Discovery of cyclooxygenase-2 inhibitors from Kadsura coccinea by affinity ultrafiltration mass spectrometry and the anti-inflammatory activity.

The medicinal plant Kadsura coccinea distributing in South China, was widely used for reducing inflammation and relieving pain. Previous study in our laboratory had proved the significant therapeutic effects of K. coccinea extract on adjuvant arthritis rats. To explore the responsible components and possible mechanisms, an AUF-HPLC-Q-TOF/ MS method was employed for screening and characterizing COX-2 ligands from K. coccinea stems for the first time. Meanwhile, the molecular docking was performed to simulate the binding modes for ligands and COX-2, the cell-free enzyme activity assay was applied to verify the direct COX-2 inhibition of potential inhibitors, and the cell-based study on COX-2 expression was to evaluate the anti-inflammatory effect of (+)-Anwulignan. As a result, the potential COX-2 inhibitor (+)-Anwulignan significantly suppressing COX-2 expressions in LPS signaling pathways might be a good candidate for anti-inflammation and analgesia. In conclusion, AUF mass spectrometry combining the molecular docking and bioassays in vitro was an efficient approach for discovering enzyme inhibitors from traditional herbs.

Baeckeins L and M, two novel C-methylated triflavonoids from the roots of Baeckea frutescens L.

Baeckea frutescens is a medicinal plant distributing from Southeast Asia to Australia. A pair of novel diastereomeric C-methylated triflavonoids named baeckeins L (1) and M (2) were isolated from the roots of B. frutescens. The structures of these isolates were elucidated by analysis of the 1D (1H/13C) and 2D NMR (HSQC/HMBC/NOESY) and HR-ESI-MS spectroscopic data, and the absolute configurations of chiral carbons (C-2/C-3/C-2°/C-3°) were established by CD spectrometry combined with quantum chemical calculations.

Identification and quantification of flavonoids and chromes in Baeckea frutescens by using HPLC coupled with diode-array detection and quadruple time-of-flight mass spectrometry.

This article marks the first report on high-performance liquid chromatography (HPLC) coupled with diode-array detection (DAD) and quadruple time-of-flight mass spectrometry (Q-TOF/MS) for the identification and quantification of main bioactive constituents in Baeckea frutescens. In total, 24 compounds were identified or tentatively characterised based on their retention behaviours, UV profiles and MS fragment information. Furthermore, a validated method with good linearity, sensitivity, precision, stability, repeatability and accuracy was successfully applied for simultaneous determination of five flavonoids and one chromone in different plant parts of B. frutescens collected at different harvest times, and their dynamic contents revealed the appropriate harvest times. The established HPLC-DAD-Q-TOF/MS using multi-bioactive markers was proved to be a validated strategy for the quality evaluation on both raw materials and related products of B. frutescens.

Baeckeins F-I, four novel C-methylated biflavonoids from the roots of Baeckea frutescens and their anti-inflammatory activities.

Baeckea frutescens is an aromatic shrub used in South China as an ornamental and as a spice. Four unusual C-methylated biflavonoids named baeckeins F-I (1-4) were isolated from the roots of B. frutescens. The baeckeins F-I possessed a unique carbon skeleton, a flavonol conjugated with a coumaronochromone molecule via the unusual linkages of C-2-C-8 and C-3-O-C-7. Their structures were elucidated by analysis of the 1D ((1)H/(13)C) and 2D NMR (HSQC/HMBC/NOESY) and HR-ESI-MS spectroscopic data, and the absolute stereochemistry for chiral carbons of C-2 and C-3 was established by CD spectrometry combined with quantum chemical calculations. Baeckeins F-I (1-4) were also evaluated for their anti-inflammatory activities by detecting the NO production of LPS-induced RAW264.7 murine macrophage cell line; baeckein I (4) with the ß-d-glucose unit and configuration of (2R,3R) exhibited the highest NO inhibitory activity (IC50=15.2 µM), which was similar to that of the positive control indomethacin.

Baeckein E, a new bioactive C-methylated biflavonoid from the roots of Baeckea frutescens.

A phytochemical study of Baeckea frutescens afforded a new biflavonoid named as baeckein E (1), along with four known C-methylated flavonols, baeckeins A (2) and B (3), 6-methylquercetin (6) and 6-methylquercetin-4'-O-ß-D-glucopyranoside (7), and two known biflavonoids baeckeins C (4) and D (5). The structure of compound 1 was elucidated on the basis of spectroscopic analysis, including HR-ESI-MS, 1D and 2D NMR spectra, and the absolute configurations of C-2 and C-3 for compound 1 were assigned by circular dichroism spectrometry combined with quantum chemical calculations. The antioxidant and cytoprotective activities of compounds 1-7 were also investigated.

Structure determination of baeckeins C and D from the roots of Baeckea frutescens.

Baeckeins C (compound 1) and D (compound 2), a pair of new diastereomeric biflavonoids, were isolated from the roots of Baeckea frutescens. Their structures were elucidated on the basis of spectroscopic analysis, including HR-ESI-MS and one- and two-dimensional NMR spectra ((1)H and (13)C NMR, HSQC, HMBC, and ROESY). The absolute configurations of the 2,3-epoxide moiety for compounds 1 and 2 were determined by circular dichroism spectrometry combined with quantum chemical calculations.

Quality evaluation of Potentilla discolor by high-performance liquid chromatography coupled with diode array detection and electrospray ionisation tandem mass spectrometry.

INTRODUCTION: The whole herb of Potentilla discolor has long been used for treatment of diarrhoea, malaria, haemoptysis and haematemesis in clinical applications. However, until now, there has been no literature regarding to the quality control of it. OBJECTIVE: To develop a simple and accurate HPLC-DAD (diode array detection)-ESI/MS(n) (electrospray ionisation multistage mass spectrometry) method for the identification of constituents in P. discolor and simultaneous quantification of its marker compounds. METHODOLOGY: Separations were performed on a Shimpack C18 column by gradient elution using acetonitrile:0.1% formic acid. The identification of constituents in P. discolor were achieved by HPLC-DAD-ESI/MS(n) while six flavonoids and five triterpenoids were determined by HPLC-DAD at 360 and 210 nm, repectively. RESULTS: A total of 23 compounds including 13 flavonoids and 10 triterpenoids were identified or tentatively characterised. A quantitative HPLC-DAD method allowing the simultaneously quantification of 11 marker compounds was optimised and validated for linearity, precision, accuracy, and limits of detection and quantification. The method was successfully applied to the quantification of 11 marker compounds in 10 samples of P. discolor collected from different provinces of China. CONCLUSION: This developed method was validated as simple, precise and accurate, and could be used for effectively and comprehensibly evaluating the quality of P. discolor.