Soybean fermentation broth alleviates indomethacin-induced gastric mucosal injury

Dietary strategies and plant-based fermented foods have attracted increasing interest for supporting gastrointestinal health, particularly under conditions of drug-induced mucosal stress. Soybean fermentation broth (SFB), a fermented soybean-derived product, may possess enhanced nutritional and functional properties through fermentation-associated generation of bioactive peptides and antioxidant metabolites. This study evaluated the gastroprotective effects of SFB in an indomethacin-induced gastric injury model in rats and investigated the underlying mechanisms. Indomethacin markedly induced gastric ulcer formation (16.61 ± 1.38 mm²), whereas SFB pretreatment significantly attenuated ulcer development in a dose-dependent manner, reducing ulcer area to 6.66 ± 0.98, 3.89 ± 0.63, and 1.46 ± 0.32 mm² in low-, medium-, and high-dose groups, respectively (p < 0.05 vs. Vehicle). Histopathological examination revealed that SFB preserved epithelial integrity and reduced submucosal edema. SFB pretreatment significantly decreased lipid peroxidation, restored gastric glutathione content, and enhanced antioxidant enzyme activities, including glutathione peroxidase (GPx), glutathione reductase (GRd), superoxide dismutase (SOD), and catalase (CAT). Furthermore, SFB suppressed pro-inflammatory mediator expression and favorably modulated cyclooxygenase-1 (COX-1) and COX-2 expression, accompanied by restoration of prostaglandin E₂ (PGE₂) production. These findings indicate that SFB protects gastric mucosa against indomethacin-induced injury through coordinated regulation of oxidative stress, inflammatory signaling, and prostaglandin-mediated mucosal defense, supporting its potential as a functional fermented soybean product.