Anti-inflammatory Effect of Pratol in LPS-stimulated RAW 264.7 Cells via NF-κB Signaling Pathways

The Trifolium pratense L. (red clover), which blossoms, leaves and stems can be used as medicines for treatment of burns, skin diseases, diabetes and other diseases. Recently study shown that pratol (7-hydroxy-4-methoxyflavone), an O-methylated flavone in T. pratense has been evaluated to induce melanogenesis in B16F10 melanoma cells. However, the anti-inflammatory effect of pratol has not been reported. In this study, we investigated the effects of pratol on anti-inflammation. We also studied the mechanism of action of pratol in LPS-stimulated RAW 264.7 cells. The cells were treated with various concentration of pratol (25, 50, or 100 μM) and 25 μM ammonium pyrrolidinedithiocarbamate (APDC) was used as control. The results in LPS-stimulated RAW 264.7 cells showed that pratol significantly reduced nitric oxide (NO) and prostaglandin E 2 (PGE 2 ) production without any cytotoxic. In addition, pratol strongly decreased the expression of inducible nitric oxide synthase (iNOS) and cyclooygenase (COX-2). Furthermore, pratol reduced proinflammatory cytokines such as tumour necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6. We also found that pratol strongly inhibited activation of nuclear factor kappa B (NF-κB) by reducing the p65 phosphorylation and protecting inhibitory factor kappa B alpha (IκBα) degradation. The results suggest that, pratol may be used to treat or prevent inflammatory diseases such as dermatitis, arthritis, cardiovascular and cancer.