Study On The Quality Of Tartary Buckwheat Resources Based On The Effect Of Regulating Glucolipid Metabolism

Buckwheat belong to Polygonaceae,mainly included F.esculentum Moench,F.tataricum?L.?Gaertn and F.emarginatum Mtissner,has cultivated in western zhou dynasty,and often divided into two categories: common buckwheat and Tartary buckwheat according to the taste of food.Tartary buckwheat was the fruit of F.tataricum.Tartary buckwheat was the main food for southwest Yi area before introduction of potato and other crops in the 16 th century.The planting area of Tartary buckwheat was about 400,000-600,000 hectares,and was the main economic source of farmers in outlying mountainous area.Tartary buckwheat were rich in flavonoids,amino acids and fatty acids,and have been reported to help control blood glucose,blood pressure and blood lipid levels.However,“Hard to digest,easy to promote feng” was recorded in <Bei Ji Qian Jin Yao Fang>.Li ShiZhen concluded that Tartary buckwheat was bitter,and would hurt the stomach if eatting too much.The regulation of glycolipid metabolism activity of Tartary buckwheat is closely related to “difficult to digestion” of tartary buckwheat.Different viewpoint about the mechanisms of these effects limitted the establishment of a good and exclusive evaluation indexes and methods for quality of buckwheat.It also hampered the selection and breeding of varieties of Tartary buckwheat and the quality control of Tartary buckwheat products.To solve this core problem,in present study,we aimed to identify the main components of Tartary buckwheat of regulaing glucolipid metabolism,through investigating the effects of Tartary buckwheat and its flavonoids on starch digestion,glucolipid metabolism and gut microbiota by in vivo and in vitro study.Base on this results,the quality standard of Tartary buckwheat was established,and the main effective component of different Tartary buckwheat were tested.The main research results are as follows:1.Flavonoids in Tartary buckwheat affect starch digestion by inhibiting amylase digestion and interacting with starch in Tartary buckwheat.The potential effect of flavonoids of Tartary buckwheat on in vitro starch digestibility was investigated in our study.We first prepared rutin enhance flavonoids extractions?REFE?and quercetin enhance flavonoids extractions?QEFE?according to the flavonoids composition in Tartary buckwheat;then,effect of flavonoids of Tartary buckwheat and individual flavonoid?rutin,quercetin and kaempferol?on,inhibition of ?-glucosidases,porcine pancreatic ?-amylase,in vitro starch digestibility and predicted glycemic index?pGI?were evaluated.Quercetin possessed highest inhibition activity of ?-glucosidases?IC50=0.006 mg/mL?.REFE and QEFE have similar antioxidant and inhibition of ?-amylase activity,but QEFE have much higher activity of ?-glucosidases inhibition than REFE?IC50 was 0.022 and 0.45mg/mL respectively?.Tartary buckwheat flour have lowest content of rapidly digestible starch?29.69%?and pGI among maize flour,wheat flour,rice flour and Tartary buckwheat flour.Addition of rutin and quercetin in wheat flour showed weakly or no effect of digestion inhibition,but they inhibited the starch digestion under solid complex condition.It was first revealed that the scientific connotation of “difficult to digestion” of Tartary buckwheat was that the flavonoids influence starch digestion by inhibiting enzyme activity or reduce starch digestion rate by changing starch gelatinization characteristics.2.Tartary buckwheat regulated gut microbiota?GM?and improved lipid metabolism by quercetin.In the present study,we first investigated the impact of rutin,quercetin and Tartary buckwheat on the lipid metabolism of rats on a high fat diet.The body weight,serum TC and TG of HFD rats after 12 weeks did not increase compared with the control group,but the liver cells showed significantly steatosis;The TNF-? and IL-6 contents increased significantly?from 16.53 to18.71 pg/mL and 27.40 to 30.14 pg/mL?;the acetic acid content of the feces increased from 806.10 ?g/g to 1424.63 ?g/g,but propionic acid and butyric acid contents decreased significantly?from 306.11 to 211.66 ?g/g and 470.04 to 152.84 ?g/g?.Quercetin could significantly reduce body weight,serum TG,LDL,TNF-?,insulin,and ameliorate glucose tolerance.It was surprising that Tartary buckwheat?80-120 mesh,contain 2.74% rutin and 0.08% quercetin?significantly increased the weight and fat accumulation of the rats.Rats treated with quercetin,rutin and Tartary buckwheat tended to have decreased fat deposition in the liver but short chain fatty acid production was little affected.The changes in the structure and diversity of the microbiota were found to be modulated by these diets,and Tartary buckwheat increased the diversity significantly.The effect of flavonoids on microbial fermentation in vitro were also evaluated.The impact of REFE,QEFE,rutin and quercetin on microbial fermentation and production of cecal short-chain fatty acids?SCFAs?were investigated using 16 SrDNA and GC-MS.Results indicated that,it's significantly different for microbial diversity and SCFAs production in individual person.Flavonoids decreased relative abundance of Allisonella?Coprococcus₃ and Catenibacterium.Flavonoids also increased propionic acid content?from 656.12 ?g/mL of control group to 726.9-896.97 ?g/mL of flavonoids and Tartary buckwheat group?,but not acetic acid,butyric acid and other SCFAs.It was concluded that Tartary buckwheat regulated gut microbiota?GM?and improved lipid metabolism by quercetin,and this effect may mediate by affecting starch digestion or modulating the gut microbiota.Quercetin can be used as the quality control index of lipid-lowering activity of Tartary buckwheat.3.Establishment of quality standards based on its effects of regulaing glucolipid metabolism.6 phenolic compounds included rutin,quercetin,kaempferol,quercitrin,caffeic acid,vitex in flour and bran of different variety of Tartary buckwheat were detected.Combined with the discussion on the preliminary analysis and investigation data of our research group,we suggested the total content of rutin and quercetin in Tartary buckwheat should not be lower than 0.64%,calculated using quercetin.Based on this standard,the varieties of Jinqiao No.2,Qianku No.3 and Qianku No.5 are wide adaptability and good varieties with high lipid regulation activity.Results also suggested quercetin should be used as control index in Tartary buckwheat products with lowering lipid activity.A total of 20 free amino acids,8 fatty acids were also quantified by UPLC-MS/MS and GC-MS,to asses the quality of Tartary buckwheat systematically.Results indicated The coefficient of variation of amino acids and fatty acids in different varieties of Tartary buckwheat were 28.00%-73.79% and 7.25%-38.63%,respectively.Free amino acids and fatty acids were 2.2-22.5,1.4-3.1 times higher in bran than in flour respectively.It was also suggested that lysine and linolenic acid should be used as the representative indexes of Tartary buckwheat nutrition based on its nutritional characteristics and distribution among different variety of Tartary buckwheat.In conclusion,in present study,we investigated the quality control standards for the function of lipid-lowering of Tartary buckwheat based on the theory of gut microbiota.We also illustrates the mechanism of regulating gut microbiota and glucolipid metabolism of Tartary buckwheat by in vitro and in vivo experiments,clarified the quality control index of Tartary buckwheat for lipid-lowering function and evaluated the quality of Tartary buckwheat systematically.Our study is useful for establishing quality standard and the development and utilization of Tartary buckwheat.It is also helpful to further explore the dynamic balance relationship between nutrients-intestinal flora-glucolipid metabolism,and explain the scientific connotation of the plant including “medicine” and “food” characteristics.It has important for the variety selection of flavonoid-rich crops,also provides some new viewpoint and understandings for the role of functional components in diet structure,and for formulating dietary guideline.