A Natural Composite Extract Restores Skin Barrier Function by Modulating Inflammatory, Hydration, and Redox Pathways

Objective This study was to evaluate the effects of a composite extract of Prunus mume flower, Lonicera japonica flower (honeysuckle), Chrysanthemum indicum flower, and Phyllostachys bambusoides , which we named PLCP, on skin hydration, inflammation, itching, and oxidative stress in pediatric (NHEK) and adult (HaCaT) keratinocytes. Methods LPS was used to simulate the external stimulation for pediatric (NHEK) and adult (HaCaT) keratinocytes. These keratinocytes were treated with different concentrations of PLCP, and the expression of inflammation, itching, and oxidative stress‐related proteins or mRNA was observed through rt‐PCR, ELISA, ROS, and SOD. Meanwhile, rt‐PCR was also used to determine the expression of Hyaluronic acid synthase (HAS) in keratinocytes under PLCP intervention for its moisturizing effects. Results PLCP treatment (0.125%–0.500%) significantly suppressed LPS‐stimulated thymic stromal lymphopoietin (TSLP) secretion by up to 40.3% in pediatric cells and 29.9% in adult cells ( p < 0.05), and reduced endothelin‐1 (ET‐1) mRNA levels by up to 69.5% and 46.0%, respectively ( p < 0.05). Concurrently, PLCP dose‐dependently upregulated hyaluronic acid synthase isoforms (HAS‐1, HAS‐2, HAS‐3) mRNA expression by 174.8%–254.2% in pediatric keratinocytes and 143.5%–198.9% in adult cells ( p < 0.05), indicating enhanced hydration potential. Antioxidant assays demonstrated that PLCP at 0.250% decreased reactive oxygen species (ROS) by 55.3% in pediatric and 41.6% in adult cells, while boosting superoxide dismutase (SOD) activity ( p < 0.05). Conclusions Across all endpoints, pediatric keratinocytes exhibited more pronounced responses, suggesting age‐dependent differences in sensitivity. These in vitro findings support PLCP's multifunctional role at anti‐inflammatory, anti‐pruritic, moisturizing, and antioxidant and highlight its promise as a safe, plant‐based alternative for managing pediatric skin disorders.