| As a characteristic medicinal and edible berry resource on the Qinghai-Tibet Plateau,Berberi dasystachya M.has great development and utilization value.According to the previous research of the research group,it was found that polysaccharide,as a natural biopolymer of Berberi dasystachya berry,has the functions of lowering blood sugar,anti-oxidation and anti-tumor.However,the underlying mechanism of polysaccharide of Berberi dasystachya M.(BDPs)in the treatment of T2 DM is still lacking,and whether there is a causal relationship between the regulation of intestinal flora and host metabolism and alleviation of T2 DM.Therefore,this subject extracted and separated the active BDPs,and further purified it by ultrafiltration membrane separation method to study its primary structure characteristics.Regulatory effects of polysaccharides on glucose metabolism and intestinal flora and metabolic dysfunction in T2 DM rats.The main research work is as follows:(1)Different components of BDPs(BDPs-70,BDPs-80 and BDPs-90)were prepared by ethanol alcohol precipitation and their primary structures were characterized by high performance gel permeation chromatography,fourier transform infrared spectroscopy and scanning electron microscopy.Comparing DPPH and ABTS free radical scavenging rate,reducing power,α-amylase and α-glucosidase inhibition rate and their effects on Lactobacillus acidophilus and Escherichia coli were compared.The results showed that the uronic acid content of BDPs-80 was the highest,and the average molecular weights of BDPs-70,BDPs-80 and BDPs-90 were 9 851,9 901 and 9855 Da,respectively,and had characteristic absorption peaks of polysaccharides,which were β-pyran polysaccharides with flaky surface structure.The scavenging rates of the three polysaccharides on DPPH and ABTS free radicals were in the following order: BDPs-90 > BDPs-80 > BDPs-70,and the reducing power of BDPs-80 was optimal.The inhibition rate of α-amylase was BDPs-90 > BDPs-80 > BDPs-70.The inhibition rate of α-glucosidase was BDPs-80 > BDPs-90 > BDPs-70.The three polysaccharides as carbon sources can promote the proliferation of Lactobacillus acidophilus(BDPs-90 shows the best promotion effect),significantly increase the content of short chain fatty acids,and inhibit the growth of Escherichia coli(BDPs-80 shows the best inhibitory effect).(2)The ultrafiltration membrane separation method was used to preliminarily purify and separate the polysaccharide of Berberi dasystachya M.,and the process parameters were optimized to obtain the ultrafiltration polysaccharide of Berberi dasystachya M.(UBDPs),the ultrafiltration time was 30 min,and the membrane molecular weight was 8 k Da.Under these conditions,the polysaccharide yield was 175.12±1.23 mg/g.(3)Taking the polysaccharides of Berberi dasystachya M.before and after ultrafiltration membrane separation as the research object,the primary structure,in vitro antioxidant,hypoglycemic activity,thermal properties and rheological properties were compared.The results showed that the effective components of polysaccharides were improved by ultrafiltration without destroying the structure of polysaccharides.Both BDPs and UBDPs were β-pyran polysaccharides and did not have triple helix structure.The results of scanning electron microscopy showed that the surface of polysaccharides after ultrafiltration was from rough and loose to smooth and compact;in vitro anti-oxidation and hypoglycemic experiments found that ultrafiltration treatment can effectively improve the activity of polysaccharides from Berberi dasystachya M.;ultrafiltration membrane separation can improve the thermal stability of polysaccharides from Berberi dasystachya M.;Polysaccharides from Berberi dasystachya M.have good rheological properties,and UBDPs have better rheological properties than BDPs,and can be used as thickeners in the food industry.Ultrafiltration significantly improved the purification process of polysaccharides from Berberi dasystachya M..(4)Taking UBDPs as the research object,metabolomics and 16 S r DNA gene sequencing were used to determine the effects of UBDPs on gut microbiota and their metabolites in a rat model of type 2 diabetes.The results showed that administration of UBDPs could significantly ameliorate glucose tolerance,improve organ function,reduce fasting blood glucose and Hb A1 c levels,decrease glycosylated hemoglobin index,improve insulin sensitivity of the pancreas,and reduce colon morphogen and oxidative stress compared with diabetic rats after treatment for 4 weeks.Furthermore,the antihyperglycemic effect of 200 mg/kg UBDPs(UBDPs-M)showed the most significant effects among the three dosage groups used in this study.4 weeks of UBDPs supplementation significantly increased the relative abundance of Firmicutes and the levels of short-chain fatty acids,suggesting that the hypoglycemic effects of UBDPs supplementation might be partially mediated by gut microbiota.Moreover,UBDPs-M intervention significantly improved the metabolic disorder in diabetic rats;27 possible biomarkers were identified,mainly involving lysine degradation;phenylalanine,tyrosine,and tryptophan biosynthesis;tyrosine metabolism;bile secretion;and nicotinate and nicotinamide metabolism.These biomarkers returned to normal levels to a certain extent,which was related to gut microbiota.This study not only reveals the potential biomarkers and related pathways of how UBDPs affected diabetic rats but also highlights the efficacy of UBDPs in the treatment of type 2 diabetes from a multidisciplinary perspective,thereby suggesting its potential use in a clinical setting.In conclusion,the regulation effect of UBDPs on blood sugar in type 2 diabetes is closely related to the reversal of intestinal flora imbalance and the production of short-chain fatty acids and other metabolites.UBDPs can be used as a prebiotic for the treatment of type 2 diabetes,and this study laid the theoretical foundation for the development of polysaccharides from Berberi dasystachya M.. |
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