In the course of screening natural products for anti-acetylcholinesterase (AChE) activity, we found that a total methanolic extract of the underground parts of Caragana chamlague (Leguminosae) had significant inhibition towards AChE. Bioactivity-guided fractionation of the total methanolic extract resulted in the isolation and identification of two active stilbene oligomers, (+)-α-viniferin (1) and kobophenol A (2). Both 1 and 2 inhibited AChE activity in a dose-dependent manner, and the IC50 values of 1 and 2 were 2.0 and 115.8 µM, respectively. The AChE inhibitory activity of 1 was specific, reversible and noncompetitive.
2002 The Pharmaceutical Society of Japan