DNA damage and aberrant crypt foci as putative biomarkers to evaluate the chemopreventive effect of annatto (Bixa orellana L.) in rat colon carcinogenesis
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Data
2005-04-04
Autores
Agner, A. R.
Bazo, A. P.
Ribeiro, Lúcia Regina [UNESP]
Salvadori, Daisy Maria Favero [UNESP]
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Editor
Elsevier B.V.
Resumo
Chemoprevention opens new perspectives in the prevention of cancer and other degenerative diseases. Use of target-organ biological models at the histological and genetic levels can markedly facilitate the identification of such potential chemopreventive agents. Colon cancer is one of the highest incidence rates throughout the world and some evidences have indicated carotenoids as possible agents that decrease the risk of colorectal cancer. In the present study, we evaluate the activity of annatto (Bixa orellaria L.), a natural food colorant rich in carotenoid, on the formation of aberrant crypt foci (ACF) induced by dimethy1hydrazine (DMH) in rat colon. Further, we investigate, the effect of annatto on DMH-induced DNA damage, by the comet assay. Male Wistar rats were given s.c. injections of DMH (40 mg/kg body wt.) twice a week for 2 weeks to induce ACE They also received experimental diets containing annatto at 20, 200 or 1000 ppm for five 5 weeks before (pre-treatment), or 10 weeks after (post-treatment) DMH treatment. In both protocols the rats were sacrificed on week 15th. For the comet assay, the animals were fed with the same experimental diets for 2 weeks. Four hours before the sacrifice, the animals received an s.c. injection of DMH (40 mg/kg body wt.). Under such conditions, dietary administration of 1000 ppm annatto neither induce DNA damage in blood and colon cells nor aberrant crypt foci in rat distal colon. Conversely, annatto was successful in inhibiting the number of crypts/colon (animal), but not in the incidence of DMH-induced ACF, mainly when administered after DMH. However, no antigenotoxic effect was observed in colon cells. These findings suggest possible chemopreventive effects of annatto through their modulation of the cryptal cell proliferation but not at the initiation stage of colon carcinogenesis. (c) 2005 Elsevier B.V. All rights reserved.
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aberrant crypt foci, annatto, chemoprevention, comet assay dimethylhidrazine
Como citar
Mutation Research-genetic Toxicology and Environmental Mutagenesis. Amsterdam: Elsevier B.V., v. 582, n. 1-2, p. 146-154, 2005.