Unusual linear polysaccharides: (1→5)-α-l-Arabinan, (1→3)-(1→4)-α-d-glucan and (1→4)-β-d-xylan from pulp of buriti (Mauritia flexuosa), an edible palm fruit from the Amazon region

A structural characterisation of polysaccharides extracted from ripe pulp of edible buriti, an exotic tropical fruit from Mauritia flexuosa palm was carried out. After fractionation by freeze–thaw treatment of an aqueous extract (BW), a fraction containing a linear (1→5)-α-l-arabinan and a linear (1→3)-(1→4)-α-d-glucan was obtained (0.2% yield). The proportion of (1→3)- and (1→4)-linked Glcp units was 1:4. After fractionation by freeze–thaw and Fehling treatments of an alkaline extract (BK), a linear (1→4)-β-d-xylan was purified (0.6% yield). Their chemical structures were performed by sugar composition, methylation and NMR spectroscopy analysis. In addition, these results together with monosaccharide analysis of SBW and SBK are discussed in relation to literature data on polysaccharide compositions of primary cell walls of palms (commelinid monocotyledons).