Isolation of constituents and anti-complement activity from Acer okamotoanum.

A novel acylated sterol glucoside (1) along with four known compounds, beta-amyrin acetate (2), 3beta,24-dihydroxytaraxer-14-ene (3), cleomiscosin A (4), and cleomiscosin C (5), were isolated from the leaf and twig of Acer okamotoanum Nakai (Aceraceae). The structure of the new compound was determined to be beta-sitosterol glucoside-3'-O-hexacosanoicate based on chemical and spectroscopic analyses. In addition, the novel compound was found to exhibit a significant inhibitory effect (IC50 value of 0.2 microM) on the complement system activated by the classical pathway.