Fruit, vegetables, and mushrooms for the preparation of extracts with α-amylase and α-glucosidase inhibition properties: A review.

Inhibition mechanism of ferulic acid against α-amylase and α-glucosidase

Background α-Amylase is a key enzyme of starch digestion, playing an important role in deciding glucose releasing amount. Inhibition of the enzyme activity by polyphenols is suggested as a potential approach in controlling starch digestion and regulating postprandial hyperglycaemia. Scope and approach α-Amylase inhibition by polyphenols results from polyphenol-enzyme binding interactions that have been characterized by inhibition kinetics, spectroscopy and thermodynamic analyses. To further elucidate the inhibition mechanism, making the inhibition visible, studies regarding biochemical, biophysical and molecular mechanisms are summarized. Key findings and conclusions Macroscopically, α-amylase inhibition causes retarded digestion of starchy substrates, visible from the production reaction color or fluorescence. Microscopically, detail inhibition kinetics reveals the inhibition types and theoretic interacting sites. X-ray diffraction (XRD) is powerful in extracting the binding modes (detail amino acid residues, polyphenol moieties and interaction forces involved in polyphenol-amylase interactions). Through polyphenol-amylase binding analysis by XRD and NOE correlation of polyphenol atoms by rotating-frame Overhauser enhancement spectroscopy (ROESY)-NMR, the contribution of intramolecular interactions between polyphenol ring-groups to the binding is evaluated. The key phenolic moieties for binding are also obtained by saturation transfer difference (STD)-NMR and/or molecular docking. Besides, by combing fluorescent properties and thermal stability of α-amylase, the enzyme conformational changes may be obtained. Additionally, following delayed starch digestion, α-amylase inhibition is indicated by retarded increase in blood glucose level and colonic fermentation properties of undigested starch. Conclusively, visible characterization helps to understand how a polyphenol develops the inhibitory activity, and to reasonably explore functional factors for alleviation of carbohydrate metabolism disorder.

Inhibition of α-amylase by polyphenolic compounds: Substrate digestion, binding interactions and nutritional intervention

Quantification of high-power ultrasound induced damage on potato starch granules using light microscopy (vol 19, pg 421, 2012)

Dietary fiber polysaccharides of amaranth, buckwheat and quinoa grains: A review of chemical structure, biological functions and food uses.

Inhibition of porcine pancreatic α-amylase activity by chlorogenic acid

Controlled ultrasound treatments modify the morphology and physical properties of rice starch rather than the fine structure.

During rice dehulling and polishing, about 14% of the rice will be broken. How to utilize those low-value broken rice effectively is a critical issue. In this study, extrusion technology was applied to restructure the broken rice. The morphology, molecular structure and digestibility of intact, broken and extruded rice were investigated with SEM, XRD, FT-IR as well as simulated in vitro gastrointestinal digestion technique. The extruded rice showed a rough surface and the crystalline structure transformed its diffraction type from an A-type to a mixture of B- and V-types. The equilibrium starch hydrolysis (C∞) and kinetic constant (k) of extruded rice was significantly lower than that of the broken rice, which was 76.10%, 2.91 × 10−2 (min−1) and 80.90%, 6.42 × 10−2 (min−1), respectively. Our results indicated that extrusion processing could modify the microstructure and digestibility of rice effectively, and be an optional way to produce staple rice with lower digestibility.

Effect of extrusion processing on the microstructure and in vitro digestibility of broken rice

Caffeic acid and maize starches were combined to prepare maize starch-caffeic acid complexes. The physicochemical properties of the complexes were characterised by X-ray, FT-IR, RVA and DSC, while the digestibility was evaluated using an in vitro digestion model. XRD patterns revealed that the complexation with caffeic acid decreased the crystallinity of maize starch from 35.71% to 19.87%, while the crystal type remained unchanged (A-type). The solubility, swelling power and freeze–thaw stability of the complexes were greater when compared with native maize starch, and the crystal type and thermal properties were confirmed by XRD, RVA and DSC, respectively. FT-IR analysis confirmed that the short-range structure of maize starch-caffeic acid complexes was reduced since the R1047/1022 value decreased from 0.932 to 0.880. Furthermore, complexes of maize starch-caffeic acid were less amenable to in vitro digestion than native maize starch. Our study might provide an option for the utilisation of caffeic acid in food systems to reduce starch hydrolysis.

Wenhan Yang

Papers

Inhibition mechanism of ferulic acid against α-amylase and α-glucosidase

Inhibition of porcine pancreatic α-amylase activity by chlorogenic acid

Controlled ultrasound treatments modify the morphology and physical properties of rice starch rather than the fine structure.

Effect of extrusion processing on the microstructure and in vitro digestibility of broken rice

Physicochemical and digestibility characterisation of maize starch–caffeic acid complexes