Neuroprotective Effects of Phenolic and Carboxylic Acids on Oxidative Stress-Induced Toxicity in Human Neuroblastoma SH-SY5Y Cells.

An increase in oxidative stress is a key factor responsible for neurotoxicity induction and cell death leading to neurodegenerative diseases including Parkinson's and Alzheimer's diseases. Plant phenolics exert diverse bioactivities i.e., antioxidant, anti-inflammatory, and neuroprotective effects. Herein, phenolic compounds, namely protocatechuic aldehyde (PCA) constituents of Hydnophytum formicarum Jack. including vanillic acid (VA) and trans-ferulic acid (FA) found in Spilanthes acmella Murr., were explored for anti-neurodegenerative properties using an in vitro model of oxidative stress-induced neuroblastoma SH-SY5Y cells. Exposure of the neuronal cells with H2O2 resulted in the decrease of cell viability, but increasing in the level of reactive oxygen species (ROS) together with morphological changes and inducing cellular apoptosis. SH-SY5Y cells pretreated with 5 µM of PCA, VA, and FA were able to attenuate cell death caused by H2O2-induced toxicity, as well as decreased ROS level and apoptotic cells after 24 h of treatment. Pretreated SH-SY5Y cells with phenolic compounds also helped to upregulate H2O2-induced depletion of the expressions of sirtuin-1 (SIRT1) and forkhead box O (FoxO) 3a as well as induce the levels of antioxidant (superoxide dismutase (SOD) 2 and catalase) and antiapoptotic B-cell lymphoma 2 (Bcl-2) proteins. The findings suggest that these phenolics might be promising compounds against neurodegeneration.

Butein, isoliquiritigenin, and scopoletin attenuate neurodegeneration via antioxidant enzymes and SIRT1/ADAM10 signaling pathway.

Neuronal cell death is a key feature of neurodegenerative disorders such as Parkinson's and Alzheimer's diseases. Plant polyphenols, namely butein, isoliquiritigenin, and scopoletin, have been shown to exhibit various biological activities including anti-inflammatory, antimicrobial, and antioxidant activities. Herein, butein, isoliquiritigenin, and scopoletin were explored for their neuroprotective properties against oxidative stress-induced human dopaminergic SH-SY5Y cell death. The cells exposed to hydrogen peroxide (H2O2) revealed a reduction in cell viability and increases in apoptosis and levels of reactive oxygen species (ROS). Interestingly, pretreatment of SH-SY5Y cells with 5 µM of butein, isoliquiritigenin, or scopoletin protected against the cell death induced by H2O2, and decreased the levels of apoptotic cells and ROS. In addition, the levels of SIRT1, FoxO3a, ADAM10, BCL-2, and antioxidant enzymes (catalase and SOD2) were maintained in the cells pretreated with butein, isoliquiritigenin, or scopoletin before H2O2 treatment compared to cells without pretreatment and the reference (resveratrol). Molecular docking analysis revealed that the interactions between the activator-binding sites of SIRT1 and the phenolic compounds were similar to those of resveratrol. Taken together, the data suggest that these polyphenolic compounds could be potential candidates for prevention and/or treatment of neurodegeneration.