Ginseng substances fight brain disease in rats (Reuters)

NEW YORK (Reuters Health) - Certain active substances in the herbal supplement ginseng appear to combat degenerative brain disease in rats, a new study shows.

The findings, according to the researchers, lay the groundwork for studying the effects of certain ginseng components on diseases marked by progressive degeneration of brain cells -- including Huntington's disease and Parkinson's disease.

Ginseng is a popular herbal supplement that has long been used in traditional Chinese medicine. In the West, it is mainly touted as a way to boost energy and immune system defenses; the various commercial preparations are generally made from the roots of one of several plant species, including Panax ginseng -- also called Asian ginseng -- and Panax quinquefolius, better known as American ginseng.

In the new study, reported in the Annals of Neurology, a whole-root preparation of American ginseng did not fight degeneration in the brains of rats. But a partially purified extract of some of the herb's active chemicals, known as ginsenosides, did.

The study focused on brain damage that, in rats, mimics the degenerative process seen in Huntington's disease, an inherited disorder of the central nervous system that progressively impairs movement and mental function. But the findings suggest that certain ginseng components have potential for treating other degenerative conditions, such as Parkinson's.

"Isolated ginsenosides or partial purifications of ginseng look promising as neuroprotective agents," study co-author Dr. Janet L. Stringer, of Baylor College of Medicine in Houston, told Reuters Health.

The partial purification of American ginseng that she and her colleagues used boosted the concentration of three ginsenosides known as Rb1, Rb3 and Rd. Animals that were given the extract before receiving a brain-cell-damaging toxin called 3-NP showed less movement impairment than animals that received 3-NP alone, and none died.

In contrast, rats given a preparation made from ginseng root showed as much impairment as animals given the toxin alone, and their death rates actually increased. The reason for the higher mortality is not yet clear.

"We are in the process of testing the other components of ginseng to determine what is causing this toxicity," Stringer noted.

The goal, she explained, is to figure out which components need to be taken out of the whole-ginseng preparation to create a safe agent that can be tested in clinical trials.

Exactly why certain ginsenosides, but not others, may protect brain cells from degeneration is unknown. The leading theory is that some of the chemicals act as antioxidants and neutralize oxygen free radicals -- substances that, though natural byproducts of metabolism, can damage cells and potentially lead to disease.

It has been suggested, Stringer noted, that such oxidative damage may contribute to conditions such as Huntington's and Parkinson's disease.

SOURCE: Annals of Neurology, May 2005.