Suffrutines A and B Inhibit the Expression of Inflammatory Mediators in LPS-Induced RAW264.7 Cells by Suppressing the NF-κB Signaling Pathway

Flueggea suffruticosa is a traditional Chinese medicine that has been commonly used for the treatment of inflammatory ailments, including rheumatism and lumbago. Suffrutines A and suffrutines B are a pair of novel E,E and Z,E isomeric indolizidine alkaloids isolated from the roots of F. suffruticosa. However, their anti- inflammatory activity has not been reported thus far. The aim of this study was to investigate the inhibitory effect of inflammatory mediators and possible mechanisms of suffrutines A and B in lipopolysaccharide-induced RAW264.7 cells. Results showed that suffrutines A and B could remarkably inhibit the production of nitric oxide, prostaglandin E-2, interleukin-6, inducible nitric oxide synthase, and cyclooxygenase-2 in lipopolysaccharide-induced RAW264.7 cells. Further evaluation demonstrated that compared with suffrutines A, suffrutines B could more significantly inhibit the phosphorylation of IKK alpha/beta, the degradation of I kappa B alpha, and the nuclear translocation of the p65 and p52 subunits in the canonical and non-canonical nuclear factor-kappa B pathways. Therefore, suffrutines B exhibited more potent inhibitory activity on inflammatory mediators than suffrutines A.