title: Antioxidant effects of lipophilic tea polyphenols on diethylnitrosamine/phenobarbital-induced hepatocarcinogenesis in rats.
abstract: BACKGROUND
  The purpose of the present study was to compare the antioxidant potential of lipophilic tea polyphenols (LTP) against the one of naturally-occurring water-soluble green tea polyphenols (GTP) in a two-stage model of diethylnitrosamine (DEN)/phenobarbital (PB)-induced hepatocarcinogenesis in Sprague-Dawley rats.
  
  
  METHODS
  GTP/LTP was given 5-times weekly by oral gavage with tea polyphenols equivalent to 0-, 40- and 400-mg/kg of body weight/day. GTP/LTP treatment was started 2 weeks prior to the initiation of DEN and continued for 30 weeks.
  
  
  RESULTS
  Histopathological and electron microscopic examination of liver tissue confirmed the protective effect of LTP on DEN/PB-induced liver damage and pre-carcinogenesis. LTP treatment significantly increased total antioxidant capacity (T-AOC) and glutathione peroxidase (GSH-Px) activity in liver tissues. Immunohistochemical detection of cellular nuclear factor erythroid-2-related factor-2 (Nrf2) and peroxiredoxin-6 (P6) indicated a down-regulation in Nrf2 and up-regulation of P6 expression in the liver of LTP-supplemented rats.
  
  
  CONCLUSIONS
  The present study provides evidence for the first time, that LTP exerts significant antioxidant effects on DEN/PB-induced liver damage and hepatocarcinogenesis through elevating T-AOC levels, enhancing GSH-Px activity and inducing P6 expression in rat liver tissues.
authors: Department of Toxicology, Zhejiang University School of Public Health, Hangzhou, Zhejiang, P.R. China Minhang District Center for Disease Control and Prevention of Shanghai, Shanghai, P.R. China.
authors: Fan
authors: F
authors: Zhou
authors: Department of Toxicology, Zhejiang University School of Public Health, Hangzhou, Zhejiang, P.R. China Xihu District Center for Disease Control and Prevention, Hangzhou, Zhejiang, P.R. China.
authors: Ting
authors: T
authors: Shen
authors: Department of Toxicology, Zhejiang University School of Public Health, Hangzhou, Zhejiang, P.R. China.
authors: Ting
authors: T
authors: Duan
authors: Department of Toxicology, Zhejiang University School of Public Health, Hangzhou, Zhejiang, P.R. China.
authors: Yu-Ying
authors: YY
authors: Xu
authors: Department of Toxicology, Zhejiang University School of Public Health, Hangzhou, Zhejiang, P.R. China.
authors: Soo Chin
authors: SC
authors: Khor
authors: Department of Toxicology, Zhejiang University School of Public Health, Hangzhou, Zhejiang, P.R. China.
authors: Jin
authors: J
authors: Li
authors: Department of Toxicology, Zhejiang University School of Public Health, Hangzhou, Zhejiang, P.R. China.
authors: Juan
authors: J
authors: Ge
authors: Department of Toxicology, Zhejiang University School of Public Health, Hangzhou, Zhejiang, P.R. China.
authors: Yi-Fan
authors: YF
authors: Zheng
authors: Department of Oral Biology and Maxillofacial Pathology, Georgia Health Sciences University, Augusta, GA, U.S.A.
authors: Stephen
authors: S
authors: Hsu
authors: Department of Periodontics, Georgia Regents University, Augusta, GA, U.S.A.
authors: Jamie
authors: J
authors: DE Stefano
authors: Department of Toxicology, Hangzhou Normal University School of Public Health, Hangzhou, Zhejiang, P.R. China.
authors: Jun
authors: J
authors: Yang
authors: Department of Biochemistry and Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang, P.R. China zhuxq@zju.edu.cn xulihong@zju.edu.cn.
authors: Li-Hong
authors: LH
authors: Xu
authors: Department of Toxicology, Zhejiang University School of Public Health, Hangzhou, Zhejiang, P.R. China zhuxq@zju.edu.cn xulihong@zju.edu.cn.
authors: Xin-Qiang
authors: XQ
authors: Zhu
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000008:administration & dosage / Q000494:pharmacology*; D001835:Body Weight / Q000187:drug effects; D002273:Carcinogens; D002471:Cell Transformation, Neoplastic / Q000139:chemically induced* / Q000187:drug effects*; D004052:Diethylnitrosamine / Q000009:adverse effects*; D007150:Immunohistochemistry; D008099:Liver / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D008114:Liver Neoplasms, Experimental; D008297:Male; D051267:NF-E2-Related Factor 2 / Q000235:genetics / Q000378:metabolism; D009929:Organ Size / Q000187:drug effects; D054465:Peroxiredoxin VI / Q000235:genetics / Q000378:metabolism; D010634:Phenobarbital / Q000009:adverse effects*; D059808:Polyphenols / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D013662:Tea / Q000737:chemistry*
chemical_list: D000975:Antioxidants; D002273:Carcinogens; D051267:NF-E2-Related Factor 2; D059808:Polyphenols; D013662:Tea; D004052:Diethylnitrosamine; D054465:Peroxiredoxin VI; D010634:Phenobarbital
keywords: Nrf2; Tea polyphenols; antioxidant capacity; hepatocarcinogenesis; peroxiredoxin 6