Figure 3

Cellular protective mechanisms of key antioxidant treatments. Curcumin, VA, TFA, PCA, and 17β-oestradiol have direct experimental evidence that they activate SIRT1. As a result, SIRT1 activates transcription factors by removal of acetyl groups: PGC1α, Nrf2, and FoxO3a. PGC1α and Nrf2 increase the expression of SOD1/2 whilst FoxO3a increases catalase expression. Other antioxidants quercetin and carotenoids increase antioxidant defenses they may act through SIRT1 activation although unclear, furthermore, they both increase glutathione expression. Metal chelators prevent the generation of .OH by binding to free Cu²⁺ and Fe²⁺ and preventing them from participating in REDOX reactions. Abbreviations: .O₂: Superoxide anions, SOD: Superoxide dismutase, H₂O₂: Hydrogen peroxide, .OH: Hydroxyl radical, GSH: Glutathione, GR: Glutathione reductase, GSSG: Glutathione disulfide, SIRT1: Silent information regulator 1, PGC1α: Peroxisome proliferator-activated receptor gamma coactivator.