Expanding the chemical space of human serine racemase inhibitors

Serine racemase, the enzyme responsible for D-serine synthesis in the central nervous system, has been identified as a potential therapeutic target to treat N-methyl-D-aspartate receptors-related pathologies. The search for specific inhibitors of the enzyme has revealed that serine racemase is a difficult target, with the best inhibitor currently identified, 2,2-dichloromalonate, showing a Ki of 19 lM. In order to expand the chemical space of hit compounds, we have performed an in silico structure-based screening campaign on a filtered ZINC library applying the FLAP software. The identified hits were docked with GOLD and re-scored with HINT, and the most promising molecules experimentally evaluated on recombinant human serine racemase. Two inhibitors, with chemical structures totally unrelated to inhibitors described so far showed Ki values of about 1.5 mM.