Indian Journal of Experimental Biology Vol. 48, April 2010, pp. 373-377 Effect of antioxidant vitamins A, C, E and their analogues on azo-dye binding protein in liver of rats treated with p-dimethylaminoazobenzene A Antony Joseph Velanganni * Department of Biochemistry, J.J. College of Arts and Science, Pudukkottai 622 422, India and C Balasundaram Department of Animal Science, Bharathidasan University, Tiruchirappalli 620 024, India Received 21 July 2009; revised 19 November 2009 p-Dimethylaminoazobenzene (DAB) is an azo-dye and known to cause liver tumour in rats. Azo-dye binding protein is a specific cytosolic protein involved in the translocation of azo-dye carcinogen metabolites from liver cytoplasm into the nucleus. Administration of vitamin A (40,000 and 50,000 IU), L-ascorbic acid (500 and 1,000 mg) and vitamin E succinate (200–500 mg) reduced the amount of azo-dye binding protein in liver of rats treated with DAB. Supplementation of high doses of vitamin A acetate, vitamin A palmitate, sodium ascorbate, ascorbyl palmitate and vitamin E acetate had no effect on the quantity of azo-dye binding protein in liver. When the vitamin mixture was given, the level of azo-dye binding protein decreased in the liver at all the studied doses, which may be due to their synergistic effect. Keywords: Antioxidant vitamins A, C and E, Azo-dye binding protein, p-Dimethylaminoazobenzene The pioneering work of Miller and Miller 1 established that aminoazo-dye, a known hepato carcinogen, binds to liver protein in rats; further in vivo studies on various animal models proved that the chosen carcinogens bound to cellular protein in tissues rendered them tissues susceptible to carcinogenic action. Azo-dye binding protein is a specific cytosolic protein involved in the translocation of azo-dye carcinogen metabolites from liver cytoplasm into the nucleus. The binding of azo-dye metabolites with nuclear macromolecule necessitate further prior processing that occur in the nucleus. The azo-dye binding protein is found in all the highly- differentiated hepatomas. It is not found in poorly differentiated hepatomas, anaplastic carcinomas and adenocarcinomas 2 . Thus the presence of azo-dye binding protein in tumour indicates the degree of cell differentiation. The hepatic binding protein is involved in the translocation of azo-dye carcinogen metabolites to the nucleus from liver cytoplasm. Interaction of azo-dye metabolites with nuclear macromolecules facilitates carcinogenesis that occurs in the nucleus 3 . Covalent binding of azo-dye metabolites to DNA occurs when the azo-dye metabolites are incubated with liver nuclei and not with isolated liver DNA. This is due to the specific soluble protein that controls the translocation form cytosol to the nucleus 4 . The amount of protein-bound azo-dye is three times more in mice after 2-3 weeks of DAB feeding; in hamster, azo-dye binding to proteins increased gradually up to 6 weeks, and then remained constant 5 . Sub-fractionation of liver homogenates on administration of azo-dyes shows that the dye is bound principally with the microsomal fraction (insoluble) and the soluble supernatant 6-8 . The soluble fraction subjected to zone electrophoresis has shown three protein fractions, namely a major basic protein fraction and two minor mono-acidic protein fractions 9 . The present study is concerned with the soluble proteins that bind specifically to the azo-dye so as to evaluate the role of antioxidant vitamins A, C, E and their analogues in preventing the binding of azo-dyes in DAB-treated rats. Materials and Methods Animals—Male albino rats of Wistar strain (170 ± 20 g), reared and maintained in the animal house of —————— *Correspondent author Telephone: +91-04322-260103 Fax: +91-04322-260103 E-mail: ajvelanganni@gmail.com