Figures and original data

Liver fibrosis is a dynamic and potentially reversible pathological consequence of chronic liver injury, in which persistent oxidative stress and inflammatory cascades drive progressive extracellular matrix deposition. Cyclic nitroxide radicals have diverse biological activities in vitro and in vivo; however, the effects of these stable radicals on liver fibrosis and other liver inflammatory diseases remain unclear. This study systematically evaluates 3-carbamoyl proxyl nitroxide (3-CP), a stable nitroxide compound, for its therapeutic potential against carbon tetrachloride (CCl₄)-induced liver fibrosis. In vitro, 3-CP inhibited the activation, migration, and proliferation of hepatic stellate cells (HSCs), and suppressed the expression of α-smooth muscle actin (α-SMA) and collagen I (COL1). In a BALB/c mouse model of CCl4-induced liver fibrosis, 20 and 40 mg/kg 3-CP reduced the fibrosis area from 13.6 ± 1.0% (model group) to 6.9 ± 0.9% and 5.7 ± 1.3%, respectively. This was corroborated by decreased serum alanine and aspartate aminotransferase levels, restored liver architecture, and diminished collagen deposition. Mechanistically, 3-CP modulated the TLR4/NF-κB signaling pathway through the downregulation of phosphorylated NF-κB p65 (p-p65), which aligns with the results of molecular docking analyses. The relative mRNA levels of interleu-1β (IL-1β), interleu-6 (IL-6), tumor necrosis factor-α (TNF-α) and transforming growth factor-β (TGF-β) were decreased by 0.99 ± 0.04%, 1.01 ± 0.03%, 0.97 ± 0.04%, and 1.02 ± 0.06%, respectively. These findings indicated that 3-CP is a therapeutic agent that concurrently addresses oxidative damage and inflammatory signaling during fibrogenesis.