2,3,7,8-Tetrachlorodibenzo-p-dioxin( TCDD) an unwanted contaminant of combustion and chlorine bleaching processes, is the most toxic member of the halogenated aromatic hydrocarbons. The disposition and pharmacokinetics of 2, 3 7, 8-tetrachlorodibenzo-p-dioxin( TCDD) has been investigated in several species and under various exposure conditions but very few studies are about its metabolites because of its high stability. The distribution profile and metabolism fate of 1, 2, 7, 8-Tetrachloro [U-14C]dibenzodioxin in carp Cyprinus carpio were studied in this paper.1,2,7,8-TCDD was dissolved in acetone/corn oil(8/95, v/v) and administrated by a single intraperitoneal injection(i.p., 46.4 mu Ci kg(-1) body weight). Liver, bile and visceral fat were sampled at 1 2,4,8, 12 days after the exposure and the radioactivities in those sample was assayed by liquid scintillation counter. 100mg tissue or 100 mu L bile in little flask was mixed with 0.2mL perchloric acid, 0.3mL, hydrogen peroxide and was put into a heating oven 75 degrees C for an hour. 10mL scintillation liquid was added into the flask immediately after the digest and bleaching procedure. The remanent bile was collected and stored in -80 degrees C for metabolite studies.The radioactivity in liver and bile increased in the first 8 days and decrease sequently. The radioactivity in visceral fat was high obviously in the first 2 days and then decreased. Time course of liver to visceral fat ratio of percent of administered dose exhibited an apparent"S" pattern which shows 1 2, 7, 8-TCDD was transferred from visceral fat to liver in the first 8 days. The concentrations of 1 2,7,8-TCDD in various organs sampled at 4 days have much difference: visceral fat > liver > gastrointestinal tract > gonad > kidney > spleen > skin > gill > muscle > brain > blood. Visceral fat I liver I gonad, gastrointestinal tract and muscle were the main disposition sites of 1 2, 7, 8-TCDD. The metabolites in bile were studied by thin layer chromatogram, radioautograph and GC/MS. Various solvent systems had been developed to separate the parent compound and its metabolites. The Ethyl acetate/Acetonitrile/Acetic acid ( 10 : 2 0.2) is better to separate the metabolites than other solvent systems such as Dichloromethane, Hexane/Ethyl acetate (2 1), Ethyl acetate/Aceton/Acetic acid ( 10 : 2 : 0.1) and Acetone/Acetonitrile/Water (4: 2: 1). The results show that it exists at least 3 kinds of metabolite in bile, and the parent compound identified by GC/MS is only a small portion of radioactive materials.
Song Shi-Bo; Hui Yang; Xu Xu-Dong; Xu Ying (email@example.com) ; Liu Jun.Preliminary studies on metabolism and distribution of C-14 labeled 1,2,7,8-tetrachlorodibenzo-p-dioxin in common carp,Acta Hydrobiologica Sinica,2005,29(4):439-443