Fraglide-1 from traditional Chinese aromatic vinegar: A natural AhR antagonist for atopic dermatitis

Traditional Chinese Zhenjiang aromatic vinegar (Kozu) contains Fraglide-1 (FG1), a bioactive lactone with demonstrated peroxisome proliferator-activated receptor gamma (PPARγ) agonist and antioxidant activities. This study explored FG1's novel ability to antagonize the aryl hydrocarbon receptor (AhR) signaling pathway, which regulates artemin expression and contributes to itching and inflammation in atopic dermatitis. Through molecular docking simulations and cell-based assays in human keratinocytes, we demonstrated FG1's potent antagonistic activity against AhR signaling. FG1 effectively suppressed FICZ-induced inflammatory responses, including artemin expression, with potency (half maximal inhibitory concentration, IC₅₀ = 5.1 μM) comparable to the synthetic antagonist StemRegenin 1 (SR1) while demonstrating a superior safety profile (median lethal concentration, LC₅₀ > 100 μM vs. 27.5 μM for SR1). These findings expand our understanding of bioactive compounds from traditional fermented foods and their regulatory effects on AhR signaling, providing a foundation for future studies on FG1's role in modulating skin inflammation.