| Sesame leaves are by-product of sesame production,which have certain edible and medicinal value.The research on sesame leaves mainly focuses on the nutritional analysis of sesame leaves and the optimization of extraction process of active substances such as polyphenols,total flavonoids and polysaccharides.However,there are few studies on the change of nutrients of sesame leaves at different growth periods,and the structural characteristics and functions of polysaccharides in sesame leaves.Therefore,this project starts from the collection of sesame leaf samples in different growth periods,the change of the main nutrients in the leaves of sesame during the initial,full,final and mature stages were studied.Then,the polysaccharide was extracted from the leaves of sesame in each growth period,and the structural characteristics,antioxidant activity in vitro,immunomodulatory activity and liver protective effect of the polysaccharide were analyzed.This can provide reference for sesame leaf and its polysaccharide in food,medicine,health product development and in-depth research.(1)In this paper,the main nutritional components of sesame leaves in the four stages were analyzed.The results showed that the crude fat content in the leaves of the two varieties was less than 3% in each growth period,and the crude fat content was the lowest in the blooming period,while the crude fiber content was higher in the blooming period.With the extension of growth period,the content of crude protein decreased,the content of total sugar and total flavone increased,the change of ash content decreased slightly,the change of polyphenol content and amino acid content was not obvious.The proportion of protein and amino acid composition of the two varieties in full bloom,final bloom and mature stage was balanced,which are ideal protein and amino acid composition.The content of fresh amino acid in sesame leaves in the initial bloom stage was higher,which is suitable for being a kind of vegetable resource.(2)The structure of sesame leaf polysaccharide extracted by ethanol precipitation method was studied and the result as follows: The extracted sesame leaf polysaccharide was a brown flocculent solid with water solubility,and the content of protein,polysaccharide and glucuronic acid were about 5%,70% and 15%,respectively.The scanning electron micrograph showed that the polysaccharide of sesame leaf presented lamellar accumulation with smooth surface and no complex structure.The weight average molecular weight and number average molecular weight of polysaccharide were larger,and the molecular weight distribution was more dispersed.Gas chromatogram showed that the polysaccharide of sesame leaf was composed of mannose,rhamnose,arabinose,glucose and galactose.The UV absorption spectrum showed that there was a weak characteristic absorption peak at about 260 nm,which contained a small amount of protein.Therefore,it was speculated that the extracted polysaccharide might be a glycoconjugate combined with protein.The infrared absorption spectrum shows that the sesame leaf polysaccharide has the characteristic absorption peak of polysaccharide,which indicates that the sample can be used in subsequent experiments.(3)The antioxidant activity of sesame leaf polysaccharide was measured in vitro.The results showed that: the two varieties of sesame leaf polysaccharide have a certain DPPH free radical scavenging ability and reducing ability in each growth period,showing a certain dose effect,and the effect of sesame leaf polysaccharide was better in full-bloom period.The two varieties of sesame leaf polysaccharides have certain hydroxyl radical scavenging ability and total antioxidant capacity,among which the effect of mature stage and full bloom stage was better.In summary,the sesame leaf polysaccharides(SLP-1 and SLP-2)at the full-bloom stage were selected for the study of immunomodulatory activity.SLP-1 and SLP-2 solutions with concentrations of 31.25,62.5,125,250,500,1000 ?g/m L did not cause toxic effects on mouse macrophages,and the cell survival rate was about 85%.SLP-1 and SLP-2 can promote the secretion of cytokines(NO,TNF-?,IL-6)by mouse macrophages,and have a certain dose effect.(4)The protective effects of SLP-1 and SLP-2 on liver were studied by animal experimental design and results showed that: The mice in each experimental group grew well without death.The high dose of SLP-1 and SLP-2 solution could inhibit the increase of liver index induced by carbon tetrachloride.High,medium and low doses of SLP-1 and SLP-2 can reduce the contents of AST,ALT,AKP and LDH in serum of mice,and can significantly reduce the contents of MDA in liver and increase the contents of CAT,GSH,SOD and T-AOC.Liver sections showed that mouse liver tissue cells in the protection group and each dose group had less necrosis compared with the model group.The protection group and the high-dose group were most similar to the normal group.The results showed that sesame leaf polysaccharide had protective effect on acute liver injury caused by carbon tetrachloride. |
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