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Novel arabinan and galactan oligosaccharides from dicotyledonous plants.

Wefers D, Tyl CE, Bunzel M - Front Chem (2014)

Bottom Line: To get a detailed insight into their fine structure, various oligosaccharides were isolated from quinoa, potato galactan, and sugar beet pulp after enzymatic treatment.Additionally, an oligosaccharide with two adjacent arabinofuranose units O2-substituted with two ferulic acid monomers was characterized.The isolated oligosaccharides gave further insight into the structures of pectic side chains and may have an impact on plant physiology and dietary fiber fermentation.

View Article: PubMed Central - PubMed

Affiliation: Department of Food Chemistry and Phytochemistry, Institute of Applied Biosciences, Karlsruhe Institute of Technology Karlsruhe, Germany.

ABSTRACT
Arabinans and galactans are neutral pectic side chains and an important part of the cell walls of dicotyledonous plants. To get a detailed insight into their fine structure, various oligosaccharides were isolated from quinoa, potato galactan, and sugar beet pulp after enzymatic treatment. LC-MS(2) and one- and two-dimensional NMR spectroscopy were used for unambiguous structural characterization. It was demonstrated that arabinans contain β-(1→3)-linked arabinobiose as a side chain in quinoa seeds, while potato galactan was comprised of β-(1→4)-linked galactopyranoses which are interspersed with α-(1→4)-linked arabinopyranoses. Additionally, an oligosaccharide with two adjacent arabinofuranose units O2-substituted with two ferulic acid monomers was characterized. The isolated oligosaccharides gave further insight into the structures of pectic side chains and may have an impact on plant physiology and dietary fiber fermentation.

No MeSH data available.


HMBC spectrum and structure of compound 1. Diagnostic long range correlations are marked and explained in the text.
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Figure 2: HMBC spectrum and structure of compound 1. Diagnostic long range correlations are marked and explained in the text.

Mentions: The oligosaccharide showed a complex 1H NMR spectrum, requiring 2D NMR experiments for unambiguous structure elucidation. A COSY spectrum allowed for the assignment of the corresponding ring protons to the well resolved anomeric protons. The signal at 5.08 ppm represents two H1 protons as indicated by the HMQC spectrum. The 13C chemical shifts of units R, A, and T (Table 1), which were obtained from the HMQC spectrum, were in good agreement with literature data for a reducing (O5 substituted), an α-(1,3,5)-substituted, and a terminal α-arabinofuranose (Westphal et al., 2010a). This was confirmed by HMBC cross peaks between C5 of unit A and H1 of unit T, and between C5 of unit R and H1 of unit A (Figure 2). Additionally, there were cross peaks between C4 and H1 for unit A and T, confirming the furanose form. The O3 substitution of unit A was confirmed by a cross peak between H1 of unit a and C3 of unit A. The 13C chemical shifts of unit a suggested an α-linked arabinose in furanose form. The δC5 value of unit a is similar to the δC5 value of unit T. Also, the carbon signal of C3 of unit a is shifted downfield to 84.48 ppm. This suggests that this arabinose is substituted at position O3 instead of O5. The 13C chemical shifts of the remaining arabinose unit b are different from those of the other arabinoses, but comparable with data for a terminal β-linked arabinofuranose (Cardoso et al., 2002). The furanose form was confirmed by the corresponding HMBC cross peak between C4 and H1. A weak HMBC cross peak between C1 of unit b and H3 of unit a (Figure 2) suggests that unit b is linked to position O3 of unit a. In conclusion, NMR and MS data suggest the structure shown in Figure 2 for compound 1.


Novel arabinan and galactan oligosaccharides from dicotyledonous plants.

Wefers D, Tyl CE, Bunzel M - Front Chem (2014)

HMBC spectrum and structure of compound 1. Diagnostic long range correlations are marked and explained in the text.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4226231&req=5

Figure 2: HMBC spectrum and structure of compound 1. Diagnostic long range correlations are marked and explained in the text.
Mentions: The oligosaccharide showed a complex 1H NMR spectrum, requiring 2D NMR experiments for unambiguous structure elucidation. A COSY spectrum allowed for the assignment of the corresponding ring protons to the well resolved anomeric protons. The signal at 5.08 ppm represents two H1 protons as indicated by the HMQC spectrum. The 13C chemical shifts of units R, A, and T (Table 1), which were obtained from the HMQC spectrum, were in good agreement with literature data for a reducing (O5 substituted), an α-(1,3,5)-substituted, and a terminal α-arabinofuranose (Westphal et al., 2010a). This was confirmed by HMBC cross peaks between C5 of unit A and H1 of unit T, and between C5 of unit R and H1 of unit A (Figure 2). Additionally, there were cross peaks between C4 and H1 for unit A and T, confirming the furanose form. The O3 substitution of unit A was confirmed by a cross peak between H1 of unit a and C3 of unit A. The 13C chemical shifts of unit a suggested an α-linked arabinose in furanose form. The δC5 value of unit a is similar to the δC5 value of unit T. Also, the carbon signal of C3 of unit a is shifted downfield to 84.48 ppm. This suggests that this arabinose is substituted at position O3 instead of O5. The 13C chemical shifts of the remaining arabinose unit b are different from those of the other arabinoses, but comparable with data for a terminal β-linked arabinofuranose (Cardoso et al., 2002). The furanose form was confirmed by the corresponding HMBC cross peak between C4 and H1. A weak HMBC cross peak between C1 of unit b and H3 of unit a (Figure 2) suggests that unit b is linked to position O3 of unit a. In conclusion, NMR and MS data suggest the structure shown in Figure 2 for compound 1.

Bottom Line: To get a detailed insight into their fine structure, various oligosaccharides were isolated from quinoa, potato galactan, and sugar beet pulp after enzymatic treatment.Additionally, an oligosaccharide with two adjacent arabinofuranose units O2-substituted with two ferulic acid monomers was characterized.The isolated oligosaccharides gave further insight into the structures of pectic side chains and may have an impact on plant physiology and dietary fiber fermentation.

View Article: PubMed Central - PubMed

Affiliation: Department of Food Chemistry and Phytochemistry, Institute of Applied Biosciences, Karlsruhe Institute of Technology Karlsruhe, Germany.

ABSTRACT
Arabinans and galactans are neutral pectic side chains and an important part of the cell walls of dicotyledonous plants. To get a detailed insight into their fine structure, various oligosaccharides were isolated from quinoa, potato galactan, and sugar beet pulp after enzymatic treatment. LC-MS(2) and one- and two-dimensional NMR spectroscopy were used for unambiguous structural characterization. It was demonstrated that arabinans contain β-(1→3)-linked arabinobiose as a side chain in quinoa seeds, while potato galactan was comprised of β-(1→4)-linked galactopyranoses which are interspersed with α-(1→4)-linked arabinopyranoses. Additionally, an oligosaccharide with two adjacent arabinofuranose units O2-substituted with two ferulic acid monomers was characterized. The isolated oligosaccharides gave further insight into the structures of pectic side chains and may have an impact on plant physiology and dietary fiber fermentation.

No MeSH data available.