Apoptosis is a biological process relevant to several human diseases that is strongly regulated through protein-protein complex formation. We have previously reported a peptidomimetic compound as potent apoptotic modulator. Structural studies of this compound showed the presence of cis/trans isomers of the exocyclic tertiary amide bond in slow exchange. This information encouraged us to perform an isosteric replacement of the amide bond by a 1,2,3-triazole moiety, where different substitution patterns would mimic different amide rotamers. The syntheses of these restricted analogs have been carried out using the Ugi multicomponent reaction followed by an intramolecular cyclization. Unexpectedly, for one of the proposed structures, a novel β -lactam compound was formed. All compounds showed to efficiently inhibit apoptosis, in vitro and in cellular extracts, with slight differences for the corresponding regioisomers. We propose the binding to Apaf-1 as the inhibition mechanism.
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http://dx.doi.org/10.1016/j.ejmech.2013.03.004 | DOI Listing |
J Am Chem Soc
December 2024
Department of Chemistry and the Hong Kong Branch of Chinese National Engineering Research Centre for Tissue Restoration & Reconstruction, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR 999077, China.
Catalytic enantioselective substitution of the readily available racemic α-halo carbonyl compounds by nitrogen nucleophiles represents one of the most convenient and direct approaches to access enantioenriched α-amino carbonyl compounds. Distinct from the two available strategies involving radicals and enolate ions, herein we have developed a new protocol featuring an electronically opposite way to weaken/cleave the carbon-halogen bond. A suitable chiral anion-based catalyst enables effective asymmetric control over the key positively charged intermediates.
View Article and Find Full Text PDFFood Chem
December 2024
Department of Food Science & Technology, School of Agriculture & Biology, Shanghai Jiao Tong University, Shanghai 200240, PR China; School of Food Science and Engineering, Ningxia University, Yinchuan 750021, China. Electronic address:
Cyclization enhances various properties of peptides and has been widely used in life sciences, but it has not been explored in taste peptides. Our study found that cyclization of the N/C termini of the peptides (head-to-tail) via amide bond is a potentially effective modification strategy for umami peptides to improve their properties. This is the first report on umami cyclic peptides.
View Article and Find Full Text PDFACS Infect Dis
December 2024
Department of Chemistry, University of Waterloo, 200 University Ave. West, Waterloo, Ontario N2L3G1, Canada.
The calcium-dependent antibiotics (CDAs) are a group of seven closely related membrane-active cyclic lipopeptide antibiotics (cLPAs) first isolated in the early 1980s from the fermentation broth of . Their target was unknown, and the mechanism of action is uncertain. Herein, we report new routes for the synthesis of CDA4b and its analogues, explore the structure-activity relationships at its lipid tail and at positions 3, 9, and 11, and determine the CDAs' lipid target.
View Article and Find Full Text PDFChem Asian J
December 2024
National Institute of Pharmaceutical Education and Research, Medicinal Chemistry, Sector 67, 160062, S. A. S. Nagar, INDIA.
Ru(II)-Catalyzed "On Water" direct aryl C(sp2)-H amidation of 2-arylbenzo[d]-thiazole/oxazole with acyl azide is reported under silver-free condition. Deuterium scrambling experiments suggested reversible C-H activation catalyzed by active cationic ruthenium species. The organic solvents such as DCE, DMF, DMSO, MeCN, dioxane, and PhMe were not conducive for the C-H amidation except for PhCl in which case, however, inferior yield (31%) was obtained.
View Article and Find Full Text PDFJ Nat Prod
December 2024
Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093-0358, United States.
Marine sponge diterpenoid isonitriles are exceptional nitrogenous natural products that exhibit antiplasmodial activity. Their biosynthesis presents a biosynthetic puzzle: how do the elements of NC engage terpenyl carbocations in isoprenoid secondary metabolism, and what is the biosynthetic precursor of the NC group? Cyanoformic acid (NC-COOH, ) is proposed as a plausible delivery vehicle of NC that resolves a paradox in the commonly held proposition that an inorganic cyanide anion, CN, terminates terpenoid isonitrile (TI) biosynthesis. DFT calculations of NC-COOH and its conjugate base, cyanoformate, NC-COO (), support high nucleophilicity at N and explain bond-forming constitutionality: attack at N and formation of an isonitrile over its nitrile isomer.
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