Despite the increasing importance of aldehyde oxidase (AO) in the drug metabolism of clinical candidates, ontogeny data for AO are limited. The objective of our study was to characterize the age-dependent AO content and activity in the human liver cytosolic fraction (HLC) and human hepatocytes (HH). HLC (n = 121 donors) and HH (n = 50 donors) were analyzed for (1) AO protein content by quantitative proteomics and (2) enzyme activity using carbazeran as a probe substrate. AO activity showed high technical variability and poor correlation with the content in HLC samples, whereas hepatocyte samples showed a strong correlation between the content and activity. Similarly, AO content and activity showed no significant age-dependent differences in HLC samples, whereas the average AO content and activity in hepatocytes increased significantly (∼20–40-fold) from the neonatal levels (0–28 days). Based on the hepatocyte data, the age at which 50% of the adult AO content is reached (age₅₀) was 3.15 years (0.32–13.97 years, 95% CI). Metabolite profiling of carbazeran revealed age-dependent metabolic switching and the role of non-AO mechanisms (glucuronidation and desmethylation) in carbazeran elimination. The content–activity correlation in hepatocytes improved significantly (R² = 0.95; p < 0.0001) in samples showing <10% contribution of glucuronidation toward the overall metabolism, confirming that AO-mediated oxidation and glucuronidation are the key routes of carbazeran metabolism. Considering the confounding effect of glucuronidation on AO activity, AO content-based ontogeny data are a more direct reflection of developmental changes in protein expression. The comprehensive ontogeny data of AO in HH samples are more reliable than HLC data, which are important for developing robust physiologically based pharmacokinetic models for predicting AO-mediated metabolism in children.

中文翻译：

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人肝醛氧化酶的个体发育：发育变化及其对药物代谢的影响

尽管醛氧化酶 (AO) 在临床候选药物代谢中的重要性日益增加，但 AO 的个体发育数据仍然有限。我们研究的目的是表征人肝胞质部分 (HLC) 和人肝细胞 (HH) 中年龄依赖性 AO 含量和活性。通过定量蛋白质组学分析HLC（n = 121 名供体）和 HH（n = 50 名供体）的 AO 蛋白质含量和 (2) 使用卡巴泽兰作为探针底物的酶活性。 AO 活性显示出较高的技术变异性，并且与 HLC 样品中的含量相关性较差，而肝细胞样品中的含量和活性之间显示出很强的相关性。同样，HLC 样本中的 AO 含量和活性没有显示出显着的年龄依赖性差异，而肝细胞中的平均 AO 含量和活性较新生儿水平（0-28 天）显着增加（~20-40 倍）。根据肝细胞数据，达到成人AO含量50%的年龄（₅₀岁）为3.15岁（0.32-13.97岁，95% CI）。卡巴嗪的代谢分析揭示了年龄依赖性代谢转换以及非 AO 机制（葡萄糖醛酸化和去甲基化）在卡巴嗪消除中的作用。在显示葡萄糖醛酸化对整体代谢的贡献<10%的样品中，肝细胞中的含量-活性相关性显着改善（R ² = 0.95；p < 0.0001），证实AO介导的氧化和葡萄糖醛酸化是卡巴嗪代谢的关键途径。考虑到葡萄糖醛酸化对AO活性的混杂影响，基于AO含量的个体发育数据更直接地反映了蛋白质表达的发育变化。 HH 样本中 AO 的综合个体发育数据比 HLC 数据更可靠，这对于开发稳健的基于生理的药代动力学模型来预测 AO 介导的儿童代谢非常重要。