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.

Acute toxicity and metabolism of arsenocholine in mice

The acute toxicity of arsenocholine was examined in mice by oral administration and intravenous injection. The LD₅₀ values of arsenocholine were 6.5 g kg^?1 for oral administration and 187 mg kg^?1 for oral administration and 187 mg kg^?1 for intravenous injection. Decreases of respiration and spontaneous motility were observed in the mice dosed orally at 12 g kg^?1. The animals exhibited ataxia and finally showed paralysis of the hind legs within 20 min of administration. When arsenocholine was administered orally to mice at 5 or 50 mg As kg^?1, the greater part of the arsenic administered was recovered in urine within 96 h. The metabolite of arsenocholine in urine was identified as arsenobetaine by high-performance liquid chromatography-inductively coupled plasma emission spectrometry (HPLC ICP) and fast atom bombardment mass spectrometry (FAB MS). These results suggested that the major part of orally administered arsenocholine was absorbed from the gastrointestinal tract in mice and then rapidly excreted in urine with biotransformation.     

Metabolic characteristics and pharmacokinetic differences of Qiwei Tongbi oral liquid in rheumatoid arthritis rats

Qiwei Tongbi oral liquid (QWTB), a classical traditional Chinese medicine formula, is widely used to treat arthritis-related diseases in clinical practice. Currently, in vivo metabolic characteristics and pharmacokinetic studies are lacking. This study analyzed the prototype components of QWTB absorbed in the blood and their metabolic transformation process after intragastric administration and compared the differences in pharmacokinetic properties between healthy and rheumatoid arthritis model rats. In sum, 17 prototype components and 21 related metabolites were identified in the plasma and urine of the treated rats. Metabolites were derived from sinomenine and magnoflorine. Through systematic methodology verification, an accurate and stable detection method for sinomenine and magnoflorine in plasma samples was established and applied to pharmacokinetic research of QWTB. At the three dose levels, the AUC_0–∞ (area under the curve) of the two components showed a good positive correlation with the dose (R² > 0.9). Compared with healthy rats, the T_max, t_1/2z, and AUC of sinomenine were markedly increased, and C_max was decreased in rheumatoid arthritis model rats, indicating that the rate of absorption and elimination rate decreased, but the body exposure increased. However, there were no significant differences in the pharmacokinetic parameters of magnoflorine under healthy and pathological conditions. In summary, the main active ingredients of QWTB are sinomenine and magnoflorine, which exhibit linear kinetic characteristics within a set dose range, and the rheumatoid arthritis pathological state is more conducive to the absorption and efficacy of sinomenine. The results of this study demonstrate the rationality of the clinical application of the QWTB.     

Biodegradation of imidacloprid in sandy loam soil by Bacillus aerophilus

A study of the biodegradation of imidacloprid in soil was carried out under laboratory conditions. Sandy soil samples were fortified with imidacloprid at 50, 100 and 150 mg kg^?1 along with 45 x 10⁷ colony forming units (cfus) of Bacillus aerophilus and the samples were compared with unamended soil. The samples were extracted with acetonitrile, cleaned up by treatment with primary secondary amine sorbent and graphitised carbon black. The residues of imidacloprid and its metabolites were analysed by high performance liquid chromatography. The parent compound, imidacloprid, was found to be more persistent in both the treatments. Among metabolites, the highest values were obtained for urea and olefin while 5-hydroxy, 6-chloronicotinic acid (6-CNA), nitrosimine and nitroguanidine (NTG) were also observed in all the treatments in amended soil. In case of unamended (control) soil, 6-CNA was found to be the most persistent metabolite followed by olefin, urea, 5-hydroxy, nitrosimine and NTG metabolites. Total imidacloprid residues for control soil samples followed first-order kinetics at 50 and 150 mg kg^?1 but in case of control imidacloprid fortified at 100 mg kg^?1, the total residues of imidacloprid and its metabolites followed pseudo-first-order kinetics. The respective half-life value for 50 mg kg^?1 was 25.08 days and 30.10 days for both 100 and 150 mg kg^?1. However, total imidacloprid residues followed pseudo-first-order kinetics for its applications at 50, 100 and 150 mg kg^?1 in sandy loam soil amended with B. aerophilus. The half-life values for 50, 100 and 150 mg kg^?1 were worked out to be 14.33, 15.05 and 18.81 days, respectively. With the use of B. aerophilus, the reduction percentage of initial applied dose imidacloprid in sandy loam soil was found to be higher in all the three doses as compared to that of the control samples.     

Detection and Identification of Dizocilpine and its Major Urinary Metabolites in the Horse: A Preliminary Report

Dizocilpine ([+]-10,11-dihydro-5-methyl-5H-dibenzo[a,d]cyclohepten-5,10-imine), is a potent and selective NMDA (N-methyl-D-aspartate) receptor antagonist, which acts by blocking receptor ion channels. Dizocilpine is pharmacologically related to ketamine and phencyclidine; as such, it has the potential to affect behavior and performance in horses, with particular efficacy at lower concentrations. We now report development of a sensitive method for the detection of dizocilpine and preliminary characterization of its urinary metabolites in the horse. Dizocilpine (MW 221) readily produces a protonated species [M+H]⁺ in formic acid, and yields a m/z 205 product ion in Multiple Reaction Monitoring (MRM), allowing highly sensitive detection of parent drug. The 17 AMU loss most likely represents an unusual loss of CH₅ from the exocyclic methyl group. No unchanged dizocilpine was identified in unhydrolysed urine, and the presence of hydroxymethyl and carboxydizocilpine glucuronide metabolites were supported by observation of m/z 414→238 and 428→235 transitions. Urine samples from horses dosed with dizocilpine (0.0132 and 0.0656 mg kg^?1, iv) were hydrolysed with glucuronidase and were found to contain dizocilpine and OH-dizocilpine. Tentatively identified phase I post-hydrolysis compounds include dizocilpine itself, an hydroxymethyl metabolite, two ring-hydroxylated metabolites, a di-hydroxy metabolite, and a carboxy-dizocilpine metabolite. Corresponding Phase II glucuronidated metabolites were also identified as well as a number of combination metabolites and a posssible n-glucuronide metabolite for a total of at least six identifiable urinary glucuronide metabolites. Among the phase I metabolites, the hydroxymethyl metabolite apparently predominated, especially at the 0.0132 mg kg^?1 dose. The goal of this research was to identify a target analyte for dizocilpine in post-administration equine urine, so that work may begin on development of a forensically validated qualitative method for this target analyte. Given the likelihood that the doses of dizocilpine used in attempts to influence the behavior or performance of horses, either alone or in combination with other agents, are expected to be in the order of 0.02 mg kg^?1 or less, these results suggest selection of the phase I hydroxymethyl metabolite of dizocilpine as the optimal target analyte for regulatory control of dizocilpine in performance horses.     

An LC–MS/MS method for the quantification of diclofenac sodium in dairy cow plasma and its application in pharmacokinetics studies

An LC–MS/MS method with internal standard tolfenamic acid for determining diclofenac sodium (DCF) in dairy cow plasma was developed and validated. Samples were processed with protein precipitation by cold formic acid–acetonitrile. Determination of DCF was performed using LC–ESI⁺–MS/MS with the matrix‐matched calibration curve. The results showed that the method was sensitive (LOD 2 ng mL^?1, LOQ 5 ng mL^?1), accurate (97.60 ± 5.64%), precise (<10%) and linear in the range of 5–10,000 ng mL^?1. A single intravenous (i.v.) or intramuscular (i.m.) administration of 5% diclofenac sodium injection at a dose of 2.2 mg kg^?1 was performed in six healthy dairy cows according to a two‐period crossover design. The main pharmacokinetic (PK) parameters after a single i.v. administration were as follows: t_1/2β, 4.52 ± 1.71 h; AUC, 77.79 ± 16.76 h μg mL^?1; mean residence time, 5.16 ± 1.11 h. The main PK parameters after a single i.m. administration were as follows: T_max, 2.38 ± 1.19 h; C_max, 7.46 ± 1.85 μg mL^?1; t_1/2β, 9.46 ± 2.86 h; AUC 67.57 ± 13.07 h μg mL^?1. The absolute bioavailability was 87.37 ± 5.96%. The results showed that the diclofenac sodium injection had PK characteristics of rapid absorption and slow elimination, and high peak concentration and bioavailability in dairy cows, and that the recommended clinical dosage of diclofenac sodium injection is 2.2 mg kg^?1.     

Systematic screening and characterization of absorbed constituents and in vivo metabolites in rats after oral administration of Rhizoma coptidis using UPLC-Q-TOF/MS

Rhizoma coptidis has been used for a long time in China owing to its anti-bacterial, anti-diabetes, anti-hyperlipidemia and anti-obesity activities. However, the in vivo biotransformation of Rhizoma coptidis is still unclear to date. In this study, a three-step strategy using UPLC-Q-TOF/MS was applied to clarify the in vivo absorbed constituents and metabolites in rats after oral administration of Rhizoma coptidis. First, alkaloids in Rhizoma coptidis extract were identified. Second, six abundant alkaloids (berberine, palmatine, coptisine, epiberberine, jatrorrhizine, and columbamine) were selected as representative prototypes and the metabolic fates of them in rats were investigated to obtain a database of Rhizoma coptidis-derived metabolites. Finally, the metabolic profiles of Rhizoma coptidis were fully elucidated based on the above-mentioned results. In summary, 29 alkaloids were identified in Rhizoma coptidis, and a database of Rhizoma coptidis-derived metabolites was obtained with 144 characterized metabolites. A total of 89 xenobiotics including 12 absorbed constituents and 77 metabolites were identified in dosed rat biosamples. Major metabolic pathways of Rhizoma coptidis were hydroxylation, reduction, methylation, demethylation, demethylenation, desaturation, glucuronidation and sulfation. This is the first systematic study on the in vivo absorbed constituents and metabolic profiling of Rhizoma coptidis and will be beneficial for its further studies.     

Analysis of tributyltin in estuarine sediments and oyster tissue,Crassostrea virginica

An analytical method to determine tributyltin (TBT) in oyster tissue, Crassostrea virginica, and estuarine sediments is described. Recoveries of TBT from oysters range from 86 to 102% when samples are fortified at concentrations ranging from 22 to 890 μg kg^?1 (wet weight); recoveries from sediment range from 92 to 105% for samples fortified from 20 to 500 μg kg^?1 (dry weight). Feral oysters and natural sediments were analysed and shown to be contaminated with TBT. Oysters collected near a marina contained concentrations as high as 1.5 mg kg^?1 (wet weight).     

HPLC–MS Profiling and Structural Identification of [14C]-Diclofenac Metabolites in Mouse Bile

Biliary metabolites present at 6 h post-dose following a single oral dose of [¹⁴C]-diclofenac (10 mg kg^?1) to male bile duct-cannulated C57BL/6 J mice were profiled and identified. Over the 6 h duration of the study ~19.5 % of the administered radioactivity was excreted into the bile as either [¹⁴C]-diclofenac or metabolites. When profiled using HPLC with online radiodetection, the presence of at least 13 radiolabelled components was indicated. These compounds were shown, by consecutive reaction mass spectrometry, to comprise a range of hydroxylated metabolites conjugated to either taurine, glucose and/or glucuronic acid. Both phenolic and acylglucuronide-containing metabolites were observed. The confirmation of the presence of these glucuronide conjugates in mouse bile may have important consequences in the light of emerging theories concerning the role of bacterial glucuronidases for the GI-tract toxicity of NSAIDs such as diclofenac.     

In-vivo and In-vitro Metabolism Study of Timosaponin B-II Using HPLC-ESI-MS n

Timosaponin B-II (TB-II), a representative furostanol saponin in Rhizoma anemarrhenae, has been used as an emperor herb in many Chinese herbal formulas to treat diabetes and senile dementia. However, its metabolism and tissue distribution had not been investigated so far. In this work, a sensitive and specific high-performance liquid chromatography-electrospray ionization tandem mass spectrometry method was applied for the identification of TB-II and its major metabolites in in-vivo and in-vitro samples. Rat urine, feces, plasma and tissues were collected after oral administration of TB-II at a single dose of 300 mg kg⁻¹. Furthermore, TB-II was incubated in artificial gastric juice (AGJ) and artificial intestinal juice (AIJ). As a result, 19 metabolites were detected and identified by comparing their HPLC behavior and MSⁿ spectra profile with those of the parent drug. Moreover, the structures of its five metabolites were identified by using the standards prepared by the acid hydrolysis of TB-II. In addition to the parent drug, 14, 12, 6, 1, 1 and 7 metabolites were detected in rat urine, feces, plasma, heart, kidney and liver, respectively, while no metabolites or the parent drug were found in rat brain, spleen and lung. Seven metabolites appeared in AIJ incubation samples, but the parent drug was absent. Nine metabolites along with the parent drug were observed in AGJ incubation samples. The biotransformation pathways of TB-II mainly included dehydration, deglycosylation, hydroxylation, oxidation and E-ring cleavage. This is the first comprehensive investigation of the in-vivo and in-vitro metabolism of TB-II. The result provided important information for further pharmacological research on TB-II.

     

Experimental assessment of a large sample cell for laser ablation-ICP-MS, and its application to sediment core micro-analysis

The coupling of laser ablation (LA) to inductively coupled plasma-mass spectrometry (ICP-MS) enables the direct analysis of solid samples with micrometric resolution. Analysis is often restricted to relatively small samples owing to the dimensions of conventional ablation cells. Here, we assess the performance of a large rectangular, commercially-available sample cell which enables analysis over a 10.2?×?5.2 cm² area. Comparison with the conventional cell shows a small to moderate performance decrease for the large cell resulting from the dilution of ablated particles in a larger volume with a 4–31% lower signal output and longer signal tailings. The performance of this cell is however sufficient for the determination of both major and trace elements in many kinds of samples. The applicability of the large cell LA-ICP-MS setup was demonstrated by the determination of Al, Si, Mn, Fe, Cu, Zn Pb and U in sediment core sections at a resolution of 0.6 mm. Detection limits for sediment analysis were 7 mg Al kg^?1, 68 mg Si kg^?1, 0.5 mg Mn kg^?1, 20 mg Fe kg^?1, 0.2 mg Cu kg^?1, 0.3 mg Zn kg^?1, 0.08 mg Pb kg^?1 and 0.003 mg U kg^?1. Cyclic patterns, which would have been overlooked by conventional analysis at cm resolution, were observed in analysed sediments. This study demonstrates the potential of LA-ICP-MS in environmental analysis, with the large sample cell setup offering the possibility to analyse a wider range of samples without sectioning.     

LC Determination and Pharmacokinetics Study of Mangiferin in Rat Plasma and Tissues

An LC method was developed for determination of mangiferin in rat plasma and tissues after oral administration of Rhizoma Anemarrhenae extract. Analysis was performed on a Gemini C₁₈ analytical column (250 × 4.6 mm, i.d.) with mobile phase consisting of acetonitrile–water (23:77, v/v) with 1% acetic acid and 1% tetrahydrofuran at a flow rate of 0.7 mL min^?1. Spinosin was used as internal standard and UV detector was set at 320 nm. The calibration curve of mangiferin in rat plasma and tissues showed excellent linear behaviors over the investigated concentration ranges with the value of R ² higher than 0.994. The within-day and between-day precisions for all samples were measured to be below 11.0%. The limit of quantitation was low enough for determination of mangiferin in all samples. After Rhizoma Anemarrhenae extract was orally administered to rats, the main pharmacokinetic parameters of mangiferin T _max, C _max, T _0.5α , T _0.5β , AUC_0 ? T and Vc were 4.20 h, 9.52 μg mL^?1, 1.21 h, 1.71 h, 29.9 mg h L^?1 and 0.18 L kg^?1, respectively. Mangiferin was extensively distributed in most of the main tissues of rats. This validated method has been successfully applied to preliminary pharmacokinetics and tissue distribution study of mangiferin in rats.     

LC and LC–MS Study of the Bioavailability and Metabolites of TM208 after Oral and Intravenous Administration to Rat

4-Methylpiperazine-1-carbodithioic acid 3-cyano-3,3-diphenylpropyl ester hydrochloride (TM208) is a new compound expected to become a new drug because of excellent in vivo and in vitro anticancer activity and low toxicity. A new, specific and sensitive LC method was set up for detecting the bioavailability of TM208 after oral administration. Samples were extracted with ethyl acetate after oral and intravenous administration. The retention times of TM208 and plunarizine (I.S.) were 5.5 and 9.9 min, respectively. The linear range was 0.125–50 μg mL^?1. The accuracy (error, %) for three concentrations was 2.7–16.6%. Intra-day precision (as RSD) was 1.6–6.9% and inter-day precision was 7.6–11.5%. Extraction recovery of TM208 was 84.15–89.51% and that of the I.S. was 83.3%. Results from stability testing indicated that samples should be analyzed within 24 h or frozen immediately for later analysis. The bioavailable fraction (F) calculated by use of a non-compartment model was 63.3%. Pharmacokinetic data for TM208 were: mean residence time 24.3 and 5.1 h, V _d 186.2 and 35.5 L kg^?1, and Cl 6.9 and 4.2 L h^?1 kg^?1 after oral and intravenous administration, respectively. LC–MS comparison of the metabolites after the two methods of administration showed the kind and content of metabolites of TM208 in rat urine after intravenous administration were more than after oral administration. The experimental results show that the low anticancer activity of TM208 after intravenous administration is related to rapid elimination of the drug, and that the kind and content of metabolites do not affect the bioactivity of TM208.     

Residue analysis of fosthiazate in cucumber and soil by QuEChERS and GC-MS

A convenient method was developed for the determination and validation of fosthiazate in cucumber and soil. The procedure is based on liquid partitioning with acetonitrile followed by dispersive solid phase extraction as the clean-up step, after which samples were analysed by gas chromatography-mass spectrometry (GC-MS). The average recoveries ranged from 91.2 % to 99.0 % with relative standard deviations (RSDs) of less than 6.05 %, at three fortification levels (0.02 mg kg^?1, 0.1 mg kg^?1, 0.5 mg kg^?1) in cucumber and soil, and the limits of quantification (LOQs) for fosthiazate were all established at 0.02 mg kg^?1. The proposed method was applied successfully to analyses of the dissipation and residue of fosthiazate in field trials. The dissipation rate of fosthiazate was described using pseudo-first-order kinetics with a half-life of 4.33 days and 4.08 days in soil in Beijing and Shandong, respectively. In the terminal residue experiment, fosthiazate residues in cucumber and soil were clearly below the maximum residue level (MRL, 0.2 mg kg^?1) set in China.     

Determination of Trace Elements in Dendrobium Officinale Cultivated in Various Conditions

Dendrobium officinale is an important medicinal plant in traditional Chinese medicine. The consumption of D. officinale has increased rapidly in recent years due to the health awareness among Chinese people. The present study aimed to determine trace elements levels in 42 D. officinale samples and to utilize the elemental data for identifying the cultivation technique. Eighteen trace elements (B, V, Cr, As, Mn, Fe, Mo, Cu, Zn, Se, Sr, Sn, Ti, Al, Co, As Pb, Cd, and Bi) were determined by inductively coupled plasma–mass spectrometry. Of the 11 essential elements, the mean concentrations ranged from 30.6?µg?kg^?1 (Mo) in D. officinale with greenhouse cultivation to 161?mg?kg^?1 (Fe) in D. officinale with rock cultivation, and the contributions of Mn may exceed the dietary reference intake value by the uptake of 20?g of D. officinale. Of the seven toxic elements, the mean concentrations ranged from 3.29?µg?kg^?1 (Bi) in the D. officinale with greenhouse cultivation to 342?mg?kg^?1 (Al) in the D. officinale with rock cultivation, and the contributions of Al may exceed the provisional tolerable daily intake value by the uptake of 20?g of D. officinale. The concentrations of seven metals (Bi, Pb, Fe, Al, Cr, As, and Mo) were utilized to identify the cultivation technique of the analyzed D. officinale samples through linear discriminant analysis.     

Rapid structural characterization of in vivo and in vitro metabolites of tinoridine using UHPLC–QTOF–MS/MS and in silico toxicological screening of its metabolites

Tinoridine is a nonsteroidal anti‐inflammatory drug and also has potent radical scavenger and antiperoxidative activity. However, metabolism of tinoridine has not been thoroughly investigated. To identify in vivo metabolites, the drug was administered to Sprague–Dawley rats (n = 5) at a dose of 20 mg kg^?1, and blood, urine and feces were collected at different time points up to 24 h. In vitro metabolism was delved by incubating the drug with rat liver microsomes and human liver microsomes. The metabolites were enriched by optimized sample preparation involving protein precipitation using acetonitrile, followed by solid‐phase extraction. Data processes were carried out using multiple mass defects filters to eliminate false‐positive ions. A total of 11 metabolites have been identified in urine samples including hydroxyl, dealkylated, acetylated and glucuronide metabolites; among them, some were also observed in plasma and feces samples. Only two major metabolites were formed using liver microsomal incubations. These metabolites were also observed in vivo. All the 11 metabolites, which are hitherto unknown and novel, were characterized by using ultrahigh‐performance liquid chromatography–quadrupole time‐of‐flight tandem mass spectrometry in combination with accurate mass measurements. Finally, in silico toxicological screening of all metabolites was evaluated, and two metabolites were proposed to show a certain degree of lung or liver toxicity. Copyright © 2015 John Wiley & Sons, Ltd.     

Multielement Analysis of South Serbian Strawberry Cultivars by Inductively Coupled Plasma—Optical Emission Spectrometry

The contents of 17 elements in thirteen strawberry cultivars grown in the five districts of Southern Serbia were determined using inductively coupled plasma optical emission spectrometry (ICP-OES). The most abundant elements are K (875–1148 mg?·?kg^?1 fresh weight), P (307–664 mg?·?kg^?1 fresh weight), Ca (192–256 mg?·?kg^?1 fresh weight), and Mg (111–189 mg?·?kg^?1 fresh weight) in all samples. Strawberries were also found to be a good source of Sr (8.05–18.6 mg?·?kg^?1 fresh weight) and Fe (3.09–10.4 mg?·?kg^?1 fresh weight). The contents of As and Cd were below the detection limit (0.0828 mg?·?kg^?1 and 0.0205 mg?·?kg^?1, respectively) in all strawberry samples, while the contents of Ni, Cr, and Cu were below the recommended tolerable levels proposed by Joint Food and Agriculture Organization of the United Nations and World Health Organization Expert Committee on Food Additives, and did not a pose a health risk for the consumer. The application of Duncan’s test showed significant differences between contents of analyzed elements in all strawberry cultivars. The highest mean levels of analyzed elements were detected in strawberries grown in the Topli?ki, Jablani?ki, and P?injski districts. The spike recovery test was used to verify the accuracy of the method, and the spike recovery was in the range 93.8–107.8%. The contents of the metals in strawberry samples were also comparable with values previously reported in the literature.     

Simultaneous Determination of Berberine and Palmatine in Rabbit Plasma by LC-MS–MS and Its Application in Pharmacokinetic Study After Oral Administration of Coptidis and Coptidis–Gardeniae Couple Extract

A valid and sensitive LC-MS–MS method is adopted for pharmacokinetics study of berberine and palmatine in rabbit plasma. After mixing with internal standard tetrahydroberberine, plasma samples were pretreated with 1.5 mL acetonitrile. Chromatographic separation was on a C₁₈ column using a mixture of water (containing 10 mmol L^?1 ammonium acetate, pH 3.5) and acetonitrile (50∶50, v/v) as mobile phase. The detection was performed by selected ion monitoring mode via electrospray ionization source operating in the positive ionization mode. The method was linear over the concentration range of 2.0–200.0 ng mL^?1 for berberine and 1.0–100.0 ng mL^?1 for palmatine. The lowest limits of quantitation (LLOQ) were 2.0 ng mL^?1 for berberine and 1.0 ng mL^?1 for palmatine. The intra- and inter-day precision values were less than 14.3% and the deviations were within ±11.0%. The fully validated LC-MS–MS method has been successfully applied to a pharmacokinetic study of berberine, palmatine in rabbit plasma after oral administration of Coptidis and coptidis–gardeniae couple extract. The results indicated that the plasma profiles of the two compounds in rabbit confirmed to one-compartment open model and the combinational utilization with Gardeniae could increase the bioavailability of berberine and palmatine, the two major active components of Coptidis.     

LC Determination and Pharmacokinetics Study of Mangiferin in Rat Plasma and Tissues

An LC method was developed for determination of mangiferin in rat plasma and tissues after oral administration of Rhizoma Anemarrhenae extract. Analysis was performed on a Gemini C₁₈ analytical column (250 × 4.6 mm, i.d.) with mobile phase consisting of acetonitrile–water (23:77, v/v) with 1% acetic acid and 1% tetrahydrofuran at a flow rate of 0.7 mL min⁻¹. Spinosin was used as internal standard and UV detector was set at 320 nm. The calibration curve of mangiferin in rat plasma and tissues showed excellent linear behaviors over the investigated concentration ranges with the value of R ² higher than 0.994. The within-day and between-day precisions for all samples were measured to be below 11.0%. The limit of quantitation was low enough for determination of mangiferin in all samples. After Rhizoma Anemarrhenae extract was orally administered to rats, the main pharmacokinetic parameters of mangiferin T _max, C _max, T _0.5α , T _0.5β , AUC_0 − T and Vc were 4.20 h, 9.52 μg mL⁻¹, 1.21 h, 1.71 h, 29.9 mg h L⁻¹ and 0.18 L kg⁻¹, respectively. Mangiferin was extensively distributed in most of the main tissues of rats. This validated method has been successfully applied to preliminary pharmacokinetics and tissue distribution study of mangiferin in rats.