Anti-inflammatory Effects of Moutan Cortex Radicis Extract, Paeoniflorin and Oxypaeoniflorin through TLR Signaling Pathway in RAW264.7 Cells

Abstract

Moutan cortex radicis (MCR), the root bark of Paeonia suffruticosa, has been widely used as a traditional herb. In this study, we evaluated whether the MCR extract and two active compounds of the bark, paeoniflorin (paeo) and oxypaeoniflorin (oxypaeo), alleviate lipopolysaccharide (LPS)-induced inflammatory responses in RAW264.7 cells and whether they controlled TLR signaling pathway. RAW264.7 cells were treated with the MCR extract or two active compounds in the presence or absence of LPS. The extract and two active compounds inhibited LPS-stimulated nitric oxide (NO) production and inducible nitric oxide synthase (iNOS) gene expression. Additionally, the extract and two active compounds suppressed inflammatory cytokine secretion and gene expression in LPS-stimulated cells. The extract and two active compounds alleviated NF-κB activation by regulating upstream genes in TLR signaling pathway. In addition, the extract and two active compounds decreased phosphorylation of ERK and p38 MAPK. These results indicate that the MCR extract, paeo and oxypaeo have anti-inflammatory effects through regulation of TLR signaling pathway in RAW264.7 cells.