Abstract:
Although many causes have been suggested, the concept of oxidative stress has often been put forward as one of the important causes of neurodegenerative diseases. Natural antioxidants such as flavonoid polyphenols are essential in protecting neuronal cells from undergoing lipid peroxidation and cell death. The present study was designed to elucidate the antioxidant mechanisms of rutin and isoquercitrin in 6-OHDA induced PC12 rat pheochromocytoma cells. Pre-treatment of PC12 cells with rutin or isoquercitrin markedly (p<0.05) reduced the toxic effects caused by exposure to 6-OHDA as this was found to increase the viability of the PC12 cells. In addition, rutin and isoquercetrin were also found to elevate the levels of the endogenous antioxidant enzymes such as superoxide dismutase (SOD), glutathione peroxidase, catalase as well as glutathione. Rutin and isoquercitrin attenuated lipid peroxidation caused by 6-OHDA with p<0.05. Gene expression study using the qPCR array technique showed rutin suppressed the expression of the Parkin genes such Park 5, Park 7 and pro-apoptotic gene Casp3 gene in the PC12 cells exposed to 6-OHDA whilst isoquercitrin pre-treatment down-regulated expression of the Park 5 and Park 7 genes in these cells. Moreover, pre-treatment with rutin stimulated the expression of the TH gene in the PC12 cells. Tyrosine hydroxylase, the protein coded by the TH gene is crucial for biosynthesis of dopamine. Thus, quercetin glycosides treatment may present a novel approach in improving neurodegenerative diseases, including Parkinson’s (PD) and Alzheimer’s (AD) diseases.
