Aryl Hydrocarbon Receptor (AhR) agonists

The IDO-dependent kynurenine (Kyn) pathway of tryptophan metabolism is a significant source of endogenous Aryl Hydrocarbon Receptor (AhR) agonists. Through this metabolic pathway, the AhR has the ability to enhance the expression of Indoleamine 2,3-Dioxygenase (IDO) / Indoleamine 2,3-dioxygenase 2 (IDO2), which in turn produces AhR ligands such as Kyn.
Snyder et al. 2025 The Journal of Immunology 214(3): 413-432

AhR agonists activate the receptor. This leads to its movement to the nucleus. It then regulates gene expression. Classic examples are environmental toxins. These include TCDD (dioxin). Some dietary metabolites are also examples. These include indoles and tryptophan catabolites.
Rothhammer et al. 2018 Sci Rep 8: 4970
De Juan & Segura 2021 Front Immunol. 12: 645168
Dai et al. 2022 Nat Commun 13: 6234

A high-affinity AHR-specific agonist is 2,3,7,8-tetrachlorodibenzo-p-dioxin.
Houser & Lawrence 2022 J Immunol 208: 2319-2330

4-n-nonylphenol / Nonylphenol, an agonist for Aryl Hydrocarbon Receptor (AhR), can induce Regulatory T Cells (Tregs)
Bruhs et al. 2015 J. Investig. Dermatol. 135: 435-444

Highly potent (EC 50 ≈ 1 nM) Aryl Hydrocarbon Receptor (AhR) Agonists, are based on 3-monosubstituted indoles [6-(indole-3-carbonyl)picolinonitrile and ([indol-3-yl)(6(trifluoromethyl)pyridin-2-yl)methanone]](?id=c28b7ed2-9226-4cf1-9ac2-7535a3ba15e8&linkText=%5Bindol-3-yl%29%286%28trifluoromethyl%29pyridin-2-yl%29methanone%5D)
Chen et al. 2020o Sci Adv 6(3): eaay8230

see also:
AhR signal transduction pathway