Combined Extracts of <i>Actinidia arguta</i> and <i>Perilla frutescens</i> , HX114, Exert Photoprotective Effects on Epidermal Barrier Function and Dermal Matrix Integrity in UVB-Irradiated Hairless Mice

Extracts of Actinidia arguta (hardy kiwi) and Perilla frutescens , which are rich in rosmarinic acid (RA) and hyperoside, are known to alleviate skin dryness; however, their photoprotective effects remain largely unclear. This study investigated the comprehensive effects of HX114, a combined extract of A. arguta fruit and P. frutescens leaves, on the epidermal barrier and dermal structure in UVB-irradiated SKH-1 hairless mice. The mice were fed HX114-supplemented diets (200, 400, or 800 mg/kg body weight or 1% in the diet) for 10 weeks, concurrent with UVB exposure. Skin health parameters—hydration, transepidermal water loss (TEWL), pH, and wrinkle indices—and key molecular factors and their processing enzymes were evaluated. UVB irradiation significantly impaired both the skin health parameters and key molecular factors. Conversely, HX114 supplementation restored all skin health parameters, showing dose-dependent improvements in hydration, TEWL, epidermal thickness, and wrinkle area. Concurrently, HX114 increased total epidermal free amino acid (FAA) levels and dose-dependently elevated the expression of filaggrin (FLG), peptidylarginine deiminase 3, and caspase-14. In addition, total ceramide levels increased in parallel with reduced aCDase expression. In the dermis, HX114 enhanced type I collagen (COL1) levels, which was accompanied by dose-dependent reductions in matrix metalloproteinase (MMP)1/MMP13 and increased tissue inhibitor of metalloproteinase 1 expression; it also dose-dependently increased hyaluronic acid (HA) levels. Furthermore, FAAs, FLG, and HA correlated strongly with skin hydration, TEWL, and pH, and COL1 correlated with wrinkle area and length. Notably, the skin health parameters were significantly interrelated, indicating a holistic protective effect. HX114, containing RA and hyperoside, appears to protect against photodamage by synergistically improving both epidermal barrier function and dermal structural integrity.