It is concluded that the screening capability of MetaboLynx(TM), together with the utilisation of MS(E) in structural elucidation, can facilitate a rapid and comprehensive detection and effective structural characterisation of Stemona alkaloids in Radix Stemonae extract, which could be applied to other Chinese medicine. The results provide helpful chemical information of Radix Stemonae extract for further pharmacology and active mechanism research.
A rapid, sensitive, specific and reliable ultra-performance liquid chromatography coupled with electrospray ionization/quadrupole-time-of-flight mass spectrometry (UPLC-ESI-Q-TOF-MS) method with MassLynx™ MassFragment was developed for the analysis of Suanzaoren decoction (SZRD), a Chinese herbal prescription. The analysis was performed on a Waters UPLC BEH C(18) column using gradient elution system. A hyphenated electrospray ionization and Q-TOF analyzer was used for the determination of accurate mass of the protonated or deprotonated molecule and fragment ion in both negative and positive modes. The chromatographic separation was achieved by UPLC, which used a column with 1.7 μm particle packing which enabled higher speed of analysis, peak capacity, greater resolution and increased sensitivity. The constituents of SZRD were identied and confirmed according to the mass spectrometric fragmentation mechanisms, MS/MS fragment ions, relevant literature and the establishment of an in-house molecular formula database. With this method, a total of 22 compounds of SZTD were tentatively identied based on MS and MS/MS data and comparison with available databases. It is concluded that a rapid and robust platform based on UPLC-ESI-Q-TOF-MS was established, which is useful for identifying multiple-constituent of traditional Chinese medicine (TCM) prescriptions. Our present results proved that the established method could provide helpful chemical information for further pharmacological mechanism research of SZRD.
In a series of studies on the metabolism of iridoid compounds, we investigated the metabolic fate of swertiamarin (1) in Wistar rats. Liquid chromatography/ion trap mass spectrometry detected new nitrogen-containing metabolite gentiandiol (3) in rat plasma. The structure of the metabolite was unequivocally identified by comparing the retention time as well as the mass spectrum with those of authentic compound, which was synthesized from swertiamarin (1). The transformation of swertiamarin to nitrogen-containing metabolite gentiandiol (3) in vivo was verified for the first time. Understanding of this unique metabolic pathway may shed light on clinical efficacy of swertiamarin (1) and will also assist in studies for the metabolism of other natural iridoids in vivo.
Isofraxidin is one of the main bioactive constituents in the root of Acanthopanax senticosus, which has antifatigue, antistress, and immuno-accommondating effects. In this study, an ultraperformance LC (UPLC)-ESI MS method was developed for analyzing isofraxidin and its metabolites in rat plasma. The analysis was performed on a UPLC coupled with ESI MS (quadropole MS tandem TOF MS). The lower LOD (LLOD) for isofraxidin was 0.25 ng/mL, the intraday precision was less than 10%, the interday precision was less than 10%, and the extraction recovery was more than 80%. Isofraxidin and two metabolites (M1 and M2) were detected in rat plasma after oral administration of isofraxidin, and the molecular polarities of M1 and M2 were both increased compared to isofraxidin. The metabolites were identified as 5,6-dihydroxyl-7-methoxycoumarin and 5-hydroxyl-6,7-dimethoxycoumarin when subjected to parent ion spectra, product ion spectra, and extract mass and element composition analyses.
A method for the rapid and simultaneous determination of 6,7-dimethylesculetin (CAS 120-08-1) and geniposide (CAS 24512-63-8) in rat plasma has been developed, using validated high performance liquid chromatography (HPLC) with solid phase extraction (SPE). The HPLC analysis was performed on a commercially available column (200 mm x 4.6 mm, 5 microm) with acetonitrile-methanol-0.1% aqueous formic acid as mobile phase and the UV detection at 343 nm and 238 nm for 6,7-dimethylesculetin and geniposide, respectively. The calibration curves for 6,7-dimethylesculetin and geniposide were linear over the range 0.4-25.6 microg/mL and 1.12-71.68 microg/mL, respectively. The lower limits of quantitation were 0.40 microg/ mL and 1.12 microg/mL, and the lower limits of detection were 0.06 microg/mL and 0.09 microg/ mL, respectively. The intra-day and inter-day precision for 6,7-dimethylesculetin and geniposide were < 5%, whereas the absolute recovery percentages were > 74%. A successful application of the developed HPLC analysis was demonstrated for the pharmacokinetic study of a Traditional Chinese Medicine formula of Yin Chen Hao Tang preparation.
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