Study on the pharmacokinetics, tissue distribution and excretion of laurolitsine from Litsea glutinosa in Sprague-Dawley rats.

CONTEXT: Laurolitsine is an aporphine alkaloid and exhibits potent antihyperglycemic and antihyperlipidemic effects in ob/ob mice. OBJECTIVE: To investigate the pharmacokinetics, tissue distribution and excretion of laurolitsine. MATERIALS AND METHODS: A LC-MS/MS method was established and validated to determine laurolitsine concentrations in the biological matrix of rats (plasma, tissue homogenate, urine and faeces). 10 Sprague-Dawley (SD) rats were used for plasma exposure study: 5 rats were injected with 2.0 mg/kg of laurolitsine via the tail vein, and the other 5 rats were administered laurolitsine (10.0 mg/kg) by gavage. 25 SD rats used for tissue distribution study and 5 SD rats for urine and faeces excretion study: rats administered laurolitsine (10.0 mg/kg) by gavage. After administered, serial blood, tissue, urine and faeces were collected. Analytical quantification was performed by a previous LC-MS/MS method. The pharmacokinetics, bioavailability, tissue distribution and excretion of laurolitsine were described. RESULTS: The pharmacokinetic parameters of oral and intravenous administration with Tmax were 0.47 and 0.083 h, t1/2 were 3.73 and 1.67 h, respectively. Oral bioavailability was as low as 18.17%. Laurolitsine was found at a high concentration in the gastrointestinal tract, liver, lungs and kidneys (26 015.33, 905.12, 442.32 and 214.99 ng/g at 0.5 h, respectively) and low excretion to parent laurolitsine in urine and faeces (0.03 and 1.20% in 36 h, respectively). CONCLUSIONS: This study established a simple, rapid and accurate LC-MS/MS method to determine laurolitsine in different rat samples and successful application in a pharmacokinetic study.

Pharmacokinetics, tissue distribution and excretion of 6-O-demethylmenisporphine, a bioactive oxoisoaporphine alkaloid from Menispermi Rhizoma, as determined by a HPLC-MS/MS method.

6-O-demethylmenisporphine, a major active oxoisoaporphine alkaloid isolated from Menispermi Rhizoma, has been confirmed to possess significant bioactivities, including anti-cancer and anti-hypoxia effects. However, few researches on quantifying 6-O-demethylmenisporphine in biosamples have been performed. In this research, a sensitive HPLC-MS/MS approach for determining 6-O-demethylmenisporphine in various biological matrices (plasma, tissue, urine, bile and feces) of rat has been constructed. Carbamazepine was chosen as the internal standard (IS). All biosamples were prepared using a simple one-step acetonitrile precipitation. A Capcell Pak C18 column coupled with an isocratic mobile phase consisted of acetonitrile (0.1% formic acid)-water (90:10, v/v), was employed to separate 6-O-demethylmenisporphine from endogenous interferences. Peak responses were detected by multiple reaction monitoring (MRM) transitions with m/z 308.0 â†’ 264.9 for 6-O-demethylmenisporphine and m/z 237.0 â†’ 194.1 for IS in positive-ion mode. The approach exhibited perfect linearity over a range of 5-2000 ng/mL for plasma and 2-1000 ng/mL for various tissue, urine, bile and feces. The lower limit of quantification (LLOQ) for analyte among different biological samples ranged from 2 ng/mL to 5 ng/mL. The newly established method was simple, efficient and sensitive, which was successfully applied to investigate the absorption, distribution, and excretion of 6-O-demethylmenisporphine after oral dosing to rats. The results indicated that 6-O-demethylmenisporphine could be well absorbed into blood circulation and widely distributed in various tissues after oral dosing, the oral bioavailability was up to 51.52%. Meanwhile, it was widely metabolized in vivo and eliminated as the metabolites, the unconverted form was excreted mainly by feces route. The bioavailability, tissue distribution and excretion characteristics of 6-O-demethylmenisporphine were firstly revealed, which will provide references for further development of 6-O-demethylmenisporphine as an anti-tumor drug candidate.

Advances in Chemistry and Bioactivity of Magnoflorine and Magnoflorine-Containing Extracts.

The review collects together some recent information on the identity and pharmacological properties of magnoflorine, a quaternary aporphine alkaloid, that is widely distributed within the representatives of several botanical families like Berberidaceae, Magnoliaceae, Papaveraceae, or Menispermaceae. Several findings published in the scientific publications mention its application in the treatment of a wide spectrum of diseases including inflammatory ones, allergies, hypertension, osteoporosis, bacterial, viral and fungal infections, and some civilization diseases like cancer, obesity, diabetes, dementia, or depression. The pharmacokinetics and perspectives on its introduction to therapeutic strategies will also be discussed.

HPLC-MS/MS method for the determination and pharmacokinetic study of six compounds against rheumatoid arthritis in rat plasma after oral administration of the extract of Caulophyllum robustum Maxim.

Caulophyllum robustum Maxim (CRM) is a well-known traditional Chinese medicine (TCM) mainly present in the northeast, northwest and southwest regions of China, which is belong to the family Berberidaceae. The roots and rhizomes of CRM have been used as a famous TCM for the treatment of rheumatoid arthritis (RA). The selective, sensitive and accurate high-performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS) method for the determination and pharmacokinetic study cauloside H, leonticin D, cauloside G, cauloside D, cauloside C and magnoflorine in rat plasma was developed and validated in this paper. Chromatographic separation was achieved by using a Waters ACQUITY UPLC HSS T3 (100 mm × 2.1 mm, 1.7 µm) with gradient elution using a mobile phase consisting of acetonitrile and 0.1 % formic acid in water at a flow rate of 0.4 mL/min. The detection was performed in multiple reaction monitoring (MRM) mode and electrospray ionization (ESI) in positive and negative modes. The linearity, precision, accuracy, extraction recovery, matrix effects and stability were assessed to validate the current high-performance liquid chromatography/mass spectrometry (HPLC-MS) assay. Good linearity was achieved for each analyte with a correlation coefficient (r2) > 0.99). All the precision (RSD) data were less than 12.20 %, the accuracies ranged from -12.39 % to 10.55 %, the recovery rates from the rat plasma ranged from 85.48%-98.69 %, and the matrix effects ranged from 80.96 % to 91.35 %. The validated approach was successfully applied to study the pharmacokinetic characteristics of saponins and alkaloids in plasma after administering CRME to rats, and this assay provides a platform for studying the active components of multicomponent traditional Chinese medicines and provides useful information for further clinical studies.

Magnoflorine: A review of its pharmacology, pharmacokinetics and toxicity.

Magnoflorine is an important quaternary aporphine alkaloid that is isolated from some commonly used herbal medicines (e.g., Sinomenium acutum (Thunb.) Rehder & E.H.Wilson and Coptis chinensis Franch.). In recent years, magnoflorine has received increasing attention due to its multiple pharmacological activities. This review provides the first comprehensive summary of the plant sources, pharmacological effects, toxicity, and pharmacokinetic characteristics of magnoflorine. The results indicated that magnoflorine possesses a wide spectrum of pharmacological properties, including anti-diabetic, anti-inflammatory, neuropsychopharmacological, immunomodulatory, hypotensive, antioxidant, and antifungal activities. Pharmacokinetic studies have shown that magnoflorine has low bioavailability and high absorption and elimination rates. However, the other compounds (e.g., berberine) present in herbal medicines could reduce the absorption and removal rates of magnoflorine and increase its bioavailability. Moreover, toxicity studies have suggested that magnoflorine is non-toxic to most cells. However, long-term and high-dose toxicity testing in animals is still lacking. In view of good pharmacological activities, magnoflorine is expected to be a potential drug candidate for the treatment of diabetes, depression, or Alzheimer's disease. However, further studies are needed to elucidate its molecular mechanisms and targets, clarify its toxicity, and improve its oral bioavailability.

Simultaneous determination of multiple components in rat plasma and pharmacokinetic studies at a pharmacodynamic dose of Xian-Ling-Gu-Bao capsule by UPLC-MS/MS.

Xian-Ling-Gu-Bao capsule (XLGB) is an effective traditional Chinese medicine prescription (TCMP) that is used for the prevention and treatment of osteoporosis in China. A rapid, simple, efficient and stable method based on UPLC-MS/MS technology was developed for simultaneous determination of multiple components of XLGB in rat plasma. Mass spectrometric detection was performed in multiple reaction monitoring (MRM) mode with electrospray ionization (ESI). For twenty-one selected quantitative prototypes, all calibration curves showed favourable linearity (r>0.9932) in linear ranges. The lower limits of quantification (LLOQs) were 2 ng/mL for psoralen (PL), 2.5 ng/mL for asperosaponin VI (AS), 1 ng/mL for isopsoralen (IPS) and sweroside (SW), 0.5 ng/mL for magnoflorine (MA), bavachinin (BVN), tanshinone IIA (TA), timosaponin BII (TBII) and icaritin (ICT), 0.1 ng/mL for epimedin B (EB) and epimedin C (EC), 0.05 ng/mL for icariin (IC), isobavachalcone (IBC), psoralidin (PD), bavachin (BV), bavachalcone (BC), epimedin A (EA) and isobavachin (IBV), 0.02 ng/mL for neobavaisoflavone (NEO) and icariside I (ICI) and 0.01 ng/mL for icariside II (ICII). The intra-day and inter-day (low, medium, high) precision (relative standard deviation) for all analytes was less than 8.63%, and the accuracies (as relative error) were in the range of -12.45% to 8.91%. Extraction recoveries and matrix effects of analytes and IS were acceptable. All analytes were stable during the assay and storage in plasma samples. The validated method was successfully applied to the pharmacokinetics (PK) studies of the twenty-one prototypes at pharmacodynamic doses (0.3 and 1 g/kg/day). In addition, dynamic profiles of 28 metabolites (phase II conjugates: 23 glucuronide conjugates, 2 sulfate conjugates and 3 glucuronide or sulfate conjugates) were also monitored by their area/IS area-time curves. As a result, coumarins, prenylated flavonoids from Psoraleae Fructus, alkaloids and prenylated flavonol glycosides from Epimedii Herba, and iridoid glycosides, triterpenoid saponins from Dipsaci Asperoidis Radix were considered to be the key effective substances of XLGB due to their high exposure and appropriate pharmacokinetic features. This is the first report to reveal pharmacodynamic ingredients by a reversed pharmacodynamic (PD) - pharmacokinetics (PK) study.

Establishment of modified biopharmaceutics classification system absorption model for oral Traditional Chinese Medicine (Sanye Tablet).

ETHNOPHARMACOLOGICAL RELEVANCE: As one of the new drugs of traditional Chinese medicine, Sanye Tablet is employed as a hypolipidemic in the traditional medicine, but the biopharmaceutical properties of the drug is still unclear. AIM OF THE STUDY: Through the study of biopharmaceutical properties, the classical biopharmaceutics classification system (BCS) can be used to classify and predict the in vivo absorption properties. On this basis, the biopharmaceutical properties closely related to traditional Chinese medicine preparations are added and a modified BCS model is established to predict and judge the absorption degree of traditional Chinese medicine compound. MATERIALS AND METHODS: Representative components of Sanye Tablet were selected and subjected to different in vitro tests. The experimental results were compared with the results of the BCS to evaluate the accuracy and applicability to Sanye Tablet. We take parameters of dissolution and stability based on product characteristics into account. A "modified-BCS" was developed and the results of the improved method and the classic method were compared. Also the ability of each classification system to predict and determine the extent of absorption of the Chinese herbal compound was investigated based on the absolute bioavailability of representative components. RESULTS: For classic BCS, the five representative components (except for nuciferine) are all class III, nuciferine is class I/II obtained by Caco-2 cell assay and class III/IV obtained by everted gut sac assay. For modified BCS, paeoniflorin is class III, rutin, hyperoside and salvianolic acid B are class III/IV, and nuciferine is class I/II based on Caco-2 cell assay, class III/IV based on everted gut sac assay. Nuciferine is the best of the five components, with absolute bioavailability reaching 61.91% based on in vivo bioavailability test. CONCLUSIONS: The five representative components (except for nuciferine) are all class III/IV, which correlates well with the absolute bioavailability results and demonstrates that they are poorly absorbed substances. The correlation between the classification results obtained using the "modified-BCS" and absorption in the body is better than the correlation obtained using the classic method, suggesting that the improved BCS is more suitable for the characterization of Sanye Tablet. These results indicate that the oral formulation of Sanye Tablet is a BCS III/IV drug.

Pharmacokinetics, tissue distribution, bioavailability, and excretion of nuciferine, an alkaloid from lotus, in rats by LC/MS/MS.

OBJECTIVE: In order to characterize the pharmacokinetics, tissue distribution, bioavailability, and excretion of nuciferine, a reliable gradient LC/MS/MS-based method was developed and validated. METHODS: Sprague-Dawley rats were intravenously injected with a bolus of nuciferine (0.2 mg/kg) and orally given a single dose of nuciferine (10.0 mg/kg). Blood samples were withdrawn via the ocular vein at specific times. Organs, including the liver, kidney, brain, lung, heart, and spleen, were collected at specific times after oral administration of 10.0 mg/kg nuciferine. The plasma and tissue samples were assayed by LC/MS/MS. RESULTS: The results indicated that nuciferine had rapid distribution and poor absorption into systemic circulation. The value of absolute bioavailability was only 1.9 ± 0.8% after administration of 10.0 mg/kg nuciferine by oral and administration of 0.2 mg/kg nuciferine intravenously (IV) to rats. The AUC0→4 h values in tissues were in the order of kidney > lung > spleen > liver > brain > heart. The majority of excretion of nuciferine (50.7%) was excreted through kidneys with parent drug after oral administration without liver metabolism. CONCLUSION: This study may provide a meaningful basis for clinical application of such a bioactive compound of herbal medicines.

Identify super quality markers from prototype-based pharmacokinetic markers of Tangzhiqing tablet (TZQ) based on in vitro dissolution/ permeation and in vivo absorption correlations.

BACKGROUND: A quality marker (Q-marker) is defined as an inherent chemical compound that is used for the quality control of a drug. Its biological activities are closely related to safety and therapeutic effects. Generally, a multiple-component herbal medicine may have many Q-markers. We therefore proposed a concept of "super Q-marker" satisfying both the criterion of Q-markers and PK-markers to be used in more effective quality control of herbal medicine. PURPOSE: The first aim was to find suitable prototype-based PK-markers from Tangzhiqing tablets (TZQ), a Chinese patent medicine. Then super Q-markers were expected to be identified from the prototype-based PK-markers based on an in vitro-in vivo correlation study. METHODS: Potentially eligible prototype-based PK-markers were identified in a single- and multiple-dose pharmacokinetic study on TZQ in 30 healthy volunteers. The in vitro dissolution and permeation profiles of the prototype-based PK-markers of TZQ were evaluated by the physiologically-based drug dissolution/absorption simulating system (DDASS). An in vitro-in vivo correlation analysis was conducted between the dissolution/permeation behaviors in DDASS and the actual absorption profiles in human to test the transferability and traceability of the promising super Q-markers for TZQ. RESULTS: In human, plasma paeoniflorin and nuciferine as prototype-based PK-markers exhibited the appropriate pharmacokinetic properties, including dose-dependent systemic exposure (AUC, Cmax) and a proper elimination half-life (1∼3h). In DDASS, it was predicted that paeoniflorin and nuciferine are highly permeable but the absorption rates are primarily limited by the dissolution rates. Moreover, the established in vitro-in vivo correlations of paeoniflorin and nuciferine were in support of the super Q-markers features. CONCLUSION: Paeoniflorin and nuciferine are identified as the super Q-markers from the prototype-based PK-markers of TZQ based on findings from a combination of in vitro, in vivo, and in vitro-in vivo correlation studies. This method is practical for optimal identification of qualified Q-markers, thus helping improve the quality control of herbal medicines.

In Vitro Intestinal Absorption and Metabolism of Magnoflorine and its Potential Interaction in Coptidis Rhizoma Decoction in Rat.

BACKGROUND AND OBJECTIVES: In our previous studies, it was found that there existed pharmacokinetic interactions between magnoflorine and the rest of the ingredients in Coptidis Rhizoma. In this study, the pharmacokinetic interaction mechanism of magnoflorine with the rest of the components in Coptidis Rhizoma was researched based on the intestinal absorption and metabolism characteristics. METHODS: The absorption characteristics of magnoflorine in each rat intestinal segments were evaluated by non-everted intestinal sac model. To identify the metabolites of magnoflorine, the acceptor solutions of each intestinal segment at 120 min were analyzed by HPLC-LTQ-Orbitrap MS. RESULTS: The accumulative absorption (Q), the absorption rate (J) and the apparent permeability coefficient (P app) of magnoflorine were increased in duodenum, jejunum, ileum and colon of the Coptidis Rhizoma group as compared to the magnoflorine group, but there was no statistical difference between the two groups (P > 0.05). Four phase I metabolites of magnoflorine were identified in intestinal acceptor solutions of pure compound, while eight metabolites were detected in that of Coptidis Rhizoma decoction including six phase I metabolites and two phase II metabolic products. CONCLUSIONS: It was shown that the rest of the ingredients in Coptidis Rhizoma accelerated the absorption of magnoflorine weakly and promoted the metabolism of magnoflorine in the gut. The effects of other processes in the pharmacokinetics should be further evaluated.

Pharmacokinetics of boldine in control and Mrp2-deficient rats.

The aim of the present study was to describe the currently poorly understood pharmacokinetics (PK) of boldine in control rats (LW, Lewis rats), and Mrp2 transporter-deficient rats (TR(-)). Animals from the LW and TR(-) groups underwent a bolus dose study with 10 mg/kg of boldine applied either orally or intravenously in order to evaluate the major PK parameters. The TR(-) rats demonstrated significantly reduced total clearance with prolonged biological half-life (LW 12+/-4.6 versus TR(-) 20+/-4.4 min), decreased volume of distribution (LW 3.2+/-0.4 l/kg versus TR(-) 2.4+/-0.4 l/kg) and reduced bioavailability (LW 7 % versus TR(-) 4.5 %). Another set of LW and TR(-) rats were used for a clearance study with continuous intravenous administration of boldine. The LW rats showed that biliary and renal clearance formed less than 2 % of the total clearance of boldine. The treatment of samples with beta-glucuronidase showed at least a 38 % contribution of conjugation reactions to the overall clearance of boldine. The TR(-) rats demonstrated reduced biliary clearance of boldine and its conjugates, which was partly compensated by their increased renal clearance. In conclusion, this study presents the PK parameters of boldine and shows the importance of the Mrp2 transporter and conjugation reactions in the elimination of the compound.

Pharmacokinetics of a multicomponent herbal preparation in healthy Chinese and African volunteers.

K-601 is an herbal formulation for influenza consisting of Lonicera japonica, Isatis indigotica, Rheum palmatum, Phellodendron chinense, and Scutellaria baicalensis. In this work, we characterized the chemical constituents in K-601, identified the absorbed compounds and determined their pharmacokinetics in 6 Chinese and African volunteers by liquid chromatography with time-of-flight mass spectrometry. Similarity evaluation for chromatographic fingerprint of nine different batches showed values above 0.983. Totally, 50 components were identified in K-601. Then, 15 major prototype compounds and 17 metabolites were identified in human plasma. Major metabolic pathways included glucuronidation, sulfation, methylation, demethylation, and reduction. The pharmacokinetics of the most abundant prototype compounds, berberine, jatrorrhizine, palmatine and magnoflorine were determined. Significant pharmacokinetic differences were observed between the African and Chinese subjects. The AUCs of the African is about 4-10 fold higher than that of the Chinese for the three benzylisoquinoline alkaloids. Magnoflorine, an aporphine alkaloid, was absorbed better in the Chinese than in the African. The biotransformation of K-601 by human intestinal microflora was also investigated. The major reactions included hydroxylation, methylation, demethylation, acetylation and reduction. Glucuronidation and sulfation were not observed with fecal flora. These results may be important and useful in linking data from pharmacological assays and clinical effects.

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.

A novel UPLC-MS/MS method for sensitive quantitation of boldine in plasma, a potential anti-inflammatory agent: application to a pharmacokinetic study in rats.

Boldine is a potential anti-inflammatory agent found in several different plants. Published bioanalytical methods using HPLC with ultraviolet and fluorescent detection lacked enough sensitivity and required tedious sample preparation procedures. Herein, we describe the development of a novel ultra-high performance LC with MS/MS for determination of boldine in plasma. Boldine in plasma was recovered by liquid-liquid extraction using 1 mL of methyl tert-butyl ether. Chromatographic separation was performed on a C18 column at 45°C, with a gradient elution consisting of acetonitrile and water containing 0.1% (v/v) formic acid at a flow rate of 0.3 mL/min. The detection was performed on an electrospray triple-quadrupole MS/MS by positive ion multiple reaction monitoring mode. Good linearity (r(2) > 0.9926) was achieved in a concentration range of 2.555-2555 ng/mL with a lower limit of quantification of 2.555 ng/mL for boldine. The intra- and inter-day precisions of the assay were 1.2-6.0 and 1.8-7.4% relative standard deviation with an accuracy of -6.0-8.0% relative error. This newly developed method was successfully applied to a single low-dose pharmacokinetic study in rats and was demonstrated to be simpler and more sensitive than the published methods, allowing boldine quantification in reduced plasma volume.

Boldine Ameliorates Vascular Oxidative Stress and Endothelial Dysfunction: Therapeutic Implication for Hypertension and Diabetes.

Epidemiological and clinical studies have demonstrated that a growing list of natural products, as components of the daily diet or phytomedical preparations, are a rich source of antioxidants. Boldine [(S)-2,9-dihydroxy-1,10-dimethoxy-aporphine], an aporphine alkaloid, is a potent antioxidant found in the leaves and bark of the Chilean boldo tree. Boldine has been extensively reported as a potent "natural" antioxidant and possesses several health-promoting properties like anti-inflammatory, antitumor promoting, antidiabetic, and cytoprotective. Boldine exhibited significant endothelial protective effect in animal models of hypertension and diabetes mellitus. In isolated thoracic aorta of spontaneously hypertensive rats, streptozotocin-induced diabetic rats, and db/db mice, repeated treatment of boldine significantly improved the attenuated acetylcholine-induced endothelium-dependent relaxations. The endothelial protective role of boldine correlated with increased nitric oxide levels and reduction of vascular reactive oxygen species via inhibition of the nicotinamide adenine dinucleotide phosphate oxidase subunits, p47 and nicotinamide adenine dinucleotide phosphate oxidase 2, and angiotensin II-induced bone morphogenetic protein-4 oxidative stress cascade with downregulation of angiotensin II type 1 receptor and bone morphogenetic protein-4 expression. Taken together, it seems that boldine may exert protective effects on the endothelium via several mechanisms, including protecting nitric oxide from degradation by reactive oxygen species as in oxidative stress-related diseases. The present review supports a complimentary therapeutic role of the phytochemical, boldine, against endothelial dysfunctions associated with hypertension and diabetes mellitus by interfering with the oxidative stress-mediated signaling pathway.

A sensitive liquid chromatography-tandem mass spectrometry method for pharmacokinetics and tissue distribution of nuciferine in rats.

Nuciferine is an important drug candidate for the treatment of obesity-related diseases. However, few investigations have been conducted about the pharmacokinetics and tissue distribution of nuciferine to better understand its behavior and action mechanism in vivo. Thus, a sensitive and reliable liquid chromatography with tandem mass spectrometry (HPLC-MS/MS) method was established and validated for the quantification of nuciferine in rat plasma and tissue samples. The validated method was successfully applied to the pharmacokinetic and tissue distribution study of nuciferine in rats. One-compartmental pharmacokinetic parameters indicated that nuciferine had rapid distribution, extensive tissue uptake, and poor absorption into systemic circulation. The values of absolute bioavailability were (3.8±1.4)%, (4.2±1.3)% and (3.9±1.0)% after oral administration of 2.0, 5.0 and 10.0mg/kg nuciferine and intravenous administration of 0.2mg/kg nuciferine in rats. The results of the tissue distribution study suggested that nuciferine was distributed into the brain, liver and adipose tissue after intravenous administration. In conclusion, the present study may provide a material basis for study of the pharmacological action of nuciferine in the treatment of obesity, and meaningful insights into further study on dosage modification.

Study on the PK profiles of magnoflorine and its potential interaction in Cortex phellodendri decoction by LC-MS/MS.

Magnoflorine, an aporphine alkaloid in Cortex phellodendri, is increasingly attracting research attention because of its antidiabetic effects. However, at present, little information on its pharmacokinetics (PK) in vivo is available. In this study, a sensitive, rapid, and selective method was developed to determine the magnoflorine content in rat plasma using liquid chromatography-tandem mass spectrometry. Following liquid-liquid extraction, the calibration curve showed good linearity within the concentration range of 2.93 to 1,500 ng ml(-1). The intra- and inter-day precisions were all below 7.8 %, and the accuracy ranged from 94.9 to 103.4 %. The method was successfully applied in investigating the PK of magnoflorine in rats. The compound had low bioavailability, a high absorption rate, and a high elimination rate. However, area under the curve, T 1/2, and MRT increased approximately twofold when the same dosage of the compound was administered in a C. phellodendri decoction (20.8 g kg(-1)). Moreover, T max was prolonged from 0.3 to 3.33 h. Furthermore, a comparison of coadministration of the mixture group, magnoflorine (40 mg kg(-1)) and berberine (696.4 mg kg(-1)), with the C. phellodendri decoction group, revealed that no statistical difference (P > 0.05) was found in the parameter AUC, and certain similar changes in the PK trend to the herbal medicine group were also observed. These results suggested that oral administration of the herbal medicine decreased the absorption and elimination rates of magnoflorine and increased its bioavailability. Berberine played a significant role in interacting with magnoflorine and in affecting the PK profiles of magnoflorine in the C. phellodendri decoction group.

Development of an HPLC fluorescence method for determination of boldine in plasma, bile and urine of rats and identification of its major metabolites by LC-MS/MS.

Boldine belongs to the group of aporphine alkaloids isolated from Boldo tree. In contrast with numerous reports on the pharmacological effects of boldine, the data about its pharmacokinetics and biotransformation are scarce. No validated bioanalytical method of sufficient sensitivity has so far been described in the literature which could be used for quantification of boldine in various body fluids collected in pharmacokinetic studies. This work presents, for the first time, the assay for boldine in the plasma, bile and urine of rats. It includes liquid-liquid extraction/back-extraction of boldine, its chromatographic separation and sensitive fluorescence detection. Separation was carried out on a pentafluorophenyl core-shell column (Kinetex PFP, 150×3mm, 2.6µm) in gradient elution mode with solvent system consisting of an acetonitrile-ammonium formate buffer (5mM, pH=3.8). Fluorimetric detection (λEX=320nm, λEM=370nm) was used for quantitative work. Validation according to the EMEA guideline proved the assay LLOQ (0.1µmolL(-1)), linearity over a broad range of 0.1-50µmolL(-1), precision (intra- and inter-day CVs less than 4.5% and 6.1%, respectively) and accuracy (relative errors between -5.8% and 4.8%). In a pilot pharmacokinetic experiment, the concentration-time profiles were described for boldine (single i.v. bolus 50mgkg(-1)) in plasma and bile and cumulative excretion in urine was investigated. The major metabolites identified by means of LC-MS(n) were boldine-O-glucuronide, boldine-O-sulphate and disulphate, boldine-O-glucuronide-O-sulphate and N-demethyl-boldine-O-sulphate.

Studies on the in vivo contribution of human cytochrome P450s to the hepatic metabolism of glaucine, a new drug of abuse.

Glaucine ((S)-5,6,6a,7-tetrahydro-1,2,9,10-tetramethoxy-6-methyl-4H-dibenzo [de,g]quinoline), main isoquinoline alkaloid of Glaucium flavum (Papaveraceae), is used as antitussive, but also as recreational drug of abuse. Glaucine was mainly metabolized by O- and N-demethylation to four isomers in rats. So far, only scarce pharmacokinetic data were available. Therefore, the aim of the presented study was to assess the involvement of the ten most important cytochrome P450 (P450) isoforms in the main metabolic steps and determination of their kinetic parameters using the metabolite formation approach. Reference standards of investigated metabolites were synthesized for quantification. In addition, the impact of isomeric standards was tested for calibration and the use of simple peak area ratios on the kinetic constants and resulting contribution of P450 isoforms on estimated hepatic clearance. Kinetic profiles of all metabolite formations followed classic Michaelis-Menten behavior. Km values were between 25 and 140µM, Vmax between 0.10 and 1.92pmol/min/pmol. Using the relative activity factor approach, the hepatic clearance was calculated to be 27 and 73% for 2-O-demethylation by CYP1A2 and CYP3A4, 82, 3, and 15% for 9-O-demethylation by CYP1A2, CYP2C19, and CYP2D6, and finally <1 and 99% for N-demethylation by CYP2D6 and CYP3A4. These data were confirmed by inhibition tests. The calibration mode for determination of the metabolite concentrations had no relevant impact on the estimation of in vivo hepatic clearance of glaucine. As glaucine was metabolized via three initial steps and different P450 isoforms were involved in the hepatic clearance of glaucine, a clinically relevant interaction with single inhibitors should not be expected.

Development and validation of a high-performance liquid chromatography coupled with ultraviolet detection method for the determination of isocorydine in rat plasma and its application in pharmacokinetics.

A new HPLC-UV method has been developed, validated and applied for the determination of isocorydine (CAS 475-67-2) in rat plasma after oral or intravenous (i. v.) administration. Caffeine was used as the internal standard (IS). The analyte and IS were extracted from rat plasma by liquid-liquid extraction (LLE) with methyl tert-butyl ether and they were separated on an XTerra C18 column (250×4.6 mm, 5 µm, pH 1-12) with UV detection at 264 nm. The mobile phase consisted of methanol and 0.02 mol/L potassium dihydrogen phosphate-phosphoric acid buffer solution (pH 3.2) (30:70, v/v) at a flow rate of 1 mL/min for 8.5 min. The retention times of isocorydine and caffeine were approximately 6.5 and 5.1 min, respectively. The good linearity of the calibration curves was observed over the concentration range of 0.05-8 µg/mL (n=8, r 2≥0.9995). The lower limit of quantification (LLOQ) was 0.05 µg/mL [signal to noise ratio (S/N)≥10], and the limit of detection (LOD) was demonstrated as 0.01 µg/mL (S/N≥3). The mean extraction recovery ranged from 83.7% to 89.5% at 3 quality control (QC) concentrations. Intra-day and inter-day precision (relative standard deviation, RSD%) were within 4.7% and accuracy (relative error, RE%) ranged from -1.2% to 4.5%. The developed method was successfully applied to determination of the pharmacokinetic properties of isocorydine in rats after oral administration at a dose of 20 mg/kg and i. v. injection at 5 mg/kg.