title: Harpagoside suppresses lipopolysaccharide-induced iNOS and COX-2 expression through inhibition of NF-kappa B activation.
abstract: Preparations of Harpagophytum procumbens, known as devil's claw, are used as an adjunctive therapy for the treatment of pain and osteoarthritis. Pharmacological evaluations have proven the effectiveness of this herbal drug as an anti-inflammatory and analgesic agent. The present study has investigated the mechanism of action of harpagoside, one of the major components of Harpagophytum procumbens, using human HepG2 hepatocarcinoma and RAW 264.7 macrophage cell lines. Harpagoside inhibited lipopolysaccharide-induced mRNA levels and protein expression of cyclooxygenase-2 and inducible nitric oxide in HepG2 cells. These inhibitions appeared to correlate with the suppression of NF-kappaB activation by harpagoside, as pre-treating cells with harpagoside blocked the translocation of NF-kappaB into the nuclear compartments and degradation of the inhibitory subunit IkappaB-alpha. Furthermore, harpagoside dose-dependently inhibited LPS-stimulated NF-kappaB promoter activity in a gene reporter assay in RAW 264.7 cells, indicating that harpagoside interfered with the activation of gene transcription. These results suggest that the inhibition of the expression of cyclooxygenase-2 and inducible nitric oxide by harpagoside involves suppression of NF-kappaB activation, thereby inhibiting downstream inflammation and subsequent pain events.
authors.affiliation: Pharmaceutical Chemistry and Herbal Medicines Research and Education Centre, Faculty of Pharmacy A15, University of Sydney, NSW 2006, Australia.
authors.forename: Tom Hsun-Wei
authors.initials: TH
authors.lastname: Huang
authors.forename: Van H
authors.initials: VH
authors.lastname: Tran
authors.forename: Rujee K
authors.initials: RK
authors.lastname: Duke
authors.forename: Sharon
authors.initials: S
authors.lastname: Tan
authors.forename: Sigrun
authors.initials: S
authors.lastname: Chrubasik
authors.forename: Basil D
authors.initials: BD
authors.lastname: Roufogalis
authors.forename: Colin C
authors.initials: CC
authors.lastname: Duke
mesh_terms: D000818:Animals; D002460:Cell Line; D051546:Cyclooxygenase 2 / Q000096:biosynthesis*; D052246:Cyclooxygenase 2 Inhibitors / Q000302:isolation & purification / Q000494:pharmacology*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000502:physiology; D006027:Glycosides; D008070:Lipopolysaccharides / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D051379:Mice; D016328:NF-kappa B / Q000037:antagonists & inhibitors* / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000037:antagonists & inhibitors* / Q000096:biosynthesis; D010936:Plant Extracts; D018517:Plant Roots; D011714:Pyrans
chemical_list: D052246:Cyclooxygenase 2 Inhibitors; D006027:Glycosides; D008070:Lipopolysaccharides; D016328:NF-kappa B; D010936:Plant Extracts; D011714:Pyrans; C033249:harpagoside; D052247:Nitric Oxide Synthase Type II; D051546:Cyclooxygenase 2