In vitro
(-)-Huperzine A is a novel alkaloid isolated from the Chinese herb Huperzia serrata. (-)-Huperzine A preferentially inhibits tetrameric AChE (G4 form). (-)-Huperzine A is more potent than tacrine, physostigmine, galanthamine, and rivastigmine with respect to inhibition of AChE activity, whereas HupA is the least potent BuChE inhibitor among the inhibitors. (-)-Huperzine A possesses the ability to protect cells against hydrogen peroxide, beta-amyloid protein, glutamate, ischemia and staurosporine-induced cytotoxicity and apoptosis. These protective effects are related to its ability to attenuate oxidative stress, regulate the expression of apoptotic proteins Bcl-2, Bax, P53, and caspase-3, protect mitochondria, upregulate nerve growth factor and its receptors, and interfere with amyloid precursor protein metabolism.