Gardeniae Fructus Enhances Skin Barrier Function via AHR-Mediated FLG/LOR/IVL Expression

Gardeniae Fructus (GF), a traditional Chinese medicine rich in iridoids, has demonstrated skin-improving effects. However, its mechanisms for enhancing epidermal barrier function remain unclear. In this study, the iridoids in GF were characterized using UPLC-MS/MS. The improvement in the barrier function by GF was assessed through in vitro experiments and a human efficacy assessment. In addition, the potential targets were predicted through proteomics analysis, molecular docking, and molecular dynamics (MD), and verified in HaCaT cells and three-dimensional epidermal models. Nine iridoids were identified in GF. In vitro, GF effectively promoted cell migration and reduced cell damage and oxidative stress. Proteomics analysis combined with molecular docking and MD simulations predicted that the primary iridoids in GF ameliorate barrier function by binding to the aryl hydrocarbon receptor (AHR) with high affinity and stability. Subsequent validation demonstrated that GF significantly upregulated AHR, filaggrin (FLG), loricrin (LOR), and involucrin (IVL) mRNA and protein expression. A 28-day randomized double-blind human efficacy assessment in subjects with sensitive skin showed that the gel with GF increased stratum corneum hydration, reduced transepidermal water loss (TEWL), and lowered erythema index and lactic acid tingling. These findings suggest that GF enhances the skin barrier via AHR activation-mediated upregulation of barrier proteins, supporting its cosmeceutical potential.