Harvesting a medical bounty

Dr. Michael Zasloff knows a lot about frogs and the medical bounty in their skin. He is an expert on poison-frogs and the president of the Magainin Research Insitute of Magainin Pharmaceuticals. His company has relied on the chemicals found in several animals to produce a number of new drugs. Magainin developed the cancer-fighting drug, Squalamine (now in human trials in the U.S.) from chemical found in the dogfish shark.

“We basically share the same genes as the frog. So whatever they pick out, we’ve got some element of in us,” Zasloff says.

A single African clawed frog contains the same amount of the hormone TRH as thousands of mammals.

For example, the skin of the African clawed frog contains a substance called thyrotropin-releasing hormone. The same substance is found in the human hypothalamus region of the brain. It is closely tied to regulating human growth. But it exists in humans in tiny, tiny quantities.
Indeed, it was with great effort that the researchers that discovered the structure of this substance in humans (and won a Nobel prize for their efforts) had to use thousands of animal brains to get a usable amount of the chemical. Today, however, we know that same amount can be found in a small section of a single frog skin.

“If you begin to appreciate that,” Zasloff says, “you realize the study of a frog by the right people might unlock secrets of the brain that we’d never be able to otherwise.”

Another example is the drug epibatidine – a drug developed originally by John Daly and now known by the name ABT-594 from Abbot Laboratories. It’s named after Epibpedobates tricolor – a frog found in Equidor, the drug works on the same chemical receptors on nerve cells that nicotine acts on. It appears to be several times more powerful than morphine in reducing pain, yet showed side effects and no signs of being addictive in animal studies.

And it’s not just these nerve toxins that are of interest. Many researchers have noticed the remarkable ability of laboratory frogs to recover from surgical procedures without getting infections. It’s now known that all frogs, whether poisonous or not, have antibiotics in their skin. These natural drugs escape when the skin is broken. In an age when some bacteria are now resistant to many traditional antibiotics, pharmaceutical companies are extremely interested in new ones to take their place.

Continued in Part III

The story of the poison-frog continues:

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