title: Inhibition of VEGF: a novel mechanism to control angiogenesis by Withania somnifera's key metabolite Withaferin A.
abstract: OBJECTIVE
  Angiogenesis, or new blood vessel formation from existing one, plays both beneficial and detrimental roles in living organisms in different aspects. Vascular endothelial growth factor (VEGF), a signal protein, well established as key regulator of vasculogenesis and angiogenesis. VEGF ensures oxygen supply to the tissues when blood supply is not adequate, or tissue environment is in hypoxic condition. Limited expression of VEGF is necessary, but if it is over expressed, then it can lead to serious disease like cancer. Cancers that have ability to express VEGF are more efficient to grow and metastasize because solid cancers cannot grow larger than a limited size without adequate blood and oxygen supply. Anti-VEGF drugs are already available in the market to control angiogenesis, but they are often associated with severe side-effects like fetal bleeding and proteinuria in the large number of patients. To avoid such side-effects, new insight is required to find potential compounds as anti-VEGF from natural sources. In the present investigation, molecular docking studies were carried out to find the potentiality of Withaferin A, a key metabolite of Withania somnifera, as an inhibitor of VEGF.
  
  
  METHODS
  Molecular Docking studies were performed in DockingServer and SwissDock. Bevacizumab, a commercial anti-VEGF drug, was used as reference to compare the activity of Withaferin A. X-ray crystallographic structure of VEGF, was retrieved from Protein Data Bank (PDB), and used as drug target protein. Structure of Withaferin A and Bevacizumab was obtained from PubChem and ZINC databases. Molecular visualization was performed using UCSF Chimera.
  
  
  RESULTS
  Withaferin A showed favorable binding with VEGF with low binding energy in comparison to Bevacizumab. Molecular Docking studies also revealed potential protein-ligand interactions for both Withaferin A and Bevacizumab.
  
  
  CONCLUSIONS
  Conclusively our results strongly suggest that Withaferin A is a potent anti-VEGF agent as ascertained by its potential interaction with VEGF. This scientific hypothesis might provide a better insight to control angiogenesis as well as to control solid cancer growth and metastasis.
authors.affiliation: Pharmacy Discipline, Life Science School, Khulna University, Khulna, 9208 Bangladesh.
authors.forename: Sanjib
authors.initials: S
authors.lastname: Saha
authors.affiliation: Pharmacy Discipline, Life Science School, Khulna University, Khulna, 9208 Bangladesh.
authors.forename: Md Khirul
authors.initials: MK
authors.lastname: Islam
authors.affiliation: Pharmacy Discipline, Life Science School, Khulna University, Khulna, 9208 Bangladesh ; Centre for Natural Products and Drug (CENAR), University of Malaya, 50603 Kuala Lumpur, Malaysia.
authors.forename: Jamil A
authors.initials: JA
authors.lastname: Shilpi
authors.affiliation: School of Medicine, The University of Queensland (UQ), Brisbane, Queensland Australia ; Bioinformatics Lab, Queensland Institute of Medical Research (QIMR), Brisbane, Queensland Australia.
authors.forename: Shihab
authors.initials: S
authors.lastname: Hasan
keywords: Angiogenesis; Bevacizumab; Chimera; DockingServer; SwissDock; VEGF; Withaferin A; Withania somnifera