Design, synthesis, and biological evaluation of small-molecule HMGB1 inhibitors for the alleviation of radiation-induced skin injury.

Radiation-induced skin injury (RSI) is a common and debilitating complication of radiotherapy, significantly impairing patients' quality of life. High-Mobility Group Box 1 (HMGB1), a key damage-associated molecular pattern (DAMP) protein, plays a critical role in propagating the inflammatory response following radiation exposure. This study aims to discover small molecule compounds that can antagonize and alleviate radiation-induced skin damage through HMGB1. Two novel classes of compounds were designed and synthesized based on molecular docking analysis of Methotrexate (MTX) and rosiglitazone (RSG) binding to HMGB1. The majority of synthesized compounds exhibited low cytotoxicity (IC₅₀ > 80 μM). Among them, 30 emerged as the lead candidate, exhibiting significant radioprotective effects in both HaCaT and JB6 cell lines. In vivo, topical application of 30-loaded hydrogel accelerated wound healing, reduced inflammatory cell infiltration, promoted skin regeneration, and significantly regulateddown the levels of inflammatory factors (HMGB1 and IL-6). Mechanistic studies suggest that 30 may exert its protective effects through the HMGB1-TLR4-NF-κB signaling pathway, while molecular dynamics simulations predicted stable binding of 30 to HMGB1. In conclusion, 30 represents a novel small-molecule HMGB1 inhibitor with significant therapeutic efficacy against RSI, validating HMGB1 as a viable target for the development of radioprotective agents.