Structural studies of the arabinogalactans in Mangifera indica L. fruit exudate

Structural studies of the arabinogalactans in Mangifera indica L. fruit exudate The arabinogalactan of ‘Nam Dokmai’ mango (Mangifera indica L.) fruit exudate was studied to elucidate major structural characteristics in comparison with commercially available type-II-arabinogalactans from acacia (gum arabic) and larch wood. From the latter two, the purified polysaccharide was distinguished by its FTIR, 1H NMR, and 13C NMR spectra and its strikingly low polydispersity around a peak molecular weight of ∼22,000. As regards carbohydrate composition and FTIR fingerprint, it ranged between the two comparison samples. The molar ratio of its major components galactose, arabinose, rhamnose, and glucuronic acid was 84:9:4:4. In the FTIR spectra, absorbance maxima ascribed to β-galactans (1076–1070 cm−1) and arabinans (1043–1032 cm−1) always predominated, but their ratios differed. 2D NMR analyses of the purified mango fruit exudate polymer revealed 11 components, including the (1→3)-linked and the (1→6)-linked β-galactopyranosyl residues of type-II-arabinogalactans. α-Arabinofuranosyl moieties, α-l-rhamnopyranosyl-(1→4)–β-glucopyranosyluronic acid, and 4-O-methyl-β-glucopyranosyluronic acid were on terminal positions. Unlike the comparison samples and various Anacardiaceae tree exudate gums, this polysaccharide had internal (1→6)-linked β-galactopyranosyl residues in abundance and internal β-arabinofuranosyl units besides a remarkable number of different α-arabinofuranosyl moieties. Its higher sensitivity to partial acid hydrolysis, which left polymeric glucuronogalactan fragments (overall molar galactose/glucuronic acid ratio: 97:3) within a broad molecular-weight range, suggested greater accessibility to internal cleavage of this polymer. 2D NMR showed these fragments to contain β-glucopyranosyluronic acid and its 4-O-methyl derivative terminally, besides the aforesaid internal β-galactopyranosyl moieties. The still prevalent (1→6)-linked β-galactopyranosyl units and limited increase in terminal β-galactopyranosyl residues indicated longer β-1,6-galactan sequences compared to larch gum. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Food Hydrocolloids Elsevier

Structural studies of the arabinogalactans in Mangifera indica L. fruit exudate

Loading next page...
 
/lp/elsevier/structural-studies-of-the-arabinogalactans-in-mangifera-indica-l-fruit-0WlUUG0tKq
Publisher
Elsevier
Copyright
Copyright © 2016 Elsevier Ltd
ISSN
0268-005X
eISSN
1873-7137
D.O.I.
10.1016/j.foodhyd.2016.05.038
Publisher site
See Article on Publisher Site

Abstract

The arabinogalactan of ‘Nam Dokmai’ mango (Mangifera indica L.) fruit exudate was studied to elucidate major structural characteristics in comparison with commercially available type-II-arabinogalactans from acacia (gum arabic) and larch wood. From the latter two, the purified polysaccharide was distinguished by its FTIR, 1H NMR, and 13C NMR spectra and its strikingly low polydispersity around a peak molecular weight of ∼22,000. As regards carbohydrate composition and FTIR fingerprint, it ranged between the two comparison samples. The molar ratio of its major components galactose, arabinose, rhamnose, and glucuronic acid was 84:9:4:4. In the FTIR spectra, absorbance maxima ascribed to β-galactans (1076–1070 cm−1) and arabinans (1043–1032 cm−1) always predominated, but their ratios differed. 2D NMR analyses of the purified mango fruit exudate polymer revealed 11 components, including the (1→3)-linked and the (1→6)-linked β-galactopyranosyl residues of type-II-arabinogalactans. α-Arabinofuranosyl moieties, α-l-rhamnopyranosyl-(1→4)–β-glucopyranosyluronic acid, and 4-O-methyl-β-glucopyranosyluronic acid were on terminal positions. Unlike the comparison samples and various Anacardiaceae tree exudate gums, this polysaccharide had internal (1→6)-linked β-galactopyranosyl residues in abundance and internal β-arabinofuranosyl units besides a remarkable number of different α-arabinofuranosyl moieties. Its higher sensitivity to partial acid hydrolysis, which left polymeric glucuronogalactan fragments (overall molar galactose/glucuronic acid ratio: 97:3) within a broad molecular-weight range, suggested greater accessibility to internal cleavage of this polymer. 2D NMR showed these fragments to contain β-glucopyranosyluronic acid and its 4-O-methyl derivative terminally, besides the aforesaid internal β-galactopyranosyl moieties. The still prevalent (1→6)-linked β-galactopyranosyl units and limited increase in terminal β-galactopyranosyl residues indicated longer β-1,6-galactan sequences compared to larch gum.

Journal

Food HydrocolloidsElsevier

Published: Dec 1, 2016

References

You’re reading a free preview. Subscribe to read the entire article.


DeepDyve is your
personal research library

It’s your single place to instantly
discover and read the research
that matters to you.

Enjoy affordable access to
over 18 million articles from more than
15,000 peer-reviewed journals.

All for just $49/month

Explore the DeepDyve Library

Search

Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly

Organize

Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.

Access

Get unlimited, online access to over 18 million full-text articles from more than 15,000 scientific journals.

Your journals are on DeepDyve

Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.

All the latest content is available, no embargo periods.

See the journals in your area

DeepDyve

Freelancer

DeepDyve

Pro

Price

FREE

$49/month
$360/year

Save searches from
Google Scholar,
PubMed

Create lists to
organize your research

Export lists, citations

Read DeepDyve articles

Abstract access only

Unlimited access to over
18 million full-text articles

Print

20 pages / month

PDF Discount

20% off