RESUMO
The cyclic decapeptide gramicidin S (GS) was used as a model for the evaluation of four turn mimetics. For this purpose, one of the D-Phe-Pro two-residue turn motifs in the rigid cyclic beta-hairpin structure of GS was replaced with morpholine amino acids (MAA 2-5), differing in stereochemistry and length of the side-chain. The conformational properties of the thus obtained GS analogues (6-9) was assessed by using NMR spectroscopy and X-ray crystallography, and correlated with their biological properties (antimicrobial and hemolytic activity). We show that compound 8, containing the dipeptide isostere trans-MAA 4, has an apparent high structural resemblance with GS and that its antibacterial activity against a panel of Gram positive and -negative bacterial strains is better than the derivatives 6, 7 and 9.
Assuntos
Aminoácidos/química , Antibacterianos/química , Antibacterianos/farmacologia , Dipeptídeos/química , Gramicidina/química , Gramicidina/farmacologia , Morfolinas/química , Sequência de Aminoácidos , Cristalografia por Raios X , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Conformação Proteica , Relação Estrutura-AtividadeRESUMO
Volatile component profiles of fresh seaweed Laminaria spp and Undaria pinnatífida were analyzed using dynamic headspace for volatile profile evaluation, which allows the direct analysis of small quantities of sample without previous treatment and have been identified by GC-MS. Alcohols were the most important class of volatile compounds identified in Wakame and Kombu (25 and 29% respectively); nine alcohols were identified. The hydrocarbons group constitute the second most important family of volatiles, in both samples entire similar % area total 13-14%, being the butane the most abundant hydrocarbon. Aldehydes and halogenated compounds are higher in Laminaria spp (10-9% total area), whereas Undaria pinnatifida presents 4-0.23% respectively.
Assuntos
Laminaria/química , Alga Marinha/química , Undaria/química , Compostos Orgânicos Voláteis/isolamento & purificação , Álcoois/isolamento & purificação , Aldeídos/isolamento & purificação , Butanos/isolamento & purificação , Cromatografia Gasosa-Espectrometria de Massas , Hidrocarbonetos Halogenados/isolamento & purificaçãoRESUMO
A simple and rapid HPLC method with UV and fluorescence detection (FLD) for the separation of ten phenolic compounds including gallic acid, catechin, epicatechin, caffeic acid, coumaric, trans-piceid, cis-piceid, trans-resveratrol, cis-resveratrol and quercetin is reported. The UV and fluorescence detector in series provided a high selectivity for the determination of these compounds. Precisions, recoveries and LODs achieved for all the analytes were satisfactory. The proposed method was applied to the determination of these compounds in commercially available red wines.