Suppression of α- amylase and α- glucosidase is favorable for improvement of postprandial hyperglycemia. Here, the inhibitory mechanisms of epicatechin gallate (ECG) on α- amylase and α- glucosidase are explored by enzyme kinetics , spectroscopy and molecular modeling approaches. ECG was found to have strong inhibitory efficiency against α- amylase and α- glucosidase in mixed−type manners with IC 50 values of 45.30 ± 0.22 and 4.03 ± 0.01 μg/mL, respectively. ECG bound to α- amylase and α- glucosidase forming ECG– α- amylase and ECG– α- glucosidase complexes, causing the conformational changes of the enzymes. Molecular simulation exhibited that ECG located into the active pocket of the enzymes likely contributed by some major amino acid residues Gln63 and Asp197 of α- amylase, and Lys156, Ser157, Arg315 and Asp352 of α- glucosidase, which may prevent the entrance of substrate leading to a decline in enzyme activity . Meanwhile, at the constant IC 50 ratios of ECG to acarbose or epigallocatechin gallate, an obvious antagonism was observed in α- amylase inhibition , while additive and synergistic effects for α- glucosidase. These findings suggest that ECG may be a potential inhibitor of α- amylase and α- glucosidase, which could be used as a nutrient supplement for the prevention of diabetes mellitus.
Hu Yinghui,An Jing,Liu Xiujie,Wang Huiheng,Dai Rongji,Deng Yulin
Enzyme immobilization increases the availability of the enzyme to the substrate with a higher turnover over a considerable period. For this purpose, a variety of mesoporous materials with different diameters were synthesized by various methods using different ratios of P123 (template
agent) to 1,3,5-trimethylbenzene (expanding agent). These versatile materials were then characterized by transmission electron microscopy and N2 adsorption–desorption analysis. α-Glucosidase was successfully immobilized on all the synthesized materials, but the
P123/TMB = 4/3-COOH-PMO material had a higher loading rate and enzyme activity. Furthermore, applications of this material were best performed in a column to immobilize the enzymes. Additionally, the synthesized material was further tested using acarbose as a model compound for drug screening.
The immobilized α-glucosidase was packed into a column and connected to HPLC instrument to screen 20 small molecular compounds. Using this method, several drugs that might strongly inhibit α-glucosidase were identified. Therefore, this method can be further used in
drug screening for chemical drugs and traditional Chinese medicines to expedite new drug research.
Epimedii herba ( Epimedium spp.) is a medicinal and edible plant, and its main active ingredient is icaritin. This study investigates the inhibitory mechanism of icaritin against α-glucosidase and cooperates with acarbose to treat diabetes. Fluorescence quenching, synchronous fluorescence, CD spectroscopy, ANS fluorescence probe, and molecular docking results suggested that after the binding of icaritin. The internal fluorescence of α-glucosidase was statically quenched, and the microenvironment and conformation of α-glucosidase were altered by hydrogen bonding interaction. Interestingly, the combination of acarbose and icaritin exhibited a strong synergistic inhibitory effect. Oral glucose tolerance tests showed that icaritin and acarbose could synergistically reduce postprandial blood glucose (PBG) in mice. In summary, this study highlights the potential of Epimedii herba as a novel functional food for the prevention and management of type 2 diabetes, contributing to its development in nutraceutical applications.
Inhibitory effects (IEs) of flavonoids from Rosa roxburghii and R. sterilis fruits against α-glucosidase were investigated. Crude extract of R. roxburghii fruits ( Rr CE) and R. sterilis fruits ( Rs CE) were extracted with ethanol. The n-butanol extraction of aqueous Rr CE dispersion ( Rr CE - B) showed the greatest inhibition of α-glucosidase. The most abundant three components in Rr CE - B were kaempferol hexose, rutin, and catechin (Cat). The predominant active compounds were characterized as flavonoids by UV–vis spectra. Combination analysis suggested that Rr CE was a favorable choice to combine with acarbose (Aca). After simulated gastric digestion, IEs of flavonoids decreased greatly, especially when sodium nitrite was supplemented in the simulated gastric fluid (SGF). The UV–vis spectra indicated that flavonoids were basically stable in the SGF without sodium nitrite, but were oxidized by the HNO 2 , a natural component in the gastric fluid. The results of this study will help food scientists design special foods for diabetic patients.
危险品化学品经营许可证（带存储）