While discovering a protein that causes muscle weakness and loss during ageing, scientists from University of Iowa have also stumbled upon two natural compounds, one found in apples and one in green tomatoes, which reduce the protein's activity in aged muscle.
The protein called ATF4 alters gene expression in skeletal muscle, causing reduction of muscle protein synthesis, strength and mass.
The team identified ursolic acid, which is found in apple peel, and tomatidine, which comes from green tomatoes, as small molecules that can prevent acute muscle wasting caused by starvation and inactivity.
Those studies set the stage for testing whether ursolic acid and tomatidine might be effective in blocking the largest cause of muscle weakness and atrophy: aging.
"Ursolic acid and tomatidine appear to have a lot of potential as tools for dealing with muscle weakness and atrophy during ageing," said Christopher Adams, professor of internal medicine and senior study author.
We might be able to use ursolic acid and tomatidine as tools to find a root cause of muscle weakness and atrophy during ageing, he added.
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The findings could lead to new therapies for age-related muscle weakness and atrophy.
In the latest study, Adams' team found that ursolic acid and tomatidine dramatically reduce age-related muscle weakness and atrophy in mice.
The scientists found that both compounds increased muscle mass by 10 percent, and more importantly, increased muscle quality or strength by 30 percent.
"By reducing the protein's activity, ursolic acid and tomatidine allow skeletal muscle to recover from effects of ageing," Adams pointed out in a paper published in the Journal of Biological Chemistry.