title: Protective effects of tea melanin against 2,3,7,8-tetrachlorodibenzo-p-dioxin-induced toxicity: antioxidant activity and aryl hydrocarbon receptor suppressive effect.
abstract: We examined the protective ability of tea melanin against 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced toxicity in C57BL6J mice. Reduced tea melanin (RTM) and non-reduced tea melanin (NRTM) were incorporated to distinguish anti-oxidant activity from alternative pathways. The mice were given a single oral dose of TCDD (100 microg/kg body weight) and then they were administered daily with NRTM or RTM (40 mg/kg, p.o.) for next 14 d. RTM protected the animals against TCDD-induced lipid peroxidation, inhibition of glutathione peroxidase, alteration in reduced and oxidized glutathione concentrations, loss of body weight, and increased relative liver weight. NRTM was less effective as compared to RTM because of its inferior antioxidant activity, but it still displayed a strong protective effect against TCDD toxicity owing to its similar suppression of the activity of the aryl hydrocarbon receptor. Both NRTM and RTM suppressed the expression of CYP1A1 gene and prevented the activation of cytochrome P450 isozyme in the livers of animals exposed to TCDD. These results suggest that tea melanin might be a potential agent offering dual protection against the development of TCDD-induced oxidative stress.
authors.affiliation: Graduate Institute of Biotechnology, Hung Kung University, and Kung Tien General Hospital, Taichung, Taiwan.
authors.forename: Yao-Ching
authors.initials: YC
authors.lastname: Hung
authors.forename: Guewha Steven
authors.initials: GS
authors.lastname: Huang
authors.forename: Vasyl Mykhailovych
authors.initials: VM
authors.lastname: Sava
authors.forename: Vyacheslav Andreevych
authors.initials: VA
authors.lastname: Blagodarsky
authors.forename: Meng-Yen
authors.initials: MY
authors.lastname: Hong
mesh_terms: D000284:Administration, Oral; D000818:Animals; D000975:Antioxidants / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D001835:Body Weight / Q000187:drug effects; D019363:Cytochrome P-450 CYP1A1 / Q000378:metabolism; D004249:DNA Damage / Q000187:drug effects; D003849:Deoxyguanosine / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005260:Female; D005978:Glutathione / Q000378:metabolism; D005979:Glutathione Peroxidase / Q000378:metabolism; D007441:Intubation, Gastrointestinal; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008543:Melanins / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D051379:Mice; D008810:Mice, Inbred C57BL; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000187:drug effects; D000072317:Polychlorinated Dibenzodioxins / Q000008:administration & dosage / Q000633:toxicity*; D018336:Receptors, Aryl Hydrocarbon / Q000037:antagonists & inhibitors* / Q000378:metabolism; D013662:Tea / Q000737:chemistry*; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism
chemical_list: D000975:Antioxidants; D008543:Melanins; D000072317:Polychlorinated Dibenzodioxins; D018336:Receptors, Aryl Hydrocarbon; D013662:Tea; D017392:Thiobarbituric Acid Reactive Substances; D005979:Glutathione Peroxidase; D019363:Cytochrome P-450 CYP1A1; D003849:Deoxyguanosine; D005978:Glutathione