Huperzine A is a naturally occurring sesquiterpene alkaloid compound found in the firmoss Huperzia serrata[2] and in varying quantities in other Huperzia species, including H. elmeri, H. carinat, and H. aqualupian.[3] Huperzine A has been investigated as a treatment for neurological conditions such as Alzheimer's disease, but a meta-analysis of those studies concluded that they were of poor methodological quality and the findings should be interpreted with caution.[4][5] Huperzine A inhibits the breakdown of the neurotransmitter acetylcholine by the enzyme acetylcholinesterase. It is commonly available over the counter as a nutrient supplement, and is marketed as a cognitive enhancer for improving memory and concentration.
Huperzine A is extracted from Huperzia serrata. It is a reversible acetylcholinesterase inhibitor and NMDA receptor antagonist that crosses the blood-brain barrier. Acetylcholinesterase is an enzyme that catalyzes the breakdown of the neurotransmitter
acetylcholine and of some other choline esters that function as
neurotransmitters. The structure of the complex of huperzine A with
acetylcholinesterase has been determined by X-ray crystallography (PDB code: 1VOT; see the 3D structure).
For some years, huperzine A has been investigated as a possible
treatment for diseases characterized by neurodegeneration, particularly Alzheimer's disease. A 2013 meta-analysis found that huperzine A may be efficacious in
improving cognitive function, global clinical status, and activities of
daily living for individuals with Alzheimer`s disease. However, due to
the poor size and quality of the clinical trials reviewed, huperzine A
should not be recommended as a treatment for Alzheimer`s disease unless
further high quality studies confirm its beneficial effects.
Huperzine A is also marketed as a dietary supplement with claims made for its ability to improve memory and mental function.
Huperzine A has also been postulated as a potential treatment for myasthenia gravis.
Huperzine A may present with mild cholinergic side effects such as nausea, vomiting, and diarrhea. The use of huperzine A during pregnancy and lactation is not recommended due to the lack of sufficient safety data
Huperzine A may have additive effects if taken with drugs causing bradycardia, such as beta-blockers which may decrease heart rate. Theoretically, there may be possible
additive cholinergic effects if huperzine A is taken with other acetylcholinesterase inhibitors or cholinergic agents.
Two scalable and efficient total syntheses of huperzine A have been reported
Pharmacological effects
Adverse effects
Drug interactions
Synthesis