Extraction,Antioxidant Activity And Effect On Sugar Metabolism Of Water Soluble Polysaccharides From Taro

Polysaccharides are one of the basic types of biological macromolecules.Studies have shown that polysaccharides extracted from some plants have various physiological functions such as anti-oxidation,anti-tumor,immune regulation,anti-diabetes,antibacterial and anti-fatigue in recent decades,and there is no toxic damage to normal cells.This paper used the taro from Guangxi as the raw material to extract and isolate the water-soluble polysaccharides.The antioxidant activity and its effect on glycometabolism in vitro were studied,which provided a scientific theoretical basis for its application in functional food.Results of this research are as follows:Water extraction and alcohol precipitation were used to extract water-soluble polysaccharide from taro,and the final extraction process was determined as follows:The traditional water extraction and alcohol precipitation method was used The extraction condition was solid-liquid ratio 1:33,and extracted at 80°C for 0.9 h.After centrifugation,the supernatant was concentrated by rotary evaporation,and then 3.5 times the volume of ethanol precipitation was added.The precipitation was collected after whole night.After redissolved,deproteinization,decolorization,dialysis and freeze-dried to obtain water-soluble polysaccharides from taro?TSP?.Among TSP,the polysaccharide content was 77.18±1.91?g/100g?.The purity determination of TSP showed that the components of TSP were heterogeneous polysaccharides with large molecular weight,among which the smallest polysaccharide had a molecular weight of 10⁴ orders of magnitude.The results of infrared spectrum analysis showed that TSP had characteristic absorption peak of pyranose of alpha-configuration.HPLC analysis showed that TSP was composed of mannose?0.62%?,rhamnose?0.61%?,galacturonic acid?3.72%?,glucose?90.64%?,galactose?3.66%?and arabinose?0.74%?.SEM shows that the shape of TSP is mainly filamentous and thin.TSP had antioxidant activity in vitro:?1?TSP had scavenging ability against DPPH and ABTS free radicals,and the semi-maximum effect concentration EC₅₀0 was 0.26 mg/mL and 4.99 mg/mL,respectively.TSP could inhibited the generation of hydroxyl radical and superoxide anion radical,and its EC₅₀0 was 0.39 mg/mL and 5.81 mg/mL respectively.Among them,the inhibition ability of TSP on hydroxyl free radicals was close to that of Vc,the inhibition ability of superoxide anion free radicals was about 5%of Vc,and the scavenging effect of DPPH and ABTS free radicals was 1-2%of Vc.?2?TSP samples can chelate ferrous ions and indirectly play the role of anti-oxidation and anti-free radical.When the concentration is 5 mg/mL,the chelating capacity reaches 82.79%.?3?TSP had different degrees of protective effect on spontaneous and H₂O₂-induced oxidative hemolysis of mice red blood cells and lipid peroxidation of mice visceral tissues.The TSP were able to inhibit alpha-amylase and alpha-glucoglucinase activity,with median inhibitory concentration IC₅₀0 of 4.02 mg/mL and 3.10mg/mL,respectively.The relative binding rates of TSP to cholate sodium,bovine cholate sodium and gcholate sodium were 36.23%,12.81%and95.72%,respectively.The results of cell experiments showed that TSP of different concentrations could promote the uptake and utilization of glucose in HepG2 cells and increase the synthesis of liver glycogen,without affecting the cell activity.TSP of low concentration could reduce the activity of?-glucosidase,but not significantly.The activity of SOD increased under the intervention of TSP,which indicated that it could play an antioxidant role in HepG2 cells.The results indicated that water-soluble polysaccharide from taro had a certain effect on glucose metabolism in vitro and had potential hypoglycemic capacity.