Purification, Characterization, and Self-Assembly of the Polysaccharides from Allium Schoenoprasum

Abstract

<jats:title>Abstract</jats:title> <jats:p><jats:bold>Background</jats:bold>: <jats:italic>Allium schoenoprasum is </jats:italic>a world-wide common vegetable while only its leave is used in the food factory. Its stalk is largely discarded, for potential heavy metal accumulations, which eventually lead to an environmental contamination. To fully utilize this vegetable and minimize its metal content, the major polysaccharide content is purified and characterized with chemical and computational approaches.<jats:bold>Results</jats:bold>: The major polysaccharide component from the stalk of <jats:italic>Allium schoenoprasum </jats:italic>(<jats:italic>As</jats:italic>sP)<jats:italic> </jats:italic>was<jats:italic> </jats:italic>extracted and purified. The gel filtration chromatography purified <jats:italic>As</jats:italic>sP exhibited a molecular weight of around 1.6 kDa, which was verified by MALDI-ToF-MS. Monosaccharide analysis revealed its composition as rhamnose: arabinose: galactose: glucose: mannose: fructose with a molar ratio of 0.0264:2.46:3.71:3.35:1.00:9.93, respectively. Multiple NMR analysis revealed its backbone as α-Ara/Glu/Gal-(1→2)-linked and β-D-Fru-(4→5)-linked sugar residues. There was no tertiary structure of this polysaccharide, however, it self-assembled into a homogenous nanoparticle with a diameter of ~600 nm. The solution behavior of this <jats:italic>As</jats:italic>sP polysaccharide was simulated, and there was no specific binding site on one molecule for another. Association of this polysaccharide was concentration dependent. As the <jats:italic>As</jats:italic>sP concentration increased, the spherical particles increased their sizes and eventually merged into cylindrical micelles. The diversity of <jats:italic>As</jats:italic>sP hydrodynamic behavior endowed potential versatility in its applications.<jats:bold>Conclusions</jats:bold>: <jats:italic>As</jats:italic>sP was characterized as a polysaccharide with identified monosaccharide compositions and linkage between them. Although there is no tertiary structure in one <jats:italic>As</jats:italic>sP molecule, self-assembly of <jats:italic>As</jats:italic>sP molecules could form nanoparticles or micelles depending on its solution concentrations. The unique <jats:italic>As</jats:italic>sP solution behavior endows itself a potential biomaterial for nanoparticles preparations.</jats:p>