Identification of the Binding Site of Chroman-4-one-Based Sirtuin 2‑Selective Inhibitors using Photoaffinity Labeling in Combination with Tandem Mass Spectrometry

Photoaffinity labeling (PAL) was used to identify the binding site of chroman-4-one-based SIRT2-selective inhibitors. The photoactive diazirine <b>4</b>, a potent SIRT2 inhibitor, was subjected to detailed photochemical characterization. In PAL experiments with SIRT2, a tryptic peptide originating from the covalent attachment of photoactivated <b>4</b> was identified. The peptide covers both the active site of SIRT2 and the proposed binding site of chroman-4-one-based inhibitors. A high-power LED was used as source for the monochromatic UV light enabling rapid photoactivation

Synthesis and Evaluation of Substituted Chroman-4-one and Chromone Derivatives as Sirtuin 2‑Selective Inhibitors

A series of substituted chromone/chroman-4-one derivatives has been synthesized and evaluated as novel inhibitors of SIRT2, an enzyme involved in aging-related diseases, e.g., neurodegenerative disorders. The analogues were efficiently synthesized in a one-step procedure including a base-mediated aldol condensation using microwave irradiation. The most potent compounds, with inhibitory concentrations in the low micromolar range, were substituted in the 2-, 6-, and 8-positions. Larger, electron-withdrawing substituents in the 6- and 8-positions were favorable. The most potent inhibitor of SIRT2 was 6,8-dibromo-2-pentylchroman-4-one with an IC₅₀ of 1.5 μM. The synthesized compounds show high selectivity toward SIRT2 over SIRT1 and SIRT3 and represent an important starting point for the development of novel SIRT2 inhibitors

Screen of Pseudopeptidic Inhibitors of Human Sirtuins 1–3: Two Lead Compounds with Antiproliferative Effects in Cancer Cells

In the past few years sirtuins have gained growing attention for their involvement in many biological processes such as cellular metabolism, apoptosis, aging and inflammation. In this contribution, we report the synthesis of a library of thioacetylated pseudopeptides that were screened against human sirtuins 1–3 to reveal their in vitro inhibition activities. Molecular modeling studies were performed to acquire data about the binding modes of the inhibitors. Three sirtuin inhibitors were subjected to cellular studies, and all of them showed an increase in acetylation of Lys382 of p53 after DNA damage. Furthermore, two of the compounds were able to inhibit both A549 lung carcinoma and MCF-7 breast carcinoma cell growth in micromolar concentration with the ability to arrest cancer cell cycle in the G₁ phase