== Propiedades xerais e distribución ==
Indole is a [[solid]] at room temperature. Indole can be produced by [[bacteria]] as a degradation product of the [[ amino acid]] [[tryptophan]]. It occurs naturally in human [[feces]] and has an intense fecal [[odor]]. At very low concentrations, however, it has a flowery smell,<ref name="smell">http://www.leffingwell.com/olfact5.htm <!-- there might be better references for its odor properties --></ref> and is a constituent of many flower [[scent]]s ( such as orange blossoms) and [[ perfumes]]. It also occurs in [[ coal tar]].
The corresponding substituent is called '''indolyl'''.
Indole undergoes [[electrophilic substitution]], mainly at position 3. [[Substituted indoles]] are structural elements of (and for some compounds the synthetic precursors for) the tryptophan-derived [[tryptamine]] alkaloids like the [[neurotransmitter]] [[serotonin]], and [[melatonin]].
Other indolic compounds include the plant hormone [[ auxin]] ( indolyl-3- acetic acid, [[ Indole-3- acetic acid|IAA]]), [[ tryptophol]], the anti-inflammatory drug [[ indomethacin]], the [[ betablocker]] [[pindolol]], and the naturally occurring hallucinogen [[ dimethyltryptamine]].
The name '' indole'' is a [[Portmanteau word|portmanteau]] of the words ''[[ indigo dye|'''ind'''igo]]'' and ''[[oleum|'''ole'''um]]'', since indole was first isolated by treatment of the indigo dye with oleum.