Indole is an aromatic heterocyclic organic compound: C8H7N.
It is widely found in the natural environment and can be produced by a variety of bacteria.
It is an intercellular signal molecule in bacteria, regulating including spore formation, plasmid stability, resistance to drugs, biofilm formation, and virulence.
An indole derivative is amino acid tryptophan, the precursor of the neurotransmitter serotonin.
Indole occurs naturally in human feces and has an intense fecal odor, yet at low concentrations, however, it has a flowery smell, and is a constituent of many perfumes.
Indole occurs in coal tar.
Indole undergoes electrophilic substitution, mainly at position 3, resulting in tryptophan derived tryptamine alkaloids.
Typtophan derived tryptamine alkaloids, which includes the neurotransmitters serotonin and melatonin, as well as the naturally occurring psychedelic drugs dimethyltryptamine and psilocybin.
Indole in the cell is usually produced from tryptophan by bacteria that express
tryptophanase.
Clostridium sporogenes metabolizes tryptophan into indole and subsequently 3-indolepropionic acid (IPA).
3-indolepropionic acid (IPA) is a neuroprotective antioxidant that scavenges hydroxyl radicals.
IPA binds intestinal cells, thereby facilitating mucosal homeostasis and barrier function.
Following absorption and distribution to the brain, IPA confers a neuroprotective effect against cerebral ischemia and Alzheimer’s disease.
Lactobacillus species metabolize tryptophan into indole-3-aldehyde (I3A) which acts on intestinal immune cells, in turn increasing interleukin-22 (IL-22) production.
Indole itself triggers the secretion of glucagon-like peptide-1 (GLP-1) in intestinal L cells..
Indole can also be metabolized by the liver into indoxyl sulfate, a compound that is toxic in high concentrations and associated with vascular disease and renal dysfunction.
Activated charcoal, an intestinal sorbent that is taken by mouth, adsorbs indole, in turn decreasing the concentration of indoxyl sulfate in blood plasma.
Indole can also be metabolized by the liver into indoxyl sulfate, a compound that is toxic in high concentrations and associated with vascular disease and renal dysfunction.
Indoles are susceptible hydrogenation.