title: High concentration of magnolol induces hepatotoxicity under serum-reduced conditions.
abstract: Although magnolol is cytoprotective against warm ischemia/reperfusion injury, its effect on cold preservation has not been fully investigated. This study aimed at examining whether magnolol maintains the liver graft integrity after cold preservation and elucidating the underlying mechanisms in terms of apoptotic signaling under both normothermic and hypothermic conditions. After being preserved in Ringer's lactate (RL) at 4 degrees C for 6h ex vivo, the magnolol-treated grafts demonstrated significantly higher AST, ALT, and LDH levels in perfusates than those from negative controls. TUNEL staining showed no difference in the number of apoptotic nuclei in both groups, whereas a more intense apoptotic signal in magnolol-treated grafts was shown as compared with the controls. In vitro data showed no significant difference in viability of RL-preserved clone-9 hepatocytes between the magnolol-treated and control groups, while magnolol pretreatment at 30min before cold preservation prominently induced hepatocyte cell death. RT-PCR and Western blotting analyses revealed a suppression in Bcl-2, but an up-regulation in Bax expression in clone-9 cells after magnolol treatment. Magnolol suppressed the ratios of NF-kappaB to I-kappaBalpha protein contents and I-kappaBalpha phosphorylation induced by TNF-alpha, and potentiated mitochondrial cytochrome c release and subsequent caspase-3 cleavage. Conversely, caspase-3 inhibitor attenuated magnolol-induced hepatotoxicity. We concluded that magnolol could not protect liver grafts from cold ischemia/reperfusion injury. High concentration of magnolol under serum-reduced conditions attenuates NF-kappaB-mediated signaling and induces intrinsic apoptotic pathway, thereby inducing in vitro hepatotoxicity.
authors.affiliation: Liver Transplantation Program and Department of Anesthesiology, Chang Gung Memorial Hospital-Kaohsiung Medical Center, Chang Gung University College of Medicine, 123 Ta-Pei Rd., Niao-Sung, Kaohsiung 83305, Taiwan.
authors.forename: Ying-Hsien
authors.initials: YH
authors.lastname: Kao
authors.forename: Bruno
authors.initials: B
authors.lastname: Jawan
authors.forename: Cheuk-Kwan
authors.initials: CK
authors.lastname: Sun
authors.forename: Shigeru
authors.initials: S
authors.lastname: Goto
authors.forename: Yu-Chun
authors.initials: YC
authors.lastname: Lin
authors.forename: Chun-Tzu
authors.initials: CT
authors.lastname: Hung
authors.forename: Mei-Chun
authors.initials: MC
authors.lastname: Pan
authors.forename: Li-Wen
authors.initials: LW
authors.lastname: Hsu
authors.forename: Yu-Fan
authors.initials: YF
authors.lastname: Cheng
authors.forename: Chia-Yun
authors.initials: CY
authors.lastname: Lai
authors.forename: Chih-Shien
authors.initials: CS
authors.lastname: Wang
authors.forename: Ching-Chou
authors.initials: CC
authors.lastname: Tsai
authors.forename: Huoy-Rou
authors.initials: HR
authors.lastname: Chang
authors.forename: Chao-Long
authors.initials: CL
authors.lastname: Chen
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001713:Biphenyl Compounds / Q000008:administration & dosage / Q000633:toxicity*; D015153:Blotting, Western; D053148:Caspase 3 / Q000378:metabolism; D056486:Chemical and Drug Induced Liver Injury / Q000209:etiology* / Q000378:metabolism; D003080:Cold Temperature; D015925:Cryopreservation; D045304:Cytochromes c / Q000378:metabolism; D020672:I-kappa B Proteins / Q000378:metabolism; D020287:In Situ Nick-End Labeling; D017705:Lignans / Q000008:administration & dosage / Q000633:toxicity*; D008099:Liver / Q000187:drug effects* / Q000378:metabolism; D016031:Liver Transplantation; D031566:Magnolia / Q000737:chemistry*; D008297:Male; D008928:Mitochondria / Q000187:drug effects; D016328:NF-kappa B / Q000378:metabolism; D024301:Plant Bark; D010936:Plant Extracts / Q000737:chemistry / Q000633:toxicity*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury; D020133:Reverse Transcriptase Polymerase Chain Reaction; D044967:Serum; D015398:Signal Transduction / Q000187:drug effects*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D051028:bcl-2-Associated X Protein
chemical_list: D001713:Biphenyl Compounds; D020672:I-kappa B Proteins; D017705:Lignans; D016328:NF-kappa B; D010936:Plant Extracts; D019253:Proto-Oncogene Proteins c-bcl-2; D014409:Tumor Necrosis Factor-alpha; D051028:bcl-2-Associated X Protein; C005498:magnolol; D045304:Cytochromes c; D053148:Caspase 3