Enzymatic Modification and Antioxidant Activity of Polysaccharides from Cordyceps militaris Fruit Bodies

Abstract

Abstract: Polysaccharides were extracted from Cordyceps militaris fruit bodies and modified using α-amylase for enhanced antioxidant activity. Response surface methodology was employed to optimize conditions for the enzymatic modification of polysaccharides based on DPPH radical scavenging activity. In addition, modified polysaccharides were tested for DPPH radical scavenging activity, ferrous ion chelating capacity and reducing power as well as triple-helical conformation. The optimized hydrolysis parameters were in decreasing order of their effects on DPPH radical scavenging activity of modified polysaccharides: enzyme dosage, temperature and pH and their optimal conditions were 259.5 U/g, 48.5 ℃ and 5.8, respectively. Under these conditions, the maximum predicted and experimental DPPH radical scavenging rates of modified polysaccharides were 81.4% and (81.6 ± 1.6)%. The results of the validation experiments showed good reproducibility and thus, the fitted prediction model is applicable in practice. The antioxidant tests showed that the EC50 values of modified polysaccharides for scavenging DPPH radical and chelating ferrous ions were 0.0247 mg/mL and 1.0120 mg/mL, respectively, which were 55.1% and 39.8% higher than before the modification, respectively. Meanwhile, the reducing power of polysaccharides significantly increased (P＜0.05) after the modification (P＜0.05), and the triple-helical conformation was well maintained but slightly damaged.

Key words: polysaccharides from Cordyceps militaris fruit bodies, enzymatic modification, process optimization, antioxidant activity, triple-helical conformation

CLC Number:

TS201
S886.9

References

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