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Seth Herzon synthesizes natural anti-Alzheimer’s compound in lab

A Yale researcher talks to EarthSky about a potential new therapeutic treatment for Alzheimer’s that’s derived from a species of moss found in China. .

A compound in a moss that’s been used in Chinese medicine for thousands of years is a potential new therapeutic treatment for Alzheimer’s, according to a paper in the August 25th issue of the journal Chemical Science.

A team of scientists from Yale, led by chemist Seth Herzon, synthesized a compound called huperzine A, which is naturally found in a species of moss, Huperzia serrata, native to China. The compound is known to be helpful in treating Alzheimer’s disease but, until now, scientists haven’t been able to easily synthesize it in the lab (or make that synthesis economically viable). Dr. Herzon talked with EarthSky about the nature of huperzine A.

A close relative of Huperzia serrata, Huperzia selago. Image Credit: Tigerente

It’s an alkaloid [a compound containing nitrogen] that’s produced by a moss that grows in China. The moss basically makes this molecule. And what they do in China is they literally grind up the moss and they have a means to extract a molecule. They found that people with Alzheimer’s respond pretty well when given huperzine on a daily basis, in China. Since about 1996, doctors have been prescribing it to patients to help alleviate some of the symptoms.

Though this moss has actually been used in Chinese medicine for thousands of years. Herzon added that the moss-derived compound is known not only to alleviate symptoms of Alzheimer’s (things like confusion and memory loss), but it also appears to have the potential to stop Alzheimer’s in its tracks. That’s because it specially inhibits the production of an enzyme called acetylcholine esterase, which has been linked to the disease.

Basically, what’s most commonly prescribed for Alzheimer’s are other acetylcholine esterase inhibitors, but they don’t really stop the disease, they’re kind of like taking Tylenol to relieve a headache. It takes care of the symptoms. But it doesn’t stop the progression of the disease. There’s a lot of evidence that huperzine may be able to do that, and now we’re going to find out whether that truly is the case. Anytime you want to take a drug to market, you have to go through a stage of clinical trials, and now we’re in a position to do that.

Hazen explains why: because he was able to synthesize the critical compound in the moss from scratch, without using the moss itself, which is actually under siege. He told EarthSky:

The reason why our work is significant is that we now have, for the first time in the United States, a stable and reliable and economical source of huperzine. We’re able to make this molecule in the lab, starting from inexpensive chemicals. The issue is that the moss that produces huperzine is most abundant in China, which does create export/import issues. The second major issue which is probably more significant is the fact that this moss grows very slowly. So it takes about 20 years to grow any sort of significant size, 20 years before you can harvest it. And what they’ve essentially done is gone after natural huperzine, harvested away this plant. And now a number of those species are in significant decline. And so having a synthetic route, the one we developed, is that we can make it in the lab, we don’t need to go out and collect moss.

According to a Yale press release, Herzon’s huperzine production process requires eight steps and produces a yield of 40 percent. Before that, the best synthetic techniques had required twice as many steps and achieved yields of only two percent. In addition, the press release states:

In some places, huperzine A can cost up to $1,000 per milligram. Herzon and his team produced several grams of the compound in their lab and are capable of creating much more. They believe they will be able to drive the cost down to just 50 cents per milligram (a projected typical dose is about one milligram per day), and have partnered with an industrial firm to help produce it on a larger scale.

Preparation for chemical warfare. Image Credit: Library of Congress

Though this research is funded by Yale University, Herzon told EarthSky, the U.S. army has also expressed interest in the project. He explained that huperzine A might “inoculate” soldiers against chemical warfare agents by keeping the enzyme acetylcholine esterase tied up.

If they went into a situation where they got exposed to chemicals used in warfare, the enzyme is already tied up with huperzine, and so it can’t react with the chemical warfare agent. So your body just metabolizes it and excretes it. Basically, what huperzine can do is provide protection against these agents.

Dr. Herzon added that years of chemical trials of the moss-derived compound still lay ahead of his team.

Bottom line: A paper in the August 25th issue of the journal Chemical Science by Yale researcher Seth Herzon describes a potential new therapeutic treatment for Alzheimer’s – a compound known as huperzine A. It’s derived from a species of moss found in China.

Beth Lebwohl