A comparison study on polysaccharides extracted from Fructus Mori using different methods: structural characterization and glucose entrapment

In this study, the structure characteristics and the hypoglycemic and antioxidant activities of mulberry fruit polysaccharides obtained by the commonly used hot water (MFPh)-, ultrasonic (MFPu)-, acid (MFPc)- and alkali (MFPa)-assisted extraction methods were investigated. NMR analysis indicated that the four polysaccharides had similar glycosidic linkage patterns. Scanning electron microscopy analyses showed that the surface morphology of the polysaccharides was greatly affected by the extraction methods. The results of the bioactivity assays indicated that MFPh exhibited stronger antioxidant and α-amylase inhibitory activities than the other polysaccharides. Moreover, all the polysaccharides showed good α-glucosidase inhibitory activities except for MFPu with the lowest molecular weight. These results suggested that acid, alkali, and ultrasonic-assisted extractions have different effects on the degradation of polysaccharides without changing the main structure compared with hot water extraction. In addition, the molecular weight of polysaccharides plays a key role in the bioactivity of the mulberry fruit polysaccharides.