作者:Jamie N. Connarn、Xinyuan Zhang、Andrew Babiskin、Duxin Sun
DOI:10.1124/dmd.115.063107
日期:2015.7
Bupropion’s metabolism and the formation of hydroxybupropion in the liver by cytochrome P450 2B6 (CYP2B6) has been extensively studied; however, the metabolism and formation of erythro/threohydrobupropion in the liver and intestine by carbonyl reductases (CR) has not been well characterized. The purpose of this investigation was to compare the relative contribution of the two metabolism pathways of bupropion (by CYP2B6 and CR) in the subcellular fractions of liver and intestine and to identify the CRs responsible for erythro/threohydrobupropion formation in the liver and the intestine. The results showed that the liver microsome generated the highest amount of hydroxybupropion ( V max = 131 pmol/min per milligram, K m = 87 μ M). In addition, liver microsome and S9 fractions formed similar levels of threohydrobupropion by CR ( V max = 98–99 pmol/min per milligram and K m = 186–265 μ M). Interestingly, the liver has similar capability to form hydroxybupropion (by CYP2B6) and threohydrobupropion (by CR). In contrast, none of the intestinal fractions generate hydroxybupropion, suggesting that the intestine does not have CYP2B6 available for metabolism of bupropion. However, intestinal S9 fraction formed threohydrobupropion to the extent of 25% of the amount of threohydrobupropion formed by liver S9 fraction. Enzyme inhibition and Western blots identified that 11 β -dehydrogenase isozyme 1 in the liver microsome fraction is mainly responsible for the formation of threohydrobupropion, and in the intestine AKR7 may be responsible for the same metabolite formation. These quantitative comparisons of bupropion metabolism by CR in the liver and intestine may provide new insight into its efficacy and side effects with respect to these metabolites.
细胞色素 P450 2B6 (CYP2B6)对安非他酮在肝脏中的代谢和羟基安非他酮的形成进行了广泛的研究;然而,羰基还原酶 (CR) 对红曲/三氢安非他酮在肝脏和肠道中的代谢和形成还没有很好的描述。这项研究的目的是比较安非他酮在肝脏和肠道亚细胞组分中两种代谢途径(CYP2B6 和 CR)的相对贡献,并确定在肝脏和肠道中形成红代/三氢安非他酮的 CR。结果表明,肝微粒体产生的羟基安非他明量最高(V max = 131 pmol/min per milligram,K m = 87 μ M)。此外,肝脏微粒体和 S9 馏分通过 CR 生成了类似水平的曲安奈德(V max = 98-99 pmol/min per milligram,K m = 186-265 μ M)。有趣的是,肝脏形成羟基安非他明(通过 CYP2B6)和曲氢安非他明(通过 CR)的能力相似。与此相反,肠道馏分均不产生羟基安非他酮,这表明肠道中没有可用于安非他酮代谢的 CYP2B6。然而,肠道 S9 组份形成的安非他酮为肝脏 S9 组份形成的安非他酮的 25%。通过酶抑制和 Western 印迹发现,肝脏微粒体部分中的 11 β - 脱氢酶同工酶 1 主要负责形成曲安奈德,而肠道中的 AKR7 可能负责形成相同的代谢物。通过这些定量比较 CR 在肝脏和肠道中的安非他酮代谢情况,可以为了解安非他酮在这些代谢物方面的疗效和副作用提供新的视角。