孤儿核受体对尿苷二磷酸葡萄糖醛酸转移酶基因转录调节的研究进展

尿苷二磷酸葡萄糖醛酸转移酶（UDP-glucuro-nosyltransferase,UGT）属于Ⅱ相药物代谢酶。它能催化葡醛酸与其相应底物结合,是化学物质在生物体内进行Ⅱ相生物转化时最重要的一类酶。越来越多的研究发现,孕烷X受体（pregnaneXreceptor,PXR）、组成型雄甾烷受体（constitutiveandrostanere-ceptor,CAR）等孤儿核受体（orphannuclearreceptors）及其他转录因子能调节UGT基因的转录,这些受体及因子分布和活性的差异可导致UGT酶表达和分布的差异。此外,研究表明化合物通过核受体（NR）介导的UGT酶表达量的变化可能是影响化合物体内代谢的一条重要途径。由于UGT酶表达量与激素平衡、药物疗效、药物毒副作用及肿瘤等多种疾病发病预后密切相关,所以研究核受体对Ⅱ相代谢酶的调节作用在预测药物相互作用、指导临床合理用药及人类疾病的预防等方面都具有重要意义。     

人尿苷二磷酸葡萄糖醛酸转移酶基因多态性与相关疾病易感性

尿苷二磷酸葡萄糖醛酸转移酶(UGT)是体内重要的药物代谢Ⅱ相酶,具有明显的基因多态性。评价基因多态性对疾病易感性影响的重要性,建立基因多态性数据库并进行致病基因-疾病易感性的种群研究具有深远意义。本文拟就人UGT基因多态性及相关疾病易感性进行简述。     

过氧化物酶体增殖物激活受体α在对乙酰氨基酚肝损伤的研究进展

对乙酰氨基酚(Acetaminophen,APAP)药物过量是我国及欧美国家急性肝衰竭的常见原因之一。正常剂量的APAP约90%以上经过肝内Ⅱ相代谢酶UDP-葡萄糖醛酸转移酶(UGT)和磺基转移酶(SULT)转化为无毒的葡萄糖醛酸盐或硫酸盐从肾脏和胆汁排泄,10%以下通过肝内I相代谢酶细胞色素P450酶转化为活性代谢产物N-乙酰基-对-苯醌亚胺(NAPQI),NAPQI随后在谷胱甘肽-S-转移酶(GST)的作用下转化为无毒的化合物。当APAP过量时,NAPQI蓄积,继而引起肝损伤。代谢性核受体过氧化物酶体增殖物激活受体α (Peroxisome proliferator activated receptor ,PPARα),作为核受体超家族成员之一,参与肝脏脂质代谢及多种生物转化过程,多个研究表明PPARα激动剂可保护APAP引起的肝损伤,该文将对PPARα在APAP引起的肝损伤中的作用及机制进行综述,以期为APAP诱导的肝损伤提供潜在的治疗靶点。     

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。     

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。     

尿苷二磷酸葡萄糖醛酸转移酶介导的药物相互作用的研究进展

葡萄糖醛酸结合反应是生物体内重要的Ⅱ相代谢途径,由尿苷二磷酸葡萄糖醛酸转移酶(UGT)催化完成,是多种内源性物质和外源性化合物清除与解毒的机制。在新药研发过程中,研究UGT介导的药物代谢以及评估潜在的药物相互作用是非常重要的,吸引了很多研究人员的关注。但目前的研究偏重于由细胞色素P450酶(CYP450)介导的药物相互作用,对UGT的关注相对较少。鉴于UGT在药物代谢中的重要性,有必要对其导致的药物相互作用进行更深入的研究。本文综述了由UGT的抑制引起的药物相互作用的相关研究进展。     

尿苷二磷酸葡醛酸转移酶介导的胆汁酸代谢过程及其内源和外源影响因素研究进展

尿苷二磷酸葡萄糖醛酸转移酶(UDP-glucuronosyltransferases, UGTs)作为人体中一种非常重要的II相代谢酶,不仅参与外源性化合物代谢清除,也在胆汁酸等内源性物质的代谢调控中扮演重要角色。解析尿苷二磷酸葡萄糖醛酸转移酶介导的胆汁酸代谢过程及其内源和外源影响因素有助于增强对相关疾病的治疗和预防。尿苷二磷酸葡萄糖醛酸转移酶对胆汁酸代谢调控作用受到多种内源性和外源性因素影响。本文将重点探讨核受体、遗传因素、外源化合物及肝脏相关疾病等因素对UGT酶作用的影响,讨论体内潜在的胆汁酸动态平衡干预机制。     

尿苷二磷酸葡萄糖醛酸转移酶的转录调节与疾病相关性的研究进展

葡萄糖醛酸结合反应是体内重要的Ⅱ相代谢途径,主要由尿苷二磷酸葡萄糖醛酸转移酶（ UGT ）催化。尿苷二磷酸葡萄糖醛酸转移酶能参与多种内源性物质如胆红素、胆汁酸、甲状腺激素等的代谢,也能参与多种药物如阿片类镇痛药、非甾体抗炎药等药物的代谢,在代谢解毒方面起着重要作用。近年来对尿苷二磷酸葡萄糖醛酸转移酶的研究越来越深入,尿苷二磷酸葡萄糖醛酸转移酶与不同疾病的研究受到普遍关注。本文就转录因子介导的尿苷二磷酸葡萄糖醛酸转移酶的分子调节机制及其与不同疾病的相关性研究进行综述。     

小分子药物Ⅱ相代谢缀合物水解方法及促进酶解反应方法的研究进展

目的:为小分子药物Ⅱ相代谢过程研究及相关分析提供参考。方法:查阅近几年相关研究文献,归纳小分子药物Ⅱ相代谢常见结合反应的类型并总结其代谢缀合物水解方法及促进酶解反应方法的研究进展。结果与结论:Ⅱ相代谢是Ⅰ相代谢物在体内的结合反应,包括糖苷结合、硫酸化、甲基化、乙酰化、氨基酸结合、谷胱甘肽结合、脂肪酸结合、缩合反应等。其中,最常见的小分子药物Ⅱ相代谢反应是与葡萄糖醛酸结合或与硫酸结合,生成葡萄糖醛酸苷缀合物或硫酸酯缀合物。小分子药物Ⅱ相代谢缀合物常见的水解方法包括酸水解、碱水解和酶水解。其中,酶水解以其安全、温和、不会引起目标物分解、重复性好、药物回收率高等优点,成为目前使用最广泛的水解方法。促进酶解反应的方法目前主要有红外辐射法和超声波法,两种方法都对不同的酶系反应有促进作用。     

尿苷二磷酸葡萄糖醛酸转移酶基因多态性对药物代谢影响的研究进展

由尿苷二磷酸葡萄糖醛酸转移酶(UDP-glucuronosyltransferase,UGT)催化完成的葡萄糖醛酸结合反应是生物体内重要的Ⅱ相代谢途径,它与毒性或活性物质结合形成葡萄糖醛酸苷,将内源性、外源性化合物通过胆汁或肾脏排出体外。UGT是一个超家族酶,因主要利用UDP-尿苷二磷酸葡糖醛酸为糖基供体而得名。人类UCT广泛分布于体内的各种组织,包括肾、脑、皮肤、肠、脾、胸腺、心脏等,其中以     

Characterization of UDP-glucuronosyltransferases (UGTS) involved in the metabolism of troglitazone in rats and humans

UDP-glucuronosyltransferases (UGTs) involved in troglitazone glucuronidation in rats and humans have been characterized to support the previous toxicity study on troglitazone in Gunn rats and to examine whether the UGT polymorphism or inhibition of bilirubin metabolism is related to the clinically reported rare cases of liver failure. The experiments using Gunn rats revealed that UGT1 enzymes are not involved in troglitazone glucuronidation and that the responsible enzyme in rats was suggested to be UGT2B2, an androsterone UGT, by inhibition studies. In humans, contribution of UGT1A1 was estimated to be about 30% of the total troglitazone glucuronidation by UGTs, using human liver microsomes and recombinant UGTs. Other UGT1 and UGT2 enzymes seem to be responsible for the rest of the troglitazone glucuronidation in humans. The multiplicity of UGTs involved in troglitazone glucuronidation in humans may allow even patients lacking bilirubin UGT (UGT1A1) activity to produce troglitazone glucuronide. These observations suggest that the polymorphism of UGT is not the reason behind the liver failure induced by the troglitazone treatment, and troglitazone does not inhibit bilirubin glucuronidation in clinical treatment. In addition, the increased bilirubin level in the blood of patients who have troglitazone-induced liver failure is a consequence of liver injury and not due to inhibition of bilirubin glucuronidation by troglitazone.     

Identification of human UDP-glucuronosyltransferases involved in N-carbamoyl glucuronidation of lorcaserin

Lorcaserin, a selective serotonin 5-HT(2C) receptor agonist, is a weight management agent in clinical development. Lorcaserin N-carbamoyl glucuronidation governs the predominant excretory pathway of lorcaserin in humans. Human UDP-glucuronosyltransferases (UGTs) responsible for lorcaserin N-carbamoyl glucuronidation are identified herein. Lorcaserin N-carbamoyl glucuronide formation was characterized by the following approaches: metabolic screening using human tissues (liver, kidney, intestine, and lung) and recombinant enzymes, kinetic analyses, and inhibition studies. Whereas microsomes from all human tissues studied herein were found to be catalytically active for lorcaserin N-carbamoyl glucuronidation, liver microsomes were the most efficient. With recombinant UGT enzymes, lorcaserin N-carbamoyl glucuronidation was predominantly catalyzed by three UGT2Bs (UGT2B7, UGT2B15, and UGT2B17), whereas two UGT1As (UGT1A6 and UGT1A9) played a minor role. UGT2B15 was most efficient, with an apparent K(m) value of 51.6 ± 1.9 μM and V(max) value of 237.4 ± 2.8 pmol/mg protein/min. The rank order of catalytic efficiency of human UGT enzymes for lorcaserin N-carbamoyl glucuronidation was UGT2B15 > UGT2B7 > UGT2B17 > UGT1A9 > UGT1A6. Inhibition of lorcaserin N-carbamoyl glucuronidation activities of UGT2B7, UGT2B15, and UGT2B17 in human liver microsomes by mefenamic acid, bisphenol A, and eugenol further substantiated the involvement of these UGT2B isoforms. In conclusion, multiple human UGT enzymes catalyze N-carbamoyl glucuronidation of lorcaserin; therefore, it is unlikely that inhibition of any one of these UGT activities will lead to significant inhibition of the lorcaserin N-carbamoyl glucuronidation pathway. Thus, the potential for drug-drug interaction by concomitant administration of a drug(s) that is metabolized by any of these UGTs is remote.     

A high throughput assay for the glucuronidation of 7-hydroxy-4-trifluoromethylcoumarin by recombinant human UDP-glucuronosyltransferases and liver microsomes

Abstract

1.?UDP-glucuronosyltransferases (UGTs) are versatile and important conjugation enzymes in the metabolism of drugs and other xenobiotics.

2.?We have developed a convenient quantitative multi-well plate assay to measure the glucuronidation rate of 7-hydroxy-4-trifluoromethylcoumarin (HFC) for several UGTs.

3.?We have used this method to screen 11 recombinant human UGTs for HFC glucuronidation activity and studied the reaction kinetics with the most active enzymes. We have also examined the HFC glucuronidation activity of liver microsomes from human, pig, rabbit and rat.

4.?At a substrate concentration of 20?µM, the most active HFC glucuronidation catalysts were UGT1A10 followed by UGT1A6 >UGT1A7 >UGT2A1, whereas at 300?µM UGT1A6 was about 10 times better catalyst than the other recombinant UGTs. The activities of UGTs 1A3, 1A8, 1A9, 2B4 and 2B7 were low, whereas UGT1A1 and UGT2B17 exhibited no HFC glucuronidation activity. UGT1A6 exhibited a significantly higher V_max and Km values toward both HFC and UDP-glucuronic acid than the other UGTs.

5.?Human, pig and rabbit, but not rat liver microsomes, catalyzed HFC glucuronidation at high rates.

6.?This new method is particularly suitable for fast activity screenings of UGTs 1A6, 1A7, 1A10 and 2A1 and HFC glucuronidation activity determination from various samples.     

Characterization of hepatic and intestinal glucuronidation of magnolol: application of the relative activity factor approach to decipher the contributions of multiple UDP-glucuronosyltransferase isoforms

Magnolol is a food additive that is often found in mints and gums. Human exposure to this compound can reach a high dose; thus, characterization of magnolol disposition in humans is very important. Previous studies indicated that magnolol can undergo extensive glucuronidation in humans in vivo. In this study, in vitro assays were used to characterize the glucuronidation pathway in human liver and intestine. Assays with recombinant human UDP-glucuronosyltransferase enzymes (UGTs) revealed that multiple UGT isoforms were involved in magnolol glucuronidation, including UGT1A1, -1A3, -1A7, -1A8, -1A9, -1A10, and -2B7. Magnolol glucuronidation by human liver microsomes (HLM), human intestine microsomes (HIM), and most recombinant UGTs exhibited strong substrate inhibition kinetics. The degree of substrate inhibition was relatively low in the case of UGT1A10, whereas the reaction catalyzed by UGT1A9 followed biphasic kinetics. Chemical inhibition studies and the relative activity factor (RAF) approach were used to identify the individual UGTs that played important roles in magnolol glucuronidation in HLM and HIM. The results indicate that UGT2B7 is mainly responsible for the reaction in HLM, whereas UGT2B7 and UGT1A10 are significant contributors in HIM. In summary, the current study clarifies the glucuronidation pathway of magnolol and demonstrates that the RAF approach can be used as an efficient method for deciphering the roles of individual UGTs in a given glucuronidation pathway in the native tissue that is catalyzed by multiple isoforms with variable and atypical kinetics.     

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.     

The glucuronidation of Delta4-3-Keto C19- and C21-hydroxysteroids by human liver microsomal and recombinant UDP-glucuronosyltransferases (UGTs): 6alpha- and 21-hydroxyprogesterone are selective substrates for UGT2B7.

The stereo- and regioselective glucuronidation of 10 Delta(4)-3-keto monohydroxylated androgens and pregnanes was investigated to identify UDP-glucuronosyltransferase (UGT) enzyme-selective substrates. Kinetic studies were performed using human liver microsomes (HLMs) and a panel of 12 recombinant human UGTs as the enzyme sources. Five of the steroids, which were hydroxylated in the 6beta-, 7alpha-, 11beta- or 17alpha-positions, were not glucuronidated by HLMs. Of the remaining compounds, comparative kinetic and inhibition studies indicated that 6alpha- and 21-hydroxyprogesterone (OHP) were glucuronidated selectively by human liver microsomal UGT2B7. 6alpha-OHP glucuronidation by HLMs and UGT2B7 followed Michaelis-Menten kinetics, whereas 21-OHP glucuronidation by these enzyme sources exhibited positive cooperativity. UGT2B7 was also identified as the enzyme responsible for the high-affinity component of human liver microsomal 11alpha-OHP glucuronidation. In contrast, UGT2B15 and UGT2B17 were the major forms involved in human liver microsomal testosterone 17beta-glucuronidation and the high-affinity component of 16alpha-OHP glucuronidation. Activity of UGT1A subfamily enzymes toward the hepatically glucuronidated substrates was generally low, although UGT1A4 and UGT1A9 contribute to the low-affinity components of microsomal 16alpha- and 11alpha-OHP glucuronidation, respectively. Interestingly, UGT1A10, which is expressed only in the gastrointestinal tract, exhibited activity toward most of the glucuronidated substrates. The results indicate that 6alpha- and 21-OHP may be used as selective "probes" for human liver microsomal UGT2B7 activity and, taken together, provide insights into the regio- and stereoselectivity of hydroxysteroid glucuronidation by human UGTs.     

Enantiomer Selective Glucuronidation of the Non‐Steroidal Pure Anti‐Androgen Bicalutamide by Human Liver and Kidney: Role of the Human UDP‐Glucuronosyltransferase (UGT)1A9 Enzyme

Bicalutamide (Casodex^®) is a non‐steroidal pure anti‐androgen used in the treatment of localized prostate cancer. It is a racemate drug, and its activity resides in the (R)‐enantiomer, with little in the (S)‐enantiomer. A major metabolic pathway for bicalutamide is glucuronidation catalysed by UDP‐glucuronosyltransferase (UGT) enzymes. While (S)bicalutamide is directly glucuronidated, (R)bicalutamide requires hydroxylation prior to glucuronidation. The contribution of human tissues and UGT isoforms in the metabolism of these enantiomers has not been extensively investigated. In this study, both (R) and/or (S)bicalutamide were converted into glucuronide (‐G) derivatives after incubation of pure and racemic solutions with microsomal extracts from human liver and kidney. Intestinal microsomes exhibited only low reactivity with these substrates. Km values of liver and kidney samples for (S)bicalutamide glucuronidation were similar, and lower than values obtained with the (R)‐enantiomer. Among the 16 human UGTs tested, UGT1A8 and UGT1A9 were able to form both (S) and (R)bicalutamide‐G from pure or racemic substrates. UGT2B7 was also able to form (R)bicalutamide‐G. Kinetic parameters of the recombinant UGT2B7, UGT1A8 and UGT1A9 enzymes support a predominant role of the UGT1A9 isoform in bicalutamide metabolism. Accordingly, (S)bicalutamide inhibited the ability of human liver and kidney microsomes to glucuronidate the UGT1A9 probe substrate, propofol. In conclusion, the present study provides the first comprehensive analysis of in vitro bicalutamide glucuronidation by human tissues and UGTs and identifies UGT1A9 as a major contributor for (R) and (S) glucuronidation in the human liver and kidney.     

Udp-glucuronosyltransferase 2b7 is the major enzyme responsible for gemcabene glucuronidation in human liver microsomes.

The predominant metabolic pathway of gemcabene in humans is glucuronidation. The principal human UDP-glucuronosyltransferases (UGTs) involved in the glucuronidation of gemcabene were determined in this study. Glucuronidation of gemcabene was catalyzed by recombinant UGT1A3, recombinant UGT2B7, and recombinant UGT2B17, as well as by human liver microsomes (HLM). Gemcabene glucuronidation in recombinant UGTs and HLM followed non-Michaelis-Menten kinetics consistent with homotropic activation, but pharmacokinetics in humans were linear over the dose range tested (total plasma C(max), 0.06-0.88 mM). Gemcabene showed similar affinity (S(50)) for recombinant UGTs (0.92-1.45 mM) and HLM (1.37 mM). S-Flurbiprofen was identified as a more selective inhibitor of recombinant UGT2B7-catalyzed gemcabene glucuronidation (>23-fold lower IC(50)) when compared with recombinant UGT1A3- or recombinant UGT2B17-catalyzed gemcabene glucuronidation. The IC(50) for S-flurbiprofen inhibition of gemcabene glucuronidation was similar in HLM (60.6 microM) compared with recombinant UGT2B7 (27.4 microM), consistent with a major role for UGT2B7 in gemcabene glucuronidation in HLM. In addition, 5,6,7,3',4',5'-hexamethoxyflavone inhibited recombinant UGT1A3 and recombinant UGT2B17-catalyzed gemcabene glucuronidation (with 4-fold greater potency for recombinant UGT1A3) but did not inhibit gemcabene glucuronidation in HLM, suggesting that UGT1A3 and UGT2B17 do not contribute significantly to gemcabene glucuronidation. Reaction rates for gemcabene glucuronidation from a human liver bank correlated well (r(2)=0.722, P<0.0001; n=24) with rates of glucuronidation of the UGT2B7 probe substrate 3'-azido-3'-deoxythymidine. In conclusion, using the three independent experimental approaches typically used for cytochrome P450 reaction phenotyping, UGT2B7 is the major enzyme contributing to gemcabene glucuronidation in human liver microsomes.     

Prominent but reverse stereoselectivity in propranolol glucuronidation by human UDP-glucuronosyltransferases 1A9 and 1A10.

Propranolol is a nonselective beta-adrenergic blocker used as a racemic mixture in the treatment of hypertension, cardiac arrhythmias, and angina pectoris. For study of the stereoselective glucuronidation of this drug, the two propranolol glucuronide diastereomers were biosynthesized, purified, and characterized. A screen of 15 recombinant human UDP-glucuronosyltransferases (UGTs) indicated that only a few isoforms catalyze propranolol glucuronidation. Analysis of UGT2B4 and UGT2B7 revealed no significant stereoselectivity, but these two enzymes differed in glucuronidation kinetics. The glucuronidation kinetics of R-propranolol by UGT2B4 exhibited a sigmoid curve, whereas the glucuronidation of the same substrate by UGT2B7 was inhibited by substrate concentrations above 1 mM. Among the UGTs of subfamily 1A, UGT1A9 and UGT1A10 displayed high and, surprisingly, opposite stereoselectivity in the glucuronidation of propranolol enantiomers. UGT1A9 glucuronidated S-propranolol much faster than R-propranolol, whereas UGT1A10 exhibited the opposite enantiomer preference. Nonetheless, the Km values for the two enantiomers, both for UGT1A9 and for UGT1A10, were in the same range, suggesting similar affinities for the two enantiomers. Unlike UGT1A9, the expression of UGT1A10 is extrahepatic. Hence, the reverse stereoselectivity of these two UGTs may signify specific differences in the glucuronidation of propranolol enantiomers between intestine and liver microsomes. Subsequent experiments confirmed this hypothesis: human liver microsomes glucuronidated S-propranolol faster than R-propranolol, whereas human intestine microsomes glucuronidated S-propranolol faster. These findings suggest a contribution of intestinal UGTs to drug metabolism, at least for UGT1A10 substrates.     

Metabolism studies on hydroxygenkwanin and genkwanin in human liver microsomes by UHPLC-Q-TOF-MS

Hydroxygenkwanin (HYGN) and genkwanin (GN) are major constituents of Genkwa Flos for the treatment of edema, ascites, cough, asthma and cancer. This is a report about the investigation of the metabolic fate of HYGN and GN in human liver microsomes and the recombinant UDP-glucuronosyltransferase (UGT) enzymes by using ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS). An on-line data acquisition method multiple mass defect filter (MMDF) combined with dynamic background subtraction (DBS) was developed to trace all probable metabolites. Based on this analytical strategy, three phase I metabolites and seven glucuronide conjugation metabolites of HYGN, seven phase I metabolites and 12 glucuronide conjugation metabolites of GN were identified in the incubation samples of human liver microsomes. The results indicated that demethylation, hydroxylation and o-glucuronidation were main metabolic pathways of HYGN and GN. The specific UGT enzymes responsible for HYGN and GN glucuronidation metabolites were identified using recombinant UGT enzymes. The results indicated that UGT1A1, UGT1A3, UGT1A9, UGT1A10 and UGT2B7 might play major roles in the glucuronidation reactions. Overall, this study may be useful for the investigation of metabolic mechanism of HYGN and GN, and it can provide reference and evidence for further experiments.