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The effect of ultrasound irradiation on the physicochemical properties and α-glucosidase inhibitory effect of blackberry fruit polysaccharide

Dou, Zuman, Chen, Chun, Fu, Xiong
Food hydrocolloids 2019 v.96 pp. 568-576
Fourier transform infrared spectroscopy, alpha-glucosidase, binding capacity, blackberries, circular dichroism spectroscopy, enzyme inhibition, fluorescence, fruits, functional foods, hydrocolloids, molecular weight, particle size, polysaccharides, ultrasonic treatment, ultrasonics
In this study, the influence of ultrasound irradiation on the characterization and α-glucosidase inhibitory effect of polysaccharide from blackberry fruit (BBP, molecular weight of 591.39 kDa) was investigated. After degraded, BBP-8, BBP-16 and BBP-24 three fractions were obtained with molecular weight of 363.93, 249.51 and 177.42 KDa, respectively. Moreover, compared with the particle size of BBP (1070.5 nm), that of BBP-8, BBP-16 and BBP-24 were decreased to 679.9, 548.8 and 395.4 nm, respectively. However, the monosaccharide composition test, FT-IR, and tertiary structure analysis all indicated that the ultrasound did not destroy the primary structure of the original polysaccharide. In addition, the degraded polysaccharide (BBP-24) exhibited the stronger α-glucosidase inhibitory activity than that of BBP. By fluorescence spectrum and circular dichroism spectrum analysis, we found that the polysaccharide could induce the structure change like rigidity structure (α-helixe) and loop structure (random coil) of α-glucosidase to inhibit its activity by binding to the α-glucosidase. The polysaccharide with different molecular weight showed different binding capacity which was related to its inhibitory effect on the α-glucosidase. In general, the results suggested that appropriate degradation was benefit for the enhancement of the inhibitory effect on α-glucosidase of blackberry polysaccharide, and ultrasound irradiation was a green and efficient method to produce bioactivity-added polysaccharide for use in the functional food.