Triterpene compounds isolated from Acer mandshuricum and their anti-inflammatory activity

In our preliminary screening study on the anti-inflammatory activity, a new triterpene compound, aceranol acetate (1), was isolated along with five known compounds: β-amyrin acetate (2); glutinol acetate (3); friedelin (4); glutinol (5); (3β)-d-glucopyranoside-stigmast-5-en-3-yl (6), from the stems and leaves of Acer mandshuricum. The structure of the new triterpene was determined to be 5α,6α-epidioxy-5β,6β-epoxy-9,13-dimethyl-25,26-dinoroleanan-3β-ol acetate by spectroscopic studies. Compounds 2–6 were isolated from this plant for the first. Five triterpene compounds (1–5) showed significant cytotoxic activity with GI50 in the range of 11.1–17.9 μM, whereas steroid compound (6) exhibited moderate activity against four human cancer cell lines (HL-60, SK-OV-3, A549, and HT-29). Furthermore, the anti-inflammatory effects of compounds 1–6 in the non-cytotoxic concentrations (1–100 nM) were evaluated for the inhibitory activity of TNF-α secretion in the lipopolysaccharide (LPS)-stimulated murine RAW264.7 macrophage cell line. Among the compounds tested, compound 2 showed the strongest anti-inflammatory activity with the inhibition rate up to 38.40% at the concentration of 100 nM, whereas other five compounds (2–6) exhibited moderate activity.

Graphical abstractBioassay-guided fractionation of the MeOH extract led to the isolation of six compounds, including one new triterpene (1). Compound 2 reduced the LPS-induced secretion of TNF-α in a RAW264.7 cell line.Figure optionsDownload full-size imageDownload as PowerPoint slide