CH-223191 is a potent and specific aryl hydrocarbon receptor (AhR) antagonist. It blocks activation by 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) (IC₅₀ = 0.03 µM). It also blocks TCDD-mediated translocation and DNA-binding activity of the AhR. Displays no AhR agonist activity (at concentrations up to 100 μM). Through its effects on AhR, CH 223191 suppresses Th17 cell differentiation both in vitro and in vivo and alters the expression of homeobox transcription factors necessary for the differentiation of embryonic stem cells to cardiomyocytes.