Purity >98%. The aryl hydrocarbon receptor (AhR) is a ligand-dependent intracellular transcription factor whose ligands include some of the most infamous xenobiotics, including dioxin, benzo[a]pyrene, and numerous polyaromatics from soot and coal tar. PDM 2 is an analog of resveratrol acting as a potent and selective aryl hydrocarbon receptor (AhR) antagonist, with a Ki of 1.2 nM. PDM 2 is inactive as a ligand for the estrogen receptor even at 100 μM. As AhR knockout mice are insensitive to the carcinogenic effects of classical AhR ligands, PDM 2 is a potential therapeutic for the treatment for dioxin and other aryl hydrocarbon poisonings.