RESEARCH PAPER Identification of plumericin as a potent new inhibitor of the NF-κB pathway with anti-inflammatory activity in vitro and in vivo N Fakhrudin 1,2 *, B Waltenberger 3 *, M Cabaravdic 4 *, A G Atanasov 1 , C Malainer 1 , D Schachner 1 , E H Heiss 1 , R Liu 1 , S M Noha 5 , A M Grzywacz 1 , J Mihaly-Bison 4 , E M Awad 4 , D Schuster 5 , J M Breuss 4 , J M Rollinger 3 , V Bochkov 4 , H Stuppner 3 and V M Dirsch 1 1 Department of Pharmacognosy, University of Vienna, Vienna, Austria, 2 Department of Pharmaceutical Biology, Faculty of Pharmacy, Universitas Gadjah Mada, Yogyakarta, Indonesia, 3 Institute of Pharmacy (Pharmacognosy), Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria, 4 Center for Physiology and Pharmacology, Institute for Vascular Biology and Thrombosis Research, Medical University of Vienna, Vienna, Austria, and 5 Institute of Pharmacy (Pharmaceutical Chemistry), Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria Correspondence Atanas G Atanasov, Department of Pharmacognosy, University of Vienna, Althanstrasse 14, Vienna A-1090, Austria. E-mail: atanas.atanasov@univie.ac.at ---------------------------------------------------------------- *These authors contributed equally to this work. ---------------------------------------------------------------- Keywords plumericin; NF-κB; inflammation; peritonitis; IκB; IKK-β; natural products; adhesion molecules ---------------------------------------------------------------- Received 2 August 2013 Revised 28 November 2013 Accepted 9 December 2013 BACKGROUND AND PURPOSE The transcription factor NF-κB orchestrates many pro-inflammatory signals and its inhibition is considered a promising strategy to combat inflammation. Here we report the characterization of the natural product plumericin as a highly potent inhibitor of the NF-κB pathway with a novel chemical scaffold, which was isolated via a bioactivity-guided approach, from extracts of Himatanthus sucuuba, an Amazonian plant traditionally used to treat inflammation-related disorders. EXPERIMENTAL APPROACH A NF-κB luciferase reporter gene assay was used to identify NF-κB pathway inhibitors from H. sucuuba extracts. Monitoring of TNF-α-induced expression of the adhesion molecules VCAM-1, ICAM-1 and E-selectin by flow cytometry was used to confirm NF-κB inhibition in endothelial cells, and thioglycollate-induced peritonitis in mice to confirm effects in vivo. Western blotting and transfection experiments were used to investigate the mechanism of action of plumericin. KEY RESULTS Plumericin inhibited NF-κB-mediated transactivation of a luciferase reporter gene (IC50 1 μM), abolished TNF-α-induced expression of the adhesion molecules VCAM-1, ICAM-1 and E-selectin in endothelial cells and suppressed thioglycollate-induced peritonitis in mice. Plumericin exerted its NF-κB pathway inhibitory effect by blocking IκB phosphorylation and degradation. Plumericin also inhibited NF-κB activation induced by transfection with the constitutively active catalytic subunit of the IκB kinase (IKK-β), suggesting IKK involvement in the inhibitory action of this natural product. CONCLUSION AND IMPLICATIONS Plumericin is a potent inhibitor of NF-κB pathways with a new chemical scaffold. It could be further explored as a novel anti-inflammatory lead compound. Abbreviations IKK, IκB kinase; INT, 2-p-iodophenyl-3-nitrophenyl tetrazolium chloride. BJP British Journal of Pharmacology DOI:10.1111/bph.12558 www.brjpharmacol.org 1676 British Journal of Pharmacology (2014) 171 1676–1686 © 2013 The Authors. British Journal of Pharmacology published by John Wiley & Sons Ltd on behalf of The British Pharmacological Society. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.