CYTOCHROME P450 MEDIATED METABOLISM, DIET, AND THE GASTROINTESTINAL TRACT

药物的口服生物利用度如果通过其吸收来确定 从胃肠道和首过代谢发生 在肠上皮和/或肝脏中。 往往 血浆浓度的显著个体间变异性， 相关的临床反应通常由这些决定 因素 对肝脏成分进行了广泛的研究 这种影响，但其他因素在很大程度上是不确定的。 为 例如，CYP 3A介导的代谢过程中， 肠上皮细胞和从该组织流出与P- 糖蛋白 这些过程以及肝脏中的代谢 可能受到饮食相关因素的潜在调节，和/或 肠道疾病。因此，研究将解决其中一些问题， 决定因素是重要的临床使用药物或可能 在癌症的化学预防中具有重要意义， 饮食和环境原致癌物。 在后一种情况下， CYP 1A、CYP 2 E1和CYP 3A等酶被激活， 原致癌物 由于蔬菜的化学保护作用 抗癌是公认的，假设某些 植物化学物质可以抑制这些酶。 这将由以下人员进行测试： 调查十字花科蔬菜与大蒜相关的能力 产品，以抑制体内探针的代谢 在人类中的单个β-同种型。 随后，研究将 扩展到检查代表性纯化学品的影响， 正在开发的化学保护剂成分 （奥替普拉、异硫氰酸苯乙酯、S-烯丙基半胱氨酸）。 的影响 还将检查饮食中的CYP 2 E1和CYP 3A活性， 不同性格特征的种族群体， 高加索人，如项目1中确定的。 尤其是日本人和 墨西哥裔美国人，经常吃“西方”的饮食相比， “本土”饮食。 膳食盐影响 某些CYP 3A/P-糖蛋白的血浆浓度-时间曲线 还将在人和动物模型中检查底物。 最后，影响肠道疾病，如乳糜泻， 热带口炎性腹泻对口服药物的生物利用度将是 确定，因为这种炎性疾病与 肠道结构和功能的严重紊乱 上皮

The oral bioavailability of drugs if determined by their absorption from the gastro-intestinal tract and first-pass metabolism occurring in either the intestinal epithelium and/or the liver. The often marked interindividual variability in plasma concentrations and associated clinical response is frequently determined by these factors. Extensive study has been made of the hepatic component of this effect, but other determinants are largely undefined. For example, CYP3A-mediated metabolism during absorption by the intestinal epithelium and efflux from this tissue associated with P- glycoprotein. Such processes as well as metabolism in the liver may be potentially modulated by dietary-related factors and/or intestinal disease. Accordingly, studies will address some of these determinants that are important in the clinical use of drugs or may be significant in the chemoprevention of cancer resulting from dietary and environmental procarcinogens. In the latter instance, it is though that enzymes like CYP1A, CYP2E1 and CYP3A activate the procarcinogen. Since the chemoprotective effect of vegetables against cancer is well-recognized, it is hypothesized that certain phytochemical may inhibit these enzymes. This will be tested by investigating the ability of cruciferous vegetables and garlic-related products to inhibit the metabolism of in vivo probes of the individual CYP isoforms in humans. Subsequently, studies will be extended to examine the effects of representative pure chemical constituents that are under development as chemoprotective agents (oltipraz, phenethyl isothiocyanate, S-allyl cysteine). The effect of diet of CYP2E1 and CYP3A activities will also be examined in racial groups with different disposition characteristics from Caucasians, as identified in Project 1. In particular, Japanese and Mexican-Americans that routinely eat a "western" diet compared to "native" diet. The mechanism(s) whereby dietary salt affects the plasma concentration-time profile of certain CYP3A/P-glycoprotein substrates will also be examined in both humans and animal models. Finally, the effect of intestinal disease such as celiac disease and tropical sprue on the oral bioavailability of drugs will be determined, since such inflammatory diseases are associated with major disturbances in the structure and functioning of the intestinal epithelium.