RESUMO
A cyclic tetrapeptide is prepared from alternating (S)-beta-Caa (C-linked carbo-beta-amino acid) and (R)-Ama (alpha-aminoxy acid). Extensive NMR (in CDCl(3) solution) and mass spectral (MS) studies show its halide binding capacity, with a special affinity to the chloride ion. At higher concentration it was found to form molecular aggregates as evidenced from transmission electron microscopic and atomic force microscopic analysis, confirming the formation of nanorods.
Assuntos
Aminoácidos/química , Cloretos/química , Íons/química , Oligopeptídeos/química , Oligopeptídeos/síntese química , Peptídeos Cíclicos/química , Peptídeos Cíclicos/síntese química , Sítios de Ligação , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Nanoestruturas/química , Conformação Proteica , Estereoisomerismo , Espectrometria de Massas em TandemRESUMO
Modafinil, adrafinil and their related substances were synthesized and analyzed by RP-LC with ESI-MS/MS. The ionization mode, polarity, cone voltage, and chromatographic conditions were evaluated. The optimum LC-MS conditions to obtain fragment ions indispensable for identification of the structures were described. The bulk drugs purity of modafinil and adrafinil was evaluated on Kromasil C(18) column with ACN/0.02 M ammonium acetate as mobile phase in gradient elution mode at 30 degrees C. The method was found to be suitable not only for monitoring the reactions during the process development but also for quality assurance of modafinil and adrafinil.
