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Lusianthridin, a bioactive component isolated from Dendrobium venustum, has been demonstrated to have many biological properties such as antioxidant and anticancer activities. However, the metabolic profiles remain unknown. This study was carried out to investigate the metabolic profiles of lusianthridin in liver microsomes. Lusianthridin was co‐incubated with liver microsomes in the presence of nicotinamide adenine dinucleotide phosphate and UDP‐glucuronic acid or glutathione at 37°C for 1 h. The incubation samples were analyzed by liquid chromatography combined with electrospray ionization high‐resolution mass spectrometry. The data were acquired and processed. The structures of the metabolites were proposed by comparing their accurate mass and MS2 spectra with those of the parent compound. A total of 15 metabolites were detected in vitro, including two phase I and 13 phase II metabolites. The phase I metabolic pathways were oxidation, demethylation and dehydrogenation. The phase II metabolic pathways referred to glucuronidation and glutathione conjugation. The present study provides an overview pertaining to the metabolic profiles of lusianthridin in vitro, which is indispensable for understanding the efficacy and safety of lusianthridin, as well as the herbal medicine D. venustum. [ABSTRACT FROM AUTHOR]

ABSTRACT The aerial parts of genus Peganum are officially used in traditional Chinese medicine. The paper aims to establish a high-performance liquid chromatography (HPLC) method for fingerprint analysis and simultaneous determination of three alkaloids and two flavonoids in aerial parts of genus Peganum, and to analyze accumulative difference of secondary metabolites in inter-species, individuals of plants, inter-/intra-population and from different growing seasons. HPLC analysis was performed on a C18 column with gradient elution using 0.1% trifloroacetic acid and acetonitrile as mobile phase and detected at 265 nm, by conventional methodology validation. For fingerprint analysis, the RSDs of relative retention time and relative peak area of the characteristic peaks were within 0.07-0.78 and 0.94-9.09%, respectively. For simultaneous determination of vasicine, harmaline, harmine, deacetylpeganetin and peganetin, all calibration curves showed good linearity ( r > 0.9990) within the test range. The relative standard deviations of precision, repeatability and stability test did not exceed 2.37, 2.68 and 2.67%, respectively. The average recoveries for the five analytes were between 96.47 and 101.20%. HPLC fingerprints play a minor role in authenticating and differentiating the herbs of different species of genus Peganum. However, the secondary metabolites levels of alkaloids and flavonoids in aerial parts of genus Peganum rely on species-, habitat-, and growth season-dependent accumulation. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

ABSTRACT Toosendanin (TSN) is a major triterpenoid existing in Melia toosendan, which has been used as a digestive tract parasiticide and insecticide but with serious hepatotoxicity. An ultra-performance liquid chromatography-electrospray ionization-mass spectrometry method was developed for determination of TSN in rat plasma. Plasma samples were separated on Acquity UPLCTM BEH C18 column with acetonitrile and water as flow phase by gradient elution and determined by quadrupole mass spectrometer in negative selective ion monitoring mode. Usolic acid was used as internal standard. The calibration curves were linear over 0.02-3.0 µg/mL for TSN with a lower limit of quantification (LLOQ) of 20 ng/mL in rat plasma. The extraction recoveries of TSN were within 74.3-80.7% with an accuracy of 94.5-108.9%. The intra- and inter-day precision values of the assay at three quality control levels were 8.8-13.8% and <13.9% at LLOQ level, respectively. The method was successfully applied to a pharmacokinetic study of TSN in rats after a single intravenous and oral administration of 2 and 60 mg/kg. The shorter Tmax, higher Vd and Cl of TSN after oral administration indicated that TSN could be absorbed, distributed and eliminated quickly in rats in vivo. The absolute bioavailability of TSN after oral administration was 9.9%. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A rapid, selective and sensitive hydrophilic interaction liquid chromatography (HILIC) coupled with tandem mass spectrometry (MS/MS) method was developed to determine 1-13C- l-methionine in rat serum. Proteins in serum were precipitated using acetonitrile and the supernatant was separated after centrifugation. 1-13C- l-phenylalnine was used as the internal standard. HILIC-tandem mass spectrometry analysis was performed on a hydrophilic interaction silica column (TSK-GEL AMIDE-80) using a linear gradient elution system, acetonitrile−5 m m ammonium acetate containing 0.1% formic acid and multiple reaction monitoring mode for 1-13C- l-methionine and 1-13C- l-phenylalnine. The assay was validated with a linear range between 10 and 150 ng mL−1 ( r ≥ 0.99) and a lower limit of quantification of 10 ng mL−1, calculated with weighted (1/ x2) least squares linear regression. The RSD of intra-day precision was smaller than 3.6% and the inter-day RSD less than 6.5%, while the average recovery was 100.48% with an RSD of accuracy within 2.9%, determined from quality control samples. The HILIC-MS/MS method was fully validated and successfully applied to the in vivo pharmacokinetic study of stable-isotope 1-13C- l-methionine in rats. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Angiotensin-converting enzyme (ACE) plays an important role in the renin-angiotensin system and ACE activity is usually assayed in vitro by monitoring the transformation from a substrate to the product catalyzed by ACE. A rapid and sensitive analysis method or ACE activity by quantifying simultaneously the substrate hippuryl-histidyl-leucine and its product hippuric acid using an ultra-performance liquid chromatography coupled with electrospray ionization-mass spectrometry (UPLC-MS) was first developed and applied to assay the inhibitory activities against ACE of several natural phenolic compounds. The established UPLC-MS method showed obvious advantages over the conventional HPLC analysis in shortened running time (3.5 min), lower limit of detection (5 pg) and limit of quantification (18 pg), and high selectivity aided by MS detection in selected ion monitoring (SIM) mode. Among the six natural products screened, five compounds, caffeic acid, caffeoyl acetate, ferulic acid, chlorogenic acid and resveratrol indicated potent in vitro ACE inhibitory activity with IC50 values of 2.527 ± 0.032, 3.129 ± 0.016, 10.898 ± 0.430, 15.076 ± 1.211 and 6.359 ± 0.086 m m, respectively. A structure-activity relationship estimation suggested that the number and the situation of the hydroxyls on the benzene rings and the acrylic acid groups may play the most predominant role in their ACE inhibitory activity. Copyright © 2009 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A novel high-performance liquid chromatographic method with mass spectrometry and diode array detection method for the simultaneous qualitative and quantitative analysis of bioactive phenols was developed. In total, nine chemically diverse phenols including five bibenzyls, three phenanthrenes and a coumarin were unambiguously identified in Dendrobium aurantiacum var. denneanum by comparison with the available references or reported data according to their retention behaviors, UV spectra and fragmentations of ESI-MS. The contents of the four main phenolic compounds, moscatilin, gigantol, moscatin and coumarin, in D. aurantiacum var. denneanum from the wild and various cultivated populations were determined by HPLC-UV. The sample preparation involved a rapid and simple procedure based on solid-phase extraction using a C18 reversed-phase cartridge. The quantitative analysis was performed on a Beckman Coulter™ ODS column (5 µm, 250 × 4.6 mm) using a linear gradient elution system of acetonitrile-0.5% formic acid. The method was validated for linearity, limits of detection (LOD) and quantification (LOQ), precision and accuracy. Good results were obtained with respect to the overall intra- and inter-day variations (RSD less than 3.22%) and the percentage recoveries (ranging from 90.50 to 99.22%). Notable differences in the contents of phenols were observed among different cultivated populations. The samples colleted in April and May (spring), or October and November (autumn) accumulated much higher contents of phenols than those collected in other seasons. Copyright © 2007 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Notoginsenoside R1 (NGR1), a diagnostic protopanaxatriol‐type (ppt‐type) saponin in Panax notoginseng, possesses potent biological activities including antithrombotic, anti‐inflammatory, neuron protection and improvement of microcirculation, yet its pharmacokinetics and metabolic characterization as an individual compound remain unclear. The aim of this study was to investigate the exposure profile of NGR1 in rats after oral and intravenous administration and to explore the metabolic characterization of NGR1. A simple and sensitive ultra‐fast liquid chromatographic–tandem mass spectrometric method was developed and validated for the quantitative determination of NGR1 and its major metabolites, and for characterization of its metabolic profile in rat plasma. The blood samples were precipitated with methanol, quantified in a negative multiple reaction monitoring mode and analyzed within 6.0 min. Validation parameters (linearity, precision and accuracy, recovery and matrix effect, stability) were within acceptable ranges. After oral administration, NGR1 exhibited dose‐independent exposure behaviors with t1/2 over 8.0 h and oral bioavailability of 0.25–0.29%. A total of seven metabolites were characterized, including two pairs of epimers, 20(R)‐notoginsenoside R2/20(S)‐notoginsenoside R2 and 20(R)‐ginsenoside Rh1/20(S)‐ginsenoside Rh1, with the 20(R) form of saponins identified for the first time in rat plasma. Five deglycometabolites were quantitatively determined, among which 20(S)‐notoginsenoside R2, ginsenoside Rg1, ginsenoside F1 and protopanaxatriol displayed relatively high exploration, which may partly explain the pharmacodynamic diversity of ginsenosides after oral dose. [ABSTRACT FROM AUTHOR]