Skin‐Protective Effects of DeinoPol‐BRD125, a Microbial Exopolysaccharide From Deinococcus radiodurans , on Epidermal Hydration and Barrier Recovery

Deinococcus radiodurans is an extremophile bacterium renowned for its extraordinary resistance to environmental stress, partly mediated by its exopolysaccharide (EPS), DeinoPol. DeinoPol‐BRD125, derived from a high‐producing strain, exhibits potent antioxidative and cytoprotective properties, but its dermatological relevance remains largely unexplored. This study aimed to investigate the skin‐protective potential of DeinoPol‐BRD125 through integrated cellular and clinical evaluations. Human keratinocytes (HaCaT) were used to assess cytoprotection against UVB‐induced oxidative stress and modulation of hydration‐, barrier‐, and innate immunity–related genes via toll‐like receptor 2 (TLR2) activation. Two randomized, split‐site clinical studies were conducted to evaluate epidermal hydration, barrier recovery, and erythema after mechanical irritation following topical application of a 0.2% DeinoPol‐BRD125 formulation. DeinoPol‐BRD125 significantly attenuated UVB‐induced reactive oxygen species accumulation and improved keratinocyte survival. It markedly upregulated genes associated with hydration ( AQP3, HAS3 ), barrier integrity ( Loricrin, CerS3 ), and innate immunity ( DEFB1, DEFB2 ) and was associated with selective activation of TLR2 signaling. Clinically, topical DeinoPol‐BRD125 significantly enhanced skin hydration over 4 weeks compared with placebo and markedly accelerated transepidermal water loss recovery and erythema resolution following mechanical irritation. DeinoPol‐BRD125 is a biologically active microbial polysaccharide that enhances epidermal hydration, reinforces barrier function, and promotes recovery from skin irritation through coordinated antioxidant, immune, and structural mechanisms. These findings suggest that DeinoPol‐BRD125 is a promising bioactive ingredient for dermocosmetic applications aimed at improving cutaneous resilience and epidermal homeostasis.