Inhibitory effects of oxyresveratrol on ERK and Smad1/2 phosphorylation and HSC activation in preventing carbon tetrachloride-induced rat liver fibrosis

Oxyresveratrol (ORes, trans-2,4,3′,5′-tetrahydroxy stilbene) naturally exists in mulberry, grapes, peanuts and other plants. It belongs to stilbene polyphenolic family and has an extra hydroxyl group at 2-position comparing with resveratrol (Res). Hence, ORes has stronger antioxidant activity than resveratrol. In present study, we employed a rat hepatic fibrosis model induced by carbon tetrachloride (CCl₄) and administrated ORes via gavage feeding to study the protective effects and potential mechanisms of ORes against hepatic fibrosis. We demonstrated that rat liver oxidative damage induced by CCl₄ was significantly alleviated after ORes feeding. Furthermore, the mRNA transcription levels of α-smooth muscle actinn (α-SMA), desmin, and two MMPs (MMP2 and MMP9) were reduced and the expression levels of transforming growth factor β1 (TGF-β1), p- small mother against decapen-taplegic protein (Smad)1/2 and p-extracellular signal-regulated kinases (ERK)1/2 in the liver tissue down-regulated dramatically. In a parallel study with Res, ORes showed more efficacious protective effect than Res against rat liver fibrosis, which is attributed to extended conjugation system due to the extra hydroxyl group at 2-position on ORes making it more electron-rich and susceptible to oxidation than Res. Therefore, dietary consumption of mulberry and other fruits containing ORes may be beneficial in the prevention of liver fibrosis.