water from green tea, black tea and Pu’er tea. Methylene blue method was used to study the effect of water soluble extracts on SH-SY5Y cells cytotoxicity assay and viability activity. The results showed that green tea, black tea, Pu’er tea extract have protective effects on6-OHDA-induced SH-SY5Y cells, and green tea had better effects than the others.The above studies show that the protective effect of tea extracts (EGCG, caffeine, L-theanine, polyphenols, theaflavins and pigments), EGCG nanoparticles and water soluble extracts on6-OHDA-induced SH-SY5Y cells showed with different degrees. The protective effect of EGCG, theaflavins and EGCG nanoparticles on SH-SY5Y cells are mediated, at least in part, by controlling the expression of apoptosis proteins such as Akt,Bcl-2and Bax.