Specific modification of xyloglucan from Hymenaea courbaril seeds

Abstract: In this work, xyloglucan extracted from the seeds of Hymenaea courbaril (jatobá) collected in Rancho Alegre, Paraná, Brazil (JRAXG), was oxidized at the C-6 position of galactose or glucose units, using 2,3,6,6-tetramethylpiperidine-1-oxyl, to form uronic acid-containning polysaccharides (JRAOXGs), with different degrees of oxidation (10, 23 and 34%) and high yield (~95%). The properties of the news polyelectrolyte were studied by intrinsic viscosity, Gel Permeation Chromatography (GPC), Infrared spectroscopy (FTIR), 13C-NMR (13C-Nuclear Magnetic Resonance), and by Atomic Force Microscopy (AFM). The FTIR and 13C-NMR spectra confirmed the oxidation process. In comparison to JRA XG the JRAOXGs derivatives showed by GPC a homogeneous profile, but with hydrodynamic volume and molecular weight (Mw) reduction. Furthermore, AFM images on mica, after dewetting hydrodynamic volume, show different states of aggregation accordingly to the degree of oxidation when compared to the native state. The native XG presents a rather compact and quite homogeneous topography with a few holes and absence of aggregates, while the oxidation products present spherical-like conformation whose diameters is in the range of 8–30 nm. The morphological changes observed by AFM to JRAOXG34 derivative, can be very important to guide to drug encapsulation, for example. [Copyright &y& Elsevier]