[Retracted] Proanthocyanidins Antagonize Arsenic-Induced Oxidative Damage and Promote Arsenic Methylation through Activation of the Nrf2 Signaling Pathway

Figure 18

The action mechanism of GSPE on oxidative stress induced by arsenic and methylation of arsenic. Arsenic can cause oxidative injuries by reducing the activity of antioxidative enzymes and increasing the amount of peroxide products. GSPE contains many phenolic hydroxyl groups and release H⁺, which can bind active oxygen radicals and competitively block the reaction chains of free radicals, reducing the consumption of antioxidants and increasing the activity of antioxidant enzymes. In addition, GSPE promotes the dissociation of Nrf2 and Keap1 proteins, allowing Nrf2 to enter the nucleus from the cytoplasm, thus promoting the expression of downstream genes of Nrf2 and increasing the antioxidant capacity. The Nrf2 pathway activation increases the level of GSH, which promotes the methylation of arsenic (arrows: promotion; blunt arrows: inhibition).