During the process of core hopping, the first step was to define the points at which the cores were attached to the scaffold. It was performed in the Define Combinations Step from the Combinatorial Screening panel [33] . The second step was to define receptor grid file, which was done in the Receptor Preparation panel [33] . The third step was to prepare the cores attached to the scaffold for the fragment database derived from ZINC [38] . Finally, the cores thus obtained were sorted and filtered by goodness of alignment and then re-docked into the receptor after attaching the scaffold, followed by using the docking scores to sort the final molecules.