OBJECTIVE: To explore the inhibitive effects of 1,3,8-trihydroxy-5-methoxyxanthone (TMX) on cytochrome P450s (CYP450s) in human liver microsomes. METHODS: Probe drugs were incubated with and without adding TMX to determine the changes of enzyme activities. The concentration ratio of metabolites to probe drugs was used to present enzyme activities. Concentrations of the probe drugs and their metabolites in the incubated mixture were detected by high performance liquid chromatography. RESULTS: The variations (mean, 95%CI) of the activities of CYP1A2, CYP2C9, CYP2C19, CYP2E1 and CYP3A4 were 2.95 x 10(-3) (2.03 x 10(-3), 3.88 x 10(-3)), 3.14 x 10(-2) (1.87 x 10(-2), 4.42 x 10(-2)), 2.27 x 10(-3) (-1.4 x 10(-2),1.81 x 10(-2)), 7.72 x 10(-2) (-0.83 x 10(-2), 0.2374), and -0.2548 (-2.9802, 2.4707), respectively. The activities of CYP1A2 and CYP2C9 were significantly reduced in the present of TMX. CONCLUSION TMX (10 micromol/L) has significant inhibitive effect on the activities of CYP1A2 and CYP2C9, but no significant inhibitive effect on the activities of CYP2C19, CYP2E1 and CYP3A4.
Cytochrome P-450 Enzyme System ; metabolism ; Humans ; Microsomes, Liver ; drug effects ; enzymology ; Xanthones ; pharmacology

To evaluate the hepatotoxicity risks of physcion on the basis of the bilirubin metabolism mediated by glucuronidation of UDP-glucuronosyltransferases 1A1(UGT1A1 enzyme). The monomers were added into the rat liver microsomes to test the hepatotoxicity by using bilirubin as UGT1A1 enzyme substrate, with apparent inhibition constant K_i as the evaluation index. Liver microsome incubation in vitro was adopted to initiate phase Ⅱ metabolic reaction and investigate the inhibitory effect of physcion. Then the phase Ⅰ and Ⅱ metabolic reactions were initiated to investigate the comprehensive inhibition of metabolites and prototype components. The results showed that when only the phase Ⅱ reaction was initiated, physcion directly acted on the UGT1A1 enzyme in a prototype form, exhibited weak inhibition and the inhibition type was mixed inhibition; When the phase Ⅰ and Ⅱ reactions were initiated simultaneously, the inhibitory effects of physcion on UGT1A1 enzyme became strong and the inhibition type was mixed inhibition, suggesting that physcion had phase Ⅰ and Ⅱ metabolic processes, and the metabolites had strong inhibitory effect on UGT1A1 enzyme. This experiment preliminarily proved that the metabolites of physcion may be the main components to induce hepatotoxicity.
Animals ; Chemical and Drug Induced Liver Injury ; Emodin ; analogs & derivatives ; toxicity ; Glucuronosyltransferase ; metabolism ; Kinetics ; Microsomes, Liver ; drug effects ; Rats

OBJECTIVETo investigate the chemical constituents of tuber of Gymnadenia conopsea.

METHODThe constituents were isolated by using a combination of various chromatographic techniques including column chromatography over silica gel, Sephadex LH-20, and C-18, as well as reversed-phase HPLC. Structures of the isolates were identified by spectroscopic data analysis.

RESULTThirty-four compounds were isolated. Their structures were identified as six 2-isobutyltartrate benzyl ester glucosides: coelovirin A (1), coelovirin B (2), coelovirin E (3), coelovirin D (4), dactylorhin B (5) and loroglossin (6). Three 2-isobutylmalate benzyl ester glucosides: dactylorhin A (7), dactylorhin E (8) and militarine (9). Three lignans: arctigenin (10), lappaol A (11) and lappaol F (12). Six aromatic acid (alhyde or alcohol) derivatives: 4-beta-D-glucopyranosyloxyl-trans-phenylpropenoic acid (13), 4-beta-D-glucopyranosyloxyl-cis-phenylpropenoic acid (14), gastrodin (15), 4-beta-D-glucopyranosyloxylphenylaldehyde (16), 4-beta-D-glucopyranosyloxylbenzyl methyl ether (17), 4-beta-D-glucopyranosyloxyloxylbenzyl ethyl ether (18), and bis(4-hydroxybenzyl) ether mono 4-O-beta-D-glucopyranoside (19). Four cyclodipeptides: cyclo(L-Leu-L-Tyr) (20), cyclo(L-Leu-L-Pro) (21), cyclo(L-Val-L-Tyr) (22), and cyclo(L-Ala-D-Phe) (23). One N6-substituted andenosine: N6-(4-hydroxybenzyl)-adenine riboside (24). An aromatic amide: N-trans-feruloyltyramine (25). Nine aromatic acids (or aldehyde or alcohol): 3-hydroxybenzoic acid (26), 4-hydroxyisophthalic acid (27), 4-hydroxybenzyl alcohol (28), 4-hydroxybenzyl methyl ether (29), 4-hydroxybenzylaldehyde (30), 4-hydroxybenzoic acic (31), 4-hydroxy-3-methoxybenzoic acid (32), trans-p-hydroxyphenylpropenoic acid (33), and cis-p-hydroxyphenylpropenoic acid (34). At a concentration of 1.0 x 10(-6) mol x L(-1), compounds 10-12 showed antioxidative activity inhibiting Fe(+2) -cystine induced rat liver microsomal lipid peroxidation with inhibitory rates of 53%, 59%, and 52%, respectively(positive control VE with 35% inhibition).

CONCLUSIONThese compounds were obtained from the genus Gymnadenia for the first time except for 5-7, 9, 15, 28-34. Compounds 10-12 possess antioxidant activity.

Animals ; Lipid Peroxidation ; drug effects ; Microsomes, Liver ; drug effects ; metabolism ; Orchidaceae ; chemistry ; Plant Extracts ; analysis ; isolation & purification ; pharmacology ; Rats

Cell Line ; Cytochrome P-450 CYP1A1 ; drug effects ; metabolism ; Hepatocytes ; cytology ; metabolism ; Humans ; Microsomes, Liver ; drug effects ; metabolism ; Quercetin ; pharmacology

The purpose of this study was to investigate the effect of apigenin on UGT1 A1 enzyme activity and to predict the potential drug-drug interaction of apigenin in clinical use. First,on the basis of previous experiments,the binding targets and binding strength of apigenin to UGT1 A1 enzyme were predicted by computer molecular docking method. Then the inhibitory effect of apigenin on UGT1 A1 enzyme was evaluated by in vitro human liver microsomal incubation system. Molecular docking results showed that apigenin was docked into the active region of UGT1 A1 enzyme protein F,consistent with the active region of bilirubin docking,with moderate affinity. Apigenin flavone mother nucleus mainly interacted with amino acid residues ILE343 and VAL345 to form hydrophobic binding Pi-Alkyl. At the same time,the hydroxyl group on the mother nucleus and the amino acid residue LYS346 formed an additional hydrogen bond,which increased the binding of the molecule to the protein. These results suggested that the flavonoid mother nucleus structure had a special structure binding to the enzyme protein UGT1 A1,and the introduction of hydroxyl groups into the mother nucleus can increase the binding ability. In vitro inhibition experiments showed that apigenin had a moderate inhibitory effect on UGT1 A1 enzyme in a way of competitive inhibition,which was consistent with the results of molecular docking. The results of two experiments showed that apigenin was the substrate of UGT1 A1 enzyme,which could inhibit the activity of UGT1 A1 enzyme competitively,and there was a risk of drug interaction between apigenin and UGT1 A1 enzyme substrate in clinical use.
Apigenin/chemistry* ; Bilirubin/chemistry* ; Drug Interactions ; Glucuronosyltransferase/metabolism* ; Humans ; Hydrogen Bonding ; Microsomes, Liver/drug effects* ; Molecular Docking Simulation

OBJECTIVEQingkailing injection (QKLI), Jinnaduo injection (JNDI), Shuxuetong injection (SXTI), Shenmai injection (SMI) and Kangai injection (KAI) are widely used in China. To predict the herb-drug interactions in clinical application, they were evaluated for their in vitro inhibition effect on CYP3A in rat liver microsomes.

METHODThe rat liver microsomes were incubated with different doses of 5 kinds of traditional Chinese medicine injections (TCMIs) in the present of testosterone, a specific substrate of CYP3A. 6beta-hydroxytestosterone, the metabolite of testosterone, was monitored by HPLC to compare the inhibition effect of 5 TCMIs on CYP3A in rat liver microsomes. Ketoconazole was used as a positive control.

RESULT10% QKLI reduced the formation of 6beta-hydroxytestosterone by approximately 93.0%, which is more significant than other four TCMIs. The half maximal inhibitory concentration (IC50) and the enzyme-inhibitor constant K(i) were 1.0% and 0.7% respectively.

CONCLUSIONQKLI showed much stronger inhibition activity against CYP3A, comparing to other 4 TCMIs. The results revealed that QKLI may be involved in herb-drug interactions by inhibition of CYP3A.

Animals ; Cytochrome P-450 CYP3A Inhibitors ; Injections ; Male ; Medicine, Chinese Traditional ; Microsomes, Liver ; drug effects ; enzymology ; Rats ; Rats, Sprague-Dawley

This project is to investigate chemical compositions from the roots of Erythrina corallodendron. Through the methods of silica gel,ODS,Sephadex LH-20 column chromatography and preparative HPLC,15 compounds were isolated from the 95% ethanol extract of the roots of E. corallodendron. Based on spectroscopic techniques,the structures of these compounds were identified as 10,11-dioxoerythraline( 1),erythrinine( 2),erythraline( 3),11-methoxyerythraline( 4),cristanines B( 5),erythratine( 6),erysotrine( 7),medioresinol( 8),( ±)-ficusesquilignan A( 9),( +)-pinoresinol( 10),nicotinic acid( 11),dibutyl phthalate( 12),vanillic acid( 13),3-hydroxy-1-( 4-hydroxy-3-methoxyphenyl)-1-propanone( 14),and syringic acid( 15). Compounds 8-10 are isolated from genus Erythrina for the first time and all compounds are isolated from E. corallodendron for the first time. Furthermore,this paper screened the antioxidant and cytotoxic activities of the compounds using models of liver microsomal oxidation inhibition and MTT.
Antioxidants ; analysis ; Chromatography, High Pressure Liquid ; Erythrina ; chemistry ; Microsomes, Liver ; drug effects ; Phytochemicals ; analysis ; Plant Extracts ; analysis ; Plant Roots ; chemistry

To study the effect of Siwu decoction (SWD) compound and its combined administration on hepatic P450 enzymatic activity and mRNA expression in rats. Rats were orally administered with SWD and water decoction combined with other medicines for two weeks, and then sacrificed. Their livers were perfused with normal saline to prepare liver micrisomes. Mixed probe and liver microsome in vitro incubation method were adopted to detect the effect of SWD on hepatic cytochrome P450. The real-time quantitative polymerase chain reaction (Q-PCR) was used to detect the effect of SWD on the expression of hepatic cytochrome P450. Compared with the control group, the SWD compound group showed higher CYP1A2 enzymatic activity (P < 0.05); Rehmanniae-paeoniae, angelicae-paeoniae, angelicae-rhizome, paeoniae-rhizome groups had lower CYP1A2 and CYP2C19 enzymatic activities (P < 0.05); And the compound group, the single component group and the combination group showed lower CYP2B6 enzymatic activities (P < 0.05). The compound could up-regulated the mRNA expression of CYP2B1 (P < 0.05); And the four single components could down-regulated the mRNA expression of CYP2B1 (P < 0.05). SWD compound had the effect in inducing CYP1A2 enzymatic activity. The rehmanniae-paeoniae group and the angelicae-paeoniae group had identical enzymatic activity with the control group, but significant down-regulation in CYP1A2 enzymatic activity after being combined with paeoniae. The compound and its combined administration showed the inhibitory effect on CYP2B6 enzymatic activity, particularly being combined with angelicae. The compound showed identical effect with the four single components in terms of CYP1A2 mRNA expression and enzymatic activity.
Animals ; Cytochrome P-450 Enzyme System ; genetics ; metabolism ; Drugs, Chinese Herbal ; pharmacology ; Liver ; drug effects ; enzymology ; Microsomes, Liver ; drug effects ; enzymology ; RNA, Messenger ; genetics ; metabolism ; Rats ; Rats, Wistar

OBJECTIVETo develop a HPLC-ESI-MS method for the determination of puerarin and its metabolite and study the metabolic kinetics in beagle dog liver microsomes.

METHODBeagle dog liver microsomes were prepared by using ultracentrifugation method. Chromatography was performed on a Shimadzu C18 column (2.0 mm x 150 mm, 5 microm). Amethanol-water gradient system was used. ESI interface was applied in the positive, and SIM m/z 417 was puerarin and m/z 531 was daidzein.

RESULTThe puerarin was metabolized by NADPH regenerating system in beagle dog microsomes. The Michaelis-Menten parameters Km and Vmax in beagle dog microsomes were initially estimated by analyzing Lineweave-Brurk plot. The Vmax Km of puerarin were (0.047 +/- 0.006) mg x min(-1) x g(-1), (1.22 +/- 0.53) mg x L(-1).

CONCLUSIONThe puerarin and daidzein can be rapidly determined by HPLC-MS in beagle dog microsomes and the puerarin was metabolized to daidzein by CY P450. The study can give help for Baige capsule.

Animals ; Chromatography, High Pressure Liquid ; Dogs ; Isoflavones ; pharmacokinetics ; Liver ; chemistry ; drug effects ; Microsomes, Liver ; chemistry ; drug effects ; Pharmacokinetics ; Spectrometry, Mass, Electrospray Ionization

The bilirubin metabolism mediated by the phase Ⅱ metabolizing enzyme UGT1A1 in the liver was evaluated to study the potential hepatotoxicity risk based on investigation on the inhibitory effect of rhein and its metabolites on the UGT1A1 enzyme in Rhei Radix et Rhizoma. Firstly, in vitro liver microsomes incubation was used to initiate the phase Ⅱ metabolic reaction to investigate the inhibitory effect of rheinon UGT1A1 enzyme. Secondly, the phase Ⅰ and phase Ⅱ metabolic reactions were initiated to investigate the hepatotoxicity risk of rhein metabolites. It was found that the rhein and its phase Ⅱ metabolites had no significant inhibitory effect on UGT1A1 enzyme, but its phase Ⅰ metabolites significantly reduced UGT1A1 enzyme activity. Based on the metabolites analysis, it is speculated that the rhein phase Ⅰ metabolite rheinhydroxylate and its tautomers have certain hepatotoxicity risks, while the toxicity risk induced by the prototype and phase Ⅱ metabolites of rheinglucoside, rheinglucuronic acid and rhein sulfate is small.
Anthraquinones/toxicity* ; Chemical and Drug Induced Liver Injury ; Drugs, Chinese Herbal/toxicity* ; Glucuronosyltransferase/metabolism* ; Humans ; Liver/enzymology* ; Microsomes, Liver/drug effects* ; Rhizome