Structural diversity of alkali-soluble polysaccharides from the fruit cell walls of tucumã (Astrocaryum aculeatum), a commelinid monocotyledon from the family Arecaceae

The polysaccharide compositions of primary and secondary cell walls of members of the family Arecaceae in the commelinid clade of monocotyledonous plants have previously been found to be distinguishable from other commelinid families, and to be more similar to those of non-commelinids. However, few studies have been conducted. We aimed to extract and characterize the main cell-wall polysaccharides in the fruit pulp of tucumã (Astrocaryum aculeatum), a member of Arecaceae family. Hemicellulosic polysaccharides extracted by alkali from the fruit pulp were present in greater proportions (6.4% yield) than water-extracted ones (3.0% yield). Thus, the former was analyzed using monosaccharide composition, methylation, molecular weight determination and 13C-NMR data. The tucumã alkaline extract presented a highly ramified acidic galactoarabinoxylan (53.7%), a linear (1 → 5)-linked α-L-arabinan (27.8%), a low branched glucuronoxylan (14.1%) and small portions of a xyloglucan (4.4%). The major polysaccharide found in A. aculeatum (acidic galactoarabinoxylan) is similar to those found in other commelinid plants such as grasses and cereals. [Display omitted] •Structural diversity of hemicelluloses in tucumã fruit cell walls has been evaluated.•Tucumã is a member of Arecaceae family in the commelinid clade of monocotyledonous plants.•Acid galactoarabinoxylan, linear arabinan, glucuronoxylan and xyloglucan have been found in tucumã.•Cell walls of Arecaceae members possess a greater diversity than previously thought.