Abstract: ObjectiveTo investigate inhibitory effect and possible mitogen-activated protein kinase signaling mechanism of saponin from Anemarrhena asphdeloids Bge(SAaB) on the release of inflammatory mediators induced by lipopolysaccharides(LPS) in cultured mouse peritoneal macrophages.MethodsAfter stimulation with LPS,the supernatants of macrophages were collected and analyzed for tumor necrosis factor-α(TNF-α),interleukin-1β(IL-1β)and nitric oxide(NO) generation,and protein expression of inducible nitric oxide synthase(iNOS) in macrophages was determined with immunocytochemical staining.ResultsLPS significantly inducedan increase in iNOS protein expression and the production of TNF-α,IL-1β,and NO in cultured macrophages.SAaB(100 μmol/L) significantly suppressed LPS-induced increase in iNOS protein level.In addition,SAaB(10,30 and 100 μmol/L) also decreased TNF-α,IL-1β and NO generation in supernatants of cultured macrophages,with the decreases of TNF-α,IL-1β,and NO from 698.8±32.0 ng/L,257.4±27.3 ng/L,and 181.0±19.9 μmol/L to 382.7±48.9 ng/L,111.6±23.9 ng/L,and 82.6±18.1 μmol/L,respectively.SB203580 and SP600125 could distinctly inhibit the production of TNF-α,IL-1β,NO,and the expression of iNOS.ConclusionSAaB could significantly inhibit the over-release of inflammatory mediators induced by LPS in cultured mouse peritoneal macrophages,which may be related to the downregulation of mitogen-activated protein kinase(MARK) signal transduction pathway.