Background: The combination of Radix Paeoniae Alba (RPA) and Rhizoma Atractylodis Macrocephalae (RAM) has long been used as a classic herb pair for the treatment of gynecologic and gastrointestinal diseases, but the underlying mechanisms of the herb pair remain unknown. This study aims to explore the anti-infammatory potentials of RPA–RAM herb pair and to elucidate the underlying mechanisms.

Methods: The bioactive parts of RPA–RAM were extracted and screened through the inhibitory efects against nitric oxide (NO) production. The efects of optimized RPA–RAM extracts (OPAE) on infammation-associated mediators were investigated by Western blotting, real-time quantitative PCR (RT-qPCR), Enzyme-linked immunosorbent (ELISA) and immunofuorescence staining. 

Results: OPAE potently suppressed the productions of NO, TNF-α, IL-6 and MCP-1 in lipopolysaccharide (LPS)- induced RAW 264.7 macrophages, concentration-dependently inhibited protein level of inducible nitric oxide synthase (iNOS), dramatically downregulated mRNA expression of iNOS, TNF-α, IL-6 and MCP-1. In addition, OPAE signifcantly prevented phosphorylation and degradation of inhibitory kappa Bα (IκBα) and subsequently restrained the nuclear translocation of NF-κB p65. Pretreatment with OPAE also attenuated the LPS-induced phosphorylation of ERK, JNK and p38.

Conclusions: Our fndings demonstrated that OPAE suppressed infammatory responses in LPS-stimulated RAW 264.7 macrophages by decreasing critical molecules involved in MAPK and NF-κB pathway, suggesting that the herb pair could be a promising therapeutic candidate for infammation-related diseases.