Pentacyclic Triterpenoids Inhibit IKKβ Mediated Activation of NF-κB Pathway: In Silico and In Vitro Evidences

PLoS One. 2015 May 4;10(5):e0125709. doi: 10.1371/journal.pone.0125709. eCollection 2015.

Abstract

Pentacyclic Triterpenoids (PTs) and their analogues as well as derivatives are emerging as important drug leads for various diseases. They act through a variety of mechanisms and a majority of them inhibit the nuclear factor kappa-beta (NF-κB) signaling pathway. In this study, we examined the effects of the naturally occurring PTs on IκB kinase-β (IKKβ), which has great scientific relevance in the NF-κB signaling pathway. On virtual screening, 109 PTs were screened through the PASS (prediction of activity spectra of substances) software for prediction of NF-κB inhibitory activity followed by docking on the NEMO/IKKβ association complex (PDB: 3BRV) and testing for compliance with the softened Lipinski's Rule of Five using Schrodinger (LLC, New York, USA). Out of the projected 45 druggable PTs, Corosolic Acid (CA), Asiatic Acid (AA) and Ursolic Acid (UA) were assayed for IKKβ kinase activity in the cell free medium. The UA exhibited a potent IKKβ inhibitory effect on the hotspot kinase assay with IC50 of 69 μM. Whereas, CA at 50 μM concentration markedly reduced the NF-κB luciferase activity and phospho-IKKβ protein expressions. The PTs tested, attenuated the expression of the NF-κB cascade proteins in the LPS-stimulated RAW 264.7 cells, prevented the phosphorylation of the IKKα/β and blocked the activation of the Interferon-gamma (IFN-γ). The results suggest that the IKKβ inhibition is the major mechanism of the PTs-induced NF-κB inhibition. PASS predictions along with in-silico docking against the NEMO/IKKβ can be successfully applied in the selection of the prospective NF-κB inhibitory downregulators of IKKβ phosphorylation.

MeSH terms

  • Animals
  • Cell Line
  • Cell Survival / drug effects
  • Computer Simulation
  • Dose-Response Relationship, Drug
  • Drug Discovery / methods
  • Enzyme Activation / drug effects
  • Gene Expression
  • Genes, Reporter
  • Humans
  • Hydrogen Bonding
  • I-kappa B Kinase / antagonists & inhibitors
  • I-kappa B Kinase / chemistry
  • I-kappa B Kinase / metabolism*
  • Interferon-gamma / biosynthesis
  • Lipopolysaccharides / immunology
  • Macrophages / drug effects
  • Macrophages / immunology
  • Macrophages / metabolism
  • Mice
  • Molecular Conformation
  • Molecular Docking Simulation
  • Molecular Dynamics Simulation
  • NF-kappa B / antagonists & inhibitors
  • NF-kappa B / chemistry
  • NF-kappa B / metabolism*
  • Pentacyclic Triterpenes / chemistry
  • Pentacyclic Triterpenes / pharmacology*
  • Protein Binding
  • Signal Transduction / drug effects*
  • Small Molecule Libraries

Substances

  • Lipopolysaccharides
  • NF-kappa B
  • Pentacyclic Triterpenes
  • Small Molecule Libraries
  • Interferon-gamma
  • I-kappa B Kinase

Grant support

The authors have no support or funding to report.