Chemical constituents and anti-inflammatory activity from Ligularia virgaurea

Abstract

Ligularia virgaurea is one of the original plants of the Tibetan medicine “Rixiao” for the treatment of clearing heat and removing yellow water. In order to study the chemical constituents and anti-inflammatory activity of L. virgaurea, the compounds were separated by silica gel, Sephadex LH-20 gel, ODS gel column chromatography and other column chromatography technologies. The structures of all isolates were identified by spectroscopic methods (NMR and HR-ESI-MS). Their inhibitory activity of the compounds on nitric oxide (NO) was determined by lipopolysaccharide (LPS)-induced RAW264.7 cell model. The results were as follows: (1) Twenty-one compounds were separated and identified from petroleum ether and n-butanol extracts of L. virgaurea, including spiroeuryolide (1), cacalol acetate (2), oplopenone (3), 8-ethyl-palmosalide A (4), 1-hydroxy-3,7-dimethyl-2-(pent-3-enyl)benzofuran (5), syringaresinol-O-β-D-glucopyranoside (6), pinoresinol-O-β-D-glucopyranoside (7), isoeucommin A (8), eucommin A (9), 6,7-dimethoxycoumarin (10), ferulic acid (11), ethyl caffeate (12), methyl caffeate (13), methyl ferulate (14), ethyl ferulate (15), caffeic acid (16), 2-［(2′E)-3′,7′-dimethyl-2′,6′-octadienyl］-4-methoxy-6-methylphenol (17), 2,8-dimethyl-6-methoxy-2-(4′-methylpent-3′-enyl)-chromene (18), β-sitosterol (19), dodecyl(Z)-9-hexadecenoate (20) and hexacosanal (21). Compounds 1-4, 6, 11-16, 18, 20, 21 were isolated from the whole herbs of L. virgaurea for the first time. (2) The anti-inflammatory activity in vitro showed that compounds 1-3, 6, 11-16, 17, 19 could significantly inhibited releases of NO at concentration ranging from 1.56 to 50.00 μmol·L-1(P<0.05 or P<0.01), Compound 5 had no inhibitory effect on the release of NO at a concentration of 50.00 μmol·L-1, but it could inhibit releases of NO at concentrations of 12.50, 25.00 μmol·L-1(P<0.05). This finding enriches the chemical constituent and biological activity research of L. virgaurea and provides a certain theoretical reference for the future development and utilization of its anti-inflammatory activity.

Keywords

• ligularia virgaurea
• sesquiterpenes
• chemical constituent
• structural identification
• anti-inflammatory activity