title: Caffeic acid prevents acetaminophen-induced liver injury by activating the Keap1-Nrf2 antioxidative defense system.
abstract: Acute liver failure induced by acetaminophen (APAP) overdose is the main cause of drug-induced liver injury (DILI). Caffeic acid (CA) is a phenolic compound from many natural products. This study aims to investigate the protective mechanism of CA in APAP-induced liver injury. The results of serum alanine/aspartate aminotransferases (ALT/AST), liver myeloperoxidase (MPO) activity, liver glutathione (GSH) and reactive oxygen species (ROS) levels demonstrated the protection of CA against APAP-induced liver injury. Liver histological observation provided further evidences of CA-induced protection. CA was found to reverse the APAP-induced decreased cell viability in human normal liver L-02 cells and HepG2 cells. CA also reduced the increased cellular ROS level induced by APAP in hepatocytes. The results of luciferase assay and Western-blot analysis showed that CA increased the transcriptional activation of nuclear factor erythroid 2-related factor 2 (Nrf2) in the presence of APAP. Nrf2 siRNA reduced the protection of CA against APAP-induced hepatotoxicity. CA also reversed the APAP-induced decreased mRNA and protein expression of heme oxygenase 1 (HO-1) and
  quinone oxidoreductase 1(NQO1). In addition, HO-1 inhibitor zinc protoporphyrin (ZnPP) and NQO1 inhibitor diminutol (Dim) reduced the protection of CA against APAP-induced hepatotoxicity. CA also decreased the expression of kelch-like ECH-associated protein-1(Keap1). Molecular docking indicated the potential interacting of CA with Nrf2 binding site in the Keap1 protein. CA had little effect on the enzymatic activity of cytochrome P450 (CYP) 3A4 and CYP2E1 in vitro. In conclusion, we demonstrated that CA prevented APAP-induced hepatotoxicity by decreasing Keap1 expression, inhibiting binding of Keap1 to Nrf2, and thus activating Nrf2 and leading to increased expression of antioxidative signals including HO-1 and NQO1.
authors.affiliation: Shanghai Key Laboratory of Complex Prescription and MOE Key Laboratory for Standardization of Chinese Medicines, Institute of Chinese Materia Medica, Shanghai University of Traditional Chinese Medicine, 1200 Cailun Road, Shanghai 201203, China; Center for Traditional Chinese Medicine and Systems Biology, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China.
authors.forename: Chun
authors.initials: C
authors.lastname: Pang
authors.affiliation: Shanghai Key Laboratory of Complex Prescription and MOE Key Laboratory for Standardization of Chinese Medicines, Institute of Chinese Materia Medica, Shanghai University of Traditional Chinese Medicine, 1200 Cailun Road, Shanghai 201203, China.
authors.forename: Zhiyong
authors.initials: Z
authors.lastname: Zheng
authors.affiliation: Shanghai Key Laboratory of Complex Prescription and MOE Key Laboratory for Standardization of Chinese Medicines, Institute of Chinese Materia Medica, Shanghai University of Traditional Chinese Medicine, 1200 Cailun Road, Shanghai 201203, China.
authors.forename: Liang
authors.initials: L
authors.lastname: Shi
authors.affiliation: Center for Drug Safety Evaluation and Research, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China.
authors.forename: Yuchen
authors.initials: Y
authors.lastname: Sheng
authors.affiliation: Center for Traditional Chinese Medicine and Systems Biology, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China.
authors.forename: Hai
authors.initials: H
authors.lastname: Wei
authors.affiliation: Shanghai Key Laboratory of Complex Prescription and MOE Key Laboratory for Standardization of Chinese Medicines, Institute of Chinese Materia Medica, Shanghai University of Traditional Chinese Medicine, 1200 Cailun Road, Shanghai 201203, China.
authors.forename: Zhengtao
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Shanghai Key Laboratory of Complex Prescription and MOE Key Laboratory for Standardization of Chinese Medicines, Institute of Chinese Materia Medica, Shanghai University of Traditional Chinese Medicine, 1200 Cailun Road, Shanghai 201203, China. Electronic address: lichenyue1307@126.com.
authors.forename: Lili
authors.initials: L
authors.lastname: Ji
mesh_terms: D000082:Acetaminophen / Q000633:toxicity*; D000410:Alanine Transaminase / Q000097:blood; D000818:Animals; D001219:Aspartate Aminotransferases / Q000097:blood; D001665:Binding Sites; D002109:Caffeic Acids / Q000737:chemistry / Q000494:pharmacology*; D056486:Chemical and Drug Induced Liver Injury / Q000517:prevention & control*; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D051547:Heme Oxygenase-1 / Q000378:metabolism; D056945:Hep G2 Cells; D006801:Humans; D000072019:Kelch-Like ECH-Associated Protein 1 / Q000737:chemistry / Q000378:metabolism*; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D008813:Mice, Inbred ICR; D062105:Molecular Docking Simulation; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000378:metabolism; D051267:NF-E2-Related Factor 2 / Q000235:genetics / Q000378:metabolism*; D018384:Oxidative Stress; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017382:Reactive Oxygen Species / Q000378:metabolism; D015533:Transcriptional Activation
chemical_list: D002109:Caffeic Acids; C117301:Keap1 protein, mouse; D000072019:Kelch-Like ECH-Associated Protein 1; D008565:Membrane Proteins; D051267:NF-E2-Related Factor 2; C495636:Nfe2l2 protein, mouse; D017382:Reactive Oxygen Species; D000082:Acetaminophen; D003577:Cytochrome P-450 Enzyme System; D051547:Heme Oxygenase-1; C496542:Hmox1 protein, mouse; D016660:NAD(P)H Dehydrogenase (Quinone); C491732:Nqo1 protein, mouse; D001219:Aspartate Aminotransferases; D000410:Alanine Transaminase; D005978:Glutathione; C040048:caffeic acid
keywords: Acetaminophen; Caffeic acid; Hepatotoxicity; Keap1; Nrf2