The effect of total flavonoids from Saussurea involucrata on the secretion of pro-inflammatory mediators in lipopolysaccharide stimulated RAW264.7 macrophages

Abstract

Background Saussurea involucrate (SI) has long been used to treat inflammatory diseases, such as rheumatoid arthritis. The main active constituents of SI are flavonoids, which are a class of polyphenolic compounds. However, few studies have investigated the anti-inflammatory activity of the total flavonoids of SI (FSI). The mechanism underlying this action is still not fully understood. In the present study, we employed RAW264.7 cell line as an inflammatory cell model to investigate the anti-inflammatory effects of FSI and explore the corresponding molecular mechanisms.Methods We extracted FSI using chromatographic column method. The cell viability was determined by MTT assay. The production of nitric oxide (NO) was detected by Griess assay. The release of cytokines and chemokines were determined by ELISA assays. The nuclear translocation of p65, c-Jun, and IRF3 was detected by immunofluorescence microscopy. Western blotting analysis was performed to determine the related protein expression.Results The results showed that the amount of FSI extracted from SI was 751.5 mg/g. The production of inflammatory mediators was effectively inhibited by FSI. Meanwhile, FSI also suppressed the nuclear translocation of p65, c-Jun, and IRF3. The elevated expression of iNOS, COX-2, p-IKKα/β, p-TBK1, p-IκBα, p-ERK, p-p38, p-JNK, p-p65, p-c-Jun, p-IRF3 induced by LPS was remarkably reduced by FSI treatment.Conclusion These findings indicated that FSI has a potential ability to inhibit the secretion of pro-inflammatory mediators and the underlying mechanism may be related to block the p65, c-Jun, and IRF3 signaling pathways. This study provided evidence for the anti-inflammatory mode and the underlying mechanism of FSI.