Fermentation of Seaweed Saccharina japonica Using Lactobacillus brevis and its In Vitro Anti-Obesity Effects

This study investigated the effects of fermenting brown seaweed Saccharina japonica with Lactobacillus brevis on bioactive products' antioxidant properties and potential anti-obesity effects. The S. japonica fermented by L. brevis (SFB) extract showed the highest ABTS scavenging activity at 3000 μg/mL (79.3%), followed by the L. brevis cells (LBC) extract (68.1%) and S. japonica hydrolysate (SJH) extract (59.5%). At the same concentration, the DPPH radical scavenging activities of the LBC and SFB extracts were 63.2% and 68.5%, respectively, significantly higher than that of the SJH extract (38.5%). After treating cells with a 400 μg/mL concentration for 8 days, Oil Red O staining revealed a dose-dependent decrease in cytoplasmic lipid droplets. The lowest lipid accumulation rates were 64.2%, 55.2%, and 51.4% for SJH, LBC, and SFB, respectively. RT-qPCR results indicate reduced mRNA levels of lipid metabolism-related gene expressions. Overall, the combination of S. japonica and L. brevis fermentation has a potential application as a dietary food process for improving obesity.