Glossogyne tenuifolia acts to inhibit inflammatory mediator production in a macrophage cell line by downregulating LPS-induced NF-κB

Glossogyne tenuifolia (hsiang-ju) (GT) is a traditional antipyretic herb used in Chinese medicine; however, no information is available to explain its action. The objective of this research was to elucidate the molecular pharmacological activity and the effective components in the ethanol extract of GT. We found that GT had potent anti-inflammatory effects on the lipopolysaccharide (LPS)activated murine macrophages, RAW264.7. GT downregulated LPS-induced expression of inducible nitric oxide synthase (iNOS) by blocking its transcription. GT also caused a dose-dependent inhibition of the release of prostaglandin E-2 by repressing the promoter activity of the inducible cyclooxygenase (COX-2) gene. Moreover, GT exerted a dose-dependent inhibition of the LPS-stimulated release of the proinflammatory cytokines, TNF-alpha, IL-1beta, IL-6, and IL-12. To determine the mechanism by which GT inhibits LPS signaling, we focused on nuclear factor-kappaB (NF-kappaB) activation. Western blot analysis revealed that GT abolished LPS-induced inhibitor-kappaB phosphorylation. The electrophoretic mobility shift assay demonstrated that GT abolished LPS-mediated kappaB DNA binding activity. Moreover, macrophages were transfected with a vector coding for the luciferase reporter gene under the control of NF-kappaB cis-acting elements, and the transfected macrophages showed that the LPS-stimulated luciferase activity was GT-sensitive. These results suggest that GT attenuates inflammatory mediator synthesis of activated macrophages through an NF-kappaB-dependent pathway. The active components of GT were identified as oleanolic acid and luteolin-7-glucoside. Both of these compounds inhibited LPS-stimulated inflammatory mediator production and NF-kappaB activation. We conclude that GT inhibits NF-kappaB-mediated gene expression and downregulates inflammatory mediator production in murine macrophages. Copyright (C) 2004 National Science Council, ROC and S. Karger AG, Basel.