Curcumin Ameliorates AAPH-induced Oxidative Stress in HepG2 Cells by Activating Nrf2

In this study, 3 major curcuminoids were analyzed and the cellular anti-oxidant activities of E-TE(K) and E-TE(M) were assessed in HepG2 cells. The contributions and molecular targets of the 3 curcuminoids in the anti-oxidant activities of E-TE(K) and E-TE(M) were revealed. The curcuminoids including curcumin (CCM) was the most abundant curcuminoid [10.7% of E-TE(K) and 17.5% of E-TE(M)] and the curcuminoid content, particularly CCM, was crucial for anti-oxidant activities of E-TE(K) and E-TE(M). The anti-oxidant activity of CCM involved the regulation of Nrf2, the central transcriptional factor for expression of phase II detoxifying enzymes such as heme oxygenase-1. The CCM-activated Nrf2 was shown to be regulated by the PI3K/Akt signaling pathway. Taken together, the results indicate that the activation of Nrf2 through PI3K/Akt signaling pathway is required for anti-oxidant activity of CCM. These findings provide the scientific evidence for the development of Nrf2 targeted dietary anti-oxidant.