Highly sensitive determination of new metabolite in rat plasma after oral administration of swertiamarin by liquid chromatography/time of flight mass spectrometry following picolinoyl derivatization

The metabolism of swertiamarin (STM) in vivo was studied by LC/MS following picolinoyl derivatization. Incubation of erythrocentaurin (ECR), one of the main in vitro metabolites of STM by intestinal bacteria, with liver microsome indicated that STM may be metabolized to the final metabolite 3,4‐dihydro‐5‐(hydroxymethyl) isochroman‐1‐one (HMIO) in vivo. After hydrolyzation with sulfatase, HMIO was successfully detected in rat plasma after oral administration of STM by LC/MS following picolinoyl derivatization. 4‐Methoxyphenyl methanol was used as the internal standard to quantify HMIO in rat plasma. The full metabolic pathway of STM in rats is proposed. STM is first hydrolyzed by bacterial β‐glucusidase to give aglycone, which is readily converted to ECR and nitrogen‐containing metabolite. ECR is further reduced to HMIO by both liver and intestinal bacteria and HMIO is finally converted to the new sulfate conjugate metabolite. The monoterpene compound STM was found to be metabolized to dihydroisocoumarin and alkaloid compounds in vivo, which may be responsible for the pharmacological effect of STM. The results may shed light on clinical efficacy of STM and the new analytical method developed may assist in studies of the metabolism of other natural iridoids and secoiridoids in vivo. Copyright © 2013 John Wiley & Sons, Ltd.     

New analytical method for the study of the metabolism of gentiopicroside in rats after oral administration by LC–TOF‐MS following picolinoyl derivatization

The metabolism of gentiopicroside (GPS) in vivo was studied for the first time by LC–MS following picolinoyl derivatization. Incubation of erythrocentaurin, one of the main in vitro metabolites of GPS by intestinal bacteria, with liver microsome indicated that GPS might be metabolized to a final metabolite 3,4‐dihydro‐5‐(hydroxymethyl)isochroman‐1‐one (HMIO) in vivo. After hydrolysis with sulfatase, HMIO was successfully detected in rat plasma after oral administration of GPS by LC–MS following picolinoyl derivatization. 4‐Methoxyphenyl methanol was used as an internal standard to quantify HMIO in rat plasma. A metabolic pathway of GPS in rats is proposed. The monoterpene compound GPS was found to be metabolized to dihydroisocoumarin, which may be responsible for the pharmacological effect of GPS.     

Pharmacokinetics of 2,3,5,4′‐tetrahydroxystilbene‐2‐O‐β‐D‐glucoside in rat using ultra‐performance LC‐quadrupole TOF‐MS

2,3,5,4′‐Tetrahydroxystilbene‐2‐O‐β‐D‐glucoside (THSG) from Polygoni multiflori has been demonstrated to possess a variety of pharmacological activities, including antioxidant, anti‐inflammatory and hepatoprotective activities. Ultra‐performance LC‐quadrupole TOF‐MS with MS Elevated Energy data collection technique and rapid resolution LC with diode array detection and ESI multistage MSⁿ methods were developed for the pharmacokinetics, tissue distribution, metabolism, and excretion studies of THSG in rats following a single intravenous or oral dose. The three metabolites were identified by rapid resolution LC‐MSⁿ. The concentrations of the THSG in rat plasma, bile, urine, feces, or tissue samples were determined by ultra‐performance LC‐MS. The results showed that THSG was rapidly distributed and eliminated from rat plasma. After the intravenous administration, THSG was mainly distributing in the liver, heart, and lung. For the rat, the major distribution tissues after oral administration were heart, kidney, liver, and lung. There was no long‐term storage of THSG in rat tissues. Total recoveries of THSG within 24 h were low (0.1% in bile, 0.007% in urine, and 0.063% in feces) and THSG was excreted mainly in the forms of metabolites, which may resulted from biotransformation in the liver.     

Analysis of lignans in Schisandra chinensis and rat plasma by high‐performance liquid chromatography diode‐array detection,time‐of‐flight mass spectrometry and quadrupole ion trap mass spectrometry

High‐performance liquid chromatography/diode‐array detection (HPLC/DAD), time‐of‐flight mass spectrometry (HPLC/TOFMS) and quadrupole ion trap mass spectrometry (HPLC/QIT‐MS) were used for separation, identification and structural analysis of lignans in Schisandra chinensis and rat plasma after oral administration of the herbal extract. Six lignans in Schisandra chinensis extract were identified unambiguously by comparing the retention time, their characteristic ultraviolet (UV) absorption and accurate mass measurement. A formula database of known lignans in Schisandra chinensis was established, against which the other 15 lignans were identified effectively based on the accurate extract masses and formulae acquired by HPLC/TOFMS. In order to distinguish the isomers, multi‐stage mass spectrometry (ion trap mass spectrometry, MSⁿ) was also used. The fragmentation behavior of the lignans in the ion trap mass spectrometer was studied by the six lignan standards, and their fragmentation rules in MSⁿ spectra were summarized. These deduced fragmentation rules of lignans were successfully implemented in distinguishing the three groups of isomers in Schisandra chinensis by HPLC/QIT‐MS. By using the three different analytical techniques, 21 lignans in Schisandra chinensis were identified within 30 min. After oral administration of the extract, 11 lignans in rat plasma were detected and identified by comparing their retention time, characteristic UV absorption and accurate mass measurement of peaks in HPLC/TOFMS chromatograms of the herbal extract. Finally, HPLC/TOFMS fingerprints of Schisandra chinensis in vitro and rat plasma in vivo were established. It is concluded that a rapid and effective method based on three analytical techniques for identification of chemical components was established, which is useful for rapid identification of multiple components in Schisandra chinensis in vitro and in vivo. In addition, it can provide help for further pharmacology and action mechanism study of lignans in Schisandra chinensis. Copyright © 2009 John Wiley & Sons, Ltd.     

UPLC–Q‐TOF–MS and UPLC–MS/MS methods for metabolism profiles and pharmacokinetics of major compounds in Xuanmai Ganjie Granules

Xuanmai Ganjie Granules (XMGJ), a widely used Chinese herbal formula in the clinic, is used for treatment of sore throats and coughs. Despite the chemical constituents having been clarifying by our previous studies, both of the metabolism and pharmacokinetic studies of XMGJ are unclear. This study aimed to explore the disposition process of XMGJ in vivo. A sensitive and selective ultra‐high performance liquid chromatography with quadrupole time‐of‐flight mass spectrometry (UPLC–Q‐TOF–MS) method was developed to analyze the absorbed components and metabolites in rat plasma and urine after oral administration of XMGJ. A total of 42 absorbed components, including 16 prototype compounds and 26 metabolites, were identified or tentatively characterized in rat plasma and urine after oral administration of XMGJ. Moreover, the pharmacokinetic studies of five compounds of XMGJ were investigated using ultra‐high liquid chromatography with tandem mass spectrometry method. The results indicated that liquiritin, harpagoside, glycyrrhetic acid, liquiritigenin, formononetin and their metabolites might be the major components involved in the pharmacokinetic and metabolism process of XMGJ. This research showed a comprehensive investigation of XMGJ in vivo, which could provide a meaningful basis for further material basis and pharmacological as well as toxicological research.     

Chemical UPLC‐ESI‐MS/MS profiling of aconitum alkaloids and their metabolites in rat plasma and urine after oral administration of Aconitum carmichaelii Debx. Root extract

In this paper, an ultra high performance liquid chromatography tandem mass spectrometric (UPLC‐ESI‐MS/MS) method in positive ion mode was established to systematically identify and to compare the major aconitum alkaloids and their metabolites in rat plasma and urine after oral administration of Fuzi extract. A total twenty‐nine components including twenty‐five C19‐diterpenoid alkaloids and four C20‐diterpenoid alkaloids were identified in Fuzi extract. Thirteen of the parent components and five metabolites were detected in rat plasma and sixteen parent compounds and six metabolites in urine. These parent components found in rat plasma and urine were mainly C19‐diterpenoid alkaloids. All of the metabolites in vivo were demethylated metabolites (phase I metabolites), which suggested that demethylation was the major metabolic pathway of aconitum alkaloids in vivo. A comparison of the parent components in rat plasma and urine revealed that 3‐deoxyacontine was found in plasma but not in urine, while kalacolidine, senbusine and 16‐β‐hydroxycardiopetaline existed in urine but not in plasma, which indicated that most alkaloids components were disposed and excreted in prototype form. This research provides some important information for further metabolic investigations of Fuzi in vivo.     

Pharmacokinetics of TAK‐875 and its toxic metabolite TAK‐875‐ acylglucuronide in rat plasma by liquid chromatography tandem mass spectrometry

TAK‐875 is a selective partial agonist of human GPR40 receptor, which was unexpectedly terminated at phase III clinical trials owing to its severe hepatotoxicity. The purpose of this study was to investigate the pharmacokinetics of TAK‐875 and its toxic metabolite TAK‐875‐acylglucuronide in rat plasma by liquid chromatography tandem mass spectrometry (LC–MS/MS). Plasma samples were extracted with ethyl acetate and chromatographic separations were achieved on a C₁₈ column with water and acetonitrile containing 0.05% ammonium hydroxide as mobile phase. The sample was detected in selected reaction monitoring mode with precursor‐to‐product ion transitions being m/z 523.2 → 148.1, m/z 699.3 → 113.1 and m/z 425.2 → 113.1 for TAK‐875, TAK‐875‐acylglucuronide and IS, respectively. The assay showed good linearity over the tested concentration ranges (r > 0.9993), with the LLOQ being 0.5 ng/mL for both analytes. The extraction recovery was >78.45% and no obvious matrix effect was detected. The highly sensitive LC–MS/MS method has been further applied for the pharmacokinetic study of TAK‐875 and its toxic metabolite TAK‐875‐acylglucuronide in rat plasma. Pharmacokinetics results revealed that oral bioavailability of TAK‐875 was 86.85%. The in vivo exposures of TAK‐875‐acylglucuronide in terms of AUC_0–t were 17.54 and 22.29% of that of TAK‐875 after intravenous and oral administration, respectively.     

Studies on oral bioavailability and first‐pass metabolism of withaferin A in rats using LC–MS/MS and Q‐TRAP

Withaferin A (WA) is one of the major bioactive steroidal lactones with extensive pharmacological activities present in the plant Withania somnifera. The absolute oral bioavailability of WA remains unknown and human‐related in vitro data are not available. Therefore, in the present study, the absolute oral bioavailability of WA in male rats and the in vitro screening of absorption factors by Q‐trap and LC–MS/MS analysis were conducted to explore possible clinical properties of WA. The developed and validated analytical methods were successfully applied to the pharmacokinetic studies and in vitro measurement of WA. The oral bioavailability was determined to be 32.4 ± 4.8% based on intravenous (5 mg/kg) and oral (10 mg/kg) administrations of WA in male rats. The in vitro results showed that WA could be easily transported across Caco‐2 cells and WA did not show as a substrate for P‐glycoprotein. Moreover, the stability of WA was similar between male rat and human in simulated gastric fluid (stable), in intestinal microflora solution (slow decrease) and in liver microsomes (rapid depletion, with a half‐life of 5.6 min). As such, the first‐pass metabolism of WA was further verified by rat intestine‐liver in situ perfusion, revealing that WA rapidly decreased and 27.1% remained within 1 h, while the content of three major metabolites (M1, M4, M5) identified by Q‐trap increased. This perfusion result is consistent with the oral bioavailability results in vivo. The first‐pass metabolism of WA might be the main barrier in achieving good oral bioavailability in male rats and it is predicted to be similar in humans. This study may hold clinical significance.     

An LC‐MS/MS method for determination of curculigoside with anti‐osteoporotic activity in rat plasma and application to a pharmacokinetic study

A rapid, simple, selective and sensitive LC‐MS/MS method was developed for the determination of curculigoside in rat plasma. The analytical procedure involves extraction of curculigoside and syringin (internal standard, IS) from rat plasma with a one‐step extraction method by protein precipitation. The chromatographic resolution was performed on an Agilent XDB‐C₁₈ column (4.6 × 50 mm, 5 µm) using an isocratic mobile phase of methanol with 0.1% formic acid and H₂O with 0.1% formic acid (45:55, v/v) at a flow rate of 0.35 mL/min with a total run time of 2.0 min. The assay was achieved under the multiple‐reaction monitoring mode using positive electrospray ionization. Method validation was performed according to US Food and Drug Administration guidelines and the results met the acceptance criteria. The calibration curve was linear over 4.00–4000 ng/mL (R = 0.9984) for curculigoside with a lower limit of quantification of 4.00 ng/mL in rat plasma. The intra‐ and inter‐day precisions and accuracies were 3.5–4.6 and 0.7–9.1%, in rat plasma, respectively. The validated LC‐MS/MS method was successfully applied to a pharmacokinetic study of curculigoside in rats after a single intravenous and oral administration of 3.2 and 32 mg/kg. The absolute bioavailability of curculigoside after oral administration was 1.27%. Copyright © 2013 John Wiley & Sons, Ltd.     

Identification of the absorbed components and their metabolites of Tianma‐Gouteng granule in rat plasma and bile using ultra‐high‐performance liquid chromatography combined with quadrupole time‐of‐flight mass spectrometry

Tianma‐Gouteng granule (TGG), a Chinese herbal formula preparation, is clinically used for the treatment of cardio‐cerebrovascular diseases such as hypertension, cerebral ischaemia, acute ischaemic stroke and Parkinson's disease. Although few reports have been published concerning the absorbed prototype components of TGG, the possible metabolic pathways of TGG in vivo remain largely unclear. In this study, a method using UPLC–Q/TOF MS was established for the detection and identification of the absorbed prototype components and related metabolites in rat plasma and bile after oral administration of TGG at high and normal clinical dosages. A total of 68 components were identified or tentatively identified in plasma and bile samples, including absorbed prototypes and their metabolites. The major absorbed components were gastrodin, isorhynchophylline, rhynchophylline, isocorynoxeine, corynoxeine, geissoschizine methyl ether baicalin, baicalein, wogonoside, wogonin, geniposidic acid, leonurine, 2,3,5,4′‐tetrahydroxystilbene‐2‐O‐β‐d ‐glucoside and emodin. The main metabolic pathways of these components involved phase I (isomerization, hydrolysis and reduction) and phase II (glucuronidation and sulfation) reaction, and the phase II biotransformation pathway was predominant. The present study provides rich information on the in vivo absorption and metabolism of TGG, and the results will be helpful for further studies on the pharmacokinetics and pharmacodynamics of TGG.     

Plasma pharmacochemistry combined with microdialysis to screen potential bioactive components and their metabolites in Anemarrhena asphodeloides saponin extract using ultrahigh‐performance liquid chromatography/quadrupole‐time‐of‐flight mass spectrometry

Although various techniques have been employed to analyze drug metabolites, the metabolism of multicomponent herbal medicine has seldom been fully addressed. In contrast to chemical drugs, a number of compounds in herbal medicine could get into circulation and then be metabolized. Metabolism study on active constituents in herbal medicine is a good way for us to explain and predict a variety of events related to the efficacy and toxicity of herbal medicine. The present work aims to elucidate the multicomponent metabolic characteristics of a herbal medicine by the combination of plasma pharmacochemistry and microdialysis sampling. Anemarrhena asphodeloides, a well‐known traditional Chinese medicine, was chosen as a model. After oral administration of A. asphodeloides saponin extract to rats, microdialysis samples were collected continuously in the jugular vein and analyzed by ultrahigh‐performance LC/quadrupole‐TOF MS. The identification of compounds in biosamples was achieved by accurate mass measurement and detailed fragmentation pathway analysis. The results showed that unbound constituents in blood circulation of the rat included seven parent saponins and six metabolites, which might be the potential active components in vivo. Among which, three metabolites have not been previously reported and were identified in this study. It is the first report on systemic metabolism of total saponins of A. asphodeloides in mammalian plasma.     

Metabolism studies of casticin in rats using HPLC‐ESI‐MSn

Casticin (3′,5‐dihydroxy‐3, 4′,6,7‐tetramethoxyflavone) has been revealed to possess various kinds of pharmacological activities, including immunomodulatory, anti‐hyperprolactinemia, anti‐tumor and neuroprotetective activities. In order to gain an understanding of the biotransformation of casticin in vivo, a systematic method based on liquid chromatography–electrospray ionization tandem mass spectrometry (LC‐ESI‐MSⁿ) was developed to identify the metabolites of casticin in rats after oral administration of single dose of casticin at 200 mg/kg. By comparing their changes in molecular masses (ΔM), retention times and spectral patterns with those of the parent drug, the parent compound and 25 metabolites were identified in rat plasma, urine and six selected tissues. This is the first systematic metabolism study of casticin in vivo. The results indicated that methylation, demethylation, glucuronidation and sulfation were the main biotransformation pathways of casticin in vivo. Copyright © 2012 John Wiley & Sons, Ltd.     

An LC–MS/MS method for quantitation of cyanidin‐3‐O‐glucoside in rat plasma: Application to a comparative pharmacokinetic study in normal and streptozotocin‐induced diabetic rats

A sensitive and reliable liquid chromatography tandem mass spectrometry (LC–MS/MS) method was developed to determine cyanidin‐3‐O‐glucoside (Cy‐3G) in normal and streptozotocin‐induced diabetic rat plasma. Chromatographic separation was carried out on a Zorbax SB‐C₁₈ (50 × 4.6 mm, 5 μm) column and mass spectrometric analysis was performed using a Thermo Finnigan TSQ Quantum Ultra triple‐quadrupole mass spectrometer coupled with an ESI source in the negative ion mode. Selected reaction monitoring mode was applied for quantification using target fragment ions m/z 447.3 → 285.2 for Cy‐3G and m/z 463.0 → 300.1 for quercetin‐3‐O‐glucoside (internal standard). The calibration curve was linear over the range 3.00–2700 ng/mL (r² ≥ 0.99) with the lower limit of quantitation at 3.00 ng/mL. Intra‐ and inter‐day precision was <14.5% and mean accuracy was from −11.5 to 13.6%. Stability testing showed that Cy‐3G remained stable during the whole analytical procedure. After validation, the assay was successfully used to support a preclinical pharmacokinetic comparison of Cy‐3G between normal and diabetic rats. Results indicated that diabetes mellitus significantly altered the in vivo pharmacokinetic characteristics of Cy‐3G after oral administration in rats.     

Analysis of phenolic and triterpenoid compounds in licorice and rat plasma by high‐performance liquid chromatography diode‐array detection,time‐of‐flight mass spectrometry and quadrupole ion trap mass spectrometry

High‐performance liquid chromatography with diode‐array detection (HPLC/DAD), time‐of‐flight mass spectrometry (HPLC/TOFMS) and quadrupole ion trap mass spectrometry (HPLC/QITMS) were used for separation and identification of several compounds in licorice and rat plasma after oral administration of the herbal extract. Three phenolic compounds and one triterpenoid in licorice extract were unambiguously identified by comparing with the standard compounds. A formula database of known compounds in licorice was established, against which the other 42 compounds were identified effectively based on the accurate extract masses and formulae acquired by HPLC/TOFMS. In order to differentiate the isomers, tandem mass spectrometry was also used. The deduced fragmentation behaviors in QITMS were used to distinguish seven groups of isomers in licorice. By means of the three detectors, 46 compounds in licorice were identified. After oral administration of the extract, 25 compounds in rat plasma were detected and identified by comparing and contrasting the compounds measured in licorice with those in the plasma samples by HPLC/TOFMS. It is concluded that a rapid and effective method based on three analytical techniques was established, which is useful for identification of multiple compounds in licorice in vitro and in vivo. The result should be very useful for the quality control and curative mechanism study of licorice. Copyright © 2009 John Wiley & Sons, Ltd.     

Analysis of the metabolic profile of parishin by ultra‐performance liquid chromatography/quadrupole‐time of flight mass spectrometry

Parishin is a dominant active ingredient originating from Gastrodia elata Blume, and has good neuroprotective effects against brain disorders. In the present study, the metabolic profile of parishin by in vitro and in vivo experiments was investigated using ultra‐high performance liquid chromatography coupled with quadrupole–time of flight mass spectrometry (UHPLC/Q‐TOF MS) combined with an automated MS^E technique. By comparison with reference compounds, accurate mass measurement, the characteristic fragmentation patterns of the parent drug parishin and gastrodin and relevant bio‐transformation knowledge, 14 metabolites (seven hydrolyzates and seven derivatives of gastrodin) were detected and identified in rat plasma and urine after intragastric administration of parishin, including processes of hydrolyzation, oxidation, sulfation and glucuronidation. According to the proposed metabolic pathways of parishin, in vitro hydrolytic experiments and metabolic study of gastrodin in rat plasma, it can be inferred that parishin mainly functions as a prodrug and undergoes hydrolysis before being absorbed into the blood. The hydrolyzate, mainly gastrodin, was involved in further metabolism, which was responsible for pharmacological activities of parishin. In conclusion, this work provides valuable information on parishin metabolism using a rapid and reliable UHPLC/Q‐TOF MS method, which could be widely used for the metabolic investigation of natural product. Copyright © 2015 John Wiley & Sons, Ltd.     

Simultaneous determination of ascaridole,p‐cymene and α‐terpinene in rat plasma after oral administration of Chenopodium ambrosioides L. by GC‐MS

A sensitive and reliable GC‐MS method was developed and validated for the simultaneous determination of ascaridole, p‐cymene and α‐terpinene in rat plasma using naphthalene as internal standard. The plasma samples were extracted with ethyl acetate. Chromatographic separation was carried out on a HP‐5MS capillary analytical column (30 m × 0.25 mm, 0.25 µm) and detection was performed on a quadrupole mass spectrometer detector operated under selected ion monitoring mode. The method showed excellent linearity over the investigated concentration range (r > 0.99) with the limit of quantitation down to 50, 10 and 5 ng/mL for ascaridole, p‐cymene and α‐terpinene, respectively. The intra‐day and inter‐day precisions (RSD) were <11.3%, and the accuracy was between 90.7 and 113.8%. The method was successfully applied to investigate the pharmacokinetics of Chenopodium ambrosioides L. following oral administration to rats. Copyright © 2015 John Wiley & Sons, Ltd.     

In vitro and in vivo identification of metabolites of magnoflorine by LC LTQ‐Orbitrap MS and its potential pharmacokinetic interaction in Coptidis Rhizoma decoction in rat

Magnoflorine, an important aporphine alkaloid in Coptidis Rhizoma, is increasingly attracting research attention because of its pharmacological activities. The in vivo and in vitro metabolism of magnoflorine was investigated by LC LTQ‐Orbitrap MS. In vivo samples including rat urine, feces, plasma and bile were collected separately after both oral (50 mg kg^?1) and intravenous administration (10 mg kg^?1) of magnoflorine, along with in vitro samples prepared by incubating magnoflorine with rat intestinal flora and liver microsome. As a result, 12 metabolites were found in biological samples. Phase I metabolites were identified in all biological samples, while phase II metabolites were mainly detected in urine, plasma and bile. In a pharmacokinetic study, rats were not only dosed with magnoflorine via oral (15, 30 and 60 mg kg^?1) and intravenous administration (10 mg kg^?1) but also dosed with Coptidis Rhizoma decoction (equivalent to 30 mg kg^?1 of magnoflorine) by intragastric administration to investigate the interaction of magnoflorine with the rest of compounds in Coptidis Rhizoma. Studies showed that magnoflorine possessed lower bioavailability and faster absorption and elimination. However, pharmacokinetic parameters altered significantly (p < 0.05) when magnoflorine was administered in Coptidis Rhizoma decoction. Oral gavage of Coptidis Rhizoma decoction decreased the absorption and elimination rates of magnoflorine, which revealed that there existed pharmacokinetic interactions between magnoflorine and the rest of ingredients in Coptidis Rhizoma. Copyright © 2015 John Wiley & Sons, Ltd.     

Identification of metabolites of isopropyl 3‐(3,4‐dihydroxyphenyl)‐2‐hydroxypropanoate in rats by high‐performance liquid chromatography combined with electrospray ionization quadrupole time‐of‐flight tandem mass spectrometry

Isopropyl 3‐(3,4‐dihydroxyphenyl)‐2‐hydroxypropanoate (IDHP) is an investigational new drug having the capacity for treating ailments in the cardiovascular and cerebrovascular system. In this work, a rapid and sensitive method using high‐performance liquid chromatography coupled with electrospray ionization quadrupole time‐of‐flight tandem mass spectrometry (HPLC‐ESI‐Q‐TOF‐MS) was developed to reveal the metabolic profile of IDHP in rats after oral administration. The method involved pretreatment of the samples by formic acid–methanol solution (v/v, 5:95), chromatographic separation by an Agilent Eclipse XDB‐C₁₈ column (150 × 4.6 mm i.dx., 5 μm) and online identification of the metabolites by Q‐TOF‐MS equipped with electrospray ionizer. A total of 16 metabolites from IDHP, including four phase I metabolites and 12 phase II metabolites, were detected and tentatively identified from rat plasma, urine and feces. Among these metabolites, Danshensu (DSS), a hydrolysis product of IDHP, could be further transformed to 11 metabolites. These results indicated that DSS was the main metabolite of IDHP in rats and the major metabolic pathways of IDHP in vivo were hydrolysis, O‐methylation, sulfation, glucuronidation and reduction. The results also demonstrated that renal route was the main pathway of IDHP clearance in rat. The present study provided valuable information for better understanding the efficacy and safety of IDHP. Copyright © 2015 John Wiley & Sons, Ltd.     

In vivo metabolism study of vaccarin in rat using HPLC‐LTQ‐MSn

In order to illustrate the main biotransformation pathways of vaccarin in vivo, metabolites of vaccarin in rats were identified using a specific and sensitive high‐performance liquid chromatography–electrospray ionization linear ion trap mass spectrometry (LTQ XL?) method. The rats were administered a single dose (200 mg/kg) of vaccarin by oral gavage. By comparing their changes in molecular masses (ΔM), retention times and spectral patterns with those of the parent drug, the parent compound and six metabolites were found in rat urine after oral administration of vaccarin. The parent compound and five metabolites were detected in rat plasma. In heart, liver and kidney samples, respectively, one, four and three metabolites were identified, in addition to the parent compound. Three metabolites, but no trace of parent drug, were found in the rat feces. This is the first systematic metabolism study of vaccarin in vivo. The biotransformation pathways of vaccarin involved methylation, hydroxylation, glycosylation and deglycosylation. Copyright © 2012 John Wiley & Sons, Ltd.