Machilus thunbergii extract inhibits inflammatory response in lipopolysaccharide-induced RAW264.7 murine macrophages via suppression of NF-κB and p38 MAPK activation

Machilus thunbergii Sieb. Zucc. (Lauraceae) is a medicinal plant used to treat edema and pain in China and Taiwan. The anti-inflammatory effects of M. thunbergii were not clear. In this study, we evaluated the anti-inflammatory effects of M. thunbergii extract in LPS-stimulated RAW 264.7 cells. The cells were pretreated with various doses (12.5 μg/mL–100 μg/mL) of M. thunbergii extract and activated with LPS. We found that 25 μg/mL M. thunbergii extract inhibited nitric oxide (NO), prostaglandin E2 (PGE2), inducible nitric oxide synthetase (iNOS), and cyclooxygenase-2 (COX-2) expression, as well as levels of proinflammatory cytokines including interleukin (IL)-6 and tumor necrosis factor-alpha (TNF-α). Furthermore, M. thunbergii extract also suppressed translocation of nuclear transcription factor kappa-B (NF-κB) subunit p65 proteins into the nucleus and induced a dose-dependent inhibition of the phosphorylation of p38 mitogen-activated protein kinase (MAPK). M. thunbergii extract also increased HO-1 and Nrf2 production in a concentration-dependent manner. Taken together, these results suggest that M. thunbergii extract has an anti-inflammatory effect because it reduces levels of proinflammatory cytokines and mediators via the suppression of NF-κB and p38 MAPK activation in RAW 264.7 cells.