Chemical constituents from the rhizome of Menispermum dauricum and their anti-inflammatory activities

Bei-dou-gen, the dried rhizome of Menispermum dauricum from the Menispermaceae family, is an important Chinese medicinal material. In order to clarify the pharmacodynamic substance basis, the methanol extract of the rhizome in M. dauricum was systematically isolated and purified using various chromatographic methods and the structures of isolated compounds were identified. The potential anti-inflammatory activity of obtained compounds from M. dauricum was measured in vitro. In this study, the chemical constituents were separated via silica gel column chromatography, macroporous adsorption resin and preparative HPLC, and their structures were determined on the basis of MS, 1H-NMR, 13C-NMR and other spectroscopic data analysis, as well as comparison with relevant literatures. Meanwhile, the anti-inflammatory activities of against NO and IL-6 production from LPS-induced RAW264.7 cells of the chemical components were evaluated in vitro. The results were as follows: (1) Fifteen compounds were isolated from the rhizome of M. dauricum, and identified as p-hydroxybenzaldehyde (1), vanillic acid (2), syringaldehyde (3), 2-hydroxy-1-(4-hydroxy-3,5-dimethoxyphenyl)-1-propanone (4), methyl 4-hydroxyphenylacetate (5), 2-(4-hydroxyphenyl)-1-nitroethane (6), 4-hydroxyphenylacetonitrile (7), dibutyl phthalate (8), fragransin B2 (9), 7-hydroxy-3,6-dimethoxy-1,4-phenanthraquinone (10), palmitic acid (11), arachidic acid (12), β-sitosterol (13), β-stigmasterol (14) and daucosterol (15). Among them, compounds 4-7, 9 and 12 were isolated from Menispermaceae for the first time, while compounds 1, 3-11 and 14 were first reported from Menispermum genus. The above compounds were all non-alkaloids components, including phenols, lignans, phenanthraquinones, fatty acids and sterols. (2) Anti-inflammatory assay in vitro showed that Compound 12 could significantly inhibited releases of NO and IL-6 induced by LPS from RAW264.7 cells at the concentrations of 25 and 50 μg·mL-1, indicating potential anti-inflammatory activity. The results of this study enrich the chemical diversity of the rhizome of M. dauricum and clarifies the active ingredients of its anti-inflammatory activity, and provide effective reference for the rational utilization of medicinal plant resources.