Isolation Of Mulberry Leaf 1-deoxynojirimycin And Its Synergistic Hypoglycemic Effect With Glycosides

High-fat diet and lack of exercise can easily lead to the occurrence of type 2 diabetes mellitus(T2DM).T2 DM is a kind of chronic metabolic disease which is impossible to be treated fundamentally,hence,the control of blood glucose levels is a long-term medication.However,the effect of current hypoglycemic drugs is relatively simple and the long-term use is prone to adverse reactions such as organ damage,abdominal distension and so on.Therefore,the study aims to explore the hypoglycemic effect and mechanism of the combined medicine food homologous natural products based on the hypoglycemic effects.In this study,1-deoxynojirimycin(DNJ,from Morus alba L.),salidroside(from Rhodiola rosea L.),and polysaccharide(from Dioscorea oppositifolia L.)(DSP)were combined with a mass ratio of 1:1:1 to study the hypoglycemic effect of DSP,and to explore the hypoglycemic mechanisms of DSP on carbohydrate and lipid metabolism in T2 DM mice.The optimal extraction process conditions of DNJ in mulberry leaves by response surface method are: 60%(V/V)ethanol solution whose p H was 3 at a solid-liquid ratio of 1:24,bathing at 60 °C for 50 min under 350 W.In order to purify DNJ,the single-factor experiments of purification were carried out and the optimal purification process conditions were optimized as: the length-to-diameter ratio was 1:15,the sample concentration was 2.5 mg/m L,the sample volume was 20 m L,the eluents concentration was 80%(V/V)ethanol solution and the velocity of desorption was 1.5 m L/min.Moreover,the concentration of the elution solution was changed to 30%(V/V)for secondary purification.Finally,the secondary purified mulberry DNJ with a purity of 56.58% was obtained.To screen the synergistic hypoglycemic agent of DNJ based on the ?-glucosidase inhibitory effect and the Chou-Talalay model was used to calculate the combination index(CI),and the extract of Rhodiola rosea L.was found to exhibate the best synergy effect with mulberry leaf DNJ.Then,the Hep G2 cell insulin resistance model was established and the glucose consumption and MTT experiments were performed.Combined with the direct action method,the extract from Dioscorea oppositifolia L.and the secondary purified mulberry leaf DNJ had a synergistic hypoglycemic effect.In order to clarify the hypoglycemic factors,salidroside(from Rhodiola rosea L.)and polysaccharide(from Dioscorea oppositifolia L.)were selected to combined with DNJ at a mass ratio of 1:1:1 to explore the hypoglycemic effect and the mechanism.The T2 DM mice model was established by the inducement of high-fat diet combined with streptozotocin.The results of blood glucose levels,glycolipid metabolism related indicators and inflammatory factors,etc.showed that DSP could regulate blood glucose levels,improve insulin resistance and glycolipid metabolism disorder of T2 DM mice.The results of H&E staining showed that DSP had a certain repairing ability to the tissues damage caused by T2 DM which suggested that DSP could reduce the occurrence of diabetes complications in T2 DM mice.Western blot(WB)was performed to analyze the related proteins in glycolipid metabolism.It was found that DSP can improve the carbohydrate and lipid metabolism disorders in T2 DM mice through PI3K/Akt/GSK3? and AMPK signaling pathways,which has certain reference significance and practical value for the development of new functional hypoglycemic health products.