RESUMO
The root of Astragalus membranaceus (AR), which has been widely used in Traditional Chinese herbal formulae for treating foot ulcer, was found to exhibit anti-inflammatory property, but its molecular mechanism still remains unknown. We previously identified the anti-inflammatory sub-fraction using bioassay-guided fractionation. The objective of the present study was to investigate the anti-inflammatory mechanism of the major active fraction (MAF) (0.039 to 0.156 mg/mL) using lipopolysaccharide (LPS)-stimulated mouse macrophage RAW 264.7 cells. MAF was shown to inhibit LPS-induced mRNA and protein expression of inducible nitric oxide synthase by 54.7% and 65.1%, respectively. Additionally, MAF down-regulated the protein expression of cyclooxygenase-2 and MAPK regulator by 45.0% to 74.6%, as well as the reduction of DNA binding activity of nuclear factor kappa B (NFκB) by 66.5%. It also attenuated the production of prostaglandin E2 , interleukin-1 beta (IL-1ß), IL-6 and tumor necrosis factor alpha by 21.2% to 86.2%. Furthermore, the chemical constituents of MAF were identified. A total of 13 known chemical compounds were found in MAF, including five isoflavonoids and eight saponins. In conclusion, a bioactive fraction of AR was identified which possessed anti-inflammatory property by reducing the release of inflammatory mediators and inactivation of NFκB through MAPK signalling pathway.
