Doenjang, a Korean soybean paste, ameliorates TNBS-induced colitis in mice by suppressing gut microbial lipopolysaccharide production and NF-κB activation

In preliminary studies, 80% ethanol extract of doenjang, a traditional Korean soybean paste, showed anti-inflammatory effect in lipopolysaccharide (LPS)-stimulated macrophages. Therefore, we investigated the effect of doenjang on 2,3,4-trinitrobenzene sulphonic acid (TNBS)-induced colitis in mice. Doenjang extract potently inhibited NF-κB activation in LPS-stimulated peritoneal macrophages. Oral administration of doenjang significantly inhibited TNBS-induced colon shortening, myeloperoxidase activity, body weight loss, and NF-κB activation in mice. Doenjang reversed the TNBS-caused suppression of tight junction proteins. Doenjang also inhibited TNBS-induced expression of inducible nitric oxide synthase, cyclooxygenase-2, TNF-α, IL-1β, and IL-6, and activation of NF-κB, but increased IL-10 expression. Doenjang significantly increased the number of Bifidobacteria in TNBS-induced colitic mice, but reduced the number of Erypsipelotrichaceae. Furthermore, doenjang suppressed TNBS-induced gut microbial LPS production. Doenjang also restored TNBS-disturbed gut microbiota, determined by principal coordinates analysis. These results indicate that Doenjang may ameliorate colitis by restoring disturbed gut microbiota and inhibiting NF-κB signaling pathway.