Structure‐Guided Optimization and Biological Validation of 1,3,4‐Thiadiazole‐Based SIRT2 Inhibitors Reinforcing Channel Entrance Interactions

ABSTRACT SIRT2, the cytoplasmic member of the sirtuin family, is generally acknowledged to promote cancer and contribute to the progression of various pathologies, including neurodegeneration, inflammation, obesity, and bacterial infection through the deacetylation of target substrates. In our previous efforts we identified potent and highly selective SIRT2 inhibitors with IC 50 values in the micromolar range. To further optimize their activity, we performed molecular docking‐guided design and subsequent synthesis of a series of novel 1,3,4‐thiadiazole derivatives. SIRT inhibitory screening identified that ST131 and ST132 achieved moderate inhibitory effects against SIRT2 with IC 50 values of 8.95 and 6.62 µM, respectively. Moreover, cellular assays in MCF‐7 breast cancer cells revealed that ST132 has shown an antiproliferative effect, as well as increased acetylated α‐tubulin expression levels, which is typically consistent with SIRT2 inhibition. In addition, docking studies were performed to analyze and rationalize the structural differences responsible for SIRT2 activity, shedding light on the importance of the interactions occurring at the entrance of the binding site. Finally, molecular mechanics‐generalized born surface area (MM‐GBSA) and molecular dynamics (MD) simulation approaches were conducted to verify the stability of ST132 in the complex with SIRT2.