Abstract: Green tea polyphenols (GTP) are thought to be effective in preventing oxidative stressrelated diseases, including cancer, cardiovascular disease, neurodegenerative disease and aging. In this study, the protective mechanisms of GTP against pro-parkinsonian neurotoxin 6-hydroxydopamine (6-OHDA) induced apoptosis in SH-SY5Y cells were investigated. The results show that GTP treatment rescued the changes in condensed nuclear and apoptotic bodies, attenuated 6-OHDA-induced early apoptosis, prevented the decrease in mitochondrial membrane potential, and suppressed accumulation of reactive oxygen species (ROS) (measured with ESR) and of intracellular free Ca²⁺. It was found that GTP treatment also counteracted 6-OHDA-induced nitric oxide increase and overexpression of nNOS and iNOS, and decreased the level of protein-bound 3-nitrotyrosine (3-NT). In addition, GTP treatment inhibited the auto-oxidation of 6-OHDA and scavenged oxygen free radicals in a dose- and time-dependent manner. Our results show that the protective effects of GTP against 6-OHDA Induced apoptosis in SH-SY5Y cells are mediated, at least in part, by controlling the ROS-NO pathway.

Key words:

ESR, Parkinson′s disease, green tea polyphenols, reactive oxygen species, nitric oxide, apoptosis