The visualization of the chemical spaces showed that de novo compounds kept the physicochemical properties of the already known DNMT1 active inhibitors reported in ChEMBL 31. This could be associated with the secondary constraints used in both strategies for the design, in the scoring function of alvaBuilder and the parameters for the BUILD module in LigBuilder. These results are encouraging, since the visualizations with the two fingerprints used as molecular representations suggest that newly designed compounds populate different areas of the chemical space. Therefore, the new focused libraries are relevant for expanding the chemical space of DNMT1 inhibitors while keeping drug-like properties.