title: Inhibition of IKKβ by celastrol and its analogues - an in silico and in vitro approach.
abstract: BACKGROUND
  Alzheimer's disease (AD) is the most common form of dementia affecting the aged population and neuroinflammation is one of the most observed AD pathologies. NF-κB is the central regulator of inflammation and inhibitor κB kinase (IKK) is the converging point in NF-κB activation. Celastrol is a natural triterpene used as a treatment for inflammatory conditions.
  
  
  OBJECTIVE
  This study determines the neuroprotective and inhibitory effect of celastrol on amyloid beta1-42(Aβ1-42) induced cytotoxicity and IKKβ activity, respectively.
  
  
  METHODS
  Retinoic acid differentiated IMR-32 cells were treated with celastrol (1 μM) before treatment with Aβ1-42(IC3010 μM) for 24 h. The cytotoxicity and IKK phosphorylation were measured by MTT and western blotting analysis, respectively. We screened 36 celastrol analogues for the IKKβ inhibition by molecular docking and evaluated their drug like properties to delineate the neuroprotective effects.
  
  
  RESULTS
  Celastrol (1 μM) inhibited Aβ1-42(10 μM) induced IκBα phosphorylation and protected IMR-32 cells from cell death. Celastrol and 25 analogues showed strong binding affinity with IKKβ as evidenced by strong hydrogen-bonding interactions with critical active site residues. All the 25 analogues displayed strong anti-inflammatory properties but only 11 analogues showed drug-likeness. Collectively, molecule 15 has highest binding affinity, CNS activity and more drug likeness than parent compound celastrol.
  
  
  CONCLUSIONS
  The decreased expression of pIκBα in celastrol pretreated cells affirms the functional representation of inhibited IKKβ activity in these cells. The neuroprotective potentials of celastrol and its analogues may be related to IKK inhibition.
authors.affiliation: a Department of Biochemistry , VRR Institute of Biomedical Science (Affiliated to University of Madras) , Chennai , Tamilnadu , India.
authors.forename: Karpagam
authors.initials: K
authors.lastname: Veerappan
authors.affiliation: b Department of Horticulture , Sunchon National University , Suncheon , Republic of Korea.
authors.forename: Sathishkumar
authors.initials: S
authors.lastname: Natarajan
authors.affiliation: c Department of Medical Research , SRM Medical College Hospital and Research Centre, SRM University , Kattankulathur , Tamilnadu , India.
authors.forename: Purushoth
authors.initials: P
authors.lastname: Ethiraj
authors.affiliation: d Center for Bioinformatics, Vision Research Foundation, Sankara Nethralaya , Chennai , Tamilnadu , India.
authors.forename: Umashankar
authors.initials: U
authors.lastname: Vetrivel
authors.affiliation: a Department of Biochemistry , VRR Institute of Biomedical Science (Affiliated to University of Madras) , Chennai , Tamilnadu , India.
authors.forename: Shila
authors.initials: S
authors.lastname: Samuel
mesh_terms: D000544:Alzheimer Disease / Q000188:drug therapy* / Q000201:enzymology / Q000473:pathology; D016229:Amyloid beta-Peptides / Q000633:toxicity; D000893:Anti-Inflammatory Agents / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D001665:Binding Sites; D045744:Cell Line, Tumor; D006801:Humans; D006860:Hydrogen Bonding; D051550:I-kappa B Kinase / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D062105:Molecular Docking Simulation; D009474:Neurons / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D018696:Neuroprotective Agents / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D053978:Pentacyclic Triterpenes; D010446:Peptide Fragments / Q000633:toxicity; D010766:Phosphorylation; D011485:Protein Binding; D011487:Protein Conformation; D047428:Protein Kinase Inhibitors / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects; D013329:Structure-Activity Relationship; D014212:Tretinoin / Q000494:pharmacology; D014315:Triterpenes / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D016229:Amyloid beta-Peptides; D000893:Anti-Inflammatory Agents; D018696:Neuroprotective Agents; D053978:Pentacyclic Triterpenes; D010446:Peptide Fragments; D047428:Protein Kinase Inhibitors; D014315:Triterpenes; C075222:amyloid beta-protein (1-42); D014212:Tretinoin; D051550:I-kappa B Kinase; C496560:IKBKB protein, human; C050414:celastrol
keywords: ADMET; Alzheimer’s disease; amyloid-β; molecular docking; neuroinflammation