RESUMO
Nystatin A1 , a polyene macrolide antifungal antibiotic, in a slightly basic or acidic solution undergoes an intramolecular transformation, yielding a structural isomer, the translactonization product, iso-nystatin A1 with lactone ring diminished by two carbon atoms. Structural evidence is provided by advanced NMR and Mass Spectrometry (MS) studies. Molecular dynamics simulations and quantum mechanics calculations gave the insight into the course and mechanism of the transformation and its effect on the conformation of the subject molecule. Copyright © 2016 John Wiley & Sons, Ltd.
Assuntos
Antifúngicos/química , Nistatina/análogos & derivados , Nistatina/química , Cromatografia Líquida de Alta Pressão , Isomerismo , Lactonas/química , Espectroscopia de Ressonância Magnética , Espectrometria de Massas , Modelos Moleculares , Conformação Molecular , Simulação de Dinâmica MolecularRESUMO
The absolute configurations of all the stereogenic centers of the antibiotic mycoheptin A(2) were established upon previously elaborated general procedure, consisting of DQF-COSY, NOESY, ROESY, HSQC and HMBC experiments as major tools. The structure of mycoheptin A(2) without stereochemistry of its aglycone has been reported before.
Assuntos
Actinomyces/química , Antibacterianos/química , Polienos/química , Espectroscopia de Ressonância Magnética , Estrutura Molecular , EstereoisomerismoRESUMO
D-Glucose, D-mannose and L-rhamnose were reacted with a racemic mixture of 2-butanol, and the resulting alpha-glycosides were analyzed by 1H NMR with COSY and NOESY experiments. Conformational analysis of alpha-glycosidic bonds performed with molecular modeling and appropriate heteronuclear long-range coupling measurements and combined with analysis of dipolar couplings observed in NOESY spectra allowed the assignment of absolute configuration in the aglycones of elucidated alpha-glycosides.
