RESUMO
The enantiomers of four unusual isoxazoline-fused 2-aminocyclopentanecarboxylic acids were directly separated on chiral stationary phases containing macrocyclic glycopeptide antibiotics teicoplanin (Astec Chirobiotic T and T2), teicoplanin aglycone (Chirobiotic TAG), vancomycin (Chirobiotic V) and vancomycin aglycone (Chirobiotic VAG) as chiral selectors. The effects of the mobile phase composition, the structure of the analytes and temperature on the separations were investigated. Experiments were performed at constant mobile phase compositions in the temperature range 5-45 °C to study the effects of temperature, and thermodynamic parameters were calculated from plots of lnk or lnα versus 1/T. Some mechanistic aspects of the chiral recognition process are discussed with respect to the structures of the analytes. It was found that the enantiomeric separations were in most cases enthalpy-driven. The sequence of elution of the enantiomers was determined in all cases.
Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Cicloleucina/isolamento & purificação , Isoxazóis/isolamento & purificação , Teicoplanina/análogos & derivados , Vancomicina/química , Cromatografia Líquida de Alta Pressão/instrumentação , Cicloleucina/química , Isoxazóis/química , Modelos Lineares , Estereoisomerismo , Teicoplanina/química , TermodinâmicaRESUMO
A novel gas chromatographic method was developed for the enantioseparation of valuable acyclic and carbocyclic cis- and trans-beta-amino acids, including cispentacin and a number of its analogues and homologues. Excellent (in most cases baseline) separation was achieved for the racemates of these beta-amino acids on CP-Chirasil-Dex CB or CP-Chirasil L-Val columns after a simple and rapid double derivatization (esterification followed by N-acylation). The elution sequences were determined in all cases.
Assuntos
Aminoácidos Cíclicos/isolamento & purificação , Cromatografia Gasosa/métodos , Aminoácidos Cíclicos/química , Ciclodextrinas/química , Cicloleucina/análogos & derivados , Cicloleucina/isolamento & purificação , Compostos Orgânicos/química , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Siloxanas/química , EstereoisomerismoRESUMO
FR109615, a new antibiotic active against Candida, was isolated from Streptomyces setonii No. 7562. Based on the spectroscopic data, the structure of FR109615 was elucidated as cis-2-aminocyclopentane-1-carboxylic acid (1). The compound showed the excellent in vivo efficacy in a generalized infection test of mice.
Assuntos
Antifúngicos/farmacologia , Candida/efeitos dos fármacos , Streptomyces/metabolismo , Animais , Antifúngicos/análise , Antifúngicos/isolamento & purificação , Candidíase/tratamento farmacológico , Cicloleucina/análise , Cicloleucina/isolamento & purificação , Cicloleucina/farmacologia , Feminino , Espectroscopia de Ressonância Magnética , Camundongos , Camundongos Endogâmicos ICR , Estrutura Molecular , Espectrofotometria InfravermelhoRESUMO
A new antibiotic, cispentacin, was isolated from the culture broth of a Bacillus cereus strain, L450-B2. The antibiotic is water-soluble and amphoteric; its structure was determined by spectroscopic analysis and chemical synthesis to be (1R,2S)-2-aminocyclopentane-1-carboxylic acid. Cispentacin demonstrated only weak in vitro activity against certain fungi but strong protection of mice from lethal infection of Candida albicans A9540.
