Methylcarvones as immunomodulators through antagonism of aryl hydrocarbon receptor

Monocyclic monoterpenoids have been demonstrated as atypical negative allosteric modulators of aryl hydrocarbon receptor AhR. The alkylation of the skeleton has been identified as a factor modulating the AhR antagonist activity of S-carvone. In the present study, we synthesized methylated derivatives of S-carvone, and a complex series of experimental approaches has been employed to characterize the interactions of novel compounds with AhR. Molecular docking to AhR carvone-binding site revealed binding energies for 6-methylated carvones superior to that of S-carvone. This prediction was corroborated by microscale thermophoresis, where 6-methylated carvones displayed stronger binding to AhR N-terminal region, as compared to S-carvone. Methylated carvones inhibited AhR transcriptional activity in vitro in cell lines, as revealed by reporter gene assay and RT-PCR. However, their effects were weaker than those predicted by molecular docking, which might be due to the transmembrane transport and metabolism. As a proof-of-concept, we show immunomodulatory effects of S-carvone and its methyl derivatives in the model of differentiated THP1 macrophages polarized into M1/M2 phenotypes.