Indole-3-acetic acid (IAA)

Indole-3-acetic acid (IAA), commonly known as auxin, is the primary naturally occurring plant growth hormone and a significant microbial metabolite in the human gut produced through the bacterial fermentation of dietary tryptophan. In human physiology, IAA acts as a multifaceted signaling molecule that primarily functions as a ligand for the Aryl Hydrocarbon Receptor (AhR), where it helps maintain intestinal barrier integrity and modulates innate and adaptive immune responses. While it demonstrates protective, anti-inflammatory, and antioxidant effects in metabolic conditions such as nonalcoholic fatty liver disease, it is also classified as a uremic toxin that accumulates in chronic kidney disease, contributing to cardiovascular and hepatic dysfunction. In oncology, recent research highlights IAA's ability to rejuvenate exhausted CD8+ T cells by suppressing the integrated stress response, thereby enhancing the efficacy of immune checkpoint inhibitors like anti-PD-1 therapy. Additionally, IAA is utilized in experimental enzyme-prodrug therapies (EPT), where it is oxidatively activated by peroxidases, such as horseradish peroxidase, to generate cytotoxic free radicals that selectively target and destroy malignant cells.

Other names

3-Indoleacetic acidAuxinHeteroauxin3-IAAIndole-3-ylacetic acidIndol-3-ylacetate