The extract from the thunder god vine reduces food intake and causes up to a 45 per cent decrease in body weight in obese mice.
The weight-loss compound, called Celastrol, produces its potent effects by enhancing the action of an appetite-suppressing hormone called leptin.
The findings are an early indicator that Celastrol could be developed into a drug for the treatment of obesity, researchers said.
"During the last two decades, there has been an enormous amount of effort to treat obesity by breaking down leptin resistance, but these efforts have failed," said senior study author Umut Ozcan, an endocrinologist at Boston Children's Hospital and Harvard Medical School.
"If Celastrol works in humans as it does in mice, it could be a powerful way to treat obesity and improve the health of many patients suffering from obesity and associated complications, such as heart disease, fatty liver, and type 2 diabetes," said Ozcan.
Leptin is a fat-cell-derived hormone that signals to the brain when the body has enough fuel and energy.
Humans and mice that lack leptin signalling eat voraciously and become morbidly obese, suggesting that leptin-enhancing drugs may be effective for treating obesity.
Despite longstanding research efforts, drugs that can effectively alleviate leptin resistance have not yet been found.
Within only one week of Celastrol treatment, obese mice reduced their food intake by about 80 per cent compared to untreated obese mice.
By the end of the third week, treated mice lost 45 per cent of their initial body weight almost entirely by burning fat stores.
This dramatic weight loss is greater than that produced by bariatric surgery - an operation on the stomach and/or intestines that helps patients with extreme obesity to lose weight, researchers said.
The study was published in the journal Cell.