Characterization of Moringa oleifera leaf polysaccharides extracted by coupling ionic liquid separation system with ultrasound irradiation

Abstract

Replacement of organic solvents and short time for purification of polysaccharides has gained attention of researchers. Ionic liquid (IL) was optimally utilized to achieve the mentioned target. IL was coupled with ultrasound irradiation to obtain good yield of partially purified Moringa oleifera leaf polysaccharides. The yield of purified polysaccharides (75.11%) was close to the predicted (75.78%). Crude polysaccharides were found to be round group-like shape while purified polysaccharides displayed compact flat thick-slice shape under scanning electron microscopy. Using gas chromatography, galacturonic acid was detected as part of monosaccharide composition of crude polysaccharides. Functional groups associated with polysaccharides were confirmed using Fourier transform infrared spectroscopy. Using Congo red assay, polysaccharides were observed to be of nonhelical structure. The crude polysaccharide was more viscous in rheological property and had molecular weight of (304,700 g/mol). Using dynamic light scattering methodology, purified polysaccharides (24,370 g/mol) aggregated in water and possessed an excellent ABTS antiradical ability. Purification of polysaccharides using IL within a short time was feasible and presented useful characteristics needed in formulations by the food and pharmaceutical industries. Practical application: Feasibility of using ionic liquid aqueous two-phase system to separate biomolecules (amino acids, saccharides) within a short time has been established by researchers. Knowledge on this was applied in the separation of proteins from polysaccharides extracted from Moringa oleifera leaf. Knowledge of structure–function relations was thoroughly established for extracted and purified polysaccharides. Characteristics of polysaccharides discovered can be useful to the food and pharmaceutical industries.