Flavonoid glycosides from Persea caerulea. Unraveling their interactions with SDS-micelles through matrix-assisted DOSY, PGSE, mass spectrometry, and NOESY.
Two flavonoid glycosides derived from rhamnopyranoside (1) and arabinofuranoside (2) have been isolated from leaves of Persea caerulea for the first time. The structures of 1 and 2 have been established by1H NMR,13C NMR, and IR spectroscopy, together with LC-ESI-TOF and LC-ESI-IT MS spectrometry. From the MS and MS/MS data, the molecular weights of the intact molecules as well as those of quercetin and kaempferol together with their sugar moieties were deduced. The NMR data provided information on the identity of the compounds, as well as the α and β configurations and the position of the glycosides on quercetin and kaempferol. We have also explored the application of sodium dodecyl sulfate (SDS) normal micelles in binary aqueous solution, at a range of concentrations, to the diffusion resolution of these two glycosides, by the application of matrix-assisted diffusion ordered spectroscopy (DOSY) and pulse field gradient spin echo (PGSE) methodologies, showing that SDS micelles offer a significant resolution which can, in part, be rationalized in terms of differing degrees of hydrophobicity, amphiphilicity, and steric effects. In addition, intra-residue and inter-residue proton-proton distances using nuclear Overhauser effect build-up curves were used to elucidate the conformational preferences of these two flavonoid glycosides when interacting with the micelles. By the combination of both diffusion and nuclear Overhauser spectroscopy techniques, the average location site of kaempferol and quercetin glycosides has been postulated, with the former exhibiting a clear insertion into the interior of the SDS-micelle, whereas the latter is placed closer to the surface. Copyright © 2016 John Wiley & Sons, Ltd.
Department of Chemistry, Universidad Nacional de Colombia, Bogota, Colombia.|Department of Chemistry, Universidad del Magdalena, Santa Marta, Colombia.
Juan M
JM
Álvarez
Department of Chemistry and Physics, ceiA3, Universidad de Almería, Almería, Spain.
Álvaro
Á
Raya-Barón
Glycosystems Laboratory, Department of Bioorganic Chemistry, Instituto de Investigaciones Químicas (CSIC - US), cicCartuja, Sevilla, Spain.
Pedro M
PM
Nieto
Department of Chemistry, Universidad Nacional de Colombia, Bogota, Colombia.
Luis E
LE
Cuca
Department of Analytical Chemistry, Universidad de Granada, Granada, Spain.
Alegría
A
Carrasco-Pancorbo
Department of Analytical Chemistry, Universidad de Granada, Granada, Spain.
Alberto
A
Fernández-Gutiérrez
Department of Chemistry and Physics, ceiA3, Universidad de Almería, Almería, Spain.|BITAL, Research Centre for Agricultural and Food Biotechnology, Almería, Spain.
Ignacio
http://orcid.org/0000-0001-8355-580X
I
Fernández
Persea caerulea; flavonoid glycosides; inter-proton distances; matrix-assisted DOSY; micelles