Work in mice paves way to new drugs
By Charlene Laino
May 28 — Studies of the ginseng berry may someday bear fruit for millions of Americans who suffer from obesity and its life-threatening complications. If new work in mice can be duplicated in people, researchers predict the development of novel drugs that deflate spare tires, while warding off diabetes.
IT’S ONE of those cases when you shrug your shoulders and ask, “Why didn’t anyone think of this sooner?”
For more than 2,000 years, Chinese practitioners have prescribed ginseng root to restore energy to patients suffering from everything from cancer to heart failure. In the United States, extracts made from the ginseng root are among the top 10 best-selling herbal supplements.
But only now, for the first time, have Chicago researchers studied the berry of the ginseng and found that it — not the root — may hold the key to wellness for millions.
“Previously, there had been no study of the ginseng berry’s biological activity,” says Dr. Chun-Su Yuan, a researcher at the University of Chicago’s Tang Center for Herbal Medicine Research and head of the new study. People believed that nutrients accumulated in the root, he says, and thus shied away from testing the berry for medicinal effects.
The new work, which appears in the June issue of the journal Diabetes, suggests they should have broadened their view long ago.
“We were stunned by how different the berry is from the root in terms of its chemical profile and by how effective it is in correcting the multiple metabolic abnormalities associated with diabetes,” Yuan says.
In fact, the berry is more effective than the root in multiple ways, he says, with an extract made from its pulp normalizing blood sugar and lowering cholesterol levels in fat mice.
Additionally, obese mice given the extract ate less and exercised more — the payoff being weight loss, he says. And if the image of slimmer, trimmer mice doesn’t do it for you, Yuan is quick to add that he expects the results to translate to humans.
“There’s some anti-diabetes effect with the root, but this is much stronger,” Yuan says. “And ginseng root doesn’t change body weight at all.”
THE KEY INGREDIENT
So what makes the ginseng berry so unique? In terms of its weight-loss effects, that remains to be seen. But when it comes to fighting diabetes, the key ingredient appears to be a substance known as ginsenoside Re, says Yuan, who is also an assistant professor of anesthesia and critical care at the University of Chicago.
Other experts, while taking a wait-and-see attitude, agree the approach is worthy of further research.
“This is very interesting,” says Dr. Nathaniel Clark, national vice president for clinical affairs at the American Diabetes Association (ADA). “The results are quite dramatic both in helping blood sugar levels to normalize and in causing weight loss, which is extremely important in type 2 diabetes.”
But only human studies can offer real answers, agree Clark and Dr. Christopher Saudek, a practitioner at Johns Hopkins University School of Medicine and president of ADA.
“It’s always difficult to tell the significance of [mice] trials to humans,” Clark says. “Here, you’re injecting a compound into a mouse with a distinct genetic problem with regard to obesity.
“Will this, if pursued, lead to new treatments for diabetes?” he asks. “We don’t know yet, but it’s certainly worthy of further study.”
For the study, Yuan and colleagues used genetic engineering to breed mice predisposed to weight gain and type 2 diabetes, which is linked to obesity.
Among the findings of the 12-day study:
Daily injections of an extract of the ginseng berry extract restored normal blood sugar in mice who had suffered “quite high” levels. Treated mice also had better scores on a glucose tolerance test, which measures how quickly the mice could remove excess sugar from the blood.
The obese diabetic mice shed more than 10 percent of their bodyweight, while untreated mice gained 5 percent of their weight. The reason: The treated mice ate 15 percent less and were 35 percent more active than untreated mice, Yuan says. Once the injections stopped, weight gain gradually resumed.
The extract improved insulin sensitivity, a risk factor for type 2 diabetes, in mice with diabetes.
Cholesterol levels dropped 30 percent in the treated mice, while the extract had no detectable effect on normal mice.
Tests using ginsenoside Re alone found that it had all of the anti-diabetic but none of the obesity-fighting activities of the extract, Yuan says.
The scientists hypothesize that ginsenoside Re may speed up sugar transport from the blood to the muscle, thereby lowering blood sugar and reducing the risk of diabetes. “But we’re still studying that,” says Yuan.
Additionally, his team is working to isolate other substances from the extract that work in concert with ginsenoside Re to induce weight loss.
The extract appears to be safe, he adds, though only tests in humans can bear that out. The next steps: Finding the right dose, isolating other obesity-fighting compounds in the berry and learning more about how the compounds exert their beneficial effects.
“Ginsenoside Re could serve as the basis for a whole new class of anti-diabetic medications,” Yuan says. “And once we identify all the obesity-fighting compounds — there may be two or three — we can develop better compounds to combat obesity.”
“There’s a long way to a cure around the corner,” the ADA’s Clark says. “But, on the other hand, for what it is, the results are striking.”