Natural and synthetic Huperzine A: effect on cholinergic function in vitro and in vivo

Huperzine A has been shown to be useful in the treatment of symptoms of dementia of the Alzheimer type. Our initial attempts to synthesize (-)Huperzine A resulted in the racemic mixture of (+/-)Huperzine A. We have therefore compared the in vitro and in vivo effects of (+/-)Huperzine A with those of (-)Huperzine A in rats. The results indicate a similar biological mechanism of action between the two, but that the racemic mixture of (+/-)Huperzine A has a weaker biological activity than the natural product (-)Huperzine A, presumably due to the presence in the mixture of (+)Huperzine A, which is considerably less potent than the (-)isomer.