April Flowers for redOrbit.com – Your Universe Online
Muscle atrophy, or wasting, is a problem caused by aging and a variety of illnesses and injuries. The surprising answer to this according to a new study from the University of Iowa might be green tomatoes.
The research team, led by Christopher Adams, M.D., Ph.D., UI associate professor of internal medicine and molecular physiology and biophysics, used a screening method that previously helped them identify a compound in apple peel as a muscle-boosting agent. The team has now discovered that tomatidine, a compound found in green tomatoes, is even more potent than apple peel for building muscle and protecting against muscle atrophy.
Muscle atrophy can be caused by such conditions as cancer, heart failure, or orthopedic injuries. People suffering from atrophy become weak and fatigued, their physical activity and quality of life become impaired, and they are predisposed to falls and fractures. More than 50 million Americans are affected annually, including 30 million over the age of 60. People with muscle atrophy are often forced into nursing homes and rehab facilities.
“Muscle atrophy causes many problems for people, their families, and the health care system in general,” said Adams. “However, we lack an effective way to prevent or treat it. Exercise certainly helps, but it’s not enough and not very possible for many people who are ill or injured.”
Adams and his team started the study trying to find a small molecule compound that might be useful in treating muscle atrophy. Using a system biology tool known as the Connectivity Map — developed at the Broad Institute of MIT and Harvard University — the team focused in on tomatidine. The gene expression changes generated by tomatidine are essentially the opposite of the changes that happen in muscle cells when they are affected by muscle atrophy.
“That result was important because we are looking for something that can help people,” Adams said.
Next, the team began to feed a diet of tomatidine to mice, finding that healthy mice on this diet grew bigger muscles, became stronger and could exercise longer. More importantly, tomatidine was found to prevent and treat muscle atrophy.
The team was surprised to find that despite the larger muscles of mice fed tomatidine, the overall body weight of the mice did not change due to a loss of fat. This suggests that tomatidine might have applications for treating obesity, as well.
One of the most attractive qualities of tomatidine for treating muscle atrophy is that it is a natural compound, produced when alpha-tomatine, which is found in tomato plants and in green tomatoes in particular, is digested in the gut.
“Green tomatoes are safe to eat in moderation. But we don’t know how many green tomatoes a person would need to eat to get a dose of tomatidine similar to what we gave the mice. We also don’t know if such a dose of tomatidine will be safe for people, or if it will have the same effect in people as it does in mice,” Adams added. “We are working hard to answer these questions, hoping to find relatively simple ways that people can maintain muscle mass and function, or if necessary, regain it.”
This same research strategy helped the team to identify ursolic acid from apple peels as a compound that promotes muscle growth.
“Tomatidine is significantly more potent than ursolic acid and appears to have a different mechanism of action. This is a step in the right direction,” Adams said. “We are now very interested in the possibility that several food-based natural compounds such as tomatidine and ursolic acid might someday be combined into science-based supplements, or even simply incorporated into everyday foods to make them healthier.”
A biotech company called Emmyon has been formed by Adams and his colleagues to accelerate this research and translate it to people. To promote the development of strategies for preserving muscle mass and function during the aging process, Emmyon recently received funding from the National Institutes of Health (NIH). Tomatidine and ursolic acid are also being used by the company as natural leads to create new therapies targeting muscle atrophy and obesity.
The results were published in a recent issue of the Journal of Biological Chemistry.