A series of novel N -alkyl-1-deoxynojirimycin derivatives 25 ∼ 44 were synthesised and evaluated for their in vitro α-glucosidase inhibitory activity to develop α-glucosidase inhibitors with high activity. All twenty compounds exhibited α-glucosidase inhibitory activity with IC 50 values ranging from 30.0 ± 0.6 µM to 2000 µM as compared to standard acarbose (IC 50 = 822.0 ± 1.5 µM). The most active compound 43 was ∼27-fold more active than acarbose. Kinetic study revealed that compounds 43 , 40 , and 34 were all competitive inhibitors on α-glucosidase with K i of 10 µM, 52 µM, and 150 µM, respectively. Molecular docking demonstrated that the high active inhibitors interacted with α-glucosidase by four types of interactions, including hydrogen bonds, π–π stacking interactions, hydrophobic interactions, and electrostatic interaction. Among all the interactions, the π–π stacking interaction and hydrogen bond played a significant role in a various range of activities of the compounds.

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In this study, the morphological, physicochemical and digestibility properties of Yugan Euryale ferox seeds starch (Y-EFS) were comprehensively analyzed. The results showed that Y-EFS contained 45.85% amylose. These starch granules of Y-EFS appeared as irregular polyhedron shape with smooth surface and relatively uniform size around 2.29 μm. The determined average molecular weight of Y-EFS were 1.85 × 10 5 and 3.00 × 10 3 Da, respectively. X-ray diffraction verified that Y-EFS was a typical A-type starch with 38.84% relative crystallinity, which demonstrated that Y-EFS had a relatively high crystallinity and larger crystallization area. Differential scanning calorimeter analysis showed that Y-EFS had relatively high gelatinization enthalpy (ΔH = 1576.0 J/g) and temperature (To = 84.69 °C, Tp = 110.30 °C and Tc = 118.10 °C). The results of rapid viscometer analyzer demonstrated that pasting temperature of Y-EFS was 82.27 °C, and high setback value indicated that Y-EFS was possibly easy to retrograde. Y-EFS gel displayed small adhesiveness and high hardness. In vitro digestion study showed that Y-EFS was indigestible because of its 37.54% slowly digestible starch and 36.46% resistant starch content. Our results suggest that Y-EFS has great application prospect in hypoglycemic functional foods.

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Chalcone-1-deoxynojirimycin heterozygote (DC-5), a novel compound which was designed and synthesized in our laboratory for diabetes treatment, showed an extremely strong in vitro inhibitory activity on α-glucosidase in our previous studies. In the current research, its potential in vivo anti-diabetic effects were further investigated by integration detection and the analysis of blood glucose concentration, blood biochemical parameters, tissue section and gut microbiota of the diabetic rats. The results indicated that oral administration of DC-5 significantly reduced the fasting blood glucose and postprandial blood glucose, both in diabetic and normal rats; meanwhile, it alleviated the adverse symptoms of elevated blood lipid level and lipid metabolism disorder in diabetic rats. Furthermore, DC-5 effectively decreased the organ coefficient and alleviated the pathological changes of the liver, kidney and small intestine of the diabetic rats at the same time. Moreover, the results of 16S rDNA gene sequencing analysis suggested that DC-5 significantly increased the ratio of Firmicutes to Bacteroidetes and improved the disorder of gut microbiota in diabetic rats. In conclusion, DC-5 displayed a good therapeutic effect on the diabetic rats, and therefore had a good application prospect in hypoglycemic drugs and foods.