Biocon Bristol-Myers Squibb Research Centre, Bengaluru, Karnataka, India.
Department of Clinical Pharmacology, Seth GS Medical College and KEM Hospital, Mumbai, Maharashtra, India.
Indian J Pharmacol. 2021 May-Jun;53(3):213-220. doi: 10.4103/ijp.IJP_463_18.
Aldehyde oxidase (AO), a molybdoflavoenzyme, is emerging as a key player in drug discovery and metabolism. Despite having several known substrates, there are no validated probes reported for studying the activity of AO in vivo. Vanillin (4-hydroxy 3-methoxy benzaldehyde) is an excellent substrate of AO, in vitro. In the present study, vanillin has been validated as an in vivo probe for AO. Subsequently, a phenotyping study was carried out using vanillin in a subset of Indian population with 100 human volunteers.
For the purposes of in vitro probe validation, initially the metabolism of vanillin was characterized in partially purified guinea pig AO fraction. Further, vanillin was incubated with partially purified xanthine oxidase fraction and AO fractions, and liver microsomes obtained from different species (in presence and absence of specific inhibitors). For the phenotyping study, an oral dose of 500 mg of vanillin was administered to the participants in the study and cumulative urine samples were obtained up to 8 h after giving the dose. The samples were analyzed by high-performance liquid chromatography and metabolic ratios were calculated as peak area ratio of vanillic acid/vanillin.
(a) The results of the in vitro validation studies clearly indicated that vanillin is preferentially metabolized by AO. (b) Normal distribution tests and probit analysis revealed that AO activity was not normally distributed and that 73.72% of the participants were fast metabolizers, 24.28% intermediate metabolizers, and 2% were slow metabolizers.
Data of the phenotyping study suggest the existence of AO polymorphism, in a Western Indian cohort.
醛氧化酶（AO）是一种钼黄素酶，作为药物发现和代谢中的关键因素而崭露头角。尽管有几个已知的底物，但目前还没有经过验证的探针可用于研究 AO 的体内活性。香草醛（4-羟基-3-甲氧基苯甲醛）是 AO 的体外优秀底物。在本研究中，香草醛已被验证为 AO 的体内探针。随后，在印度人群的一个亚组中使用香草醛进行表型研究，共纳入 100 名志愿者。
为了进行体外探针验证，首先在部分纯化的豚鼠 AO 级分中对香草醛的代谢进行了特征描述。此外，香草醛与部分纯化的黄嘌呤氧化酶级分和 AO 级分以及来自不同物种的肝微粒体（在存在和不存在特定抑制剂的情况下）孵育。在表型研究中，给研究参与者口服 500mg 香草醛，并在给药后 8 小时内获得累积尿液样本。通过高效液相色谱法对样品进行分析，并计算香草酸/香草醛峰面积比作为代谢比值。
（a）体外验证研究的结果清楚地表明，香草醛优先由 AO 代谢。（b）正态分布检验和概率分析表明，AO 活性呈非正态分布，73.72%的参与者为快速代谢者，24.28%为中间代谢者，2%为缓慢代谢者。
表型研究的数据表明，在一个印度西部队列中存在 AO 多态性。
