Anti-inflammatory effects of ethyl acetate fraction from Melilotus suaveolens Ledeb on LPS-stimulated RAW 264.7 cells

Abstract

Aim of the study: This paper aimed to elucidate the anti-inflammatory effects of EtOAc fraction prepared from Melilotus suaveolens Ledeb ethanol extract with a cellular model of LPS-stimulated RAW 264.7 cell.

Materials and methods: Some key pro-inflammatory cytokines and mediators including IL-1 beta, IL-6, NO, iNOS, COX-2 and TNF-alpha, two important anti-inflammatory cytokines and mediators IL-10 and HO-1, I-kappaB and NF-kappaB were studied by sandwich ELISA, real-time PCR, western blot analysis and immunocytochemistry. At last a HPLC fingerprint was taken to evaluate the fraction.

Results: The EtOAc fraction could significantly inhibit the production of IL-1 beta, IL-6, NO, TNF-alpha, COX-2 in LPS-stimulated cell than that of single LPS-stimulated cell (p<0.01 or p<0.05), and the extract could increase the production of IL-10 and HO-1 than that of single LPS intervention cell (p<0.01 or p<0.05). Meanwhile, the extract also could inhibit the production of NF-kappaB compared to single LPS-stimulated cell. All the results showed that the extract had a good anti-inflammatory effect on LPS-stimulated RAW264.7 cell.

Conclusions: Taken together, the anti-inflammatory actions of M. suaveolens Ledeb EtOAc fraction might be due to the down-regulation of IL-1 beta, IL-6, NO, TNF-alpha and COX-2 via the suppression of NF-kappaB activation, and another pathway was up regulating the production of IL-10 and HO-1. Meanwhile, the EtOAc fraction might be further studied to isolate the active anti-inflammatory ingredients besides coumarin.