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Science: Potent painkiller from poisonous frog

  • 30 May 1992 by JOHN EMSLEY
  • Magazine issue 1823

A chemical extracted from the skin of an Ecuadorian frog has turned out to be a painkiller 200 times as potent as morphine. The chemical, dubbed epibatidine after the frog (Epipedobates tricolor), seems to work in a different way to current painkillers, blocking hitherto unknown receptors in the brain.

John Daly and his colleagues at the National Institutes of Health at Bethesda, Maryland, extracted 60 milligrams of material from a total of 750 frogs. They purified this using chromatography to obtain 24 milligrams of the new chemical. Analysis by mass spectrometry indicated that the compound had a chemical formula C11H13N2Cl.

When Daly's team subjected the compound to infrared and nuclear magnetic resonance spectroscopy (NMR), they found that it consists of a pyridine ring with a chlorine atom attached (see Diagram). This ring is joined to another ring of six carbon atoms, with a nitrogen bridge across the middle (Journal of ...

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