Curare – Once known as the "flying death of the Amazon," curare is a mixture of rainforest plants that indigenous peoples smear on the tips of their arrows or blowdarts to give them a deadly effectiveness. In the hands of western physicians, however, curare has been converted into a life-sustaining medication, a muscle relaxant in abdominal surgery. 

Sources:

Balick, Michael J., and Paul Alan Cox. Plants, People, and Culture the Science of Ethnobotany. CRC Press, 2020.  

Marks, Geoffrey, and William K. Beatty. The Medical Garden: Illustrated. Charles Scribner's Sons, 1971. 

Plotkin, Mark J. Amazon: What Everyone Needs to Know®. Oxford University Press, 2020. 

Plotkin, Mark J. Tales of a Shaman's Apprentice: an Ethnobotanist Searches for New Medicines in the Amazon Rain Forest. Viking, 1993. 

Prance, Ghillean T., et al. Ethnopharmacologic Search for Psychoactive Drugs. Synergetic Press, in Association with Heffter Research Institute, 2018. 

Schultes, Richard Evans., and Albert Hofmann. Plants of the Gods. Vandermarck, 1979.