title: Licorice compounds glycyrrhizin and 18beta-glycyrrhetinic acid are potent modulators of bile acid-induced cytotoxicity in rat hepatocytes.
abstract: The accumulation of hydrophobic bile acids results in cholestatic liver injury by increasing oxidative stress, mitochondrial dysfunction, and activation of cell signaling pathways. Licorice root and its constituents have been utilized as antihepatotoxic agents. The purpose of this study was to evaluate the potential modulation by a primary component of licorice root, glycyrrhizin (GL), and its metabolite, 18beta-glycyrrhetinic acid (GA), in a hepatocyte model of cholestatic liver injury. Preincubation of fresh rat hepatocyte suspensions with GL or GA reduced glycochenodeoxycholic acid (GCDC)-dependent reactive oxygen species generation, with GA more potent than GL. Interestingly, GL and GA had opposing effects toward GCDC-induced cytotoxicity; GA prevented both necrosis and apoptosis, whereas GL enhanced apoptosis. GCDC promoted activation of caspase 10, caspase 3, and PARP; all were inhibited by GA but not GL. Induction of apoptosis by GCDC was also associated with activation of JNK, which was prevented by GA. Activation of caspase 9 and dissipation of mitochondrial membrane potential were prevented by GA but not GL. In liver mitochondrial studies, GL and GA were both potent inhibitors of the mitochondrial permeability transition, reactive oxygen species generation, and cytochrome c release at submicromolar concentrations. Results from this study suggest that GL exhibits pro-apoptotic properties, whereas GA is a potent inhibitor of bile acid-induced apoptosis and necrosis in a manner consistent with its antioxidative effect.
authors.affiliation: Pediatric Liver Center, Section of Pediatric Gastroenterology, Hepatology, and Nutrition, Department of Pediatrics, University of Colorado School of Medicine, Denver, Colorado 80262, USA.
authors.forename: Eric
authors.initials: E
authors.lastname: Gumpricht
authors.forename: Rolf
authors.initials: R
authors.lastname: Dahl
authors.forename: Michael W
authors.initials: MW
authors.lastname: Devereaux
authors.forename: Ronald J
authors.initials: RJ
authors.lastname: Sokol
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000378:metabolism / Q000494:pharmacology; D017209:Apoptosis; D001647:Bile Acids and Salts / Q000378:metabolism*; D053455:Caspase 10; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D045304:Cytochromes c / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005434:Flow Cytometry; D006034:Glycyrrhetinic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology*; D006035:Glycyrrhiza / Q000737:chemistry*; D019695:Glycyrrhizic Acid / Q000494:pharmacology*; D022781:Hepatocytes / Q000378:metabolism*; D015151:Immunoblotting; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D008099:Liver / Q000293:injuries / Q000378:metabolism; D048670:MAP Kinase Kinase 4; D008297:Male; D008564:Membrane Potentials; D008856:Microscopy, Fluorescence; D008928:Mitochondria / Q000378:metabolism; D008930:Mitochondria, Liver / Q000378:metabolism; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D009336:Necrosis; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species; D013997:Time Factors
chemical_list: D000975:Antioxidants; D001647:Bile Acids and Salts; D017382:Reactive Oxygen Species; C119129:18alpha-glycyrrhetinic acid; D019695:Glycyrrhizic Acid; D045304:Cytochromes c; D011065:Poly(ADP-ribose) Polymerases; D048031:JNK Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases; C505410:Casp3 protein, rat; C506435:Casp9 protein, rat; D053455:Caspase 10; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases; D006034:Glycyrrhetinic Acid