Effect of Siam weed extract and its bioactive component scutellarein tetramethyl ether on anti-inflammatory activity through NF-κB pathway

Abstract

Ethnopharmacological relevance Siam weed (Chromolaena odorata (L.) King and Robinson) is a medicinal herb used for wound healing and inflammation-related diseases. Aim of the study In this study, we evaluated the molecular mechanism by which Siam weed extract (SWE) and its bioactive components, scutellarein tetramethyl ether (scu), stigmasterol, and isosakuranetin affect anti-inflammatory activity. Materials and methods The expression of several inflammatory proteins in RAW 264.7 (murine) macrophages was assessed by Western blot and reverse transcription-polymerase chain reaction (RT-PCR). Biochemical assays including prostaglandin E2(PGE2) and nitric-oxide (NO) quantification were performed. Luciferase promoter activity and immunocytochemistry of Nuclear factor-κB (NF-κB) were investigated. Results Cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) are critical pro-inflammatory proteins. The level of protein and mRNA expression of these enzymes induced by lipopolysaccharide (LPS) was dramatically suppressed by treatment with SWE, scu, or stigmasterol compounds in a dose-dependent manner. They also reduced PGE2and NO release. We further analyzed the NF-κB pathway and found that the scu compound suppressed IκB kinase complex alpha/beta (IKKα/β) and Inhibitory-kappa-B-alpha (IκBα), thereby suppressing COX-2 and iNOS expression. Conclusion This is the first report of the anti-inflammatory molecular mechanism in SWE and/or its bioactive component scu, indicating alteration NF-κB pathway and further providing potential uses in the treatment of inflammatory-related diseases. © 2013 Elsevier Ireland Ltd. All rights reserved.