GABA-enriched rice bran inhibits inflammation in LPS-stimulated macrophages via suppression of TLR4-MAPK/NF-κB signaling cascades.

Gamma-aminobutyric acid (GABA)-enriched products (GEP) exhibited a wide range of pharmaceutical properties. In this study, anti-inflammatory activity of GEP from Lactobacillus fermentum-fermented water solution of rice bran was evaluated on lipopolysaccharide-activated macrophage model. GABA content in L. fermentum-fermented rice bran solution was determined up to 1.27 g/L. GEP was shown to inhibit the expression levels of inducible nitric oxide synthase and cyclooxygenase-2 enzymes. Moreover, pretreatment of GEP attenuated the generation level of interleukin (IL)-6, IL-1β, tumor necrosis factor α, and monocyte chemoattractant protein-1. Especially, the activation of signaling pathways due to nuclear factor-κB (NF-κB) and mitogen-activated protein kinases (MAPKs) was interrupted in GEP-exposed cells. Notably, molecular docking result showed a potential binding of GABA to Toll-like receptor 4 with a binding energy of -3.88 kcal/mol, suggesting the role of GABA in suppression of Toll-like receptor 4-MAPK/NF-κB signaling cascades. As the result, GEP from L. fermentum-fermented rice bran solution could be suggested as a promising food for suppression of inflammatory responses. PRACTICAL APPLICATIONS: GABA-enriched products have been evidenced to possess various pharmaceutical properties and health beneficial effects. In this study, GABA-enriched product from L. fermentum-fermented rice bran solution exhibited the inhibition on inflammatory response in macrophages. Hence, it could be used as a potential ingredient for the mitigation of inflammatory responses.