An undescribed xanthone dimer, 1,3,5,8-tetrahydroxy-7-(1',5',8'-trihydroxy-3'-methoxy-2'-xanthonyl)xanthone (1) was separated together with eleven known compounds (2-12) from the dried whole herb of Swertia pseudochinensis. It was the first time that the compounds 8-12 were isolated from the Swertia genus. The structure of compound 1 was illuminated based on chemical evidence and spectral data analysis (UV, 1D and 2D-NMR, HR-ESI-MS). Moreover, the inhibitory effects of all compounds on NO production in LPS-induced RAW 264.7 cells were tested, compounds 8, 9, 10, 11 and 12 showing significant inhibition. The IC50 value of compound 12 was 3.05±1.10 μM. Using target screening and molecular docking, we hypothesized that compound 12 may bind neutrophil elastase to exert its anti-inflammatory effects.
Keywords: Swertia pseudochinensis; anti-inflammatory activity; phenylpropanoids; xanthone dimer; xanthones.
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