Association between polyphenol metabolism and polymorphisms in intestinal drug metabolising enzymes and its relation to health benefits

多酚代谢与肠道药物代谢酶多态性的关联及其与健康益处的关系

• 批准号: BB/H016414/1
• 金额: $ 9.59万
• 依托单位: Newcastle University
• 依托单位国家: 英国
• 项目类别: Training Grant
• 财政年份: 2011
• 资助国家: 英国
• 起止时间: 2011 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FH016414%2F1
• 关键词: Association; between; polyphenol; metabolism; polymorphisms

Epidemiological studies suggest that regular consumption of black and green tea is associated with a reduction in risk of a range of pathological conditions including cardiovascular diseases and selected cancers. In vitro studies suggest that the effects seen in epidemiological studies are partially caused by catechins and polymers thereof present in tea. However, limitations in these studies are that they mostly do not take into account the very low bioavailability of polyphenols with peak plasma concentration in the sub-micromolar range. To date it is still unclear which molecular forms of polyphenols could mediate these effects, and what the potential mechanisms of action are. The poor bioavailability of polyphenols is caused inter alia by extensive biotransformation by xenobiotic metabolising enzymes. Metabolism of catechins by intestinal phase II metabolising enzymes such as catechol-O-methyl-transferase (COMT) and UDP-glucuronosyltransferases (UGT's) has been shown. In addition, in vitro data suggest that selected polyphenols can induce activity of a number of phase I metabolising enzymes such as cytochroms CYP450 1A1. In turn, activation of phase I and phase II enzymes could change bioavailability of other polyphenolic compounds. Furthermore, polymorphism in those enzymes has been suggested to influence metabolic rate and absolute bioavailability of polyphenols. Overall, there is a lack of understanding how and to which extent polyphenols are biotransformed during absorption and how this process is related to their potential health beneficial effects. The overall aim of the proposed project is therefore to discover the effects of green and black tea polyphenols on phase I, II and III enzymes using both tissue culture and a human intervention study. The goal of the project is to elucidate which different polyphenol metabolites are produced and how genetic variation might explain some of the observed between-subject differences seen in human studies. Finally, the project aims at identifying whether polyphenol metabolites are able to reduce mitochondrial DNA damage. The main objectives are to identify metabolic profiles of tea polyphenols in tissue cultures, phase I, II and III enzymes involved, and genetic differences in phase I, II and III metabolism. An important early milestone will be the identification of major tea polyphenol metabolites using appropriate in vitro models for intestinal and liver metabolism. To achieve this we will make use of established models such as intestinal microsomes, HepG2 cells and liver slices. Metabolic profiles will be determined using state-of-the-art HPLC-MS/MS methods. Results from metabolic profiling will be used to identify the major xenobiotic metabolising enzymes involved. In addition, it is planned to determine gene and protein expression of key phase I, II and III enzymes involved in metabolism of tea polyphenols in tissue cultures and buccal mucosal cells. Quantitative PCR as well as microarray analysis will highlight metabolic pathways as well as key phase I, II and III enzymes differentially regulated after tea administration. The subsequent step will be identification of common single nucleotide polymorphisms in key phase I, II and III enzymes in human buccal mucosal cells. The scientific challenge will be to link those polymorphism with a frequency >5% to metabolic profiles in humans. A human intervention study will be performed to address these questions. This project will be a major milestone in unravelling the potential health beneficial effects of tea polyphenol by shedding more light on which metabolites are produced by phase I, II and III enzymes, at which concentrations they circulate in plasma and to what extent the large observed between-subject variation in humans is linked to genetic variations in xenobiotic metabolising enzymes.

流行病学研究表明，经常饮用红茶和绿茶可以降低患一系列病理疾病的风险，包括心血管疾病和某些癌症。体外研究表明，流行病学研究中看到的影响部分是由茶中的儿茶素及其聚合物引起的。然而，这些研究的局限性在于，它们大多没有考虑到多酚的生物利用度非常低，血浆浓度峰值在亚微摩尔范围内。迄今为止，尚不清楚多酚的哪种分子形式可以介导这些作用，以及潜在的作用机制是什么。多酚的生物利用度差是由外源代谢酶广泛的生物转化引起的。肠道II期代谢酶如儿茶素- o -甲基转移酶（COMT）和udp -葡萄糖醛酸转移酶（UGT）对儿茶素的代谢作用已被证实。此外，体外数据表明，选定的多酚可以诱导一些I期代谢酶的活性，如细胞色素CYP450 1A1。反过来，I相和II相酶的激活可以改变其他多酚化合物的生物利用度。此外，这些酶的多态性被认为会影响多酚的代谢率和绝对生物利用度。总的来说，人们对多酚在吸收过程中如何以及在多大程度上进行生物转化以及这一过程与它们潜在的有益健康效果之间的关系缺乏了解。因此，拟议项目的总体目标是通过组织培养和人为干预研究来发现绿茶和红茶多酚对I， II和III期酶的影响。该项目的目标是阐明产生了哪些不同的多酚代谢物，以及遗传变异如何解释在人类研究中观察到的一些受试者之间的差异。最后，该项目旨在确定多酚代谢物是否能够减少线粒体DNA损伤。主要目的是确定茶多酚在组织培养中的代谢谱，所涉及的I， II和III期酶，以及I， II和III期代谢的遗传差异。一个重要的早期里程碑将是使用适当的肠道和肝脏代谢体外模型确定主要的茶多酚代谢物。为了实现这一目标，我们将利用已建立的模型，如肠微粒体、HepG2细胞和肝脏切片。代谢谱将使用最先进的HPLC-MS/MS方法确定。代谢谱分析的结果将用于鉴定所涉及的主要异种代谢酶。此外，计划在组织培养和口腔粘膜细胞中检测茶多酚代谢的关键I、II、III期酶的基因和蛋白表达。定量PCR和微阵列分析将突出代谢途径以及关键的ⅰ、ⅱ和ⅲ期酶在给茶后的差异调节。接下来的步骤将是鉴定人类口腔粘膜细胞中关键I、II和III期酶的常见单核苷酸多态性。科学上的挑战将是把这些频率为0.5%的多态性与人类的代谢谱联系起来。将进行一项人为干预研究来解决这些问题。这个项目将是揭示茶多酚潜在的健康益处的一个重要里程碑，它揭示了由I期、II期和III期酶产生的代谢物，它们在血浆中循环的浓度，以及在多大程度上观察到的人类受试者之间的巨大差异与异种代谢酶的遗传变异有关。