Huperzia serrata, a type of fir moss, is also known as Chinese club moss. It is used as a component in traditional Chinese herbal formulas for blood circulation and to relieve pain. A purified alkaloid extract from this plant known as Huperzine A has neuroprotective effects and has been developed as a treatment for Alzheimer’s disease and dementia in Asia (1). In the US, it is available as a dietary supplement to promote cognitive function. It is also used by some cancer patients to relieve pain and neurological dysfunction due to chemotherapy.
Huperzine A is a potent acetylcholinesterase inhibitor, raising the levels of acetylcholine in the basal ganglia (1). Animal studies show it has antiapoptotic, anti-inflammatory, and antioxidative properties which contribute to its protective effects in nerve agent poisoning (2), myasthenia gravis (3), hepatic reperfusion injury (4), and diabetes-associated cognitive decline (5). Clinical studies on Huperzine A as a treatment for Alzheimer’s disease have yielded mixed results (6) (7) (8). One study found it to improve cognitive function in vascular dementia patients (9).
Although a US patent has been filed claiming its use for cancer pain and neuropathy (10) , no clinical trials for these indications have been conducted.
Mild adverse effects from Huperzine A have been reported (7). Because it acts as an acetylcholinesterase inhibitor, it can potentially interact with many drugs including other anticholinergic drugs, dopamine D2 receptor blockers, calcium channel blockers, and beta adrenergic receptor antagonists (11).