Stability,Auxiliary Hypoglycemic Effect And Mechanism Of Blueberry Anthocyanins Loaded With Graphene Oxide-chitosan Oligosaccharide

Anthocyanin(An)is a water-soluble pigment that belongs to the polyphenol flavonoids and is the most important functional component in blueberries.Anthocyanins have physiological functions such as anti-aging,anti-inflammatory,antibacterial,regulating blood sugar and regulating intestinal microorganisms.However,blueberry anthocyanins are easily degraded during processing and long-term storage,resulting in low stability and reduced nutritional value and functionality.Graphene oxide(GO)has high specific surface and good biocompatibility,and can be used as an effective drug delivery material,but GO has poor dispersibility in physiological environment,and chitosan oligosaccharide(COS)is used to improve its dispersibility.In this study,GO and COS were used for synthesis,as a carrier to load anthocyanins to obtain graphene oxide-chitooligosaccharide-anthocyanins(GO-COS-An),and its stability,antioxidant activity,cytotoxicity,in vitro The changes of anthocyanin content and composition before and after digestion were simulated,and the inhibitory relationship between GO-COS-An and protein tyrosine phosphatase 1B(PTP1B)was studied by in vitro,cell and animal experiments,and the target of GO-COS-An on PTP1 B was explored.The possible hypoglycemic mechanisms and pathways of action.(1)GO and COS were loaded with anthocyanins through amide bond.Their dispersion,structure,morphology and composition were analyzed by dynamic light scattering(DLS),Fourier transform infrared spectroscopy(FTIR),ultraviolet visible absorption spectroscopy(UV-Vis),thermal properties(TGA),X-ray electron spectroscopy(XPS),X-ray diffraction(XRD),transmission electron microscopy(TEM)and nuclear magnetic resonance(NMR),The results showed that go-cos was successfully connected,with a diameter of 262.5 ± 7.47 nm,and showed good dispersion in physiological environment.A total of 13 anthocyanin monomers were identified by HPLC-MS.(2)Temperature,p H value,illumination,avoid light,ascorbic acid,sugars,oxidants and reductants have significant effects on the stability of GO-COS-An,The GO-COS-An complex has a protective effect on blueberry anthocyanins and improves its stability.The thermal degradation of GO-COS-An conforms to the first-order kinetic reaction model.The degradation increases with the increase of temperature,and the maximum activation energy is 45.51 kg/mol.The thermal degradation of GO-COS-An is an endothermic process,not a spontaneous reaction,and the structural freedom of the transition state is lower than that of the reactant.At the same time,it can effectively inhibit the loss of antioxidant activity of anthocyanins.(3)During simulated digestion in vitro,blueberry anthocyanins were relatively stable during saliva and gastric digestion,but unstable during intestinal digestion,and GO-COS loading of anthocyanins reduced its loss during digestion,and the stability of blueberry anthocyanins to blueberry anthocyanins and antioxidant protection.Through the analysis of blueberry anthocyanin monomers,GO-COS can prevent the degradation of most monomers during digestion and improve the bioavailability of blueberry anthocyanins during intestinal digestion.The GO-COS-An complex was not cytotoxic.(4)GO-COS-An inhibited the activities of PTP1 B and α-glucosidase,while showing reversible mixed-type inhibition of PTP1 B and reversible non-competitive inhibition of α-glucosidase.Through circular dichroism,fluorescence quenching and molecular docking results,it was shown that M3 G interacts with certain amino acid residues of PTP1 B and α-glucosidase,weakening their intrinsic fluorescence intensity,supporting that non-covalent forces are mainly responsible for the inhibition of PTP1 B and α-glucosidase.GO-COS-An can increase glucose consumption in a dose-dependent manner.PCR and Western blot results show that GO-COS-An can improve the IRS1/PI3K/Akt pathway involved in PTP1 B and inhibit PTP1 B.(5)GO-COS-An can significantly reduce the fasting blood glucose,serum insulin and glycosylated hemoglobin content of mice,significantly improve oral glucose tolerance and insulin resistance index,reduce lactic acid content,and increase liver glycogen synthesis.GOCOS-An can also effectively Increased superoxide dismutase(SOD),catalase(CAT)and reduced glutathione(GSH)activities and decreased malondialdehyde(MDA)concentration levels in diabetic mice,revealing GO-COS-An Enhance the body’s antioxidant capacity,relieve insulin resistance,and improve the symptoms of hyperglycemia in diabetic mice.GO-COS-An was also able to repair liver tissue and pancreatic tissue of injured mice.GO-COS-An evaluated the expression of PTP1 B and the changes of IRS1/PI3K/AKT/GSK3β pathway by Western blot,thereby improving the insulin resistance state of diabetic mice and achieving the effect of lowering blood sugar.