Study On Preparation Of Anthocyanins From Purple Sweet Potato And Its Effect On Hypolipidemic Activity And Regulating The Activity Of Intestinal Flora

Purple sweet potato is a special variety of sweet potato with rich natural pigments.It is a recommendable resource to extract natural anthocyanins.This thesis takes the liquid from purple sweet potato to prepare anthocyanins,and conducts the research on its auxiliary hypolipidemic activity and regulating the activity of intestinal flora in order to provide reference for the comprehensive utilization and development of purple sweet potato.The main research contents and results are as follows:1.Based on the single factor experiment,this thesis selects the citric acid concentration,extraction time and the ratio of material to liquid as independent variables,and takes extraction content of the purple sweet potato anthocyanins as the response value in order to optimize the extraction process of purple sweet potato anthocyanins(PSPAs).In this thesis,the Box-Behnken center combination test design and the method response surface analysis(RSM)were used to optimize the extraction process of PSPAs.The results showed that the optimum extraction conditions were as follows:the citric acid concentration was 2.9%,the ratio of material to liquid was 1:7,extraction time was 70 min,Under this condition,the maximum extraction amount of anthocyanins was 94.91 mg/100g.2.By means of mice feeding experiment,TC,TG,LDL-C,HDL-C,ALT and AST indexes of mice’s serum in each group were measured so as to explore the effects of PSPAs on blood lipid in mice with high fat diet.The research revealed that PSPAs had the effect of lowering blood lipid,which could significantly lower the content of TC,TG,LDL-C and increase the content of HDL-C in serum of mice with high fat diet.In contrast to the model control group,the comprehensive lipid-lowering effect of low-dose(13 mg/kg/d)PSPAs was the best,which could promote TC to decrease 15.10%,TG to decrease 21.77%,LDL-C to decrease 33.33%,and HDL-C to increase 6.29%.Moreover.low-dose PSPAs could restore the content of TG and HDL-C in serum to the normal level in mice with high fat diet,whose effect was not different from that of the positive control group.Meanwhile,the effect of low-dose PSPAs on reducing AI index was the best,which could decrease AI index 27.46%,reaching a very significant difference(P<0.01).In addition,it could make AI index of mice with high-fat diet restore to normal levels,and the effect was not different from that of the positive control group.PSPAs could also effectively reduce the risk of liver enlargement in mice with high fat diet,protect the liver,keep the liver index within the normal range,and reduce the risk of fatty liver.Among these,the low-dose PSP As could make the liver index,serum ALT,and AST index of mice with high fat diet restore to the normal level.3.The effects of PSP As on intestinal microbial diversity in high-fat diet mice were studied through applying Illumina high-throughput sequencing technology.By means of analyzing the effects of PSP As on intestinal flora community structure and dynamic changes in mice fed with high fat diet,it was found that:(1)The results of Alpha diversity analysis revealed that high-fat diet could decrease the diversity and richness of the intestinal microbial species in mice.Intragastric administration with PSP As to mice could improve the diversity and richness of intestinal flora in mice fed with high-fat diet,among which the low and medium doses(13 mg/kg/d and 26 mg/kg/d)of PSP As were more effective.The results of Wayne diagram analysis indicated that the high-fat diet weakened the similarity of intestinal flora with that of the normal control group.Low-dose(13 mg/kg/d)intragastric administration of PSP As could improve the similarity of intestinal flora between high-fat diet mice and normal mice.(2)The dominant bacteria and subdominant bacteria in the intestine of mice were changed by the feeding of high-fat diet.In comparison with the normal control group,the subdominant bacteria,including Blautia,Bacteroides,and norank_f_Lachnospiraceae,were less in the model control group,while Desulfovibrio became a new subdominant bacteria;with the application of PSP As,the abundances of the two bacteria--Blautia and norank_f_Lachnospiraceae restored to the subdominant bacteria in the middle-dose group and the high-dose group,respectively.