A pro-drug of the green tea polyphenol (-)-epigallocatechin-3-gallate (EGCG) prevents differentiated SH-SY5Y cells from toxicity induced by 6-hydroxydopamine

Regular consumption of green tea benefits people in prevention from cardiovascular disorders, obesity as well as neurodegenerative diseases. (-)-Epigallocatechin-3-gallate (EGCG) is regarded as the most biologically active catechin in green tea. However, the stability and bioavailability of EGCG are restricted. The purpose of the present study was to investigate whether a pro-drug, a fully acetylated EGCG (pEGCG), could be more effective in neuroprotection in Parkinsonism mimic cellular model. Retinoic acid (RA)differentiated neuroblastoma SH-SY5Y cells were pre-treated with different concentrations of EGCG and pEGCG for 30 min and followed by incubation of 25 mu M 6-hydroxydopamine (6-OHDA) for 24 h. We found that a broad dosage range of pEGCG (from 0.1 to 10 mu M) could significantly reduce lactate dehydrogenase release. Likewise, 10 mu M of pEGCG was effective in reducing caspase-3 activity, while EGCG at all concentrations tested in the model failed to attenuate caspase-3 activity induced by 6-OHDA. Furthermore, Western-blot analysis showed that Akt could be one of the specific signaling pathways stimulated by pEGCG in neuroprotection. It was demonstrated that 25 mu M of 6-OHDA significantly suppressed the phosphorylation level of Akt. Only pEGCG at 10 mu M markedly increased its phosphorylation level compared to 6-OHDA alone. Taken together, as pEGCG has higher stability and bioavailbility for further investigation, it could be a potential neuroprotective agent and our current findings may offer certain clues for optimizing its application in future. (C) 2009 Elsevier Ireland Ltd. All rights reserved.