Indole (benzopiran) - compounds, formed in the human intestine from the amino acid tryptophan. At the same time, the formation of skatole (methylindole). Both compounds are present in the faeces, give them an unpleasant smell. Indole poisonous; it is he is neutralized in the body, becoming indican (see), and presented with urine. Indole is a part of some medicinal substances (ezerin, strychnine and others).