95465-24-0Relevant academic research and scientific papers
Termination of the structural confusion between plipastatin A1 and fengycin IX
Honma, Miho,Tanaka, Kazuaki,Konno, Katsuhiro,Tsuge, Kenji,Okuno, Toshikatsu,Hashimoto, Masaru
experimental part, p. 3793 - 3798 (2012/08/28)
Plipastatin A1 and fengycin IX were experimentally proven to be identical compounds, while these had been considered as diastereomers due to the permutation of the enantiomeric pair of Tyr in most papers. The 1H NMR spectrum changed to become quite similar to that of plipastatin A1, when the sample which provided resembled spectrum of fengycin IX was treated with KOAc followed by LH-20 gel filtration. Our structural investigations disclosed that the structures of these molecules should be settled into that of plipastatin A1 by Umezawa (l-Tyr4 and d-Tyr10).
Chiral separation of enantiomers of amino acid derivatives by HPLC on vancomycin and teicoplanin chiral stationary phases
Lehotay, Jozef,Hrobonova,Krupcik,Cizmarik
, p. 863 - 865 (2007/10/03)
The chiral separation of α-amino acids by liquid chromatography using macrocyclic antibiotic bonded stationary phases were studied. Teicoplanin and vancomycin bonded stationary phases have been used to separate enantiomers of dansyl amino acids in the reversed - phase high performance liquid chromatography mode. By comparison of chromatographic parameters obtained by use of both chiral stationary phases it the mechanism of chiral separation could be suggested. The better separation - greater value of R(j,i) of enantiomers - was achieved by the teicoplanin column.
Direct resolution of optically active isomers on chiral packings containing ergoline skeletons. 5. Enantioseparation of amino acid derivatives
Messina,Girelli,Flieger,Sinibaldi,Sedmera,Cvak
, p. 1191 - 1196 (2007/10/03)
A new procedure for ergot alkaloid-based chiral stationary phase preparation is described. Synthesis is based on bonding the allyl derivative of terguride to mercaptopropylsilanized silica gel. The packing exhibits higher content of chiral selector, stability, reproducibility, and enantioselectivity toward amino acids compared to that previously studied. The chromatographic behavior of amino acids with different side chains and substituent groups is investigated in order to obtain a deeper insight into the enantiodiscriminative mechanism as well as to determine the limitations and strengths of terguride as a chiral selector for this class of compounds. A variety of factors, including mobile phase parameters such as pH, ionic strength, content and nature of organic modifier, and temperature, are examined. A new procedure for ergot alkaloid-based chiral stationary phase preparation is described. Synthesis is based on bonding the allyl derivative of terguride to mercaptopropylsilanized silica gel. The packing exhibits higher content of chiral selector, stability, reproducibility, and enantioselectivity toward amino acids compared to that previously studied. The chromatographic behavior of amino acids with different side chains and substituent groups is investigated in order to obtain a deeper insight into the enantiodiscriminative mechanism as well as to determine the limitations and strengths of terguride as a chiral selector for this class of compounds. A variety of factors, including mobile phase parameters such as pH, ionic strength, content and nature of organic modifier, and temperature, are examined.
Enantioselective Fluorescence Quenching by a Chiral Copper(II) Complex in Ligand Exchange Equilibria
Corradini, Roberto,Sartor, Giorgio,Marchelli, Rosangela,Dossena, Arnaldo,Spisni, Alberto
, p. 1979 - 1983 (2007/10/02)
The first case of enantioselective fluorescence quenching of dansyl(DNS)-amino acids (2) by a chiral complex, bis-(L-phenylalanylamidato)copper(II) (1) in aqueous solution is reported.The nature of the quenching, whether static or dynamic, has been investigated by time-resolved fluorescence techniques.The fluorescence lifetimes of the unquenched D- and L-DNS-phenylalanine were found to be the same as the quenched ones: 90percent of the total fluorescence intensity for all samples was due to a 8.9 ns component.Thus, the decrease in the fluorescence intensities was ascribed to ground state interactions between the dansyl moiety and the copper complex (static quenching).From the Stern-Volmer plot it was possible to calculate the formation constants of the ternary diastereomeric complexes formed according to a ligand exchange reaction.The difference between the logarithms of the stability constants of these complexes accounts for the enantioselectivity observed in aqueous solutions.The present results are relevant also for the understanding of the mechanism of chiral recognition in HPLC using chiral copper(II) complexes as additives to the eluent (Chiral Ligand Exchange Chromatography), and must be taken into account for correct quantitative determination.
