The Anti-Inflammatory Action of Fermented Soybean Products in Kidney of High-Fat-Fed Rats

Soybean has many compounds with a variety of biological properties that potentially benefit human health; among them, isoflavones have inhibitory effects on lipid oxidation in adipose tissue. In this study, we examined two Korean traditional fermented soybean products-doenjang (DNJ) and cheonggukjang (CGJ)-for their ability to suppress redox-sensitive nuclear factor kappa B (NF-kappa B) activation in the kidney of rats fed a high-fat diet. Sprague-Dawley rats, 4 weeks old, were fed soybean, DNJ, or CGJ (1 g/kg/day) with a 20% fat diet for 6 weeks. Body weight and food intake were carefully monitored. NF-kappa B-related activities of genes for inflammatory proteins, such as inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and vascular cell adhesion molecule-1 (VCAM-1), were determined. The soybean products exhibited antioxidative action by maintaining redox regulation, suppressing NF-kappa B activation, and modulating the expression of genes for NF-kappa B-induced inflammatory proteins such as COX-2, iNOS, and VCAM-1. Based on these results, we conclude that Korean traditional soybean fermented products, especially CGJ, suppress the generation of reactive species, NF-kappa B activity, and NF-kappa B-related inflammatory genes.