The structure characterized of Nostoc commune polysaccharide and antioxidant activity of Gansu Nostoc commune

Abstract In this paper，Nostoc commune crude polysaccharide was extracted by hot water and Ultrasonic-assisted extraction, then purified by DEAE-cellulose52 cellulose column chromatography and Sephacryl G-100 gel column chromatography. Homogeneous polysaccharide HNCP3 extracted with hot water and UNCP4 extracted by ultrasound were obtained. The structures of HNCP3 and UNCP4 were characterized by molecular weight determination, infrared spectroscopy, DSC detection, sodium periodate oxidation, smith degradation reaction and methylation analysis. The conformation of the solution was studied by SEM and AFM. The results showed that the Ultrasonic-assisted extraction had an effect on the molecular weight, monosaccharide composition molar ratio and configuration of Nostoc commune. The main chains of HNCP3 and UNCP4 were mainly →6) -D-Glcp (1→ and →2,6) -D -Glcp, but there are 1,2,6-galactose branches and 2,3-Me2-D-Ara in UNCP4 and there is no HNCP3. The results of the composition of monosaccharides showed that both HNCP3 and UNCP4 have the presence of mannose. SEM and AFM showed that the structure of UNCP4 was helical, and the solution conformation of HNCP3 and UNCP4 was different in different solution environments. In experiments on the antioxidant activity and hypoglycemic effect of HNCP3 and UNCP4 in vitro, it was shown that UNCP4 has higher antioxidant activity scavenging ability and UNCP4 is stronger than HNCP3 inhibitory activity. Therefore, UAE increases the NCP extraction rate while also increasing the biological activity in NCP.