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

• 6′-O-acetyl mangiferin (OAM) from Iris rossii Baker was isolated and characterized.
• OAM decreased NO and PGE2 production in RAW 264.7 cells.
• OAM strongly suppressed pathways of MAP kinases signaling.
• OAM strongly suppressed nuclear translocation of NF-κB using Immunofluorescence assay.

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 E2 (PGE2), and cytokines such as tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), 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-κB) and inhibitor kappa B (IκB)-α 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-κB and the MAPK signaling pathway in RAW264.7 macrophages.