Vaccinium bracteatum extract alleviates inflammatory responses in LPS-stimulated RAW264.7 macrophages

Abstract

Vaccinium bracteatum Thunb. is found in coastal areas and mountainous regions in Southeast Asia, and in traditional medicine, has been used to cure a variety of illnesses, notably inflammation, diarrhea, and skin eruptions. However, no extensive studies have been undertaken on its anti-inflammatory activity in RAW264.7 cells. The purpose of this study was to investigate the anti-inflammatory effects of a methanolic extract of V. bracteatum (VB) and the mechanism underlying its immunological regulation in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. Quercetin was identified in the VB extract at 0.71 mg/mL, as determined by high-performance liquid chromatography. Our results revealed that the extract considerably and dose-dependently reduced the generation of NO (nitric oxide) and PGE2 (prostaglandin E2) and that these reductions were associated with suppressions of iNOS (inducible nitric oxide synthase) and COX-2 (cyclooxygenase-2). VB extract also inhibited LPS-stimulated mRNA expressions of TNF-α (tumor necrosis factor-α), IL-1β (interleukin-1β), and IL-6, and the expressions of CD14 (cluster of differentiation 14), CD86, and TLR4 (toll-like receptor 4) in LPS-stimulated macrophages. In addition, VB extract significantly reduced the expressions of proteins by activating the concentration-dependent phosphorylation of NF-κB-p65, ERK1/2, JNK, and p38. This study shows that the methanolic extract of Vaccinium bracteatum Thunb. reduces inflammation by down-regulating the NF-κB and MAPK signaling cascades in LPS-induced RAW264.7 cells. Furthermore, the extract was found to have potent antioxidant activity, suggesting pharmaceutical and food applications.