Abstract
The 80% aqueous methanolic extract from the bulbs of Crinum yemense showed a potent inhibitory effect on nitric oxide production in lipopolysaccharide-activated macrophages. Three new crinine-type alkaloids, yemenines A (1), B (2), and C (3), were isolated from the herbal extract together with six known alkaloids. The absolute configurations of 1-3 were determined on the basis of chemical and physicochemical evidence. The effects of the isolated alkaloids on nitric oxide production in lipopolysaccharide-activated macrophages were examined, and several alkaloids, e.g. 1, (+)-bulbispermine (6), (+)-crinamine (7), (+)-6-hydroxycrinamine (8), and (-)-lycorine (9), showed inhibitory effects on nitric oxide production and induction of inducible nitric oxide synthase.