Welcome to NNFA - Products and Services Science and Quality Assurance: "Huperzine A is an alkaloid isolated from a Chinese herbal medicine prepared from the moss Huperzia serrata. It is a potent inhibitor of the enzyme acetylcholinesterase (1B). The neurotransmitter acetylcholine is destroyed by this enzyme. Since acetylcholine production in the brain is reduced in Alzheimer's disease, inhibitors of acetylcholinesterase have been found useful in treating this disorder. Huperzine A has been tested in small clinical trials in China and improved memory, cognition and behavior in a majority of patients (2A, 3A). No severe adverse effects were found."