Carcinogenesis Advance Access originally published online on January 12, 2008
Carcinogenesis 2008 29(2):411-417; doi:10.1093/carcin/bgn008
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Modulation of aflatoxin biomarkers in human blood and urine by green tea polyphenols intervention
Department of Environmental Toxicology, The Institute of Environmental and Human Health, Texas Tech University, PO Box 41163, Lubbock, TX 79409-1163, USA
1 Guangxi Cancer Institute, Nanning, Guangxi 530021, China
* To whom correspondence should be addressed. Tel: +1 806 8850320; Fax: +1 806 8852132; Email: js.wang{at}ttu.edu
To evaluate the efficacy of green tea polyphenols (GTPs) in modulating aflatoxin B1 (AFB1) biomarkers, a total of 352 serum samples and 352 urine samples collected from a 3 month chemoprevention trial with 500 mg GTPs, 1000 mg GTPs and a placebo were measured for AFB1–albumin adducts (AFB–AA), aflatoxin M1 (AFM1) and aflatoxin B1–mercapturic acid (AFB–NAC). Levels of AFB–AA at baseline were comparable for all three dose groups (P = 0.506). No significant differences were observed in AFB–AA levels in the placebo group over the 3 month period (P = 0.252). However, a significant reduction in AFB–AA levels was observed in the 500 mg group (P = 0.002). A marginally significant reduction in AFB–AA levels was also found in the 1000 mg group over the 3 month intervention period (P = 0.051). An analysis using a mixed-effects model indicated that the reduction in AFB–AA levels over time was dose and time dependent (dose–time interaction P = 0.049). There were no significant differences in median AFM1 levels among the three study groups at the baseline (P = 0.832), 1 month (P = 0.188) and 3 months (P = 0.132) of the GTP intervention; however, reduction of 42 and 43% in median AFM1 levels, as compared with the placebo, were found in 500 mg (P = 0.096) and 1000 mg (P = 0.072) groups at 3 months of the intervention. Significant elevations in median AFB–NAC levels and the ratio of AFB–NAC:AFM1 were found in both 500 and 1000 mg groups compared with the placebo group at both 1 month (P < 0.001) and 3 months (P < 0.001) of GTPs intervention. These results demonstrate that GTPs effectively modulate AFB1 metabolism and metabolic activation.
Abbreviations: AF, aflatoxin; AFB1, aflatoxin B1; AFB–AA, aflatoxin B1–albumin adducts; AFM1, aflatoxin M1; AFB–NAC, aflatoxin B1–mercapturic acid; ELISA, enzyme-linked immunosorbent assay; GST, glutathione S-transferase; GTP, green tea polyphenol; HBV, hepatitis B virus; HCC, hepatocellular carcinoma; HPLC, high-performance liquid chromatography; IAC, immunoaffinity column; MeOH, methanol; PBS, phosphate buffering solution; RIA, radioimmunoassay; SD, standard deviation
Received August 28, 2007; revised December 28, 2007; accepted January 2, 2008.