[Show abstract][Hide abstract] ABSTRACT: As an edible traditional Chinese herb, Fructus Psoraleae (FP) has been widely used in Asia for the treatment of vitiligo, bone fracture and osteoporosis. Several cases on markedly elevated bilirubin and acute liver injury following administration of FP and its related proprietary medicine have been reported, but the mechanism in FP-associated toxicity has not been well investigated yet. This study aimed to investigate the inhibitory effects of FP extract and its major constituents against human UDP-glucuronosyltransferase 1A1 (UGT1A1), the key enzyme responsible for metabolic elimination of bilirubin. To this end, N-(3-carboxy propyl)-4-hydroxy-1,8-naphthalimide (NCHN), a newly developed specific fluorescent probe for UGT1A1, was used to evaluate the inhibitory effects of FP extract or its fractions in human liver microsomes (HLM), while LC-UV fingerprint and UGT1A1 inhibition profile were combined to identity and characterize the naturally occurring inhibitors of UGT1A1 in FP. Our results demonstrated that both the extract of FP and five major components of FP displayed evident inhibitory effects on UGT1A1 in HLM. Among these five identified naturally occurring inhibitors, bavachin and corylifol A were found to be strong inhibitors of UGT1A1 with the inhibition kinetic parameters (Ki) values lower than 1 μM, while neobavaisoflavone, isobavachalcone, and bavachinin displayed moderate inhibitory effects against UGT1A1 in HLM, with the Ki values ranging from 1.61 to 9.86 μM. These findings suggested that FP contains natural compounds with potent inhibitory effects against human UGT1A1, which may be one of the important reasons for triggering FP-associated toxicity, including elevated bilirubin levels and liver injury.
Toxicology and Applied Pharmacology 09/2015; DOI:10.1016/j.taap.2015.09.003 · 3.71 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Stauntonia brachyanthera Hand-Mazz., an evergreen shrub belonging to the family of Lardizabalaceae, is traditionally used in China to treat various diseases. Its fruit, zhuyaozi, is extremely popular in the southwest of China because of its fresh taste and abundant nutrients. The chemical study on this fruit resulted in the isolation of eight new nor-oleanane type triterpenoid saponins, brachyanthera acid A, brachyantheraoside A1–A5 and brachyantheraoside B6, B9, along with nine known compounds. Their structures were determined by extensive 1D and 2D NMR experiments along with HRESIMS analysis. Nine compounds including four new ones showed hepatoprotective activities against DL-galactosamine-induced toxicity in WB-F344 cells, with their survival rates being very close to that of bicyclol. Additionally, the results of the inhibitory study of brachyantheraoside A5 (15) on 4-MU glucuronidation indicated its less probability leading to drug–drug interaction, which revealed that brachyantheraoside A5 and its analogues might be new safe leading compounds for further investigation as hepatoprotectants.
[Show abstract][Hide abstract] ABSTRACT: UDP-glucuronosyltransferases (UGTs) are involved in the clearance of many important drugs and endogenous substances, and inhibition of UGTs' activity by herbal components might induce severe herb-drug interactions or metabolic disturbances of endogenous substances. The present study aims to determine the inhibition of UGTs' activity by podophyllotoxin derivatives, trying to indicate the potential herb-drug interaction or metabolic influence towards endogenous substances' metabolism. Recombinant UGT isoforms (except UGT1A4)-catalyzed 4-methylumbelliferone (4-MU) glucuronidation reaction and UGT1A4-catalyzed trifluoperazine (TFP) glucuronidation were employed to firstly screen the podophyllotoxin derivatives' inhibition potential. Structure-dependent inhibition behavior of podophyllotoxin derivatives towards UGT isoforms was detected. Inhibition kinetic type and parameter (Ki) were determined for the inhibition of podophyllotoxin towards UGT1A1, and competitive inhibition of podophyllotoxin towards UGT1A1 was observed with the inhibition kinetic parameter (Ki) to be 4.0 μM. Furthermore, podophyllotoxin was demonstrated to exert medium and weak inhibition potential towards human liver microsomes (HLMs)-catalyzed SN-38 glucuronidation and estradiol-3-glucuronidation. In conclusion, podophyllotoxin inhibited UGT1A1 activity, indicating potential herb-drug interactions between podophyllotoxin-containing herbs and drugs mainly undergoing UGT1A1-mediated metabolism.
[Show abstract][Hide abstract] ABSTRACT: The mechanism of shengmai injection- (SMI-) related drug-drug interaction remains unclear. Evaluation of the inhibition potential of SMI's ingredients towards UDP-glucuronosyltransferases (UGTs) activity will provide a new insight to understand SMI-related drug-drug interaction. In vitro incubation system to model UGT reaction was used. Recombinant UGT isoforms-catalyzed 4-methylumbelliferone (4-MU) glucuronidation and UGT1A4-catalyzed trifluoperazine (TFP) glucuronidation reactions were employed to phenotype the inhibition profile of maidong's components towards the activity of UGT isoforms. Different inhibition potential of maidong's components towards various UGT isoforms was observed. Based on the inhibition kinetic investigation results, ophiopogonin D (OD) noncompetitively inhibited UGT1A6 and competitively inhibited UGT1A8, ophiopogonin D' (OD') noncompetitively inhibited UGT1A6 and UGT1A10, and ruscorectal (RU) exhibited competitive inhibition towards UGT1A4. The inhibition kinetic parameters were calculated to be 20.6, 40.1, 5.3, 9.0, and 0.02 μM, respectively. In combination with our previous results obtained for the inhibition of UGT isoforms by ginsenosides and wuweizi components, the important SMI ingredients exhibiting strong inhibition towards UGT isoforms were highlighted. All the results obtained in the present study provide a new insight to understand SMI-related drug-drug interaction.
Evidence-based Complementary and Alternative Medicine 10/2014; 2014:594354. DOI:10.1155/2014/594354 · 1.88 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Abstract 1. Endogenous compounds have been reported to be the regulators of UDP-glucuronosyltransferases (UGTs) isoforms. This study aims to investigate the regulatory effects of the activity of UGT isoforms by two important lipid components phosphatidylcholine (PC) and lysophosphatidylcholines (LPC) using in vitro incubation system. 2. UGTs supersomes-catalyzed 4-methylumbelliferone (4-MU) glucuronidation was used as the probe reaction to evaluate the inhibition of compounds towards UGT isoforms except UGT1A4, and UGT1A4-catalyzed trifluoperazine (TFP) glucuronidation reaction was utilized to phenotype the activity of UGT1A4. 3. About 50 μM of LPC15:0, LPC16:0, LPC17:0, LPC18:0, LPC18:1 and PC16:0, 2:0 exhibited inhibition towards more than 90% activity of UGT isoforms, and other LPC and PC components showed negligible inhibitory potential towards all the UGT isoforms. UGT1A6 and UGT1A8 were identified to be the most sensitive UGT isoforms susceptible for the inhibition by LPC15:0, LPC16:0, LPC17:0, LPC18:0, LPC18:1 and PC16:0, 2:0, indicating the strong influence of these LPC and PC components towards UGT1A6 and UGT1A8-catalyzed metabolic reaction when the concentrations of these components increased.
[Show abstract][Hide abstract] ABSTRACT: A new ratiometric fluorescent probe derived from 2-(2-hydroxy-3-methoxyphenyl) benzothiazole (HMBT) has been developed for selective monitoring of human carboxylesterase 1 (hCE1). The probe is designed by introducing benzoyl moiety to HMBT. The prepared latent spectroscopic probe 1 displays satisfying stability under physiological pH conditions with very low background signal. Both the reaction phynotyping and chemical inhibition assays demonstrated that hCE1 mediated the specific cleavage of the carboxylic ester bond of probe 1 in human biological samples. The release of HMBT leads to a remarkable red-shifted emission in fluorescence spectrum (120 nm large emission shift). Furthermore, human cell-based assays show that probe 1 is cell membrane permeable, and it can be used for bioassay and cellular imaging of hCE1 activity in HepG2 cells. These findings lead to the development of a simple and sensitive fluorescent method for measurement of hCE1 activity in vitro or in living cells, in the presence of additional enzymes or endogenous compounds.
[Show abstract][Hide abstract] ABSTRACT: Herb-drug interaction strongly limits the clinical application of herbs and drugs, and the inhibition of herbal components towards important drug-metabolizing enzymes (DMEs) has been regarded as one of the most important reasons. The present study aims to investigate the inhibition potential of andrographolide derivatives towards one of the most important phase II DMEs UDP-glucuronosyltransferases (UGTs). Recombinant UGT isoforms (except UGT1A4)-catalyzed 4-methylumbelliferone (4-MU) glucuronidation reaction and UGT1A4-catalyzed trifluoperazine (TFP) glucuronidation were employed to firstly screen the andrographolide derivatives' inhibition potential. High specific inhibition of andrographolide derivatives towards UGT2B7 was observed. The inhibition type and parameters (Ki) were determined for the compounds exhibiting strong inhibition capability towards UGT2B7, and human liver microsomes (HLMs)-catalyzed zidovudine (AZT) glucuronidation probe reaction was used to furtherly confirm the inhibition behaviour. In combination of inhibition parameters (Ki) and in vivo concentration of andrographolide and dehydroandrographolide, the potential in vivo inhibition magnitude was predicted. Additionally, both the in vitro inhibition data and computational modeling results provide important information for the modification of andrographolide derivatives as selective inhibitors of UGT2B7. Taken together, data obtained from the present study indicated the potential herb-drug interaction between Andrographis paniculata and the drugs mainly undergoing UGT2B7-catalyzed metabolic elimination, and the andrographolide derivatives as potential candidates for the selective inhibitors of UGT2B7.
[Show abstract][Hide abstract] ABSTRACT: Bakuchiol is a promising anti-tumor candidate with resveratrol-like structure. The present study aims to evaluate the inhibition potential of bakuchiol towards UDP-glucuronosyltransferases (UGT) 1A isoforms. An in vitro incubation system using 4-methylumbelliferone (4-MU) glucuronidation was used to evaluate the inhibition capability of bakuchiol towards UGT1A1, 1A3, 1A6, 1A7, 1A8, 1A9 and 1A10. The glucuronidation of trifluoperazine (TFP) was employed as the probe reaction to determine bakuchiol's inhibition towards UGT1A4. At 1 microM and 10 microM of bakuchiol, no or weak inhibition was observed for all the tested UGT1A isoforms. At 100 microM of bakuchiol, the activity of UGT1A1, 1A3, 1A4, 1A6, 1A7, 1A8, 1A9 and 1A10 was inhibited by -46.2%, 74.7%, 17.8%, 98.7%, 70.4%, 99.2%, 75.8%, and 93.3%, respectively. Further inhibition kinetic behaviour was determined for UGT1A6, 1A8, and 1A10. Both Dixon plot and Lineweaver-Burk plot showed the noncompetitive inhibition of bakuchiol towards all these three UGT isoforms. The inhibition kinetic parameters (Ki) were calculated to be 5.3, 1.8, and 92.6 microM for UGT1A6, 1A8, and 1A10, respectively. In combination with the in vivo exposure of bakuchiol, the high possibility of in vivo inhibition of UGT1A6 and 1A8 was predicted. However, relatively low possibility of in vivo inhibition towards UGT1A10 was predicted due to lower in vivo concentration of bakuchiol than its inhibition parameter (Ki). All these information will be helpful for the R&D of bakuchiol as a promising anti-tumor drug.
[Show abstract][Hide abstract] ABSTRACT: Bufalin 5β-hydroxylation was found to be an isoform-specific biotransformation probe substrate for cytochrome P450 3A4 (CYP3A4). The probe reaction was well-characterized and it can be used for measuring the real catalytic activities of CYP3A4 from different enzyme sources.
Chemical Communications 09/2013; 49(84). DOI:10.1039/c3cc45250f · 6.83 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Bisphenol A (BPA), the important endocrine-disrupting chemical (EDC), has been reported to be able to induce various toxicity. The present study aims to understand the toxicity behavior of bisphenol A through evaluating the inhibition profile of bisphenol A towards UDP-glucuronosyltransferase (UGT) isoforms. In vitro recombinant UGTs-catalyzed 4-methylumbelliferone (4-MU) glucuronidation reaction was employed as probe reaction for all the tested UGT isoforms. The results showed that bisphenol A exerted stronger inhibition towards UGT2B isoforms than UGT1A isoforms. Furthermore, the inhibition kinetic type and parameters (Ki) were determined for the inhibition of bisphenol A towards UGT2B4, 2B7, 2B15, and 2B17. Bisphenol A exhibited the competitive inhibition towards UGT2B4, and noncompetitive inhibition towards UGT2B7, 2B15 and 2B17. The inhibition kinetic parameters (Ki) were calculated to be 1.1, 32.6, 5.6, and 19.9μM for UGT2B4, 2B7, 2B15 and 2B17, respectively. In combination with the in vivo concentration of bisphenol A, the elevation of exposure dose was predicted to increase by 29.1%, 1%, 5.7%, and 1.6% for UGT2B4, 2B7, 2B15, and 2B17, indicating the high influence of bisphenol A towards the in vivo UGT2B isofroms-mediated metabolism of xenobiotics and endogenous substances. All these data provide the supporting information for deeper understanding of toxicology of bisphenol A.
[Show abstract][Hide abstract] ABSTRACT: Objectives:
The aim of this work was to identify the uridine glucuronosyltransferase (UGT) isoforms involved in the metabolism of the broad-spectrum antiviral drug arbidol.
A human liver microsome (HLM) incubation system was employed to catalyse the formation of arbidol glucuronide. The glucuronidation activity of commercially recombinant UGT isoforms towards arbidol was screened. A combination of kinetic analysis and chemical inhibition study was used to determine the UGT isoforms involved in arbidol's glucuronidation.
The arbidol glucuronide was detected when arbidol was incubated with HLMs in the presence of UDP-glucuronic acid. The Eadie-Hofstee plot showed that glucuronidation of arbidol was best fit to the Michaelis-Menten kinetic model, and K(m) and apparent V(max) were calculated to be 8.0 ± 0.7 μm and 2.03 ± 0.05 nmol/min/mg protein, respectively. Assessment of a panel of recombinant UGT isoforms revealed that UGT1A1, UGT1A3 and UGT1A9 could catalyse the glucuronidation of arbidol. Kinetic analysis and chemical inhibition study demonstrated that UGT1A9 was the predominant UGT isoform involved in arbidol glucuronidation in HLMs.
The major contribution of UGT1A9 towards arbidol glucuronidation was demonstrated in this study.
[Show abstract][Hide abstract] ABSTRACT: Danshen is one of the most famous herbs in the world, and more and more danshen-prescribed drugs interactions have been reported in recent years. Evaluation of inhibition potential of danshen's major ingredients towards UDP-glucuronosyltransferases (UGTs) will be helpful for understanding detailed mechanisms for danshen-drugs interaction. Therefore, the aim of the present study is to investigate the inhibitory situation of cryptotanshinone and dihydrotanshinone I towards UGT enzymes-catalyzed propofol glucuronidation. In vitro human liver microsomes (HLMs) incubation system was used, and the results showed that cryptotanshinone and dihydrotanshinone I exhibited dose-dependent inhibition towards HLMs-catalyzed propofol glucuronidation. Dixon plot and Lineweaver-Burk plot showed that the inhibition type was best fit to competitive inhibition type for both cryptotanshinone and dihydrotanshinone I. The second plot using the slopes from the Lineweaver-Burk plot versus the concentrations of cryptotanshinone or dihydrotanshinone I was employed to calculate the inhibition parameters (K(i)) to be 0.4 and 1.7μM, respectively. Using the reported maximum plasma concentration (C(max)), the altered in vivo exposure of propofol was increased by 10% and 8.2% for the co-administration of dihydrotanshinone I and cryptotanshinone, respectively. All these results indicated the possible danshen-propofol interaction due to the inhibition of of dihydrotanshinone I and cryptotanshinone towards the glucuronidation reaction of propofol.
[Show abstract][Hide abstract] ABSTRACT: The wide utilization of ginseng provides the high risk of herb-drug interaction (HDI) with many clinical drugs. The inhibition of ginsenosides towards drug-metabolizing enzymes (DMEs) has been regarded as an important reason for herb-drug interaction (HDI). Compared with the deep studies on the ginsenosides' inhibition towards cytochrome P450 (CYP), the inhibition of ginsenosides towards the important phase II enzymes UDP-glucuronosyltransferases (UGTs) remains to be unclear. The present study aims to evaluate the inhibition behaviour of ginsenosides towards important UGT isoforms located in the liver and intestine using in vitro methods. The recombinant UGT isoforms-catalyzed 4-methylumbelliferone (4-MU) glucuronidation reaction was employed as in vitro probe reaction. The results showed that structure-dependent inhibition existed for the inhibition of ginsenosides towards UGT isoforms. To clarify the possibility of in vivo herb-drug interaction induced by this kind of inhibition, ginsenoside Rg(3) was selected as an example, and the inhibition kinetic type and parameters (K(i)) were determined. Rg(3) competitively inhibited UGT1A7, 2B7 and 2B15-catalyzed 4-MU glucuronidation reaction, and exerted noncompetitive inhibition towards UGT1A8-catalyzed 4-MU glucuronidation. The inhibition parameters (K(i) values) were calculated to be 22.6, 7.9, 1.9, and 2.0μM for UGT1A7, 1A8, 2B7 and 2B15. Using human maximum plasma concentration of Rg(3) (400ng/ml (0.5μM)) after intramuscular injection of 60mg Rg(3), the area under the plasma concentration-time curve (AUC) was extrapolated to increase by 2.2%, 6.3%, 26.3%, and 25% for the co-administered drugs completely undergoing the metabolism catalyzed by UGT1A7, 1A8, 2B7 and 2B15, respectively. All these results indicated that the ginsenosides' inhibition towards UGT isoforms might be an important reason for ginseng-drug interaction.
[Show abstract][Hide abstract] ABSTRACT: Isoquiritigenin, a herbal ingredient with chalcone structure, has been speculated to be able to inhibit one of the most drug-metabolizing enzymes (DMEs) UDP-glucuronosyltransferase (UGT). Therefore, the aim of the present study was to investigate the inhibition of isoquiritigenin towards important UGT isoforms in the liver and intestine, including UGT1A1, 1A3, 1A6, 1A7, 1A8, 1A9 and 1A10. The recombinant UGTs-catalyzed 4-methylumbelliferone (4-MU) glucuronidation was used as probe reactions. The results showed that 100 μM of isoquiritigenin inhibited the activity of UGT1A1, UGT1A3, UGT1A6, UGT1A7, UGT1A8, UGT1A9, and UGT1A10 by 95.2%, 76.1%, 78.9%, 87.2%, 67.2%, 94.8%, and 91.7%, respectively. The data fitting using Dixon plot and Lineweaver-Burk plot showed that the inhibition of UGT1A1, UGT1A9 and UGT1A10 by isoquiritigenin was all best fit to the competitive inhibition, and the second plot using the slopes from the Lineweaver-Burk plot versus isoquiritigenin concentrations was used to calculate the inhibition kinetic parameter (K(i)) to be 0.7 μM, 0.3 μM, and 18.3 μM for UGT1A1, UGT1A9, and UGT1A10, respectively. All these results indicated the risk of clinical application of isoquiritigenin on the drug-drug interaction and other possible disease induced by the inhibition of isoquiritigenin towards these UGT isoforms.