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Clinical data | |
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Other names | HupA |
Routes of administration | By mouth |
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Pharmacokinetic data | |
Elimination half-life | 10–14 hours [1] |
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ChEBI | |
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CompTox Dashboard (EPA) | |
ECHA InfoCard | 100.132.430 |
Chemical and physical data | |
Formula | C15H18N2O |
Molar mass | 242.322 g·mol−1 |
3D model (JSmol) | |
Melting point | 217 to 219 °C (423 to 426 °F) |
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Huperzine A, a Lycopodium alkaloid, was first isolated in 1983 from Huperzia serrata , [2] [3] [4] a plant used in Chinese folk medicine. Huperzine A also exists in other Huperzia species, including H. elmeri, H. carinat, and H. aqualupian with varying quantities. [5]
Huperzine A has been investigated as a treatment for neurological conditions such as Alzheimer's disease, but a 2013 meta-analysis of those studies concluded that they were of poor methodological quality and the findings should be interpreted with caution. [6] [7] Huperzine A inhibits the breakdown of the neurotransmitter acetylcholine (ACh) by the enzyme acetylcholinesterase. It is also an antagonist of the NMDA receptor. It is commonly available over the counter as a nutritional supplement and marketed as a memory and concentration enhancer.
Huperzine A may present with mild cholinergic side effects such as nausea, vomiting, and diarrhea. [7] Slight muscle twitching and slurred speech might also occur, as well as hypersalivation and sweating. The use of huperzine A during pregnancy and lactation is not recommended due to the lack of sufficient safety data. [8]
Huperzine A is a reversible acetylcholinesterase inhibitor [9] [10] [11] [12] and NMDA receptor antagonist [13] that crosses the blood–brain barrier. [14] Acetylcholinesterase is an enzyme that catalyzes the breakdown of the neurotransmitter ACh and 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). [15]
Huperzine A may have additive effects if taken with drugs causing bradycardia, such as beta-blockers, [16] 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. [17]
Huperzine A, in spite of the possible cholinergic side effects, seems to have a wide margin of safety. Toxicology studies show huperzine A to be non-toxic even when administered at 50-100 times the human therapeutic dose. The extract is active for 6 hours at a dose of 2 μg/kg with no remarkable side effects. [18]
Two scalable and efficient total syntheses of huperzine A have been reported. [19] [20]
In 1989, a research study found [21] that the chemical structure of the alkaloid selagine reported in 1960 from a study of Lycopodium slago L. [22] (analyzed using 60-MHz NMR) was identical to that of Huperzine A.
Huperzine A has been investigated as a possible treatment for diseases characterized by neurodegeneration such as Alzheimer's disease, [23] [24] and there is some evidence from small-scale studies that it can benefit cognitive functioning, global clinical status, and ability to engage in activities of daily living (ADLs) among individuals with the disease. In a 2016 systematic review of systematic reviews, [25] huperzine A was associated with a standardized mean difference of 1.48 (95% CI, 0.95-2.02) compared to placebo on measures of ADL among people with dementia, but the evidence was very low-quality and uncertain. In a 2022 umbrella review, [26] huperzine A was associated with broad benefits to dementia patients' cognitive functioning, but the degree of heterogeneity in measurements and outcomes of the reviewed studies indicated publication bias toward huperzine A benefit.
Huperzine A might be useful in the treatment of organophosphate nerve agent poisoning by preventing damage to the central nervous system caused by such agents. [27] [28]
Huperzine A (HupA), a novel alkaloid isolated from the Chinese herb Huperzia serrata, is a potent, highly specific and reversible inhibitor of acetylcholinesterase (AChE).