β-L-Araf-containing arabinan and glucuronoxylan from guavira fruit pomace.

Guavira is a plant that belongs to Myrtaceae family, being widespread in the Brazilian Cerrado. In this study, pectic and hemicellulosic polysaccharides from guavira pomace, an agroindustry residue from pulp production, were structurally characterized using GPC, monosaccharide composition, methylation and NMR experiments. The absolute configurations of monosaccharides and the nature of uronic acids were attributed according to numerous data on the composition of related plant arabinogalactans and hemicelluloses present in the literature. An arabinan was purified, presenting Ara (85.0%), Rha (3.3%), Gal (7.7%) and GalA (4.0%). Mono and bidimensional NMR analyses of this arabinan demonstrated the presence of terminal β-L-Araf units, whose occurrence has been scarcely reported in the literature. Hemicellulosic fraction contained a glucuronoxylan, with α-D-GlcpA/4-O-methyl-α-D-GlcpA group linked to O-2 of a (1 → 4)-β-D-xylan, presenting one uronic acid residue for every six xylose units. These findings about guavira pomace polysaccharides could contribute to develop future nutraceutical and technological uses for this industrial waste.