尿苷二磷酸葡萄糖醛酸转移酶的研究进展

目的:介绍尿苷二磷酸葡萄糖醛酸转移酶(UGT)的最近研究进展;方法:查阅了大量相关文献,总结了UGT的功能、诱导、底物及其基因研究等内容;结果:UGT是一种最重要的Ⅱ相代谢酶,对它的研究已经深入到基因水平,且可从分子水平上去解释它的作用机理;结论:人们对UGT有了更深更全面的了解。     

UGT1A1基因多态性与伊立替康所致不良反应的相关性分析

目的：研究本院肿瘤患者UGT1A1基因多态性分布,探讨UGT1A1基因多态性与伊立替康所致不良反应的相关性。方法：回顾性分析2016~2018年就诊于本院并接受伊立替康治疗的肿瘤患者UGT1A1基因多态性分布,分析用药后不良反应发生情况,比较不同基因型之间的差异。结果：共计76例肿瘤患者被纳入分析。76例患者均行UGT1A1*28基因检测（突变比率23.68%）,其中有45例患者同时行UGT1A1*6基因检测（突变比率24.44%）。UGT1A1*28基因突变患者发生Ⅲ~Ⅳ度白细胞减少的风险显著高于野生型（OR=10.79,95% CI：1.24~93.86, P=0.016）。伊立替康化疗引起的其他不良反应,包括血小板减少、中性粒细胞减少、腹泻、肝损伤在本研究中未显示出与UGT1A1基因型的显著相关性（P>0.05）。结论：UGT1A1*28基因多态性与伊立替康引起的严重白细胞减少相关。     

UGT1A4基因多态性对儿童拉莫三嗪药动学影响的研究进展

UGT1A4是尿苷二磷酸葡萄糖醛酸基转移酶(UGT)重要的一种亚型,参与生物体内Ⅱ相生物转化,代谢大量的外源性和内源性物质,研究发现UGT1A4基因多态性是多种药物体外代谢速率存在差异的重要原因之一。拉莫三嗪作为一种新型的抗癫痫药物,已广泛用于癫痫患儿的治疗,它主要通过UGT1A4进行代谢,故UGT1A4基因多态性可能会对其代谢产生影响。本文就UGT1A4基因多态性对儿童拉莫三嗪药物动学影响的研究现状作一综述。     

UGT1A4基因多态性对儿童拉莫三嗪药动学影响的研究进展

UGT1A4是尿苷二磷酸葡萄糖醛酸基转移酶(UGT)重要的一种亚型,参与生物体内Ⅱ相生物转化,代谢大量的外源性和内源性物质,研究发现UGT1A4基因多态性是多种药物体外代谢速率存在差异的重要原因之一。拉莫三嗪作为一种新型的抗癫痫药物,已广泛用于癫痫患儿的治疗,它主要通过UGT1A4进行代谢,故UGT1A4基因多态性可能会对其代谢产生影响。本文就UGT1A4基因多态性对儿童拉莫三嗪药物动学影响的研究现状作一综述。     

人体内的葡醛酸结合反应及其影响因素

目的：为了解葡醛酸结合反应转移酶（UGTs)在体内Ⅱ相代谢中的作用及机体对它的影响因素。方法：从UGTs的结构和作用。UGTs的基因结构和基因多态性。UGTs的组织分布。药物在人体内葡醛酸结合反应的范围。影响UGT活性变化的因素等方面分别进行总结，结果与结论：UGTs催化人体内的葡醛酸结合反应。该酶为一个超基因家族，其中有些具有基因多态性，从而影响酶的活性。UGTs在体内有广泛的分布且具有组织特异性。在药物中，有一部分主要通过葡醛酸结合反应清除。UGTs的活性受到年龄，吸烟，饮食，疾病情况，治疗药物，种族，激素因素等的影响。与CYP450相比，关于UGT活性的变化对机体的影响的研究还十分滞后。UGTs的代谢作用和调节机制及其对治疗的影响这方面的知识还存在很大的空白，由于UGT酶在人类药的代谢方面的重要性，对关键UGT酶的鉴定是十分重要的，需要引起人们日益的重视。     

葡萄糖醛酸转移酶UGT2B7-A268G基因多态性对癫痫儿童丙戊酸血药浓度的影响

目的：在丙戊酸（VPA）单药治疗的癫痫儿童中评估葡萄糖醛酸转移酶UGT2B7-A268G位点的遗传基因多态性对VPA血清浓度的影响。方法：本研究纳入200例癫痫患儿的丙戊酸血药浓度,测定VPA稳态血清浓度。对UGT2B7编码区的A268G采用聚合酶链反应（RPLF）扩增进行基因鉴定分型。根据UGT2B7基因多态性分析VPA血清药物浓度与基因多态性的关系。结果：携带变异UGT2B7-268G一个基因型或纯合基因患儿的VPA血清药物浓度显著高于携带AA基因的患儿。由于儿童个体差异较大,根据年龄、体质量调整VPA浓度后与基因多态性仍然显著关联（P<0.05）。UGT2B7-A268G的基因多态性与Hardy-Weinberg平衡一致（P>0.05）,其中UGT2B7-268A>G等位基因频率分布的是30.00%,而G突变的基因分布频率为70.00%。结论：癫痫患儿UGT2B7基因的A268G突变可能改变丙戊酸的药物代谢动力学过程,并且不受年龄、体质量等因素干扰。UGT2B7的基因多态性对儿童丙戊酸血药浓度产生影响,测定其基因型对于获得适当的丙戊酸稳态浓度和设定起始用药剂量有积极意义     

UGT1A1基因多态性对药物代谢和临床作用影响的进展

UGT1A1基因是参与人体代谢循环的重要基因,随着药物基因组学的发展,发现其基因多态性与某些药物代谢水平相关,进而影响疾病的发生、发展及治疗等诸多方面。随着研究进展,UGT1A1的底物在不断扩展,包括胆红素、雌激素、伊立替康及其他一些药物已有研究。研究UGT1A1基因多态性对药物代谢情况的影响,在临床疾病的诊治、预后判断及药物不良反应等方面有重要的指导意义。     

人葡糖醛酸基转移酶介导的黄酮Ⅱ相代谢研究进展

人葡糖醛酸基转移酶(UGT)同工酶在黄酮类化合物Ⅱ相代谢反应中呈重要的作用。本综述总结了近年来国内外学者对黄酮类化合物Ⅱ相代谢中UGT的研究情况,包括各同工酶间的底物差异,结构-代谢活性关系,基因多态性的影响以及黄酮对UGT调控的研究。结果表明,人UGT1A1,1A3,1A8,1A9,1A10和2B15主要参与了广泛黄酮类化合物的葡醛酸结合反应,而UGT1A5,1A7和2B7对黄酮代谢的作用有待于进一步研究证明,UGT的基因多态性、结构-代谢关系、调控机制为生物黄酮的合理利用以及此类化合物的合理药物设计提供了重要的参考依据。     

UGT2B17拷贝数变异的研究进展

尿苷二磷酸葡萄糖醛酸基转移酶（UDP-g1ucuronosyltransferase,UGT）是人体内重要的Ⅱ相代谢酶,UDP-尿苷二磷酸葡萄糖醛酸为其主要的糖基供体。UGT为多基因编码并且含有大量同工酶的超基因家族,包括UGT1和UGT2两个亚家族。UGT2B17是UGT2B家族的一员,越来越多的研究发现UGT2B17基因存在普遍遗传缺失现象,其造成的遗传差异对疾病的影响已引起了众多关注。UGT2B17基因拷贝数变异（Copy Number Variants,CNV）源自4号染色体上一段约120 kb的DNA序列缺失和插入,CNV发生频率高,种族差异明显,与器官移植、骨质疏松、肿瘤发生,乃至兴奋剂检测密切相关。UGT2B17的CNV研究及功能意义具有重大遗传药理学及药物基因组学意义。我们将从UGT2B17的基因拷贝数变异与种族差异、移植排斥反应与肿瘤发生发展等几个方面进行探讨。     

UGT酶的遗传药理学研究进展

尿苷二磷酸葡萄糖醛酸基转移酶(UDP-glucuronosyltransferase,UGT),是人体内重要的催化II相结合反应的酶。UGT广泛分布于人体的肝、肾、胃肠道以及各种腺体组织,因其结构和细胞内分布的特殊性,对其研究落后于CYP450酶。近20年来随着实验技术的发展,越来越多的研究开始关注UGT。随着研究进展,UGT的底物在不断地扩展,包括有内源性激素、药物以及毒物。个体间、种族间葡萄糖醛酸化活性存在明显差异,UGT基因多态性是此现象的重要原因之一。对UGT基因多态性的研究日益增多,已经成立命名委员会。UGT按照序列相似性分两个大的亚家族,本文分别对其中主要参与药物代谢的UGT1A和UGT2家族的某些成员的遗传药理学研究进展进行综述。     

Raloxifene glucuronidation in liver and intestinal microsomes of humans and monkeys: contribution of UGT1A1, UGT1A8 and UGT1A9

1.?Raloxifene is an antiestrogen that has been marketed for the treatment of osteoporosis, and is metabolized into 6- and 4′-glucuronides by UDP-glucuronosyltransferase (UGT) enzymes. In this study, the in vitro glucuronidation of raloxifene in humans and monkeys was examined using liver and intestinal microsomes and recombinant UGT enzymes (UGT1A1, UGT1A8 and UGT1A9).

2.?Although the K_m and CL_int values for the 6-glucuronidation of liver and intestinal microsomes were similar between humans and monkeys, and species differences in V_max values (liver microsomes, humans?>?monkeys; intestinal microsomes, humans?<?monkeys) were observed, no significant differences were noted in the K_m or S₅₀, V_max and CL_int or CL_max values for the 4′-glucuronidation of liver and intestinal microsomes between humans and monkeys.

3.?The activities of 6-glucuronidation in recombinant UGT enzymes were UGT1A1?>?UGT1A8?>UGT1A9 for humans, and UGT1A8?>?UGT1A1?>?UGT1A9 for monkeys. The activities of 4′-glucuronidation were UGT1A8?>?UGT1A1?>?UGT1A9 in humans and monkeys.

4.?These results demonstrated that the profiles for the hepatic and intestinal glucuronidation of raloxifene by microsomes were moderately different between humans and monkeys.     

In vitro inhibition of UGT1A3, UGT1A4 by ursolic acid and oleanolic acid and drug–drug interaction risk prediction

1.?Ursolic acid (UA) and oleanolic acid (OA) may have important activity relevant to health and disease prevention. Thus, we studied the activity of UA and OA on UDP-glucuronosyltransferases (UGTs) and used trifluoperazine as a probe substrate to test UGT1A4 activity. Recombinant UGT-catalyzed 4-methylumbelliferone (4-MU) glucuronidation was used as a probe reaction for other UGT isoforms.

2.?UA and OA inhibited UGT1A3 and UGT1A4 activity but did not inhibit other tested UGT isoforms.

3.?UA-mediated inhibition of UGT1A3 catalyzed 4-MU-β-d-glucuronidation was via competitive inhibition (IC₅₀ 0.391?±?0.013?μM; K_i 0.185?±?0.015?μM). UA also competitively inhibited UGT1A4-mediated trifluoperazine-N-glucuronidation (IC₅₀ 2.651?±?0.201?μM; K_i 1.334?±?0.146?μM).

4.?OA offered mixed inhibition of UGT1A3-mediated 4-MU-β-d-glucuronidation (IC₅₀ 0.336?±?0.013?μM; K_i 0.176?±?0.007?μM) and competitively inhibited UGT1A4-mediated trifluoperazine-N-glucuronidation (IC₅₀ 5.468?±?0.697?μM; K_i 6.298?±?0.891?μM).

5.?Co-administering OA or UA with drugs or products that are substrates of UGT1A3 or UGT1A4 may produce drug-mediated side effects.     

Metabolism of kurarinone by human liver microsomes and its effect on cytotoxicity

Context: Kurarinone, the most abundant prenylated flavonoid in Sophora flavescens Aiton (Leguminosae), is a promising antitumor therapeutic. However, it shows significant hepatotoxicity. Furthermore, how kurarinone is metabolized in humans remains unclear.

Objective: The objective of this study is to investigate kurarinone metabolism in human liver microsomes (HLMs) and the role of metabolism in kurarinone-induced cytotoxicity.

Materials and methods: The UDP-glucuronosyltransferase isoforms (UGTs) involved in kurarinone glucuronidation were identified using chemical inhibitors (100–1000?µM phenylbutazone; 10–100?µM β-estradiol; 10–100?µM 1-naphthol; 10–500?µM propofol; and 100–1000?µM fluconazole) and recombinant human UGTs. Kurarinone (2–500?µM) was incubated with HLMs and UGTs (0.5?mg/mL) for 15?min to determine enzyme kinetic parameters. The IC₅₀ value of kurarinone (10–200?µM) was evaluated in a HLMs/3T3 cell co-culture system.

Results: Kurarinone is extensively converted to two glucuronides (M3 and M4) in HLMs. M3 formation was catalyzed by multiple UGT1As, with UGT1A3 showing the highest intrinsic clearance (120.60?mL/min/mg). M4 formation was catalyzed by UGT1A1, UGT2B4, and UGT2B7. UGT1A1 showed the highest intrinsic clearance (60.61?mL/min/mg). The kinetic profiles of the five main UGTs and HLMs fit substrate inhibition kinetics, with K_m values ranging from 5.20 to 46.52?µM, V_max values ranging from 0.20 to 3.06?µmol/min/mg, and K_si values ranging from 25.58 to 230.30?µM. The kurarinone IC₅₀ value was 93?μM in the control group, 102?μM in HLMs with NADPH, and 160?μM in HLMs with UDPGA.

Discussion and conclusion: Kurarinone glucuronidation is a detoxification pathway. This information may help to elucidate the risk factors regulating kurarinone toxicity.     

Influence of UDP-glucuronosyltransferase polymorphisms on valproic acid pharmacokinetics in Chinese epilepsy patients

Purpose

The aim of this study was to investigate the genetic polymorphisms of UGT1A3, UGT1A6, and UGT2B7 in Chinese epilepsy patients and their potential influence on the pharmacokinetics of valproic acid (VPA).

Methods

The genetic architectures of UGT1A3, UGT1A6, and UGT2B7 in 242 epilepsy patients were detected by DNA sequencing and PCR-restriction fragment length polymorphism. Steady-state plasma concentrations of VPA in 225 patients who had received VPA (approx. 250–1,000?mg/day) for at least 2 weeks were determined and associated with UGT polymorphisms.

Results

The allelic distribution of UGT1A3 in our Chinese epilepsy patients was significantly different from that in healthy subjects based on reference data. The standardized trough plasma concentration (C_S) of VPA was much lower in our patients with the UGT1A3*5 variant than in the wild type carriers (3.24?±?1.05 vs. 4.68?±?1.24?μg·kg·mL^-1·mg^-1, P?Conclusion Our results suggest that UGT1A3*5 may be an important determinant of individual variability in the pharmacokinetics of VPA and that it may be necessary to increase VPA dose for UGT1A3*5 carriers to ensure its therapeutic range of 50–100?μg/mL.     

Bisphenol-A glucuronidation in human liver and breast: identification of UDP-glucuronosyltransferases (UGTs) and influence of genetic polymorphisms

1.?Bisphenol-A is a ubiquitous environmental contaminant that is primarily metabolized by glucuronidation and associated with various human diseases including breast cancer. Here we identified UDP-glucuronosyltransferases (UGTs) and genetic polymorphisms responsible for interindividual variability in bisphenol-A glucuronidation in human liver and breast.

2.?Hepatic UGTs showing the highest bisphenol-A glucuronidation activity included UGT2B15 and UGT1A9. Relative activity factor normalization indicated that UGT2B15 contributes?>80% of activity at bisphenol-A concentrations under 5?μM, while UGT1A9 contributes up to 50% of activity at higher concentrations.

3.?Bisphenol-A glucuronidation by liver microsomes (46 donors) ranged from 0.25 to 4.3 nmoles/min/mg protein. Two-fold higher glucuronidation (p?=?0.018) was observed in UGT1A9 *22/*22 livers compared with *1/*1 and *1/*22 livers. However, no associations were observed for UGT2B15*2 or UGT1A1*28 genotypes.

4.?Bisphenol-A glucuronidation by breast microsomes (15 donors) ranged from <0.2 to 56 fmoles/min/mg protein. Breast mRNA expression of UGTs capable of glucuronidating bisphenol-A was highest for UGT1A1, followed by UGT2B4, UGT1A9, UGT1A10, UGT2B7 and UGT2B15. Bisphenol-A glucuronidation was over 10-fold lower in breast tissues with the UGT1A1*28 allele compared with tissues without this allele (p?=?0.006).

5.?UGT2B15 and UGT1A9 contribute to glucuronidation variability in liver, while UGT1A1 is important in breast.     

Correlation of the UGT1A4 gene polymorphism with serum concentration and therapeutic efficacy of lamotrigine in Han Chinese of Northern China

Objective

The pharmacokinetics of lamotrigine (LTG) varies significantly among individuals and particularly among different ethnic groups. This is in part due to the presence of genetic polymorphisms affecting genes that metabolize LTG. UGT1A4 is a major metabolizing enzyme of LTG. The aim of this study was to investigate the effect of two UGT1A4 gene polymorphisms, UGT1A4 (70C?>?A) and UGT1A4 (142 T?>?G), on the levels and efficacy of LTG in Han Chinese patients with epilepsy.

Methods

The study cohort comprised 106 Han Chinese patients patients with epilepsy who were receiving LTG monotherapy. Blood samples were taken and LTG levels measured. The presence of UGT1A4 (70C?>?A) and UGT1A4 (142 T?>?G) was determined. The therapeutic efficacy of LTG at the 1-year time-point was assessed.

Results

All patients were homozygous for the CC genotype of UGT1A4 (70C?>?A), while the distribution of UGT1A4 (142 T?>?G) varied among patients. Two patients had a single nucleotide deletion at position 127 (UGT1A4 127delA). To evaluate the effect of the UGT1A4 (142 T?>?G) polymorphism on LTG pharmacokinetics, patients were divided into two groups. Group A included patients with the 142TG or 142GG polymorphism and Group B patients had the 142TT polymorphism. The normalized blood concentration and the efficacy of LTG were higher in Group B patients than in Group A patients (P?<?0.05). The two patients with UGT1A4 127delA genotype had extremely high blood levels of LTG, and treatment was discontinued in one of these patients due to a severe LTG-associated rash.

Conclusion

Patients with the UGT1A4 142TT polymorphism had a higher blood LTG concentration and better therapeutic efficacy, suggesting that this polymorphism influences LTG activity. The UGT1A4 127delA polymorphism significantly affected LTG levels and increased one of our patient's susceptibility to LTG-related adverse events.     

Human UDP-glucuronosyltransferase isoforms involved in haloperidol glucuronidation and quantitative estimation of their contribution

A major metabolic pathway of haloperidol is glucuronidation catalyzed by UDP-glucuronosyltransferase (UGT). In this study, we found that two glucuronides were formed by the incubation of haloperidol with human liver microsomes (HLM) and presumed that the major and minor metabolites (>10-fold difference) were O- and N-glucuronide, respectively. The haloperidol N-glucuronidation was catalyzed solely by UGT1A4, whereas the haloperidol O-glucuronidation was catalyzed by UGT1A4, UGT1A9, and UGT2B7. The kinetics of the haloperidol O-glucuronidation in HLM was monophasic with K(m) and V(max) values of 85 μM and 3.2 nmol · min?1 · mg?1, respectively. From the kinetic parameters of the recombinant UGT1A4 (K(m) = 64 μM, V(max) = 0.6 nmol · min?1 · mg?1), UGT1A9 (K(m) = 174 μM, V(max) = 2.3 nmol · min?1 · mg?1), and UGT2B7 (K(m) = 45 μM, V(max) = 1.0 nmol · min?1 · mg?1), we could not estimate which isoform largely contributes to the reaction. Because the haloperidol O-glucuronidation in a panel of 17 HLM was significantly correlated (r = 0.732, p < 0.01) with zidovudine O-glucuronidation, a probe activity of UGT2B7, and the activity in the pooled HLM was prominently inhibited (58% of control) by gemfibrozil, an inhibitor of UGT2B7, we surmised that the reaction would mainly be catalyzed by UGT2B7. We could successfully estimate, using the concept of the relative activity factor, that the contributions of UGT1A4, UGT1A9, and UGT2B7 in HLM were approximately 10, 20, and 70%, respectively. The present study provides new insight into haloperidol glucuronidation, concerning the causes of interindividual differences in the efficacy and adverse reactions or drug-drug interactions.     

Inhibitory effect of anthocyanidins on hepatic glutathione S-transferase,UDP-glucuronosyltransferase and carbonyl reductase activities in rat and human

Abstract

1. Anthocyanins and their aglycone anthocyanidins represent the most abundant flavonoids in human diet and popular constituents of various dietary supplements. The aim of this study was to evaluate inhibitory effect of four anthocyanidins (delphinidin, cyanidin, malvidin and pelargonidin) on three families of important drug-metabolizing enzymes: carbonyl reductases (CBRs), glutathione S-transferases (GSTs) and UDP-glucuronosyltransferases (UGT).

2. Human or rat hepatic subcellular fractions were incubated with or without pure anthocyanidins (100?µM) and the activities of CBR, GST and UGT were assayed using menadione, 1-chloro-2,4-dinitrobenzene and p-nitrophenol as substrates, respectively. For the most potent inhibitors, half maximal inhibitory concentrations (IC₅₀) were determined and the inhibition kinetics study was performed.

3. Anthocyanidins inhibited weakly the activity of GST and moderately the activities of CBR and UGT. Cyanidin was the most potent inhibitor of human UGT with IC₅₀?=?69?µM (at 200?µM substrate concentration) and competitive type of action. Delphinidin acted as significant non-competitive inhibitor of human CBR with IC₅₀?=?16?µM (at substrate concentration 500?µM). The inhibitory potency of anthocyanidins differed in rat and human samples significantly.

4. Anthocyanidins are able to inhibit CBR and UGT in vitro. Possible interference of anthocyanidins (in high-dose dietary supplements) with simultaneously administered drugs, which are UGT or CBR substrates, should be checked.     

Human liver UDP-glucuronosyltransferase isoforms involved in the glucuronidation of 7-ethyl-10-hydroxycamptothecin

1. The human liver UDP-glucuronosyltransferase (UGT) isoforms involved in the glucuronidation of 7-ethyl-10-hydroxycamptothecin (SN-38), the active metabolite of irinotecan (CPT-11), have been studied using microsomes from human liver and insect cells expressing human UGTs (1A1, 1A3, 1A4, 1A6, 1A9, 2B7, 2B15). 2. The glucuronidation of SN-38 was catalysed by UGT1A1, UGT1A3, UGT1A6 and UGT1A9 as well as by liver microsomes. Among these UGT isoforms, UGT1A1 showed the highest activity of SN-38 glucuronidation at both low (1 µM) and high (200 µM) substrate concentrations. The ranking in order of activity at low and high substrate concentrations was UGT1A1 > UGT1A9 > UGT1A6> UGT1A3 and UGT1A1 > UGT1A3 > UGT1A6 ≥ UGT1A9, respectively. 3. The enzyme kinetics of SN-38 glucuronidation were examined by means of Lineweaver-Burk analysis. The activity of the glucuronidation in liver microsomes exhibits a monophasic kinetic pattern, with an apparent K m and V max of 35.9 µM and 134pmol?min -1?mg -1 protein, respectively. The UGT isoforms involved in SN-38 glucuronidation could be classified into two types: low- K m types such as UGT1A1 and UGT1A9, and high- K m types such as UGT1A3 and UGT1A6, in terms of affinity toward substrate. UGT1A1 had the highest V max followed by UGT1A3. V max of UGT1A6 and UGT1A9 were approximately 1/9 to 1/12 of that of UGT1A1. 4. The activity of SN-38 glucuronidation by liver microsomes and UGT1A1 was effectively inhibited by bilirubin. Planar and bulky phenols substantially inhibited the SN-38 glucuronidation activity of liver microsomes and UGT1A9, and/or UGT1A6. Although cholic acid derivatives strongly inhibited the activity of SN-38 glucuronidation by UGT1A3, the inhibition profile did not parallel that in liver microsomes. 5. These results demonstrate that at least four UGT1A isoforms are responsible for SN-38 glucuronidation in human livers, and suggest that the role and contribution of each differ substantially.