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: beta-amyrin acetate (2); glutinol acetate (3); friedelin (4); glutinol (5); (3beta)-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 5alpha,6alpha-epidioxy-5beta,6beta-epoxy-9,13-dimethyl-25,26-dinoroleanan-3beta-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 GI(50) in the range of 11.1-17.9microM, 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 (1-100nM) were evaluated for the inhibitory activity of TNF-alpha 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 100nM, whereas other five compounds (2-6) exhibited moderate activity.