Quercetin ameliorates liver injury induced with Tripterygium glycosides by reducing oxidative stress and inflammation

Quercetin (Que) is one of main compounds in Lysimachia christinae Hance (Christina loosestrife), and has both medicinal and nutritional value. Glycosides from Tripterygium wilfordii Hook. f. (lei going teng [the thunder duke vine]; TG) have diverse and broad bioactivities but with a high incidence of liver injury. Our previous study reported on the hepatoprotective properties of an ethanol extract from L. christinae against TG-induced liver injury in mice. This research is designed to observe, for the first time, the possible protective properties of the compound Que against TG-induced liver injury, and the underlying mechanisms that are involved in oxidative stress and anti-inflammation. The results indicated that TG caused excessive elevation in serum levels of alanine/aspartate transaminase (ALT/AST), alkaline phosphatase (ALP), gamma glutamyl transferase (gamma-GT), and pro-inflammatory cytokine tumor necrosis factor-alpha (TNF-alpha), as well as hepatic lipid peroxidation (all P < 0.01). On the other hand, following TG exposure, we observed significantly reduced levels of biomarkers, including hepatic glutathione (GSH), glutathione-S-transferase (GST), glutathione peroxidase (GPx), and the anti-inflammatory cytokine interleukin (IL)-10, as well as the enzyme activity and mRNA expression of copper-and zinc-containing superoxide dismutase (CuZn-SOD) and catalase (CAT) (all P < 0.01). Nevertheless, all of these alterations were reversed by the pre-administration of Que or the drug bifendate (positive control) for 7 consecutive days. Therefore, this study suggests that Que ameliorates TG-induced acute liver injury, probably through its ability to reduce oxidative stress and its anti-inflammatory properties.