Mossy memory-booster for Alzheimer's?

For hundreds of years, Chinese folk doctors have known an intriguing but mysterious fact: Drinking tea brewed with a type of club moss (Huperzia serrata) can perk up people's memories.

Western doctors pooh-poohed this folklore--until recently.

About seven years ago, researchers at the Shanghai Institute of Materia Medica isolated a natural compound in the tea that is "a potent inhibitor of acetylcholinesterase," says Xu-Chang He, a chemist with the Chinese Academy of Sciences in Shanghai. Acetylcholinesterase, an enzyme, breaks down acetylcholine, a key chemical messenger in the brain involved in memory and awareness.

The Chinese finding galvanized Alzheimer's researchers in the West. Now the chemical, called huperzine A, is the subject of intense research at the Mayo Clinic in Jacksonville, Fla., reports Giuseppe Campiani, a medicinal chemist there.

Huperzine A is proving to be one of the most potent and selective acetylcholinesterase inhibitors under study for the treatment of Alzheimer's disease, which damages memory and affects 4 million U.S. residents, says Campiani. Alzheimer's patients suffer a depletion of acetylcholine. Huperzine A, like the drug tacrine (THA), prevents acetylcholinesterase from breaking down this essential chemical, thus raising levels of acetylcholine in the brain and improving memory.

Huperzine A is a "more effective, more specific agent than THA," says Alan P. Kozikowski, a Mayo chemist heading the huperzine A research. Mayo, he adds, has licensed use of huperzine A to Interneuron Pharmaceuticals, in Lexington, Mass., which is seeking FDA permission to test the compound in humans in 1994.