Structural and conformational characterization of linear O-acetyl-glucomannan purified from gel of Aloe barbadensis Miller.

Aloe barbadensis Miller (Aloe vera) is a kind of popular medicinal and horticultural crops widely cultivated around the world. Polysaccharides with different structural features and bioactivities have been isolated from the pulp of Aloe vera. In the current study, a novel polysaccharide fraction (AGP) isolated and purified from gel juice of Aloe vera was subjected to structural and conformational analysis. AGP had a backbone consisting of major →4)-β-Manp-(1 → residues and minor →3)-β-Manp-(1 → and →4)-β-Glcp-(1 → residues. Low degree of branches distributed at O-6 of 4-linked mannose in the main chain. The acetyl groups in AGP presented as mono- or di-substituents (O-2, O-3, O-6, O-2,3, O-2,6 and O-3,6). AGP performed as random coil conformation in 0.1 M NaNO solution, and had fibrous filaments and irregular spherical structures in solid state. Detailed structural and conformational analysis of AGP in the present study may greatly improve the bioactive function investigation and mechanism explanation of acetyl glucomannans in the future.