Probing pyrazolo-pyrimidines as SIRT2 inhibitors via molecular modelling and biological assays.

Sirtuins (SIRTs) involvement in different biological pathways opens a promising scenario for the development of related ligands to be evaluated as therapeutic agents in different diseases, such as cancer, neurodegenerative disorders, diabetes, cardiovascular and autoimmune diseases. The continuous elucidation of several SIRT2-ligand complexes fostered the discovery of novel and more selective SIRT2 inhibitors (SIRT2Is). Among them, SIRT2 in the presence of SirReal2 analogues was the most investigated. We recently reported pyrazolo-pyrimidine compounds (1-5) as SIRT2Is (1, SIRT2 % inhibition = 81.2%, at 150 μM). Herein, combined ligand- and structure-based approaches enabled us to filter a further series of pyrazolo-pyrimidine-based analogues (6-16) endowed with improved SIRT2 inhibitory activity in comparison to 1-5. The applied molecular modelling studies revealed superimposable molecular interaction fields (MIFs) and protein-ligand contacts compared with the reference SIRT2Is. Subsequent biochemical and biological assays validated the reported strategy and pointed to compounds 11 and 15 (SIRT2 IC50 = 0.3 and 0.1 μM, respectively) as the most promising SIRT2Is, to be further investigated as anticancer agent.