Anti-inflammatory effects of 6′-O-acetyl mangiferin from Iris rossii Baker via NF-κb signal blocking in lipopolysaccharide-stimulated RAW 264.7 cells

A series of acylated xanthone C-glucosides were identified from the methanolic extract of whole Iris rossii Baker. The major constituent was characterized as 6'-O-acetyl mangiferin (OAM), and complete structure elucidation was carried out using 2D NMR (COSY, HSQC, and HMBC) and LC-IT-TOF-MS analyses. The present study is the first to report the anti-inflammatory effects of 6'-O-acetyl mangiferin from Iris rossii Baker on the lipopolysaccharide (LPS)-induced inflammatory response in RAW264.7 macrophage cells. OAM strongly suppressed protein expression of inducible nitric oxide (iNOS) and cyclooxygenase-2 (COX-2), thereby inhibiting the production of nitric oxide (NO), prostaglandin E-2 (PGE(2)), and cytokines such as tumor necrosis factor-alpha (INF-alpha), interleukin-1 beta (IL-1 beta), and interleukin-6 (IL-6). Furthermore, OAM inhibited the LPS-induced phosphorylation of ERK, JNK, and p38, which led to the blockade of nuclear factor-kappa B (NF-kappa B) and inhibitor kappa B (I kappa B)-alpha activation. These results suggest that the anti-inflammatory effects of OAM may be attributed to the downregulation of COX-2 and iNOS via the suppression of NF-kappa B and the MAPK signaling pathway in RAW264.7 macrophages. (C) 2016 Elsevier Ireland Ltd. All rights reserved.