Synergistic Antioxidant Effects of C3G-Enriched Oryza sativa L. cv. RD83 Extract and α-Tocopherol Against H2O2-Induced Oxidative Stress in SH-SY5Y Cells

Oxidative stress, which contributes to neuronal cell dysfunction, is a critical factor in the pathogenesis of neurodegenerative diseases. Anthocyanins and α-tocopherol have shown potential in mitigating oxidative damage, and their combination may provide synergistic effects. This study investigated the combined effects of a cyanidin-3-glucoside (C3G)-enriched extract derived from <i>Oryza sativa</i> L. cv. RD83 and α-tocopherol (C3GE) on hydrogen peroxide (H₂O₂)-induced oxidative stress in SH-SY5Y cells. Cells were treated with C3GE during exposure to 200 µM H₂O₂. Cell viability, intracellular reactive oxygen species (ROS), and oxidative stress biomarkers, including the activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px), as well as malondialdehyde (MDA) levels, were evaluated. Protein expression levels of histone deacetylase 1 (HDAC1), nuclear factor erythroid 2 related factor 2 (Nrf2), heme oxygenase 1 (HO-1), and SOD1 were also assessed. The combined treatment markedly improved cell viability, suppressed ROS accumulation, enhanced antioxidant enzyme activities, and significantly reduced MDA levels, suggesting effective protection against oxidative damage. Mechanistically, C3GE downregulated HDAC1 expression while upregulating Nrf2, HO-1, and SOD1, indicating that its antioxidant and neuroprotective effects are mediated, at least in part, through epigenetic modulation of redox-related signaling pathways. These results demonstrate a synergistic interaction between C3G and α-tocopherol that enhances cellular antioxidant defenses and supports redox homeostasis. In conclusion, the C3GE combination offers a promising therapeutic approach for preventing or attenuating oxidative stress-induced neuronal injury, with potential relevance for the treatment of neurodegenerative disorders.