The researchers tested MSI-1436--a natural compound derived from cholesterol obtained from the liver of dogfish sharks--on normal and obese mice and rats. "Our findings were striking," said Michael Zasloff, Dean of research and translational science at Georgetown and the senior author of this article. "The mice receiving the MSI-1436 ate less and lost weight. But the really remarkable thing was that they lost fat instead of muscle, and they experienced no decrease in their metabolism."
Many diets are unsuccessful because when people eat less, their bodies compensate for the reduced caloric intake by slowing metabolism; these people also tend to lose muscle and not fat, Zasloff said, adding that MSI-1436 could potentially counter these limitations. In previous studies, MSI-1436 was shown to correct Type II diabetes in animals with both the genetic and dietary forms of obesity.
MSI-1436 was discovered unintentionally, when the researchers were studying the dogfish shark liver during a search for naturally occuring antibiotics. It is a chemical related to squalamine, which also comes from the dogfish liver and is currently in clinical trials as a cancer treatment. Squalamine, also discovered by Zasloff, belongs to a previously unknown, completely new class of chemicals.
The researchers initially thought that MSI-1436 could be an effective treatment for HIV because it stopped the reproduction of the virus in the lab. However, when the researchers tested it in animals they discovered that it caused them to stop eating and therefore could not be used safely as an HIV treatment.
Contact: Beth Porter
Georgetown University Medical Center