Postmortem Diffusion of Aconitum Alkaloids and Their Metabolites in Rabbits.

OBJECTIVES: To explore the postmortem diffusion rule of Aconitum alkaloids and their metabolites in poisoned rabbits, and to provide a reference for identifying the antemortem poisoning or postmortem poisoning of Aconitum alkaloids. METHODS: Twenty-four rabbits were sacrificed by tracheal clamps. After 1 hour, the rabbits were administered with aconitine LD50 in decocting aconite root powder by intragastric administration. Then, they were placed supine and stored at 25 ℃. The biological samples from 3 randomly selected rabbits were collected including heart blood, peripheral blood, urine, heart, liver, spleen, lung and kidney tissues at 0 h, 4 h, 8 h, 12 h, 24 h, 48 h, 72 h and 96 h after intragastric administration, respectively. Aconitum alkaloids and their metabolites in the biological samples were analyzed by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). RESULTS: At 4 h after intragastric administration, Aconitum alkaloids and their metabolites could be detected in heart blood, peripheral blood and major organs, and the contents of them changed dynamically with the preservation time. The contents of Aconitum alkaloids and their metabolites were higher in the spleen, liver and lung, especially in the spleen which was closer to the stomach. The average mass fraction of benzoylmesaconine metabolized in rabbit spleen was the highest at 48 h after intragastric administration. In contrast, the contents of Aconitum alkaloids and their metabolites in kidney were all lower. Aconitum alkaloids and their metabolites were not detected in urine. CONCLUSIONS: Aconitum alkaloids and their metabolites have postmortem diffusion in poisoned rabbits, diffusing from high-content organs (stomach) to other major organs and tissues as well as the heart blood. The main mechanism is the dispersion along the concentration gradient, while urine is not affected by postmortem diffusion, which can be used as the basis for the identification of antemortem and postmortem Aconitum alkaloids poisoning.

Comparative pharmacokinetics, intestinal absorption and urinary excretion of six alkaloids from herb pair Phellodendri Chinensis cortex-Atractylodis Rhizoma.

Phellodendri Chinensis Cortex (PCC) and Atractylodis Rhizoma (AR) are frequently used as herb pair to treat eczema and gout owing to their synergistic effects. Alkaloids are the major ingredients from PCC and the effect of their combination on the in vivo processing of alkaloids remains unclear. In this study, a simple and reliable UPLC-MS/MS method for simultaneous determination of six alkaloids in rat plasma was developed. This method was applied to a comparative pharmacokinetic study between PCC and PCC-AR in rats. Effect of AR on absorption of alkaloids was investigated by a single-pass intestinal perfusion study. The effect of AR on urinary excretion of alkaloids was studied. Pharmacokinetic studies showed that the values of rea under the concentration-time curve of phellodendrine, magnoflorine and palmatine were greater in the PCC-AR group than in the PCC group. The intestinal absorptive parameters absorption rate constant and effective permeability of phellodendrine and jatrorrhizine in PCC-AR groups were higher than those in the PCC group. Urinary excretion studies revealed that the excreted amount of alkaloids in the PCC-AR group was lower than that in the PCC group. The results revealed that the combination of PCC and AR improves intestinal absorption of alkaloids and reduces their urinary excretion, which enhances their systemic exposure. This study may explain the synergetic effects of PCC and AR in clinical applications.

Optimization and validation of a new approach based on CE-HRMS for the screening analysis of novel psychoactive substances (cathinones, phenethylamines, and tryptamines) in urine.

The continuous introduction in the market of new psychoactive drugs (NPS) represents a well-known international emergency. Indeed, the European Monitoring Centre for Drugs and Drug Addiction and the United Nations Office on Drugs and Crime are paying great attention to the spread of NPS. In addition to the traditional analytical approaches based on GC-MS and HPLC-MS, also CE coupled with MS has proved to be a precious tool for the toxicological screening of biosamples. On these grounds, the aim of the present work was to test the application of CE-HRMS as a new screening tool for the rapid detection of these novel drugs in urine. Separations were performed in an uncoated fused-silica capillary with id of 75 µm with a total length of 100 cm, by applying a constant voltage of 15 kV. The QTOF-MS was implemented with an electrospray ion source operating in positive ionization full scan mode in the range of 100-1000 m/z. Under these conditions, different NPS has been tested, including eight cathinones, five phenethylamine, and seven tryptamines. The method was validated after optimization of the following analytical parameters: BGE composition and pH, separation voltage, sheath liquid composition, and flow rate and ESI source settings. The applicability of the method was successfully tested by analyzing a series of real urine samples obtained from drug users.

Rapid detection of nine synthetic cathinones in blood and urine by direct analysis in real-time-tandem mass spectrometry.

RATIONALE: Designer drugs of cathinone, a kind of hallucinogen, were abused in the recent years. They were also known as bath salts, plant fertilizers, and zombie potions in drug market. The abuse of synthetic cathinones caused many bad effects on social order. Rapid detection of synthetic cathinones became an important subject of study in forensic science. METHODS: Direct analysis in real-time-tandem mass spectrometry (DART-MS/MS) was used to develop an effective method on nine synthetic cathinones in human whole blood and urine. The reference materials with 100 ng/mL were prepared for mass spectrometry optimization with electrospray ionization (ESI) probe tandem QTRAP 4000 mass spectrometer. The temperature of DART ion source was optimized to 400°C. The volumes of 4/1 (v/v) MeCN/MeOH with 0.69 mL were selected for the preparation of 0.31 mL blood and urine samples, respectively. Then the spiked analytes were prepared for detection by the DART 12Dip-it autosampler module. RESULTS: The results showed that the linearities range between 0.1 and 5 µg/mL, the correlation coefficients (r2 ) ranged from 0.99 to 1, the limits of detection (LODs) were all between 0.5 and 50 ng/mL, and the relative standard deviations (RSDs) of repeatability, intra-day and inter-day precisions were all below 13% and 14% in blood and urine, respectively. CONCLUSION: The results indicated that the method could meet the needs of rapid screening of samples that may contain synthetic cathinones. In addition, the method developed has many advantages, such as efficient, fast sample preparation, and environmental protection. Therefore, the DART-MS/MS method would provide effective data support for rapid screening of synthetic cathinones in forensic science.

A sensitive HPLC-MS/MS method for the detection, resolution and quantitation of cathinone enantiomers in horse blood plasma and urine.

Resolution of cathinone enantiomers in equine anti-doping analysis is becoming more important to distinguish the inadvertent ingestion of plant-based products from those of deliberate administration of designer synthetic analogs. With this in mind, a rapid and sensitive method was developed and validated for the detection, resolution and quantitative determination of cathinone enantiomers in horse blood plasma and urine. The analytes were recovered from the blood plasma and urine matrices by using a liquid-liquid extraction after adjusting the pH to 9. The recovered analytes were derivatized with Nα-(2,4-dinitro-5-fluorophenyl)-L-valinamide, a chiral derivatizing agent analogous to Marfey's reagent. The resulting diastereoisomers were baseline resolved under a reversed-phase liquid chromatographic condition. Derivatization of the analytes not only allowed the separation of the enantiomers using cost-effective traditional liquid chromatography conditions and reversed-phase columns but also increased the sensitivity, at least to an order of magnitude, when tandem mass spectrometry is used for the detection. A limit of detection of 0.05 ng/mL was achieved for cathinone enantiomers for both matrices. Acceptable intraday and interday precision and accuracy along with satisfactory dilution accuracy and precision were observed during the method validation. The method suitability was tested using the post administration urine samples collected after single doses of cathinone and ephedrine as single-enantiomeric form and methcathinone as racemic form. Finally, a proof of concept of the isomeric ratio in urine samples to distinguish the presence of cathinone as a result of accidental ingestion of plant-based product from that of an illicit use of a designer product is demonstrated. To the best of our knowledge, this is the first such work where cathinone enantiomers were resolved and quantified in horse blood plasma and urine at sub nanogram levels.

Metabolic profile of alkaloids in Rhizoma Coptidis in rat plasma, urine and feces after oral administration using ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry.

RATIONALE: Rhizoma Coptidis (RC) has been used to treat diabetes, pertussis, bacillary dysentery, sore throat, eczema, and aphtha for thousands of years. Alkaloids are the major components in RC, and its curative effect is achieved by oral administration. However, information on its composition in vivo is weak. METHODS: In this study, ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC/QTOF-MS) was used to analyze the major active components and their metabolites in rat plasma, urine and feces after oral administration of RC extract. RESULTS: A total of 96 compounds including 8 prototype compounds and 88 metabolites were identified, and hydroxylation, reduction, demethylenation, demethylation, dehydrogenation, sulfation, glucuronidation and methylation were the major metabolic pathways. CONCLUSIONS: This study analyzed metabolic processes of the major active components in RC in vivo, which provided important information for its active composition and in vivo mechanism research. Meanwhile, metabolic profile studies on representative compounds provided valuable reference materials to elucidate the full-scale metabolites of RC.

Determination of synthetic cathinone α-pyrrolidinovalero-phenone and its metabolite in urine using solid-phase extraction and gas chromatography-mass spectrometry.

RATIONALE: The presence of α-pyrrolidinovalerophenone (α-PVP) and its metabolites in urine is evidence of the administration of α-PVP. A toxicological challenge is that the metabolites of α-PVP exhibit amphoteric properties, which make them unsuitable for detection using gas chromatography-mass spectrometry (GC/MS). In the study reported, proper derivatization and sample extraction were essential for improving the sensitivity for GC/MS analysis. METHODS: An automated solid-phase extraction (SPE) method has been developed and optimized. The derivatization efficiency was tested using longer reaction time and the addition of polar pyridine into a mixture of N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) with 1% trimethylchlorosilane. Method validation, including linearity, limit of detection, precision, accuracy, and recovery, was evaluated using automatic SPE and GC/MS. RESULTS: The results suggested that adding pyridine to BSTFA (1:1, v/v) significantly improved derivatization efficiency and precision. After optimization, the linear range was from 25 to 1000 ng mL-1 with R2 > 0.9950. The limit of detection was 5 ng mL-1 for α-PVP and 25 ng mL-1 for OH-α-PVP. The recovery for SPE was over 88%. The inter-day and intra-day precisions were less than 15%. A forensic sample has been found containing α-PVP (67.3 ng mL-1 ) and OH-α-PVP (560.2 ng mL-1 ). CONCLUSIONS: This study is the first to validate an auto-SPE-GC/MS method for the quantification and qualification of α-PVP and OH-α-PVP in urine. We have successfully improved the derivatization efficiency and developed a sensitive and semi-automatic approach. This approach is desirable for the detection of synthetic cathinone at trace levels in biological samples.

Field-amplified sample injection combined with CE for the enantiodetermination of cathinones in urine samples.

This work presents a capillary electrophoresis methodology for the enantiodetermination of cathinones in urine employing a liquid-liquid extraction sample pretreatment. The cathinones were enantioseparated by adding a mixture of 8 mM 2-hydroxypropyl ß-cyclodextrin and 5 mM ß-cyclodextrin to the background electrolyte, which consists of 70 mM of monosodium phosphate aqueous solution at pH 2.5. Field-amplified sample injection was used as preconcentration strategy to improve the sensitivity. We studied various parameters that affect this stacking strategy, in particular, the sample solvent and its pH, the presence or absence of a low conductivity solvent plug introduced before the sample injection, the nature and volume of this plug, and the voltage and time of the electrokinetic injection of the sample. The optimum conditions were achieved by injecting a plug of isopropanol:H2 O 50/50 at 50 mbar for 5 s prior to the electrokinetic injection of the sample prepared in an aqueous solution of HCl 10-6  M. The sensitivity enhancement factors were from 562 to 601 in terms of peak area and from 444 to 472 in terms of peak height. The method was validated by analyzing spiked urine samples, obtaining a linear range of 25 to 1000 ng/mL and limits of detection ranging from 15 to 45 ng/mL.

Enantioselective determination of cathinones in urine by high pressure in-line SPE-CE.

This work presents a strategy based on the in-line coupling of SPE and CE for the chiral determination of cathinones (R,S-mephedrone, R,S-4-methylephedrine, and R,S- methylenedioxypyrovalerone) in urine samples, using a sample pretreatment based on liquid-liquid extraction. The chiral separation of the compounds is achieved by adding a mixture of 8 mM 2-hydroxypropil ß-CD and 5 mM ß-CD to the BGE, which consists of 70 mM of monosodium phosphate aqueous solution at pH 2.5. Oasis HLB was the selected sorbent for the in-line SPE device, and to reduce analysis time and LODs, several parameters affecting the in-line SPE system were evaluated, such as pressure and time of sample injection and dimensions of the SPE device. The highest preconcentration factors were achieved by using 3 bar of injection pressure for 20 min with an in-line SPE device of 2 mm length and 150 µm of i.d. The developed method was applied to determine the presence of the compounds in spiked urine samples. The LODs obtained were between 3 and 8 ng/mL, and these levels were below the usual concentrations at which these drugs are present in urine from cathinone abusers. Thus, the optimized method has the potential to be applied for toxicological and forensic purposes.

Ultra-fast retroactive processing of liquid chromatography high-resolution full-scan Orbitrap mass spectrometry data in anti-doping screening of human urine.

RATIONALE: Retroactive analysis of previously tested urine samples has become an important sports anti-doping tool. Retroactive reprocessing of old data files acquired from a generic screening procedure can reveal detection of initially unknown substances, like illegal drugs and newly identified metabolites. METHODS: To be able to efficiently search through hundreds to thousands of liquid chromatography high-resolution full-scan Orbitrap mass spectrometry data files of anti-doping samples, a combination of MetAlign and HR_MS_Search software has been developed. MetAlign reduced the data size ca 100-fold making possible local storage of a massive volume of data. RESULTS: The newly developed HR_MS_Search module can search through the reduced data files for new compounds (mass or isotope pattern) defined by mass windows and retention time windows. A search for 33 analytes in 940 reduced data files lasted 10 s. The output of the automatic search was compared to the standard manual routine evaluation. The results of searching were evaluated in terms of false negatives and false positives. The newly banned b2-agonist higenamine and its metabolite coclaurine were successfully searched in reduced data files originating from a testing period for which these substances were not banned, as an example of retroactive analysis. CONCLUSIONS: The freeware MetAlign software and its automatic searching module HR_MS_Search facilitated the retroactive reprocessing of reduced full-scan high-resolution liquid chromatography/mass spectrometry screening data files and created a new tool in anti-doping laboratories' network.

A novel two-dimensional liquid chromatography system for the simultaneous determination of three monoterpene indole alkaloids in biological matrices.

The present paper describes a novel two-dimensional liquid chromatography (2D-LC) system, which is comprised of a first-dimensional ion exchange chromatography (IEX1) column, trap column, and second-dimensional reversed-phase chromatography (RP2) column system. The biological sample is separated by the first-dimensional LC using an IEX column to remove interferences. The analytes are transferred to the trap column after heart-cutting. Then, the analytes are transferred to the second-dimensional LC using an RP2 column for further separation and ultraviolet detection. This 2D-LC system can offer a large injection volume to provide sufficient sensitivity and exhibits a strong capacity for removing interferences. Here, the determination of three monoterpene indole alkaloids (MIAs; gelsemine, koumine, and humantenmine) from Gelsemium in biological matrices (plasma, tissue, and urine) was used this 2D-LC system. After a rapid and easy sample preparation method based on protein precipitation, the sample was injected into the 2D-LC. The method was developed and validated in terms of the selectivity, LOD, LOQ, linearity, precision, accuracy, and stability. The sample preparation time for the three MIAs was 15 min. The LOD for these compounds was 10 ng/mL, which was lower than the developed HPLC methods. The results showed that this method had good quantitation performance and allowed the determination of gelsemine, koumine, and humantenmine in biological matrices. The method is rapid, exhibits high selectivity, has good sensitivity, and is low-cost, thus making it well-suited for application in the pharmaceutical and toxicological analysis of Gelsemium. Graphical abstract.

Determination of several synthetic cathinones and an amphetamine-like compound in urine by gas chromatography with mass spectrometry. Method validation and application to real cases.

Most routine practices for drugs-of-abuse testing do not include screening procedures for new psychoactive substances, despite their increasing diffusion, preventing clear knowledge of the real consumption of these drugs in the populations. To make up for this shortcoming, a gas chromatography with mass spectrometry method was developed for the simultaneous determination of 18 synthetic cathinones and one amphetamine-like compound in human urine. The sample preparation was based on liquid-liquid extraction under alkaline condition followed by derivatization with trifluoroacetic anhydride. The separation of the 19 analytes was achieved in less than 10 min. The whole methodology was validated according to national and international guidelines. Selectivity, linearity range, limit of detection and limit of quantitation, precision and accuracy were evaluated. For all the analytes, the calibration curve was linear in the 100-1000 ng/mL concentration range. The limits of detection ranged from 10 to 30 ng/mL and limits of quantitation from 30 to 100 ng/mL. Precisions were in the ranges 0.1-10.4%, and 1.0-12.1% for low (100 ng/mL) and high (1000 ng/mL) concentration, respectively. The accuracy, expressed as bias% was within ±20% for all the analytes. The present method was successfully applied to urine samples originating from autopsies, drug abuse/withdrawal controls, clinical investigations, roadside controls, driving re-licensing, and workplace testing.

Comparative pharmacokinetics of oxyresveratrol alone and in combination with piperine as a bioenhancer in rats.

BACKGROUND: Oxyresveratrol is a major bioactive component derived from the heartwood of Artocarpus lacucha. This compound exerts several biological activities, including neuroprotective effects in vitro and in vivo. However, there is limited pharmacokinetic information on this compound, especially its distribution in neuronal tissue and its route of excretion. The aim of this study was to investigate the pharmacokinetic profiles of oxyresveratrol alone and in combination with piperine as a bioenhancer in rats. METHODS: Male Wistar rats were administered with oxyresveratrol 10 mg/kg, oxyresveratrol 10 mg/kg plus piperine 1 mg/kg via intravenous or oxyresveratrol 100 mg/kg, oxyresveratrol 100 mg/kg plus piperine 10 mg/kg via oral gavage. Plasma, internal organs, urine, and feces were collected. Determination of the oxyresveratrol concentration in biological samples was performed by liquid chromatography tandem mass spectrometry. RESULTS: The combination with piperine had shown a significantly higher maximum concentration in plasma approximately 1500 µg/L within 1-2 h after oral dosing, and could increase oral bioavailability of oxyresveratrol approximately 2-fold. Oxyresveratrol could widely distributed most of the internal organs with a tissue to plasma ratio of 10-100 fold within 5 min after dosing. Urinary excretion of oxyresveratrol glucuronide was the major route of excretion after administration of oxyresveratrol alone and in combination with piperine. CONCLUSION: The addition of piperine could enhance some of the pharmacokinetic properties of oxyresveratrol via both intravenous and oral administration. This pharmacokinetic information will be useful for appropriate strategies to develop oxyresveratrol as a phytopharmaceutical product.

Molecularly imprinted polymer solid-phase extraction of synthetic cathinones from urine and whole blood samples.

In forensic drug analysis, extractive pretreatment is required prior to instrumental analysis to ensure successful detection of the target compounds. However, conventional extraction methods such as hydrophilic polymer-based solid-phase extraction and liquid-liquid extraction are unsuitable for an emerging class of new psychoactive substances, namely, synthetic cathinones, because they exhibit a lack of class selectivity and increased risk of target analyte decomposition during extraction. To address these issues, we describe a highly class-selective sample clean-up method for the extraction of synthetic cathinones from urine and whole blood samples, exploiting a molecularly imprinted polymer solid-phase extraction cartridge. In terms of the influence of the synthetic cathinone molecular structure on the extraction recovery, we showed that while longer alkyl side chains slightly reduced the extraction efficiency, substituent variation on the aromatic ring exerted no effect. Molecularly imprinted polymer solid-phase extraction of 11 synthetic cathinones from urine samples yielded higher recoveries than the two conventional extraction methods, and smaller matrix effect was observed than that with hydrophilic polymer-based solid-phase extraction. Molecularly imprinted polymer solid-phase extraction from whole blood samples gave recoveries comparable to those of urine samples. Therefore, the proposed method is applicable for the extraction and quantitative determination of synthetic cathinones in biological samples.

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-ß-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 and metabolism of olerciamide A from Portulaca oleracea L. in rats by UHPLC-UV and UHPLC-ESI-Q-TOF/MS.

The aim of this study was to elucidate the pharmacokinetics of olerciamide A in rats after oral and intravenous administration of Portulaca oleracea L. extract by a simple and rapid ultra high-performance liquid chromatography method with bergapten as internal standard. The pharmacokinetic results indicated that olerciamide A was rapidly distributed with a time to peak concentration of 30 min after oral administration and presented a low oral absolute bioavailability of 4.57%. The metabolism of olerciamide A in rats was also investigated using ultra-high-performance liquid chromatography electrospray coupled with quadrupole-time of flight mass spectrometry to elucidate the reason for the low absolute bioavailability of olerciamide A and seven metabolites of oleraciamide A were found in rat plasma and urine.

Qualitative and Quantitative Analysis of Cathinones in Human Urine by SPE-GC-MS.

OBJECTIVES: To propose an alternative solid phase extraction-gas chromatography-mass spectrometry （SPE-GC-MS） method for the sensitive determination of cathinones in human urine samples, plus methodological verification. METHODS: Human urine samples were concentrated by solid phase extraction （SPE） sorbent and converted into the corresponding heptafluorobutyric acid anhydride derivatives. Methcathinone, 4-methyl methcathinone and 3,4-methylenedioxy-N-methylcathinone were detected by gas chromatography-mass spectrometry （GC-MS）. With quantitative analysis by internal standard method, methodological verification was carried out from the aspects of specificity, precision and reco-very rate. RESULTS: Methcathinone, 4-methyl methcathinone and 3,4-methylenedioxy-N-methylcathinone showed good linearly in the range of 25-200 ng/mL of urine （r>0.99）, with the limits of detection 2.0 ng/mL, limit of quantitation 25.0 ng/mL, both intra- and inter-day coefficients of variation lower than 6.0%, and recovery rates of 98.4%-105.7%. CONCLUSIONS: he proposed SPE-GC-MS procedure has good accuracy and specificity, can meet the need of qualitative and quantitative analysis of cathinones in the urine of drug abusers, and therefore provide technical support for the detection of cathinone abuse.

Identification of Urinary Food Intake Biomarkers for Milk, Cheese, and Soy-Based Drink by Untargeted GC-MS and NMR in Healthy Humans.

The measurement of food intake biomarkers (FIBs) in biofluids represents an objective tool for dietary assessment. FIBs of milk and cheese still need more investigation due to the absence of candidate markers. Thus, an acute intervention study has been performed to sensitively and specifically identify candidate FIBs. Eleven healthy male and female volunteers participated in the randomized, controlled crossover study that tested a single intake of milk and cheese as test products, and soy-based drink as a control. Urine samples were collected at baseline and up to 24 h at distinct time intervals (0-1, 1-2, 2-4, 4-6, 6-12, and 12-24 h) and were analyzed using an untargeted multiplatform approach (GC-MS and 1H NMR). Lactose, galactose, and galactonate were identified exclusively after milk intake while for other metabolites (allantoin, hippurate, galactitol, and galactono-1,5-lactone) a significant increase has been observed. Urinary 3-phenyllactic acid was the only compound specifically reflecting cheese intake although alanine, proline, and pyroglutamic acid were found at significantly higher levels after cheese consumption. In addition, several novel candidate markers for soy drink were identified, such as pinitol and trigonelline. Together, these candidate FIBs of dairy intake could serve as a basis for future validation studies under free-living conditions.

In Vitro and In Vivo Study of the Gastrointestinal Absorption and Metabolisation of Hymenocardine, a Cyclopeptide Alkaloid.

Hymenocardine is a cyclopeptide alkaloid present in the root bark of Hymenocardia acida. In traditional African medicine, the leaves and roots of this plant are used to treat malaria, and moderate in vitro antiplasmodial activity has been reported for hymenocardine. However, in view of its peptide-like nature, potential metabolisation after oral ingestion has to be taken into account when considering in vivo experiments. In this study, the stability and small intestinal absorption of hymenocardine was assessed using an in vitro gastrointestinal dialysis model. In addition, potential liver metabolisation was investigated in vitro by incubation with a human S9 fraction. Moreover, hymenocardine was administered to rats per os, and blood and urine samples were collected until 48 and 24 h after oral administration, respectively. All samples resulting from these three experiments were analyzed by LC-MS. Analysis of the dialysate and retentate, obtained from the gastrointestinal dialysis model, indicated that hymenocardine is absorbed unchanged from the gastrointestinal tract, at least in part. After S9 metabolisation, several metabolites of hymenocardine could be identified, the major ones being formed by the reduction and/or the loss of an N-methyl group. The in vivo study confirmed that hymenocardine is absorbed from the gastrointestinal tract unchanged, since it could be identified in both rat plasma and urine, together with hymenocardinol, its reduction product.

Screening and Identification of the Metabolites in Rat Plasma and Urine after Oral Administration of Areca catechu L. Nut Extract by Ultra-High-Pressure Liquid Chromatography Coupled with Linear Ion Trap-Orbitrap Tandem Mass Spectrometry.

Areca catechu L. nut, a well-known toxic traditional herbal medicine, has been widely used to treat various diseases in China and many other Asian countries for centuries. However, to date the in vivo absorption and metabolism of its multiple bioactive or toxic components still remain unclear. In this study, liquid chromatography coupled with tandem mass spectrometry was used to analyze the major components and their metabolites in rat plasma and urine after oral administration of Areca catechu L. nut extract (ACNE). A total of 12 compounds, including 6 alkaloids, 3 tannins and 3 amino acids, were confirmed or tentatively identified from ACNE. In vivo, 40 constituents, including 8 prototypes and 32 metabolites were identified in rat plasma and urine samples. In summary, this study showed an insight into the metabolism of ACNE in vivo, which may provide helpful chemical information for better understanding of the toxicological and pharmacological profiles of ACNE.