Preparation, Structural Characterization and in Vitro Activity of Chromium Complexes of Sweet Corn Cob Polysaccharide

To enhance the biological activity of sweet corn cob polysaccharide, a sweet corn cob polysaccharide chromium complex (SCP80-Cr) was prepared, characterized and its in vitro activity was also explored. The results showed that the optimal process conditions for the preparation were pH10.1, reaction temperature 74 ℃, polysaccharide concentration of 3 mg/mL, and the reaction time of 60 min. The weight percentage of Cr(III) in SCP80-Cr was 21.08% and the elemental percentage was 6.67%. The characterization revealed that SCP80-Cr contained almost no protein, nucleic acid or pigment, while Cr was conjugated with SCP80 in the form of Cr-O and Cr-OH and had strong molecular agglomeration properties. The molar percentage of the monosaccharide composition of SCP80-Cr was mannose: glucose: galactose: xylose: arabinose = 0.58: 89.50: 4.65: 1.33: 3.58. The results of in vitro hypoglycemia experiments showed that the IC₅₀ of SCP80-Cr on α-amylase and α-glucosidase inhibitions were 4.70±0.38 mg/mL and 3.99±0.26 mg/mL, respectively. Moreover, the results of in vitro antioxidant experiments showed that SCP80-Cr scavenged DPPH radicals and hydroxyl radicals with IC₅₀ of 4.80±0.34 mg/mL and 4.99±0.28 mg/mL, respectively, indicating that SCP80-Cr had better in vitro hypoglycemic and antioxidant activities compared with SCP80. The results of the study provided some references for the study of sweet corn cob polysaccharides in functional foods.