DIETARY MONOTERPENOIDS AS A NEW CLASS OF ALLOSTERIC HUMAN ARYL HYDROCARBON RECEPTOR ANTAGONISTS

Abstract

Carvones, the constituents of essential oils of dill, caraway, and spearmint, were reported to antagonize the human aryl hydrocarbon receptor (AhR); however, the exact molecular mechanism remains elusive. We show that carvones are non-competitive allosteric antagonists of the AhR that inhibit the induction of AhR target genes in a ligand-selective and cell type-specific manner. Carvones do not displace radiolabeled ligand from binding at the AhR, but they bind allosterically within the bHLH/PAS-A region of the AhR. Carvones did not influence a translocation of ligand-activated AhR into the nucleus. Carvones inhibited the heterodimerization of the AhR with its canonical partner ARNT and subsequent binding of the AhR to the promotor of CYP1A1. Interaction of carvones with potential off-targets, including ARNT and protein kinases, was refuted. This is the first report of a small dietary monoterpenoids as a new class of AhR non-competitive allosteric antagonists with the potential preventive and therapeutic application.