Inhibitory constituents of Euonymus alatus leaves and twigs on nitric oxide production in BV2 microglia cells

The excessive and prolonged nitric oxide (NO) production has been linked to various inflammatory diseases as well as tumourigenesis. On the search for anti-inflammatory and anti-cancer compounds from the medicinal plants, the methanolic extract of Euonymus alatus (Thunb.) Sieb. (Celastraceae) was found to have significant inhibitory activity on NO production in lipopolysaccharide (LPS)-stimulated BV2 microglia cells. Hence, we attempted to isolate the inhibitory constituent of E. alatus leaves and twigs on NO production. Thirteen compounds including two new glycerol derivates (1, 2), two C13 isoprenoids (3, 4), two phenolics (5, 6) and seven flavonoids (7–13) were isolated, and the structures of 1–13 were elucidated by extensive 1D and 2D spectroscopic methods. The isolated compounds significantly inhibited NO production induced by LPS in BV2 microglia cells.