TautomerCanonicalizer implemented in the molecule validation and standardization tool MolVS, as described in previous works. In short, the Simplified Molecular Input Line Entry System 56 (SMILES) of each compound was standardized, those compounds consisting of multiple components were split and the largest component was retained. Compounds containing any element other than H, B, C, N, O, F, Si, P, S, Cl, Se, Br and I, as well as compounds with valence errors, were removed from the data set. The remaining compounds were neutralized and reionized to subsequently generate a canonical tautomer without preserved stereochemistry. Once all compounds were standardized, those with molecular weight higher than 800 Da as well as duplicated compounds with contradictory labels were removed. We preserved compound-protein associations only for those targets with at least 30 compounds labeled as "active," corresponding to 72 different targets. Since chemogenomic data for these epigenetic targets include a higher proportion of associations for "active" compounds (64% on average), we extended our initial data with "inactive" compounds from PubChem. We included only compounds with annotated quantitative data (IC 50 ), all these compounds were curated using the same procedure described above and added only if they were not already included in the datasets. Finally, we kept 58 target-associated datasets containing at least 30 compounds labeled as "inactive."