Inhibitory effects of tea catechins, black tea extract and oolong tea extract on hepatocarcinogenesis in rat.
Inhibitory effects of individual tea catechins ((--)-epicatechin, (--)-epigallocatechin, (--)-epicatechin gallate, (--)-epigallocatechin gallate), black tea extract and oolong tea extract on hepatocarcinogenesis were investigated. Male F344 rats received a single dose of diethylnitrosamine (200 mg/kg, i.p.), and thereafter phenobarbital (0.05%) was administered in the drinking water for a period of 6 weeks. Tea catechins, black tea extract or oolong tea extract were given during the entire experimental period, during only the initiation period or during only the promotion period. All four tea catechins, black tea extract and oolong tea extract (0.05 or 0.1%) significantly decreased the number and area of preneoplastic glutathione S-transferase placental form-positive foci in the liver. These results suggest that tea catechins, black tea extract and oolong tea extract have a chemopreventive action against hepatocarcinogenesis.
Matsumoto
N
N
Food Research Laboratories, Mitsui Norin Co., Ltd., Shizuoka, Japan.
Kohri
T
T
Okushio
K
K
Hara
Y
Y
D000818:Animals; D016588:Anticarcinogenic Agents / Q000494:pharmacology*; D002273:Carcinogens; D002392:Catechin / Q000031:analogs & derivatives / Q000494:pharmacology*; D004052:Diethylnitrosamine; D004354:Drug Screening Assays, Antitumor; D005982:Glutathione Transferase / Q000037:antagonists & inhibitors; D008099:Liver / Q000187:drug effects* / Q000201:enzymology; D008114:Liver Neoplasms, Experimental / Q000139:chemically induced / Q000201:enzymology / Q000517:prevention & control*; D008297:Male; D010634:Phenobarbital; D010936:Plant Extracts / Q000494:pharmacology; D011230:Precancerous Conditions / Q000139:chemically induced / Q000201:enzymology / Q000517:prevention & control*; D051381:Rats; D011916:Rats, Inbred F344
D016588:Anticarcinogenic Agents; D002273:Carcinogens; D010936:Plant Extracts; D004052:Diethylnitrosamine; D002392:Catechin; C062669:epicatechin gallate; D005982:Glutathione Transferase; D010634:Phenobarbital