Alzheimer's Disease and Huperzine A
Huperzine A (HUP-er-zeen) is a medicinally active, plant-derived chemical that belongs to the class known as alkaloids. This substance is really more a drug than an herb, but it is sold over-the-counter as a dietary supplement for memory loss and mental impairment. In studies on Alzheimer's patients, Huperzine A has been shown to improve mental and memory function, which are key symptoms of Alzheimer's Disease.
Effect of Huperzine A on Alzheimer's Disease
Huperzine A can help improve mental function in Alzheimer's patients. It inhibits the enzyme acetylcholinesterase (uh-SEE-tul-co-lin-ES-ter-ase). This enzyme breaks down acetylcholine, a substance that plays an important role in mental function. When the enzyme that breaks it down is inhibited, acetylcholine levels in the brain tend to rise. Drugs that inhibit acetylcholinesterase (such as tacrine and donepezil) improve memory and mental functioning in people with Alzheimer's and other severe conditions. The research on huperzine A indicates that it works in much the same way.
The chemical action of huperzine A is very precise and specific. It "fits" into a niche on the enzyme where acetylcholine is supposed to attach.22,23 Because huperzine A is in the way, the enzyme can't grab and destroy acetylcholine. This mechanism has been demonstrated by considerable scientific work, including sophisticated computer modeling of the shape of the molecule.24 Huperzine may also help protect nerve cells from damage.25-28
Side Effects and Warnings
Perhaps because it works so specifically, huperzine A appears to have few side effects. However, children, pregnant or nursing women, or those with high blood pressure or severe liver or kidney disease should not take huperzine A except on a doctor's recommendation. We also don't know for sure whether huperzine A interacts adversely with any drugs; however, it seems likely that huperzine might interact with drugs that function in a similar fashion (such as standard drugs for Alzheimer's Disease).
- Raves ML, Harel M, Pang YP, et al. Structure of acetylcholinesterase complexed with the nootropic alkaloid, (-)-huperzine A. Nat Struct Biol. 1997;4:57–63.
- Ashani Y, Peggins JO III, Doctor BP. Mechanism of inhibition of cholinesterases by huperzine A. Biochem Biophys Res Commun. 1992;184:719–726.
- Pang YP, Kozikowski AP. Prediction of the binding sites of huperzine A in acetylcholinesterase by docking studies. J Comput Aided Mol Des. 1994;8:669–681.
- Ved HS, Koenig ML, Dave JR, et al. Huperzine A, a potential therapeutic agent for dementia, reduces neuronal cell death caused by glutamate. Neuroreport. 1997;8:963–968.
- Zhou J, Zhang HY, Tang XC. Huperzine A attenuates cognitive deficits and hippocampal neuronal damage after transient global ischemia in gerbils. Neurosci Lett. 2001;313:137-140.
- Zhou J, Fu Y, Tang XC. Huperzine A protects rat pheochromocytoma cells against oxygen-glucose deprivation. Neuroreport. 2001;12:2073-2077.
- Wang LM, Han YF, Tang XC. Huperzine A improves cognitive deficits caused by chronic cerebral hypoperfusion in rats. Eur J Pharmacol. 2000;398:65-72.