Constituents of stem bark of Callistemon rigidus showing inhibitory effects on mouse alpha-amylase activity.

From stem bark of Callistemon rigidus (Myrtaceae), piceatannol and scirpusin B were isolated as components that exhibit inhibitory effects on alpha-amylase activity in isolated mouse plasma. In particular, scirpusin B also inhibited alpha-amylase in mouse gastrointestinal tract. Thus, we expect the depressive effect on the elevation of postprandial blood glucose may be a new medicinal use of this compound as well as the plant itself.