液相色谱-电喷雾离子阱质谱法分析大鼠血浆中的樟柳碱及其代谢物

目的用液相色谱-电喷雾离子阱串联质谱(LC-MS^{n)联用方法鉴定大鼠血浆中的樟柳碱及其主要代谢物。方法取单剂量灌胃樟柳碱20 mg的大鼠血浆，甲醇沉淀蛋白，采用LC-MSn等方法分析血样。与空白血样及樟柳碱对照品相比较，根据血样中代谢物相对分子质量的变化及其多级质谱数据，鉴定并阐述其结构。结果在服药后的大鼠血样中发现4种代谢物， 分别为东莨菪醇、 N-去甲基东莨菪醇、 羟基化樟柳碱以及N-氧化樟柳碱。结论 该方法灵敏、快速、简便，适合于药物及其代谢物的快速鉴定。}     

Characterization of metabolites of worenine in rat biological samples using liquid chromatography–tandem mass spectrometry

The in vivo and in vitro metabolites of worenine in rat were identified or characterized using a specific and sensitive liquid chromatography–tandem mass spectrometry (LC–MS/MS) method. In vivo samples including rat urine, feces, and plasma samples were collected after ingestion of 25 mg/kg worenine to healthy rats. The in vivo and in vitro samples were cleaned up by a solid-phase extraction procedure (C18 cartridges) and a liquid–liquid extraction procedure, respectively. Then these pretreated samples were injected into a reversed-phase C18 column with mobile phase of methanol–ammonium acetate (2 mM, adjusted to pH 3.5 with formic acid) (60:40, v/v) and detected by an on-line MS/MS system. As a result, at least twenty-seven metabolites and the parent medicine were found in rat urine after ingestion of worenine. Seven metabolites and the parent medicine were identified or characterized in rat feces. Three metabolites and the parent medicine were detected in rat plasma. One metabolite was found in the rat intestinal flora incubation mixture, and three metabolites were characterized in the homogenized liver incubation mixture. The main phase I metabolism of worenine in rat was dehydrogenization, hydrogenation, hydroxylation, and demethylene reactions, and that of phase II was sulfation and glucuronidation.     

Investigation of the metabolic fate of dihydrocaffeic acid

The antioxidant dihydrocaffeic acid is a dietary constituent and a microbial metabolite of flavonoids. Orally administered to rats, dihydrocaffeic acid was very rapidly absorbed most probably by the gastric or duodenal epithelium and excreted in urine as free and conjugated forms. LC-MS2 analysis of plasma and urine samples allowed confident identification of the dihydrocaffeic acid metabolites. The parent compound was glucuronidated, sulphated or methylated, on one of the hydroxyl groups present on its phenyl ring. All the dihydrocaffeic acid metabolites peaked in plasma within the first 30min following ingestion, suggesting a metabolism possibly by the gastric or duodenal cells and by the liver. Using in vitro and ex vivo models of the intestinal epithelium and the liver, the identity and source of the metabolites detected in vivo were examined. The data obtained suggest that, in rats, intestinal cells are more able to glucuronidate dihydrocaffeic acid, whereas liver favours sulphation. Moreover, glucuronidation, sulphation and methylation seem to be regio-selective, preferably on the 3-OH of dihydrocaffeic acid. The methyl conjugate, dihydroferulic acid, was shown to be oxidized into ferulic acid by intestinal and hepatic cells, which were also able to perform the reverse reaction, the reduction of ferulic acid into dihydroferulic acid. As a conclusion, the main form of dihydrocaffeic acid circulating in plasma after its ingestion is a mixture of different primary and secondary metabolites.     

Identification of in‐vivo and in‐vitro metabolites of palmatine by liquid chromatography–tandem mass spectrometry

Objectives Despite its important therapeutic value, the metabolism of palmatine is not yet clear. Our objective was to investigate its in‐vivo and in‐vitro metabolism. Methods Liquid chromatography–tandem electrospray ionization mass spectrometry (LC‐ESI/MSⁿ) was employed in this work. In‐vivo samples, including faeces, urine and plasma of rats, were collected after oral administration of palmatine (20 mg/kg) to rats. In‐vitro samples were prepared by incubating palmatine with intestinal flora and liver microsome of rats, respectively. All the samples were purified via a C₁₈ solid‐phase extraction procedure, then chromatographically separated by a reverse‐phase C₁₈ column with methanol–formic acid aqueous solution (pH 3.5, 70: 30 v/v) as mobile phase, and detected by an on‐line MSⁿ detector. The structure of each metabolite was elucidated by comparing its molecular weight, retention time and full‐scan MSⁿ spectra with those of the parent drug. Key findings The results revealed that 12 metabolites were present in rat faeces, 13 metabolites in rat urine, 7 metabolites in rat plasma, 10 metabolites in rat intestinal flora and 9 metabolites in rat liver microsomes. Except for six of the metabolites in rat urine, the other in‐vivo and in‐vitro metabolites were reported for the first time. Conclusions Seven new metabolites of palmatine (tri‐hydroxyl palmatine, di‐demethoxyl palmatine, tri‐demethyl palmatine, mono‐demethoxyl dehydrogen palmatine, di‐demethoxyl dehydrogen palmatine, mono‐demethyl dehydrogen palmatine, tri‐demethyl dehydrogen palmatine) were reported in this work.     

Identification of metabolites of tectoridin in-vivo and in-vitro by liquid chromatography-tandem mass spectrometry

In this work, liquid chromatography-electrospray ionization tandem ion-trap mass spectrometry (LC-MS(n)) was used to investigate the in-vivo and in-vitro metabolism of tectoridin. After oral administration of a single dose (100 mg kg(-1)) of tectoridin to healthy rats, faeces and urine samples were collected for 0-48 h and 0-24 h, respectively. Tectoridin was also incubated with rat intestinal flora and rat liver microsomes. Samples from in-vivo and in-vitro metabolism studies were purified using a C(18) solid-phase extraction cartridge, then separated using a reverse-phase C(18) column with methanol/ water (30:70, v/v, adjusted to pH 10.0 with ammonia water) as mobile phase and detected by an on-line MS(n) system. The structure of the metabolites was elucidated by comparing their molecular weights, retention times and full-scan MS(n) spectra with those of the parent drug. The results revealed six metabolites of tectoridin in urine (tectorigenin, hydrogenated tectorigenin, mono-hydroxylated tectorigenin, di-hydroxylated tectorigenin, glucuronide-conjugated tectorigenin and sulfate-conjugated tectorigenin); three metabolites in faeces (tectorigenin, di-hydroxylated tectorigenin and sulfateconjugated tectorigenin); one metabolite in the intestinal flora incubation mixture (tectorigenin), and four in the liver microsomal incubation mixture (tectorigenin, hydrogenated tectorigenin, mono-hydroxylated tectorigenin and di-hydroxylated tectorigenin). Except for tectorigenin, all other metabolites of tectoridin are reported for the first time.     

Sensitive and specific liquid chromatographic-tandem mass spectrometric assay for atropine and its eleven metabolites in rat urine

A sensitive and specific method is described for the simultaneous determination of atropine and its metabolites in rat urine by combining liquid chromatography and tandem mass spectrometry (LC-MS(n)). Various extraction techniques (free fraction, acid hydrolyses and enzyme hydrolyses) and their comparison were carried out for investigation of the metabolism of atropine. After extraction procedure the pretreated samples were separated on a reversed-phase C18 column using a mobile phase of methanol/ammonium acetate (2 mM, adjusted to pH 3.5 with formic acid) (70: 30,v/v) and detected by an on-line LC-MS(n) system. Identification and structural elucidation of the metabolites were performed by comparing their changes in molecular masses (DeltaM), retention-times and full scan MS(n) spectra with those of the parent drug. The results revealed that at least eleven metabolites (N-demethyltropine, tropine, N-demethylatropine, p-hydroxyatropine, p-hydroxyatropine N-oxide, glucuronide conjugates and sulfate conjugates of N-demethylatropine, p-hydroxyatropine and the parent drug) and the parent drug existed in rat urine after ingesting 25 mg/kg atropine. p-Hydroxyatropine and the parent drug were detected in rat urine for up 106 h after ingestion of atropine.     

Isolation, identification and antiviral activities of metabolites of calycosin-7-O-β-D-glucopyranoside

In vivo and in vitro metabolites of calycosin-7-O-β-d-glucopyranoside in rats were identified using a specific and sensitive high performance liquid chromatography-tandem mass spectrometry (HPLC-MSⁿ) method. The parent compound and twelve metabolites were found in rat urine after oral administration of calycosin-7-O-β-d-glucopyranoside. The parent compound and six metabolites were detected in rat plasma. In heart, liver, spleen, lung and kidney samples, respectively, six, eight, seven, nine and nine metabolites were identified, in addition to the parent compound. Three metabolites, but no trace of parent drug, were found in the rat intestinal flora incubation mixture and feces, which demonstrated cleavage of the glycosidic bond of the parent compound in intestines. The main phase I metabolic pathways of calycosin-7-O-β-d-glucopyranoside in rats were deglycosylation, dehydroxylation and demethylation reactions; phase II metabolism included sulfation, methylation, glucuronidation and glycosylation (probably). Furthermore, two metabolites commonly found in rat urine, plasma and tissues were isolated from feces and characterized by NMR. The antiviral activities of the metabolite calycosin against coxsackie virus B₃ (CVB₃) and human immunodeficiency virus (HIV) were remarkably stronger than those of calycosin-7-O-β-d-glucopyranoside.     

Polymethoxylated flavones metabolites in rat plasma after the consumption of Fructus aurantii extract: analysis by liquid chromatography/electrospray ion trap mass spectrometry

A LC with full scan MS(n) method was developed in order to investigate the in vivo absorption and biotransformation of polymethoxylated flavones (PMFs) by analysis of plasma samples from rats after ingestion of Fructus aurantii extract. Four parent compounds and six metabolites with intact flavonoid structures were tentatively identified. The metabolites were either glucuronides of parent compounds or glucuronides of demethylated products of parent compounds.     

大鼠粪样中山莨菪碱及其代谢物的串联质谱法检测

目的运用液相色谱-电喷雾串联质谱(LC-MSn)法检测大鼠粪样中山莨菪碱及其代谢物。方法收集灌胃山莨菪碱(25 mg·kg^-1)的大鼠粪样,用水浸泡后,以乙酸乙酯萃取,采用LC-MS及LC-MSn等方法检测原药及其代谢物。根据代谢物相对分子质量的变化(ΔM)及其多级质谱数据,鉴定并阐述其结构,同时与空白粪样及山莨菪碱相比较。结果在服药后的大鼠粪样中发现山莨菪碱及其7种代谢产物, 分别为6β-羟基托品、N-去甲基-6β-羟基托品、N-去甲基脱水山莨菪碱、脱水山莨菪碱、N-去甲基山莨菪碱、羟基山莨菪碱以及托品酸等。结论该方法灵敏、快速、简便、有效,适合于生物样品中的药物及其代谢产物的快速鉴定。     

The metabolites of chlorpromazine N-oxide in rat bile.

1. The metabolism of chlorpromazine N-oxide was studied in female rats after a 20 mg/kg single i.p. dose. 2. Metabolites identified in urine and faeces were chlorpromazine, 7-hydroxychlorpromazine, chlorpromazine sulphoxide, N-desmethylchlorpromazine and N-desmethylchlorpromazine sulphoxide. As these same five metabolites were previously shown to be present after oral administration this indicates that reduction of chlorpromazine N-oxide occurs not only in the gastrointestinal tract but also at other sites. 3. The metabolism of chlorpromazine N-oxide was studied following its administration by either i.p., i.v. or oral routes to female rats in which the bile duct was cannulated. 4. There were no qualitative differences between the three routes of administration with respect to the metabolites identified. With the exception of the absence of N-desmethylchlorpromazine and N-desmethylchlorpromazine sulphoxide, all metabolites previously identified in urine and faeces were also present in bile. 5. Additionally there were three compounds present in rat bile which were not identified in urine or faeces. These were chlorpromazine N-oxide, chlorpromazine N,S-dioxide and 7-hydroxychlorpromazine O-glucuronide. This is the first unequivocal evidence for the identification of intact 7-hydroxychlorpromazine O-glucuronide in any species. 6. The inability to detect chlorpromazine N-oxide and chlorpromazine N,S-dioxide in the faeces of rats is likely to be due to the reduction of the N-oxide group on the passage of these biliary metabolites down the intestinal tract.     

Structure elucidation of in vivo and in vitro metabolites of mangiferin

The in vivo and in vitro metabolism of mangiferin was systematically investigated. Urine, plasma, feces, contents of intestinal tract and various organs were collected after oral administration of mangiferin to healthy rats at a dose of 200mg/kg body weight. For comparison, mangiferin was also incubated in vitro with intestinal flora of rats. With the aid of a specific and sensitive liquid chromatography coupled with electrospray ionization tandem hybrid ion trap mass spectrometry (LC-ESI-IT-MS(n)), a total of thirty-three metabolites of mangiferin were detected and their structures were tentatively elucidated on the basis of the characteristics of their precursor ions, product ions and chromatographic retention times. The biotransformation pathways of mangiferin involved deglycosylation, dehydroxylation, methylation, glycosylation, glucuronidation and sulfation.     

The metabolic profile of azimilide in man: in vivo and in vitro evaluations

The metabolic fate of azimilide in man is unusual as it undergoes a cleavage in vivo resulting in the formation of two classes of structurally distinct metabolites. During a metabolite profiling study conducted in human volunteers to assess the contribution of all pathways to the clearance of (14)C-azimilide, greater than 82% of radioactivity was recovered in urine (49%-58%) and feces (33%). Urine, feces, and plasma were profiled for metabolites. A cleaved metabolite, 4-chloro-2-phenyl furoic acid was present at high concentration in plasma (metabolite/parent AUC ratio approx. 4), while other plasma metabolites, azimilide N-oxide (metabolite/parent AUC ratio 0.001), and a cleaved hydantoin metabolite (metabolite/parent AUC ratio = 0.3) were present at lower concentrations than azimilide. In urine, the cleaved metabolites were the major metabolites, (> 35% of the dose) along with phenols (as conjugates, 7%-8%), azimilide N-oxide (4%-10%), a butanoic acid metabolite (2%-3%), and desmethyl azimilide (2%). A limited investigation of fecal metabolites indicated that azimilide (3%-5%), desmethyl azimilide (1%-3%), and the butanoic acid metabolite (< 1%) were present. Contributing pathways for metabolism of azimilide, identified through in vitro and in-vivo studies, were CYPs 1A1 (est. 28%), 3A4/5 (est. 20%), 2D6 (< 1%), FMO (est. 14%), and cleavage (35%). Enzyme(s) involved in the cleavage of azimilide were not identified.     

大鼠肠内菌转化连翘苷的代谢产物

应用液相色谱-串联质谱法研究肠内菌转化连翘苷的代谢产物.将连翘苷与大鼠肠内菌于体外厌氧温孵培养,在温孵液中检测到连翘苷及其3种代谢产物.放大制备了转化产率高的代谢物,依据1H NMR和ESI-MS数据推测代谢物结构并假设了连翘苷可能的代谢途径.     

Determination of plasma and urine levels of Delta9-tetrahydrocannabinol and its main metabolite by liquid chromatography after solid-phase extraction

Delta9-Tetrahydrocannabinol is the most widespread drug of abuse in the world and it is also currently available as the active principle of formulations for the treatment of chronic pain. Its main metabolite, 11-nor-Delta9-tetrahydrocannabinol-9-carboxylic acid, is the most important marker of Delta9-tetrahydrocannabinol consumption. An original liquid chromatographic method has been developed for the determination of these two analytes in human plasma and urine. Separation was obtained on a C8 column using a mobile phase with 35% phosphate buffer at pH 2.7 and 65% acetonitrile. The UV detector was set at 220 nm and indomethacin was used as the internal standard. Sample pre-treatment was carried out by solid-phase extraction with C8 cartridges; urine samples were subjected to basic hydrolysis before extraction. Both extraction yields (>91%) and precision values were highly satisfactory. The method was successfully applied to biological samples collected from Cannabis users. Accuracy and selectivity results were satisfactory. This is the first HPLC-UV method developed for the simultaneous quantification of Delta9-tetrahydrocannabinol and 11-nor-Delta9-tetrahydrocannabinol-9-carboxylic acid in both plasma and urine for the monitoring of either therapeutic or recreational use.     

Simultaneous determination of albendazole metabolites, praziquantel and its metabolite in plasma by high-performance liquid chromatography-electrospray mass spectrometry

The analysis of albendazole sulfoxide, albendazole sulfone, praziquantel and trans-4-hydroxypraziquantel in plasma was carried out by high-performance liquid chromatography-mass spectrometry ((LC-MS-MS). The plasma samples were prepared by liquid-liquid extraction using dichloromethane as extracting solvent. The partial HPLC resolution of drug and metabolites was obtained using a cyanopropyl column and a mobile phase consisting of methanol:water (3:7, v/v) plus 0.5% of acetic acid, at a flow rate of 1.0 mL/min. Multi reaction monitoring detection was performed by electrospray ionization in the positive ion mode, conferring additional selectivity to the method. Method validation showed relative standard deviation (precision) and relative errors (accuracy) lower than 15% for all analytes evaluated. The quantification limit was 5 ng/mL and the linear range was 5-2500 ng/mL for all analytes. The method was used for the determination of drug and metabolites in swine plasma samples and proved to be suitable for pharmacokinetic studies.     

大鼠肠内菌转化间尼索地平的代谢产物

应用LC-MS/MS法研究肠内菌转化间尼索地平的代谢产物.将间尼索地平与大鼠肠内菌于体外厌氧温孵培养,放大制备转化产率最高的代谢物.依据1H NMR和ESI-MS/MS数据确认代谢物结构,推断可能的代谢途径.结果在温孵液中发现了间尼索地平及其2种代谢产物.     

Metabolism of loprazolam in rat, dog and man in vivo

The metabolism of 14C-loprazolam has been studied in rat, dog and man in vivo. In rat, the major metabolic pathways were hydroxylation on the benzodiazepine ring, and reduction and acetylation of the nitro group. Both metabolites were identified by co-chromatography with standards, and were present in urine and bile conjugated with glucuronic acid. In both dog and human urine and bile significant amounts of the piperazine-N-oxide were found. This N-oxide was identified by co-chromatography with authentic compound and by mass spectroscopy. Both loprazolam and the dog biliary metabolites were hydrolysed spontaneously to polar material. Neither treatment with beta-glucuronidase nor incubation with gut microflora had any further effect. Only polar metabolites were found in dog and human faeces. The principal non-polar material found in rat plasma was the diazepine-hydroxy compound, and little loprazolam was present. Significant levels of loprazolam and lower levels of an unidentified metabolite were found in ether extracts of dog and human plasma. Both the piperazine-N-oxide and loprazolam were found in similar quantities in chloroform extracts of human plasma, and at two hours after dosage, the N-oxide and loprazolam accounted for greater than 90% of the radioactivity present in the plasma.     

Disposition of [14C]pinacidil in humans

Pinacidil [(+/-)-2-cyano-1-(4-pyridyl)-3-(1,2,2-trimethylpropyl)guanidine monohydrate] is a novel, direct-acting vasodilator antihypertensive agent. The cyano 14C-labeled drug is rapidly and completely absorbed after an oral 12.5-mg dose in solution. The blood:plasma concentration ratios (0.8-0.9) indicate transient penetration of radioactivity into blood cells. Blood and plasma tmax (0.5 h) and t 1/2 (4 h) of [14C]pinacidil equivalents are similar. Pinacidil (51%), pinacidil N-oxide (28%), and unidentified polar metabolites (21%) comprise the plasma radioactivity. The plasma t 1/2 of pinacidil is 2-3 h, and that of pinacidil N-oxide is 4-5 h. Renal excretion of radioactivity is the major route (80-90% dose) of drug elimination; fecal elimination accounted for 4% of the dose. Renal clearance of the N-oxide is 10 times the renal clearance of the parent drug and exceeds the creatinine clearance. Biotransformation products in 0-24-h urine samples include pinacidil (10%), pinacidil N-oxide (60%), and free and conjugated analogues of pinacidil and metabolites (30%). Stereoselective metabolism is not a major biotransformation pathway of pinacidil or the N-oxide metabolite.     

Analytical methods for the determination of naftifine and its metabolites in human plasma and urine

Analytical procedures have been worked out for the determination both of naftifine, the antifungal constituent of Exoderil, and its demethyl derivative in plasma, and of the metabolites p-hydroxyphenyl-, 3,4-dihydrodiol- and 7,8-dihydrodiol-naftifine and naphthoic acid in urine. For plasma a HPLC-method with UV-detection after extraction of the samples with hexane is used. In urine samples the metabolites are deconjugated, extracted with chloroform, silylated and measured by GC with flame ionization detection. The standard calibration curves for the parent compound and metabolites are linear. The detection limit for naftifine and its demethyl derivative is ca. 5 ng/ml, for naphthoic acid 1 microgram/ml and for the other metabolites 2 micrograms/ml.     

GC-MS method for the simultaneous determination of β-blockers, flavonoids, isoflavones and their metabolites in human urine

A sensitive and selective method based on gas chromatography hyphenated to mass spectrometry (GC-MS) for the screening of 23 different compounds including β-blockers, flavonoids, isoflavones and metabolites in human urine sample was developed and validated. The present paper reports, for the first time, the method for the simultaneous determination of β-blockers, isoflavones, flavonoids and metabolites in human urine samples. When flavonoids are ingested in combination with drugs that have a narrow therapeutic range, interactions between flavonoids and drugs should be investigated.Substances of interest were extracted from urine samples by solid-phase extraction (SPE) employing a mixture of tert-butyl methyl ether:methanol:formic acid (4.5:4.5:1; v/v/v) as a mobile phase and Oasis HLB (Waters) as a stationary phase. Before extraction, urine samples were incubated with β-glucuronidase/sulfatase in order to achieve enzymatic hydrolysis. Before GC-MS analysis the analytes had to be derivatized with N-methyl-N-(trimethylsilyl)trifluoroacetamide (MSTFA) into their trimethylsilyl derivatives by incubating for 60 min at 60 °C. Statistical central composite design and response surface analysis were used to optimize the derivatization reagent. These multivariate procedures were efficient in determining the optimal separation condition, using peak areas as responses.The calibration curves were indicative of high linearity (r² ≥ 0.9992) in the range of interest for each analyte. LODs (S/N = 3) ranged between 0.6 and 9.7 ng/ml. Intra-day and inter-day precision (CV, %) was less than 4.96%, accuracy between 0.01 and 4.98% and recovery was found in the range from 70.20 to 99.55%.The developed method can be applied to the routine determination of examined compounds’ concentrations in human urine. Moreover the method is suitable for detecting pharmaceutical compounds containing β-blockers, isoflavones and flavonoids in urine after administration to humans.