(−)-Huperzine A

(−)-Huperzine A is a potent and reversible inhibitor of acetylcholinesterase. It shows an IC₅₀ value of 82 nM against acetylcholinesterase in the rat cortex in vitro. It also acts as an antagonist of the N-methyl-D-aspartate (NMDA) receptor and inhibits NMDA induced toxicity. It is beneficial in improving cognitive function in Alzheimer’s disease.