Screening and characterization of an acid polysaccharide with antioxidant activity in vitro and in vivo from Dendrobium aurantiacum var. denneanum (Kerr)

Aim: We aimed to monitor an acid polysaccharide with antioxidant activity. Materials and Methods: Three acidic polysaccharides (DAP-A40, DAP-A60, and DAP-A80) were extracted from D. aurantiacum imbricate by alkaline aqueous solution extraction and ethanol precipitation. The structure characterization and antioxidant activity in vitro and in vivo were examined. Results: The molecular weight (M_W) of three polysaccharides was 1.70 mol⁵ Da, 5.78 mol⁴ Da, and 1.36 mol⁴ Da, respectively, by high-performance gel chromatography. The consequences of infrared spectrum displayed that three polysaccharides enclosed uronic acid and sulfuric acid groups. DAP-A40 and DAP-A60 were collected of α-configuration pyranose. DAP-A80 was composed of β-configuration pyranose. Antioxidant test exhibited that DAP-A80 had outstanding antioxidant activity. The half-maximal inhibitory concentration of DAP-A80 in dipping power and scavenging the 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), DPPH, and OH radicals was 163.5 μg/mL, 613.2 μg/mL, 583.2 μg/mL, and 365.1 μg/mL, respectively. The grades of correlation analysis showed that the ability of DAP-A80 to scavenge ABTS, DPPH, and OH radicals was negatively connected with the M_W of polysaccharides and certainly correlated with the content of sulfate group. The results of in vivo experiments exposed that DAP-A80 might knowingly decline the formation of malondialdehyde. High levels of DAP-A80 could evocatively upsurge the activity of superoxide dismutase and GSH-Px in mouse serum. Conclusion: DAP-A80 has an antioxidant effect and can be reconnoitered as a health medicine and food.