代谢
当前研究调查了由于参与形成和解毒1'-羟基香叶醇这两种关键代谢反应的变异,导致个体之间肝脏中1'-羟基香叶醇(一种直接致癌代谢物)水平的变化。1'-羟基香叶醇的形成主要是由P450 1A2、2A6和2E1催化,目前的研究结果支持1'-羟基香叶醇的氧化是由17beta-羟基类固醇脱氢酶2(17beta-HSD2)催化。在第一种方法中,研究为14个个体人类受试者定义了基于生理的biokinetic(PBBK)模型,揭示了这个人类受试者群体中1'-羟基香叶醇的肝脏浓度-时间曲线下面积(AUC)有1.8倍的个体间变异。17beta-HSD2催化1'-羟基香叶醇的氧化导致的变异比P450酶活性变异引起的影响更大。在第二种方法中,进行了蒙特卡洛模拟,以评估整个群体中1'-羟基香叶醇的肝脏水平可能发生的变异程度。这种分析可以用来推导一个特定化学品的调整因子(CSAF),定义为预测的1'-羟基香叶醇在肝脏中AUC分布的99th百分位数除以50th百分位数。估计CSAF的范围在1.6到4.0之间,这取决于考虑到的1'-羟基香叶醇氧化的变异水平。将CSAF与生物动力学中人类变异的默认不确定性因子3.16进行比较,显示默认不确定性因子足以保护99%的人群。
The present study investigates interindividual variation in liver levels of the proximate carcinogenic metabolite of estragole, 1'-hydroxyestragole, due to variation in two key metabolic reactions involved in the formation and detoxification of this metabolite, namely 1'-hydroxylation of estragole and oxidation of 1'-hydroxyestragole. Formation of 1'-hydroxyestragole is predominantly catalyzed by P450 1A2, 2A6, and 2E1, and results of the present study support that oxidation of 1'-hydroxyestragole is catalyzed by 17beta-hydroxysteroid dehydrogenase type 2 (17beta-HSD2). In a first approach, the study defines physiologically based biokinetic (PBBK) models for 14 individual human subjects, revealing a 1.8-fold interindividual variation in the area under the liver concentration-time curve (AUC) for 1'-hydroxyestragole within this group of human subjects. Variation in oxidation of 1'-hydroxyestragole by 17beta-HSD2 was shown to result in larger effects than those caused by variation in P450 enzyme activity. In a second approach, a Monte Carlo simulation was performed to evaluate the extent of variation in liver levels of 1'-hydroxyestragole that could occur in the population as a whole. This analysis could be used to derive a chemical-specific adjustment factor (CSAF), which is defined as the 99th percentile divided by the 50th percentile of the predicted distribution of the AUC of 1'-hydroxyestragole in the liver. The CSAF was estimated to range between 1.6 and 4.0, depending on the level of variation that was taken into account for oxidation of 1'-hydroxyestragole. Comparison of the CSAF to the default uncertainty factor of 3.16 for human variability in biokinetics reveals that the default uncertainty factor adequately protects 99% of the population.
来源:Hazardous Substances Data Bank (HSDB)