Dual‐frequency ultrasound‐assisted alcohol/salt aqueous two‐phase extraction and purification of astragalus polysaccharides.

Abstract

The study investigated the effect of dual-frequency ultrasound-assisted alcohol/salt aqueous two-phase extraction and desalination on the yield, microstructure and antioxidant properties of Astragalus polysaccharides (APS). Extracts were desalinated for 10 (APS10), 20 (APS20), and 30 (APS30) minutes. A 28.40% experimental yield, well correlated to the response surface methodology predicted model was achieved. Thermodynamic parameters were non-spontaneous, irreversible and endothermic. Moreover, ultrasound enhanced the desalination rate and did not alter the chemical structure in the APS. Fourier Transform Infrared Spectroscopy showed a similar spectrum in all the APS samples. High-performance gel chromatography and scanning electron microscopy, respectively presented reduced molecular weights and altered microstructures in the samples. Monosaccharide analysis revealed the existence of xylose, mannose, galactose, glucose, arabinose, rhamnose, and ribose in the APS samples. Moreover, the APS20 showed strong hydroxyl and 2,2-diphenyl-1-picrylhydrazyl radical scavenging activities, thus showing its potency in reducing oxidative stress. Hence, this study demonstrates that coupled ultrasound and alcohol/salt ATPS is a sustainable technique, which generates high yields of simultaneously extracted products.