Stemona alkaloids isolated from Stemona tuberosa roots and their inhibitory activity on lipopolysaccharide-induced nitric oxide production

A methanol extract of the roots of Stemona tuberosa (Stemonaceae) significantly inhibited lipopolysaccharide-induced nitric oxide production in murine BV2 microglial cells. Eight alkaloids tuberostemonine K (1), neotuberostemonine (2), oxotuberostemonine (3), bisdehydroneotuberostemonine (4), epibisdehydrotuberostemonine J (5), bisdehydrotuberostemonine (6), tuberostemoninol (7), and neostenine (8) were isolated from the methanolic extract using bioactivity-guided fractionation. Among them, compounds 4, 5 and 6 showed significant inhibitory effect on lipopolysaccharide-induced nitric oxide production in BV2 microglia at 100 m M