Curarine is an alkaloid that can be obtained from curare. Curare is the substance extracted from certain poisonous plants, such as Strychnos spp., Chondrodendron tomentosum, Curarea sp., particularly species C. toxicofera and C. tecunarum, Sciadotenia toxifera, Telitoxicum sp., Abuta sp., Caryomene sp., Anomospermum sp., Orthomene sp., Cissampelos sp., etc.
Curarine is used as a muscle relaxant and therefore an adjunct in anesthesia. It is also used as arrow poisons. It is prepared by combining the bark scrapings of Strychnos plant and fragments of other poisonous sources (e.g. snake venom, venomousants, etc.), and then boiling the mixture in water, strained, and evaporated into a dark, heavy, viscid paste.1
Parenteral administration of curare containing curarine at certain lethal dose would bring death to hunted animals (e.g. birds, tapirs, and certain mammals) within (few) minutes.
Oral administration of this substance in humans, though, does not result in death. Furthermore, in 1811, Sir Benjamin Brodie observed that curare did not cause the heart beat to stop.1 Curare is able to relax and affect skeletal muscles but not involuntary muscles.
The formula of curarine is C19 H26 O N2
1Curare, A South American Arrow Poison. [Link]