indole-3-carbaldehyde indole-3-carbaldehyde indole-3-carbaldehyde (i3a), also known as indole-3-aldehyde and 3-formylindole, is a metabolite of dietary l-tryptophan which is synthesized by human gastrointestinal bacteria, particularly species of the lactobacillus genus. i3a is a biologically active metabolite which acts as a receptor agonist at the aryl hydrocarbon receptor in intestinal immune cells, in turn stimulating the production of interleukin-22 which facilitates mucosal reactivity. indole-3-carbaldehyde names iupac name 1h-indole-3-carbaldehyde other names 3-formylindole; indole-3-carboxaldehyde; indole-3-aldehyde identifiers cas number 487-89-8 3d model (jsmol) interactive image beilstein reference 5-21-08-00246 chembl chembl147741 chemspider 9838 echa infocard 100.006.969 ec number 207-665-8 pubchem cid 10256 unii 7fn04c32uo comptox dashboard (epa) dtxsid5060069 inchi inchi=1s/c9h7no/c11-6-7-5-10-9-4-2-1-3-8(7)9/h1-6,10hkey: olnjuiskuqqnim-uhfffaoysa-n smiles c1=cc=c2c(=c1)c(=cn2)c=o properties chemical formula c9h7no molar mass 145.161 g·mol−1 melting point 198 °c (388 °f; 471 k) structure crystal structure orthorhombic space group pca21 lattice constant a = 14.076, b = 5.8059, c = 8.6909 lattice volume (v) 710.3 formula units (z) 4 hazards ghs labelling: pictograms signal word warning hazard statements h315, h319, h335 precautionary statements p261, p264, p271, p280, p302+p352, p304+p340, p305+p351+p338, p312, p321, p332+p313, p337+p313, p362, p403+p233, p405, p501 except where otherwise noted, data are given for materials in their standard state (at 25 °c , 100 kpa). infobox references biosynthesis in humans and cellular effects tryptophan metabolism by human gastrointestinal microbiota () tryptophan clostridiumsporogenes lacto-bacilli tryptophanase-expressingbacteria ipa i3a indole liver brain ipa i3a indole indoxylsulfate ast-120 ahr intestinalimmunecells intestinalepithelium pxr mucosal homeostasis:↓tnf-α↑junction protein-coding mrnas l cell glp-1 t j neuroprotectant:↓activation of glial cells and astrocytes↓4-hydroxy-2-nonenal levels↓dna damage–antioxidant–inhibits β-amyloid fibril formation maintains mucosal reactivity:↑il-22 production associated with vascular disease:↑oxidative stress↑smooth muscle cell proliferation↑aortic wall thickness and calcification associated with chronic kidney disease:↑renal dysfunction–uremic toxin kidneys this diagram shows the biosynthesis of bioactive compounds (indole and certain other derivatives) from tryptophan by bacteria in the gut. indole is produced from tryptophan by bacteria that express tryptophanase. clostridium sporogenes metabolizes tryptophan into indole and subsequently 3-indolepropionic acid (ipa), a highly potent neuroprotective antioxidant that scavenges hydroxyl radicals. ipa binds to the pregnane x receptor (pxr) in intestinal cells, thereby facilitating mucosal homeostasis and barrier function. following absorption from the intestine 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 the aryl hydrocarbon receptor (ahr) in 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 and acts as a ligand for ahr. 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. ast-120 (activated charcoal), an intestinal sorbent that is taken by mouth, adsorbs indole, in turn decreasing the concentration of indoxyl sulfate in blood plasma. chemistry indole-3-carbaldehyde has reactivity typical of aromatic aldehydes. it can is easily oxidized to indole-3-carboxylic acid. it condenses with nitromethane in a henry reaction to give 3-nitrovinyl indole. antifungal properties indole-3-carbaldehyde has antifungal properties, and partially accounts for the protection from chytridiomycosis seen in amphibian species which carry janthinobacterium lividum on their skin.