alkaloids A group of bitter tasting plant poisons, many of which are of medical importance. The alkaloids, which include nicotine, strychnine, morphine, codeine, atropine, caffeine and quinine, have powerful actions on the body. Alkaloids are small, complex, nitrogen-containing molecules often produced by plants as an evolutionary survival characteristic in an environment containing herbivorous animals.
alkaloids basic organic compounds containing nitrogen that are found in some families of plants (e.g. Papaveraceae). Alkaloids have poisonous and medicinal properties. Examples include nicotine, quinine, morphine and cocaine.