A traditional Chinese medicine may be beneficial for people suffering from type 2 diabetes.
The Oregon grape contains berberine
Berberine, found in the roots and barks of some plants, has been documented in Chinese literature as being able to lower glucose levels in diabetics.
Now scientists have found that studies on rodents support this claim.
Writing in the journal Diabetes, they added that berberine reduced the animals' body weight, suggesting it could also be used to treat obesity.
Berberine is a compound found in several plants, including goldenseal, the Oregon grape and barberry.
It has been used by a number of different cultures for medicinal purposes, most commonly to treat diarrhoea.
It is also being employed, particularly in traditional Chinese medicine, to treat diabetes.
To investigate its reported glucose-lowering effects, an international team examined the effect of berberine on mice and rats.
The researchers found that a dose of the compound, given orally, caused blood sugar levels to go down, led to fewer fats circulating in the bloodstream, made insulin work better and lowered the animals' body weights.
Professor David James, head of the diabetes and obesity research programme at the Garvan Institute, Sydney, Australia, said: "We are interested in type 2 diabetes, which is caused by a malfunctioning of insulin action, causing blood sugar regulation to go haywire.
"We have now obtained scientific evidence that shows berberine helps insulin to work much better.
"It helps insulin to control blood sugar. But it also helps to clear fats out of the bloodstream, and we think that this leads to one of its other major end points, which is reduction of body weight."
The team believes the plant product is "turning on" an enzyme found in body tissue, which improves the body's sensitivity to insulin, in turn lowering blood sugar levels and reducing the level of circulating fats.
Professor James said: "This is a very nice example of how there is validity to some of these traditional medicines.
"Type 2 diabetes and obesity are a huge problem and, although there are some nice medicines on the market, they have their limitations and there is a tremendous need for new therapies.
"This represents a potential new therapy for treatment of diabetes and obesity."
However, he cautioned that more clinical studies were needed on humans before berberine should be recommended for diabetics, particularly to investigate how the compound interacts with other drugs.
Cathy Moulton, a care advisor at Diabetes UK, said: "There are already many treatments for type 2 diabetes available but this research is slightly different as it's based on a natural remedy.
"We would not recommend that anyone attempts to use this as a treatment in its current form as this research only focuses on animals.
"We will wait to see the results of further research with interest."