Physical And Chemical Characterization And Activity Evaluation Of Quinoa Leaves And Seed Polysaccharides

Quinoa,a genus of quinoa in the amaranth family,is a pseudocereal crop with a high protein content and a high nutritional content,and is usually eaten mainly from the seeds.However,quinoa leaves are also rich in nutrients and the leaves are also consumed abroad as a vegetable.Polysaccharides are also functional active substances in quinoa seeds and leaves,with physiological effects such as antioxidant,anti-inflammatory and hypoglycaemic.Regular consumption of quinoa is beneficial in preventing chronic diseases and improving human health.Therefore,in order to understand the physicochemical structure and biological activity of quinoa leaf polysaccharides and to further promote the development of quinoa-related products,as well as to provide a scientific and theoretical basis for the development of quinoa and quinoa leaf polysaccharide series functional foods and health products,this study firstly clarified the physicochemical structure and biological activity of quinoa leaf polysaccharides.In this study,the physicochemical structure and biological activity of quinoa leaf polysaccharides were determined.At the same time,the differences in physicochemical properties and biological activities between quinoa seeds and quinoa leaf polysaccharides were compared:1.Extraction rates and chemical composition of polysaccharides from quinoa leaves and seeds of different varietiesIn this study,the physicochemical properties of quinoa leaf and quinoa seed polysaccharides of varieties HQ-1,ZL-6 and QHXL were compared.The results showed that the extraction rate of quinoa leaf polysaccharide was significantly higher than that of quinoa seed polysaccharide,with the extraction rate of quinoa leaf polysaccharide ranging from 3%to 4%,which was twice as high as that of quinoa seed polysaccharide.The free bound phenols were removed during the extraction of quinoa polysaccharide,so the bound phenols determined in the polysaccharide should be complexed in the polysaccharide.The average content of complex-bound phenols in quinoa leaf polysaccharides is approximately four times higher than in quinoa seed polysaccharides,and the average protein content of quinoa leaf and seed polysaccharides is very low.Compared to quinoa seeds,quinoa leaves had a higher polysaccharide extraction rate,glyoxylate content and total phenolic content.2.2.Comparative study of the physicochemical properties of quinoa leaf and seed polysaccharidesThe high performance exclusion chromatogram of quinoa leaf polysaccharides showed that there was only one polysaccharide fraction,with an average heavy average molecular weight of 4 x 10~4 Da and an average dispersion coefficient of 1.4.The high performance liquid chromatogram showed that quinoa leaf polysaccharides contained eight monosaccharides,of which mannose,rhamnose,galacturonic acid,galactose and arabinose were the main monosaccharide types.Infra-red spectroscopic analysis calculated the average degree of esterification of quinoa leaf polysaccharides to be 44%.The high performance exclusion chromatograms of the different varieties of quinoa seed polysaccharides showed two polysaccharide fractions,with the heavy average molecular weight distribution of fraction 1 ranging from 2.476×10~5 Da to 6.678×10~4Da with an average dispersion coefficient of 1.35 and fraction 2 ranging from 4.188×10~4Da to 2.617×10~5 Da with an average dispersion coefficient of 1.07.The high performance liquid chromatograms of quinoa seed polysaccharides showed that galacturonic acid,galactose,xylose and arabinose were the main monosaccharide types.Infrared spectroscopy analysis calculated that the esterification of quinoa seed polysaccharides averaged 26%,which was significantly(P<0.05)lower than that of quinoa leaves.The polysaccharides isolated from quinoa leaves and seeds were found to be amorphous polymers without crystalline structure,as determined by XRD analysis of quinoa leaves and seeds.The DSC thermal analysis showed that both quinoa leaf and seed polysaccharides had good thermal stability.Infrared spectroscopy further showed that both quinoa seed and quinoa leaf polysaccharides of different varieties contained acidic polysaccharides,but with significant differences in their esterification.The monosaccharide types of both sites were analysed by NMR in bothα-andβ-configurations,and the monosaccharide types were consistent with those determined by high performance liquid chromatography.Quinoa leaf and quinoa seed polysaccharides showed differences in molecular weight,composition of the main monosaccharides and esterification,while the differences in physicochemical structure such as functional groups,monosaccharide conformation,crystalline structure and heat deformation were not significant.3.Comparative study of the bioactivity of quinoa leaf and seed polysaccharidesThe results of the in vitro bioactivity evaluation showed that both quinoa leaf and quinoa seed polysaccharides exhibited good in vitro antioxidant activity(ABTS radical scavenging activity,DPPH radical scavenging activity and total reducing power),anti-glycosylation activity,immunological activity and probiotic activity,as well as good in vitro lipid adsorption and bile acid adsorption capacity.Quinoa leaf polysaccharides were superior to quinoa seed polysaccharides in terms of antioxidant,antiglycosylation activity and pro-life properties.This may be closely related to its higher content of bound phenols.However,quinoa seed polysaccharides were superior to quinoa leaf polysaccharides in terms of in vitro adsorption capacity and immunological activity.The results of this study suggest that quinoa leaf polysaccharides and quinoa seed polysaccharides have good potential for application in functional foods and health foods,and that quinoa leaf and quinoa seed polysaccharides each have advantages in terms of bioactivity.The study is also expected to be applied to industrial applications.The study is also expected to be applied to the industrial extraction of quinoa leaf polysaccharides for food development,making use of quinoa leaves as an abandoned resource and increasing quinoa-related revenue.It will also promote the development of quinoa-related deep processing industries.