20.500.12556/RUL-136689 Fragment-sized and bidentate (immuno)proteasome inhibitors derived from cysteine and threonine targeting warheads Constitutive- and immunoproteasomes are part of the ubiquitin–proteasome system (UPS), which is responsible for the protein homeostasis. Selective inhibition of the immunoproteasome offers opportunities for the treatment of numerous diseases, including inflammation, autoimmune diseases, and hematologic malignancies. Although several inhibitors have been reported, selective nonpeptidic inhibitors are sparse. Here, we describe two series of compounds that target both proteasomes. First, benzoxazole-2-carbonitriles as fragment-sized covalent immunoproteasome inhibitors are reported. Systematic substituent scans around the fragment core of benzoxazole-2-carbonitrile led to compounds with single digit micromolar inhibition of the β5i subunit. Experimental and computational reactivity studies revealed that the substituents do not affect the covalent reactivity of the carbonitrile warhead, but mainly influence the non-covalent recognition. Considering the small size of the inhibitors, this finding emphasizes the importance of the non-covalent recognition step in the covalent mechanism of action. As a follow-up series, bidentate inhibitors are disclosed, in which electrophilic heterocyclic fragments, i.e., 2-vinylthiazole, benzoxazole-2-carbonitrile, and benzimidazole-2-carbonitrile were linked to threonine-targeting (R)-boroleucine moieties. These compounds were designed to bind both the Thr1 and β5i-subunit-specific residue Cys48. However, inhibitory activities against (immuno)proteasome subunits showed that bidentate compounds inhibit the β5, β5i, β1, and β1i subunits with submicromolar to low-micromolar IC$_{50}$ values. Inhibitory assays against unrelated enzymes showed that compounds from both series are selective for proteasomes. The presented nonpeptidic and covalent derivatives are suitable hit compounds for the development of either β5i-selective immunoproteasome inhibitors or compounds targeting multiple subunits of both proteasomes. immunoproteasome benzoxazole-2-carbonitriles bidentate covalent inhibitors fragments non-covalent recognition farmacevtska kemija true false true Angleški jezik Slovenski jezik Članek v reviji 2022-05-16 10:13:30 2022-05-16 10:13:36 2022-09-15 04:14:11 0000-00-00 00:00:00 2021 0 0 19 str. iss. 12, art. 3431 Vol. 10 2021 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 615.4:54 2073-4409 10.3390/cells10123431 88025091 cells-10-03431-v2.pdf cells-10-03431-v2.pdf 1 649CB936B0D06CA2B0B3134F8E6B021B 7997d927bf2f7ce8016e81a126b4696886896d6ffcb9419a6c693817d5ee2b88 453792d9-d4f0-11ec-8aca-00155dcfd717 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=156427 https://www.mdpi.com/2073-4409/10/12/3431 1 f9219303-d4ef-11ec-8aca-00155dcfd717 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=156426 Fakulteta za farmacijo 0 0 0