Birch bark drug may aid heart treatment

The compound, called betulin, targets genes involved in the production of harmful blood fats.

In animal studies it lowered cholesterol levels, helped to prevent diet-induced obesity, and reduced the risk of diabetes by improving insulin sensitivity.

Betulin is "abundant in birch bark" according to the Chinese team, led by Dr Bao-Liang Song, from the Shanghai Institutes for Biological Sciences.

Its medical potential was discovered after the researchers screened a number of compounds in search of a drug that targeted key gene-activating proteins.

Sterol regulatory element-binding proteins (SREBPs) help to "switch on" genes for cholesterol, fatty acids, and triglyceride blood fats. Laboratory cell studies showed that betulin lowered the activity of genes normally activated by SREBPs.

Further work confirmed the beneficial effects of betulin in mice.

Animals fed a high-fat Western diet were treated with betulin, the cholesterol-lowering drug lovastatin, or an inactive salt solution for six weeks.

Compared with the inactive treatment, both drugs caused over-fed mice to gain less weight, while working in different ways. Betulin led the animals to burn up more calories, while lovastatin reduced the amount of fatty molecules called lipids taken up from the diet.

Betulin also lowered lipids in blood, liver, and fatty tissue, and made the mice more sensitive to the sugar uptake hormone insulin.

Heart disease-prone mice suffered less atherosclerosis - the build-up of harmful hard deposits on artery walls - when treated with either betulin or lovastatin.

Reporting their findings in the journal Cell Metabolism, the researchers wrote: "We have identified a specific small molecule inhibitor of SREBP, betulin, which decreases lipid levels, enhances insulin sensitivity, and reduces the development of atherosclerotic plaques."