Background:

Tapinarof is a natural aryl hydrocarbon receptor (AhR) agonist with an EC50 of 13 nM.

Tapinarof activates the AhR pathway through direct binding. Tapinarof dose-dependently induces nuclear translocation of AhR in immortalized keratinocytes (HaCaT) (EC50=0.16 nM)[1].

Tapinarof acts through AhR to reduce inflammation in IMQ-treated mice. AhR-sufficient mice on a C57Bl/6 background exhibit a reduced clinical score after treatment with Tapinarof or 6-formylindolo(3,2-b)carbazole (FICZ). In contrast, AhR KO mice do not respond to the anti-inflammatory effects of Tapinarof. FICZ is used as a comparator in these studies and yields similar results, with dramatically reduced inflammatory responses in wild-type, but not AhR KO mice[1].

[1]. Smith SH, et al. Tapinarof Is a Natural AhR Agonist that Resolves Skin Inflammation in Mice and Humans. J Invest Dermatol. 2017 Oct;137(10):2110-2119.