Xyloglucans Case Study

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Xyloglucans (XGs) are complex polysaccharides found in the primary cell walls of higher plants. However, few studies report the characterization of xyloglucans from the pulp of fruits. In this work a xyloglucan rich fraction, PF-SPK-100R, was obtained from alkali prune extract. Characterization was conducted through monosaccharide composition, methylation and 13C-NMR analysis. PF-SPK-100R was composed of a fucogalactoxyloglucan (∼68%) and an arabinoxylan. Finally, this paper brings important features of xyloglucans found in prunes, and provides new insights into the diversity of fruit hemicellulosic polymers.

Keywords: Prunes/ Prunus domestica/ Polysaccharides/ Xyloglucan/ Structural characterization.

1. Introduction
Xyloglucans
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Derivatives 2,3,4-Me3-Fuc-ol acetate, 2,3,4-Me3-Ara-ol-acetate and 2,3,5-Me3-Ara-ol-acetate, indicate the presence of terminal units of Fucp, Arap and Araf, respectively . Terminal fucose units are commonly found in xyloglucans from dicotyledonous (Hayashi, 1989). Moreover, instead of fucose units, Araf units were identified in side chains of xyloglucans of solanaceous plants (York, Kolli, Orlando, Albersheim, & Darvill, 1996). Despite this, the concomitant presence of Fucp, Arap and Araf units is an unusual feature in xyloglucans. Thus, these Araf are likely to be side chains in the xylan, corroborating for the assumption that fraction PF-SPK-100R is composed by a mixture of a fucogalactoxyloglucan and an heteroxylan. The xyloglucan content in fraction PF-SPK-100R was estimated to be ∼68% based on the sum of 4-O and 4,6-O-linked glucose, terminal and 2-O-substituted xylose and terminal galactose and fucose.
The presence of xylan–xyloglucan complexes has been previously identified in the cell walls of olive pulp (Coimbra et al., 1995). In our group of research, a xyloglucan and an acid heteroxylan were also found together in alkaline extracts from starfruit (Averrhoa carambola L.) and separated trough anion exchange chromatography (unpublished data). In fraction PF-SPK-100R however, the absence of uronic acid linked
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So far only XGs from apple (Renard, Lomax, & Boon, 1992), olive fruits (Vierhuis et al., 2001) and tomato (Jia, Cash, Darvill, & York, 2005) were described in the literature. Finally, it’s noteworthy that dietary fibers may possess a variety of biological actions closely related to their chemical structures. Even small differences in these polymers may lead to different effects, for example, in the modulation of the gut microbiome (Hamaker & Yunus, 2014). Thus, this paper brings important features of xyloglucan found in

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