In view of the emerging clinical indications for Phosphodiesterase 9 inhibitors e.g. treatment
of Alzheimer, diabetes, cancer, and the limited number of its selective inhibitors which possess a
single chemical scaffolds, a structure-based approach was undertaken to mine the ZINC database by
virtual screening to identify novel PDE9 inhibitors. The database, which was never reported to have
been used before for discovery of PDE9 inhibitors, was screened against the ligand binding pocket of
the PDE9 complex (PDB:4GH6) using molecular docking programs, MOE and AutoDock Vina in
PyRx. Three different scoring functions were used to evaluate the docking poses and scores of the compounds, and the
compounds were selected through consensus selection, thus reducing the margin of error in docking. The highest scoring
compounds were then selected and purchased for in vitro testing as PDE9 inhibitors and cancer growth inhibitory agents.
This led to the discovery of three previously unreported potent PDE 9 inhibitory compounds with two unique chemical
scaffolds. Consistent with the role of PDE9 in cancer cell growth, the compounds also inhibited the growth of breast tumor
cell lines, MCF-7 and MDA-468 at concentrations comparable to those that inhibited PDE9.