Indole-3-propionic acid is a tryptophan metabolite long recognised as a plant growth regulator. Indole-3-propionic acid is produced by microbiota in the human gut, including Clostridium sporogenes. Indole-3-propionic acid is a potent antioxidant and free radical scavenger that binds to the pregnane X receptor in intestinal cells, thereby facilitating mucosal homeostasis and protecting against intestinal epithelial barrier damage. Indole-3-propionic acid is neuroprotective in vivo, inhibiting β-amyloid fibril formation. Indole-3-propionic acid inhibits the growth of E. coli in vitro via its ability to block endogenous tryptophan formation.
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