Protective effect of rutaecarpine against t-BHP-induced hepatotoxicity by upregulating antioxidant enzymes via the CaMKII-Akt and Nrf2/ARE pathways

Abstract Rutaecarpine, an indolopyridoquinazolinone alkaloid isolated from the unripe fruit of Evodia rutaecarpa , has been shown to have cytoprotective potential, but the molecular mechanism underlying this activity remains unclear. Our study was designed to investigate the cytoprotective effect of rutaecarpine against tert -butyl hydroperoxide ( t -BHP) and to elucidate its action mechanism of action of rutaecarpine in a cultured HepG2 cell line and in mouse liver. Rutaecarpine decreased t -BHP–induced reactive oxygen species (ROS) production, cytotoxicity, and apoptosis in HepG2 cells. Pretreatment with rutaecarpine prior to the injection of t -BHP significantly prevented the increase in serum levels of AST, ALT, and lipid peroxidation in mice liver. It increased the transcriptional activity of NF-E2–related factor 2 (Nrf2) as well as the products of the Nrf2 target genes hemeoxygenase-1 (HO-1), NAD(P)H:quinone oxidoreductase 1 (NQO1), and glutamate cysteine ligase (GCL). Moreover, rutaecarpine also enhanced the phosphorylation of Akt and Ca 2+ /calmodulin-dependent protein kinase-II (CaMKII). The pharmaceutical inhibitors, such as KN-93 (CaMKII inhibitor) and LY294002 (Akt inhibitor) suppressed rutaecarpine-induced HO-1 expression and cytoprotection. Our findings identify the CaMKII-PI3K/Akt-Nrf2 cascade as an antioxidant pathway mediating rutaecarpine signaling and leading to HO-1 expression in hepatocytes.