Assessing the quantification of acetylation in konjac glucomannan via ATR-FTIR and solid-state NMR spectroscopy

Kash A Bhullar; Michael I M Horgan; Ashley Le; David Fania; Richard Wuhrer; Valentina Razmovski-Naumovski; Kelvin Chan; Patrice Castignolles; Marianne Gaborieau

doi:10.1016/j.carbpol.2022.119659

Assessing the quantification of acetylation in konjac glucomannan via ATR-FTIR and solid-state NMR spectroscopy

Carbohydr Polym. 2022 Sep 1:291:119659. doi: 10.1016/j.carbpol.2022.119659. Epub 2022 May 26.

Authors

Kash A Bhullar¹, Michael I M Horgan¹, Ashley Le¹, David Fania², Richard Wuhrer², Valentina Razmovski-Naumovski³, Kelvin Chan⁴, Patrice Castignolles⁵, Marianne Gaborieau⁶

Affiliations

¹ Western Sydney University, Australian Centre for Research on Separation Science (ACROSS), School of Science, Parramatta Campus, Locked Bag 1797, Penrith, NSW 2751, Australia.
² Western Sydney University, Advanced Materials Characterisation Facility, Parramatta Campus, Locked Bag 1797, Penrith, NSW 2751, Australia.
³ Western Sydney University, NICM Health Research Institute, School of Science, Campbelltown Campus, Locked Bag 1797, Penrith, NSW 2751, Australia; South West Sydney Clinical Campuses, Discipline of Medicine, University of New South Wales Sydney, NSW 2170, Australia.
⁴ Western Sydney University, NICM Health Research Institute, School of Science, Campbelltown Campus, Locked Bag 1797, Penrith, NSW 2751, Australia; Liverpool John Moores University, School of Pharmacy & Biomolecular Sciences, Liverpool L3 3AF, United Kingdom.
⁵ Western Sydney University, Australian Centre for Research on Separation Science (ACROSS), School of Science, Parramatta Campus, Locked Bag 1797, Penrith, NSW 2751, Australia; Sorbonne University, Parisian Institute of Molecular Chemistry, UMR 8232, Polymer Chemistry team, 75252 Paris, France. Electronic address: patrice.castignolles@sorbonne-universite.fr.
⁶ Western Sydney University, Australian Centre for Research on Separation Science (ACROSS), School of Science, Parramatta Campus, Locked Bag 1797, Penrith, NSW 2751, Australia. Electronic address: m.gaborieau@westernsydney.edu.au.

PMID: 35698423
DOI: 10.1016/j.carbpol.2022.119659

Abstract

Dietary fiber like konjac glucomannan (KGM) is important in maintaining good human health. There is no established method for quantifying the average degree of acetylation DA of this polysaccharide. Polysaccharides are notoriously difficult to dissolve. In this study, KGM could not be fully dissolved in common solvents and was characterized in the solid state. ATR-FTIR spectroscopy enabled a fast qualitative assessment of acetylation, selective to the outer layer of KGM particles, and identifying excipients like magnesium stearate. Average DA was quantified for the first time with solid-state ¹³C NMR in KGM: semi-quantitative measurements on the same arbitrary scale by cross polarization (1 to 2 days) were calibrated with a few longer single-pulse excitation measurements (approximately 1 week). DA values ranged from 4 to 8% of the hexoses in the backbone, in agreement with previously reported values. This method could be used for quality control and standardization of KGM products.

Keywords: ATR-FTIR spectroscopy; Degree of acetylation; Konjac glucomannan; Quantification; Solid-state NMR spectroscopy; Solubility.

MeSH terms

Acetylation
Ataxia Telangiectasia Mutated Proteins
Humans
Magnetic Resonance Spectroscopy
Mannans* / chemistry
Polysaccharides*
Spectroscopy, Fourier Transform Infrared

Substances

Mannans
Polysaccharides
(1-6)-alpha-glucomannan
ATR protein, human
Ataxia Telangiectasia Mutated Proteins