Scientists have been scouring the world in recent decades for all manner of miracle plants that can help people slim down. As the market for weight-loss products and supplements has grown to a multi-billion-dollar industry, they've looked at dandelions, coffee and nuts, among other things. They've been cultivating an edible succulent called the caralluma fimbriata chewed by tribesmen in rural India to control their hunger during a day's hunt. And they have been trying to isolate and extract whatever it is in an African plant called hoodia, which looks like a spikey pickle, that tricks you into feeling full even if you haven't eaten a bite.

But none of these has been more promising in early studies than a traditional Chinese medicine known as thunder god vine.

In a paper published in the journal Cell on Thursday, scientists said an extract made from the plant reduces food intake and has led to a dramatic 45 percent decrease in body weight in obese mice.

Study author Omut Ozcan, an endocrinologist at Boston Children's Hospital and Harvard Medical School, said the substance appears to work by enhancing a fat-derived hormone called leptin that signals to the body when it has enough fuel and energy. Humans who lack leptin, can eat voraciously and can become morbidly obese.

"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. The message from this study is that there is still hope for making leptin work," Ozcan said in a statement.

In the study, Ozcan found that with only one week of treatment with an extract made from thunder god vine -- which they called Celastrol -- the mice reduced their food intake by 80 percent as compared with those who did not get the extract. Three weeks later, those mice had lost nearly half of their initial body weight.

The results were even more effective than a drastic measure used to reduce weight: bariatric surgery. In addition, scientists reported that they saw other positive health effects from decreased cholesterol levels to improved liver functions.

While the team did not find any toxic effects of the extract in mice, the researchers strongly cautioned that more studies needed to be done to demonstrate the compound's safety in humans.

"Celastrol is found in the roots of the thunder god vine in small amounts, but the plant's roots and flowers have many other compounds," Ozcan said. "As a result, it could be dangerous for humans."