Herbal agent limits alcohol absorption.

A traditional Chinese herbal medicine, long rumored to squelch alcohol's intoxicating effects, appears to live up to its thousand-year-old reputation.

Masayuki Yoshikawa, a chemist at Japan's Kyoto Pharmaceutical University, reports that extracts from several Chinese plants and trees, when consumed by rats in the laboratory, indeed curb the absorption of ethanol.

By chemically separating components of the plant extracts, Yoshikawa's team identified the active ingredients as triterpene oligoglycosides, members of a class of sugar derivatives called saponins that have a tendency to produce soapy lathers.

Saponins appear in a variety of plants, particularly in the barks and roots of the Japanese angelica tree, the ovary of the soapnut tree, and the seeds of horse chestnuts and camellias.

Traditional Chinese and Japanese doctors use angelica root and bark to treat arthritis and diabetes, saving its decorative shoots as a culinary garnish. Horse chestnut extracts possess antiinflammatory properties, while soapnut derivatives yield an expectorant.

Yoshikawa and his colleagues prepared extracts from these plants and fed solutions containing different concentrations to rats. Then the researchers served the animals water spiked with as much as 20 percent ethanol, and monitored their blood-alcohol concentrations over the next several hours.

The saponins inhibited absorption of alcohol. The best extracts--from angelica bark--lowered the animal's blood alcohol levels by as much as one fifth in comparison to unmedicated animals, Yoshikawa reported this week in Chicago at a meeting of the American Chemical Society.

While the Japanese researchers have not yet determined the chemical mechanism by which saponins inhibit alcohol absorption, they have divided the inhibiting compounds into three classes according to their chemical structure. Examples of the three structural types of the alcohol-inhibiting saponins include elatoside, escin, and senegasaponin.

Yoshikawa believes that further structural analysis will give researchers clues that would help them design other intoxication-fighting pharmaceuticals.

"While the [inhibition] mechanism itself is still somewhat mysterious, there does appear to be an effect," says Kazuo Yamasaki, a chemist at Hiroshima University in Japan. "We don't yet know if this effect is good for someone's health, but it looks promising."

Such compounds might help treat patients suffering from uncontrolled alcoholism or prevent acute alcohol toxicity. "Alcoholism, which is a major health problem in the world, causes as much trouble physiologically as it does socially," Yoshikawa says. "Excessive consumption of ethanol is known to affect profoundly nearly every organ in the body, particularly the endocrine system, heart, central nervous system, immune system, and liver."

Indeed, he argues, an agent for limiting alcohol toxicity "could prevent many alcohol-related deaths."