Analysis of antibacterial activity and cytotoxicity in fermented soybeans under varied conditions against hepatocellular carcinoma cell lines

Background: Soybean fermentation with Bacillus spp.enhances nutritional quality by degrading anti-nutritional factors and improving protein digestibility via proteolytic activity.However, bioactive peptide production depends on optimal fermentation conditions and strain-specific proteolytic efficiency.Objective: To evaluate the antioxidant potential of protein hydrolysates from fermented soybean meal (FSM) using the DPPH assay and assess their cytotoxic effects on HepG2 hepatocellular carcinoma cells via the MTT assay.Methods: Bacillus siamensis serotype MH3 was used for solid-state fermentation of soybean meal.Substrate thickness and initial moisture content were optimized to maximize protein yield.Hydrolysates from fermented samples (e.g., 10 cm thickness, 45% moisture, 72 hours; 1045-72) were extracted and analyzed for antioxidant activity (DPPH assay) and cytotoxicity against HepG2 cells (MTT assay).Results: Fermentation conditions significantly influenced bioactive compound production.Hydrolysates from 1045-72 showed higher antioxidant activity than those from 0550-72 (5 cm thickness, 50% moisture) and unfermente controls.Both hydrolysates exhibited selective cytotoxicity against HepG2 cells, with IC 50 values of 95.3 g/mL (1045-72) and 133.8 g/mL (0550-72), compared to ~330.0 g/mL for normal cells. Conclusion:This study highlights that substrate thickness and moisture content critically impact the bioactivity of FSM hydrolysates.Optimized fermentation (10 cm thickness, 45% moisture) yielded hydrolysates with enhanced antioxidant activity and selective cytotoxicity against HepG2 cells, supporting their potential in functional foods or nutraceuticals targeting liver health.Process optimization is key to unlocking bioactive peptides for therapeutic applications.