RESUMO
An efficient two-step procedure is described to convert the Biginelli 3,4-dihydropyrimidin-2(1H)-one to various multifunctionalized pyrimidines via the Kappe dehydrogenation and a new mild PyBroP-mediated coupling with C, N, O, and S nucleophiles, which provides a readily accessible multifunctionalized pyrimidine template for diversity-oriented synthesis.
Assuntos
Pirimidinas/síntese química , Pirimidinonas/química , Hidrogenação , Estrutura Molecular , Pirimidinonas/síntese químicaRESUMO
Cationic steroid antibiotics have been developed that display broad-spectrum antibacterial activity. These compounds are comprised of steroids appended with amine groups arranged to yield facially amphiphilic morphology. Examples of these antibiotics are highly bactericidal, while related compounds effectively permeabilize the outer membranes of Gram-negative bacteria sensitizing these organisms to hydrophobic antibiotics. Cationic steroid antibiotics exhibit various levels of eukaryote vs. prokaryote cell selectivity, and cell selectivity can be increased via charge recognition of prokaryotic cells. Studies of the mechanism of action of these antibiotics suggest that they share mechanistic aspects with cationic peptide antibiotics.
Assuntos
Antibacterianos/farmacologia , Peptídeos Catiônicos Antimicrobianos/farmacologia , Antibacterianos/química , Antibacterianos/farmacocinética , Peptídeos Catiônicos Antimicrobianos/metabolismo , Peptídeos Catiônicos Antimicrobianos/farmacocinética , Proteínas da Membrana Bacteriana Externa/metabolismo , Colestanóis/farmacocinética , Hemólise , Testes de Sensibilidade Microbiana , Modelos Estruturais , Polimixina B/farmacocinética , Esteroides/química , Esteroides/classificação , Esteroides/farmacologiaRESUMO
The antibacterial activities of cationic steroid antibiotics and cationic peptide antibiotics have been compared. Depolarization of bacterial membranes, activation of bacterial stress-related gene promoters, and changes in bacterial morphologies caused by these antibiotics suggest that cationic steroid and peptide antibiotics share mechanistic aspects. Modified cationic steroid antibiotics display improved selectivity for prokaryotic cells over eukaryotic cells presumably due to increased charge recognition.