Tectorigenin inhibits IFN-gamma/LPS-induced inflammatory responses in murine macrophage RAW 264.7 cells.

Tectorigenin (Tg) and tectoridin (Td) are the major compounds isolated from the rhizomes of iridaceous plant Belamcanda chinensis which is well known as a chinese traditional medicine for the treatment of inflammatory diseases. In this study we investigated whether tectorigenin and tectoridin can be applied to the suppression of interferon-gamma and lipopolysaccharide (IFN-gamma/LPS)-induced inflammatory responses in macrophages. Anti-inflammatory activities of tectorigenin and tectoridin were compared with genistein (Ge), well known isoflavonoid as a phytoestrogen and regarded as an emerging anti-inflammatory agent. Both compounds showed low cytotoxic effect. In Raw 264.7 cells activated with IFN-gamma/LPS, pre-treated tectorigenin was found to inhibit the expression of inducible nitric oxide synthase (iNOS), the production of nitric oxide (NO) and the secretion of interleukin (IL)-1beta dose-dependently. Tectorigenin also decreased the expression of cyclooxigenase (COX)-2 and the production of prostaglandin E(2) (PGE(2)) in dose-dependent manner. These inhibitory effects of tectorigenin were found to be caused by the blocking of nuclear factor kappa-B (NF-kappaB) activation. Compared with genistein and tectoridin, tectorigenin showed significant inhibitory effect for almost anti-inflammatory tests in this study. All these results clearly demonstrated that tectorigenin appears to have the potential to prevent inflammation.