Galanthamine, a natural product for the treatment of Alzheimer's disease.

(-)-Galanthamine is a selective, reversible competitive acetylcholinesterase inhibitor that has been recently approved for the symptomatic treatment of Alzheimer's disease. Galanthamine is a natural product belonging to the Amaryllidaceae family of alkaloids. The pharmacological history of galanthamine shows that the bioactive compound was discovered accidentally in the early 1950s, and the plant extracts were initially used to treat nerve pain and poliomyelitis. In addition, galanthamine had since been tested for use in anesthesiology, from facial nerve paralysis to schizophrenia. Galanthamine is a long-acting, selective, reversible and competitive AChE inhibitor that has recently been tested in AD patients and found to be readily absorbed, to be a performance enhancer on memory tests in some patients, and to be well tolerated, although some cholinergic side effects were observed. A number of total synthetic approaches have been reported, and a method for the industrial scale-up preparation of galanthamine is now being developed and patented. A variety of galanthamine derivatives have also been synthesized aiming to develop an agent free from cholinergic adverse effects. Galanthamine is a natural product that complements other synthetic drugs for the management of AD. In this account we will review the recent patent literature showing the most important advance on the chemistry of galanthamine.