Tulayakul P, Dong K S, Li J Y, Manabe N, Kumagai S
Graduate School of Agricultural and Life Sciences, University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan.
Toxicon. 2007 Sep 1;50(3):339-48. doi: 10.1016/j.toxicon.2007.04.005. Epub 2007 Apr 22.
To clarify whether enzymes involved in aflatoxin B1 (AFB1) metabolism in pigs respond to antioxidant agents, the effect of feeding piglets with diets containing green tea extracts (Sunphenon) and coumarin on in vitro AFB1 metabolism by their liver and intestinal tissues was studied. The results showed that coumarin reduced AFB1-DNA adduct formation by both liver and intestinal microsomes, while Sunphenon did not have any effects. Both coumarin and Sunphenon enhanced the glutathione S-transferase (GST) activity to conjugate AFB1 to glutathione GSH in the intestine, although no effects were noted in the liver. Changes of the expression of mRNA of GSTA2 and GSTO1 were not in parallel with the observed changes of GST activity, suggesting that other GST subtypes are involved in the GST activity toward AFB1. As for lipophilic-free AFB1 metabolites, coumarin reduced the liver microsomal conversion of AFB1 to aflatoxin M1 (AFM1) and aflatoxin Q1 (AFQ1), but Sunphenon exerted no effects. Both coumarin and Sunphenon enhanced the conversion of AFB1 to aflatoxicol in the liver. All the results suggest that feeding with a diet containing coumarin affects AFB1 metabolism to enhance AFB1 detoxification through the suppression of P450 enzyme activity in the liver and the enhancement of GST activity in the intestine. Feeding with a diet containing Sunphenon enhances AFB1 detoxification, but the effects are noted mainly in the intestine.
为了阐明猪体内参与黄曲霉毒素B1（AFB1）代谢的酶是否对抗氧化剂有反应，研究了用含绿茶提取物（Sunphenon）和香豆素的日粮喂养仔猪对其肝脏和肠道组织体外AFB1代谢的影响。结果表明，香豆素可降低肝脏和肠道微粒体中AFB1-DNA加合物的形成，而Sunphenon则无任何作用。香豆素和Sunphenon均可增强肠道中谷胱甘肽S-转移酶（GST）将AFB1与谷胱甘肽GSH结合的活性，尽管在肝脏中未观察到作用。GSTA2和GSTO1 mRNA表达的变化与观察到的GST活性变化不平行，表明其他GST亚型参与了GST对AFB1的活性。至于亲脂性游离AFB1代谢物，香豆素可降低肝脏微粒体中AFB1向黄曲霉毒素M1（AFM1）和黄曲霉毒素Q1（AFQ1）的转化，但Sunphenon无作用。香豆素和Sunphenon均可增强肝脏中AFB1向黄曲霉毒素醇的转化。所有结果表明，用含香豆素的日粮喂养会影响AFB1代谢，通过抑制肝脏中P450酶活性和增强肠道中GST活性来增强AFB1解毒。用含Sunphenon的日粮喂养可增强AFB1解毒，但主要在肠道中观察到作用。
