Repurposing Fluphenamic Acid and Glibenclamide for the design and optimisation of AKR1C1 receptor inhibitors

Abstract

The NSAID Fluphenamic Acid and the oral hypoglycaemic Glibenclamide successfully antagonised the receptor AKR1C1, which is over expressed in bladder cancers in in vitro assays. These scaffolds were modelled and repurposed in this study to identify novel antagonist molecules which are capable of inhibiting the AKR1C1 receptor. The Protein Data Bank 4YVP which describes the crystal structure of the AKR1C1 receptor complexed with Glibenclamide was used in this study to extract the Glibenclamide molecule while Fluphenamic Acid was generated de novo. Two approaches were used in this study - Virtual Screening (ligand-based drug design) and de novo (using the 3-d shape of a receptor for the purpose of drug design). Molecules which are 3-dimensionally, spatially and electronically similar to the lead molecules were identified using Virtual Screening. A graph of Ligand binding Affinities vs Ligand Binding Energy vs Conformer number for the 20 generated Fluphenamic Acid Conformers was plotted and the two optimal confermers were chosen. Using the co ordinates of the two optimal conformers of Fluphenamic Acid and the bioactive Glibenclamide, a consensus Pharmacophore was generated. using Sybyl-X® a Protomol was modelled . This study was valuable in modelling a unique pharmacophore representing the two lead molecules Fluphenamic acid and Glibenclamide and the average structure was used to identify analogous low molecular hits. These hits were docked into the generated protomol and analysed for Lipinski Rule compliance and affinity. In the De novo approach, a 2D topology map was used to exhibit optimal conformers’ interactions with the AKR1C1 receptor active site and this was used to illustrate the pharmacophoric moieties which were inhibiting the active site. Different seeds were seeded in the AKR1C1 receptor Ligand Binding Pocket and left to grow. The Structures were then proposed for activity and affinity at the target LBP which is of vital importance when testing for prospective clinical use and the molecules with the highest affinities are proposed for further validation.