Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.6.5.2 (NQO1)
 6,196 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

It has been reported that several naturally occurring and related synthetic organosulfur compounds exert chemopreventive effects in several target organs in rodent models. The chemopreventive actions of 40 and 80% maximum tolerated doses (MTD) of organosulfur compounds, namely anethole trithione, diallyl disulfide, N-acetylcysteine, and taurine, administered in AIN-76A diet, on azoxymethane (AOM)-induced neoplasia were investigated in male F344 rats. Also, the effects of these agents on the activities of phase II enzymes, namely glutathione S-transferase (GST), NAD(P)H-dependent quinone reductase, and UDP-glucuronosyl transferase, in the liver and colonic mucosa and tumors were assessed. The MTD levels of anethole trithione, diallyl disulfide, N-acetylcysteine, and taurine were determined in male F344 rats and found to be 250, 250, 1500, and 1500 ppm, respectively. At 5 weeks of age, animals were fed the control diet (AIN-76A) or experimental diets containing 40 or 80% MTD levels of each test agent. All animals in each group, except those allotted for vehicle (saline) treatment, were administered AOM s.c. at a dose rate of 15 mg/kg body weight once weekly for 2 weeks. All animals were necropsied during week 52 after the second AOM injection. Colonic mucosal and tumor and liver enzyme activities were measured in animals fed 80% MTD levels of each test agent. Colon tumors were subjected to histopathological evaluation and classified as invasive or noninvasive adenocarcinomas. Colon tumor incidence (percentage of animals with tumors) and tumor multiplicity (tumors/animal) were compared among various dietary groups. The results indicated that administration of 200 ppm (80% MTD) anethole trithione significantly inhibited the incidence and multiplicity of both invasive and noninvasive adenocarcinomas, whereas feeding of 100 ppm (40% MTD) anethole trithione or 100 (40% MTD) or 200 ppm (80% MTD) diallyl disulfide suppressed only invasive adenocarcinomas of the colon. Although diets containing N-acetylcysteine and taurine inhibited colon tumor multiplicity, the effect was somewhat marginal. GST, NAD-(P)H-dependent quinone reductase, and UDP-glucuronosyl transferase activities in colonic mucosa and tumor and liver were significantly elevated in animals fed anethole trithione or diallyl disulfide, compared to those fed the control diet. N-Acetylcysteine and taurine slightly but significantly increased only the GST activity in the liver. Although other mechanisms are not excluded, inhibition of AOM-induced colon carcinogenesis by anethole trithione and diallyl disulfide may be associated, in part, with increased activities of phase II enzymes such as GST, NAD(P)H-dependent quinone reductase, and UDP-glucuronosyl transferase in the liver and colon.
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PMID:Chemoprevention of colon carcinogenesis by organosulfur compounds. 833 52

Broccoli belongs to a group of cruciferous vegetables characterized by its content of glucosinolates, secondary metabolites that, upon hydrolysis, release bioactive isothiocyanates (ITCs). Sulforaphane, the major ITC from broccoli, is believed to protect the body from cancer by induction of detoxification enzymes such as quinone reductase (QR). Sulforaphane provides powerful protection against carcinogenesis, mutagenesis, and other forms of toxicity by electrophiles and reactive forms of oxygen. The purpose of this study was to investigate the effects of processing methods on the ability of broccoli to induce QR in various rat tissues. Male F344 rats (four per group) received an AIN 76B-40 diet containing either 0% or 20% broccoli processed by different methods (dehydrated, freeze-dried, or freeze-dried and hydrolyzed) for 5 days. Colon tissues of rats receiving dehydrated, freeze-dried, and hydrolyzed broccoli diets showed QR induction of 9.1-, 10.5-, and 6.4-fold, respectively. Induction of QR by dehydrated broccoli in the liver and kidney was significantly less robust than in colon, being 2.3- and 1.6-fold over control, respectively. These results suggest that freeze-drying and dehydration are promising approaches for providing the public with the functional benefits of broccoli consumption.
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PMID:Effects of different processing methods on induction of quinone reductase by dietary broccoli in rats. 1511 60