Neuroprotective Effects of Bioavailable Polyphenol-Derived Metabolites against Oxidative Stress-Induced Cytotoxicity in Human Neuroblastoma SH-SY5Y Cells

Oxidative stress is involved in cell death in neurodegenerative diseases. Dietary polyphenols can exert health benefits, but their direct effects on neuronal cells are debatable because most phenolics are metabolized and do not reach the brain as they occur in the dietary sources. Herein, we evaluate the effects of a panel of bioavailable polyphenols and derived metabolites at physiologically relevant conditions against H2O2-induced apoptosis in human neuroblastoma SH-SY5Y cells. Among the 19 metabolites tested, 3,4-dihydroxyphenylpropionic acid, 3,4-dihydroxyphenylacetic acid, gallic acid, ellagic acid, and urolithins prevented neuronal apoptosis via attenuation of ROS levels, increased REDOX activity, and decreased oxidative stress-induced apoptosis by preventing the caspase-3 activation via the mitochondrial apoptotic pathway in SH-SY5Y cells. This suggests that dietary sources containing the polyphenol precursors of these molecules such as cocoa, berries, walnuts, and tea could be potential functional foods to reduce oxidative stress associated with the onset and progress of neurodegenerative diseases.