(-)-Huperzine A

(-)-Huperzine A is an Acetylcholinesterase inhibitor and NMDA receptor antagonist with an IC50 of 126 μM for NMDA-induced current. Huperzine A, is a naturally occurring sesquiterpene alkaloid compound found in the plant firmoss Huperzia serrata. The IC (50) values of huperzine A were neither altered by changing the concentrations of glycine (2-0.2 μM) and pH (7.4-6.7) in the external solution, nor by addition of Zn (2+) (5 μM) and dithiothreitol (5 mM) to the external solution.