SIRT-IN-1 is a potent inhibitor of SIRT1/2/3, with IC50s of 15, 10, 33 μM, respectively.IC50 & Target: IC50: 15 nM (SIRT1), 10 nM (SIRT2), 33 nM (SIRT3).In Vitro: SIRT-IN-1 (compound 28) is one of the most potent truncated pan SIRT1/ 2/3 inhibitor, the IC50 values are 0.015, 0.010, 0.033 μM, respectively. SIRT-IN-1 (SIRT1/2/3 pan inhibitor) binds identically in the catalytic active site (RMS=0.29 ?), occupying the nicotinamide C-pocket and acetyl lysine substrate channel.