Huperzine A (shuangyiping): a promising drug for Alzheimer's disease.

Hup A, a novel alkaloid isolated from Chineses herb Huperzia serrata, is a potent and selective inhibitor of AChE, with a rapid absorption and penetration into the brain in experimental animals. The inhibition is reversible with a longer duration of action. Hup A exhibited memory-enhancing activities in a broad range of animal cognitive model. Compared to Phy, Tac, and Gal, Hup A has better therapeutic indices, and peripheral cholinergic side effects are minimal at therapeutic doses. These findings suggest that Hup A is a promising candidate for clinical development as a symptomatic treatment for AD.