Abstract: Polysaccharides from the fruiting body of Clitocybe squamulosaruiting (CSFP) were extracted by ultrasonic-assisted hot water extaction and were degraded by three different methods, i.e., H2O2 degradation, ultrasonic degradation and ultrasonic-assisted H2O2 degradation. The resulting products were named as H-CSFP, U-CSFP, and UH-CSFP, respectively. CSFP consisted of three fractions (I, II and III) with different molecular masses. The molecular masses of fractions I and III in H-CSFP, U-CSFP and UH-CSFP were lower than those in CSFP, and their proportions were higher in these degraded polysaccharides than in CSFP; however, the opposite was true for the molecular mass and proportion of fraction III. The monosaccharide composition of CSFP was not affected by each of the degradation methods. Scanning electron microscopy (SEM) showed that the density or diameter of pores on the surface of CSFP increased after degradation, indicating looser structure. The zero shear viscosity and average particle size of CSFP decreased significantly after degradation. Fourier transform infrared spectroscopy (FTIR) showed the major functional groups of CSFP were not damaged after degradation, while the apparent viscosity and gel properties were weakened. Compared with CSFP, all degraded polysaccharides except UH-CSFP showed no significant difference in total sugar content but an increase in the contents of sulfate and uronic acid. The decreasing order of the antioxidant activity in vitro was UH-CSFP > U-CSFP > H-CSFP > CSFP. Pearson correlation analysis showed that the content of sulfate group was largely significantly correlated with the hydrolxyl radical scavenging capacity and total reducing power (P < 0.01) as well as the scavenging capacity against 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical cation (P < 0.05), although it was not correlated with the scavenging capacity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical (P > 0.05). The results of this study provide a theoretical reference for the application of Clitocybe squamulosa polysaccharides in the fields of food, medicine and health products.

Key words: Clitocybe squamulosa; polysaccharide; degradation; phsicochemical properties; antioxidant activity