Tribes in the Amazon discovered long ago that these small, intensely colorful frogs produced potent toxins in their skins. Hunters would coat the tips of their arrows in these deadly cocktails before going on a hunt. When scientists first encountered these tribes, they were intrigued by their use of the toxins and wondered what unusual compounds they might contain.
During the early 1990's, scientists isolated an unusual alkaloid from a poison-dart frog in Ecuador. The compound produced by Epipedobates tricolor, or the phantasmal poison frog, as it was nicknamed, was found to be 200 times more effective than morphine in relieving pain, at least in mice. Though an effective painkiller, epibatidine, as it is now known, was too toxic to be used as a drug (perhaps unsurprising considering its use in the Amazon).
To overcome this obstacle, researchers have been trying to tweak epibatidine's chemical structure in order to eliminate its toxicity. They succeeded in producing hundreds of new compounds, one of which, ABT-594, has looked promising in trials.