Quaternary alkaloid, pseudocoptisine isolated from tubers of Corydalis turtschaninovi inhibits LPS-induced nitric oxide, PGE 2, and pro-inflammatory cytokines production via the down-regulation of NF-κB in RAW 264.7 murine macrophage cells

Abstract

It is well known that pro-inflammatory mediators like nitric oxide (NO), prostaglandin E 2 (PGE 2), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) contribute to the courses of many inflammatory diseases. In the present study, the authors investigated the anti-inflammatory effects of pseudocoptisine, a quaternary alkaloid with a benzylisoquinoline skeleton, which was isolated from the tubers of Corydalis turtschaninovii by examining its inhibitory effects on pro-inflammatory mediators in lipopolysaccharide (LPS)-stimulated murine macrophage RAW 264.7 cells. Pseudocoptisine caused dose-dependent reductions in the levels of inducible nitric oxide (iNOS) and cyclooxygenase-2 (COX-2) at both protein and mRNA levels and concomitant decreases in PGE 2 and NO production. In addition, it was found that pseudocoptisine suppressed the production and mRNA expressions of inflammatory cytokines, such as, TNF-α and IL-6. Furthermore, molecular data revealed that pseudocoptisine inhibited the LPS-stimulated DNA binding activity and the transcription activity of nuclear factor-kappa B (NF-κB). Moreover, this effect was accompanied by decreases in the phosphorylation of inhibitory κB (IκB)-α and in the subsequent blocking of p65 subunit of NF-κB translocation to the nucleus. In addition, pseudocoptisine dose-dependently inhibited the phosphorylations of ERK and p38. Taken together, these results suggest that pseudocoptisine reduces levels of the pro-inflammatory mediators, such as, iNOS, COX-2, TNF-α, and IL-6 through the inhibition of NF-κB activation via the suppression of ERK and p38 phosphorylation in RAW 264.7 cells. These findings reveal in part the molecular basis for the anti-inflammatory properties of pseudocoptisine.