Showing papers on "Amylase published in 2020"

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

Abstract: 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.

Antioxidant, α-amylase and α-glucosidase inhibitory activities of bound polyphenols extracted from mung bean skin dietary fiber

Abstract: In this study, bound polyphenols were extracted from mung bean skin dietary fiber by acid hydrolysis or alkaline hydrolysis. It was found that alkaline hydrolysis was more thorough than acid hydrolysis, the highest yield of bound polyphenols was 37.638 (mg FAE/g). In addition, the compositions of bound polyphenols were identified and quantified by UPLC-ESI-QTOF-MS/MS and UPLC-ESI-QqQ-MS/MS. In the study of antioxidant properties, we found that with the increase of polyphenol concentration, the scavenging rate of DPPH free radical, the absorption ability of oxygen free radical and the inhibition of ABAP were increased. Moreover, the inhibition rate of bound polyphenols on α-amylase and α-glucosidase increased in a dose dependent manner. The results could provide perspective for using the bound polyphenols in mung bean skin as the functional components of health food.

Inhibition of α-amylase, α-glucosidase and pancreatic lipase by phenolic compounds of Rumex maderensis (Madeira sorrel). Influence of simulated gastrointestinal digestion on hyperglycaemia-related damage linked with aldose reductase activity and protein glycation

Abstract: In this work, we report the in vitro inhibitory potential of Rumex maderensis methanolic extracts (leaves, flowers, and stems) towards key digestive enzymes linked to type-2 diabetes and obesity (α-amylase, α-glucosidase, pancreatic lipase). The inhibitory activity towards aldose reductase and glycation of bovine serum albumin (BSA) is also reported; in these latter assays, the effect of simulated digestion on the bioactivities was evaluated. The inhibitory activities of R. maderensis extracts were statistically compared with the inhibition produced by reference compounds for each assay. The analysed extracts exhibited significant inhibitory activities, which decreased after the gastrointestinal digestion, possibly due to some loss of phenolics that took place during the digestion process. The most important results were observed during the BSA-glycation assay, in which the analysed extracts presented higher potency than a reference compound: aminoguanidine (AMG). This research is the first showing the potential anti-diabetic activity of R. maderensis.

Sourdough Fermentation Degrades Wheat Alpha-Amylase/Trypsin Inhibitor (ATI) and Reduces Pro-Inflammatory Activity.

Abstract: The ingestion of gluten-containing foods can cause wheat-related disorders in up to 15% of wheat consuming populations. Besides the role of gluten, α-amylase/trypsin inhibitors (ATI) have recently been identified as inducers of an innate immune response via toll-like receptor 4 in celiac disease and non-celiac wheat sensitivity. ATI are involved in plant self-defense against insects and possibly in grain development. Notably, they are largely resistant to gastrointestinal proteases and heat, and their inflammatory activity affects not only the intestine, but also peripheral organs. The aim of this study was to understand the changes of ATI throughout the sourdough and yeast-fermented bread-making processes. ATI tetramers were isolated, fluorescein-labelled, and added to a mini-dough bread-making system. When the pH decreased below 4.0 in sourdough fermentation, the ATI tetramers were degraded due to the activation of aspartic proteases, whilst in yeast fermentation, ATI tetramers remained intact. The amylase inhibitory activity after sourdough fermentation decreased significantly, while the concentration of free thiol groups increased. The glutathione reductase activity of Fructilactobacillus sanfranciscensis did not contribute to the reduction of ATI tetramers. Compared to the unfermented wheat, sourdough fermentation was able to decrease the release of pro-inflammatory cytokines monocyte chemoattractant protein-1 (MCP-1) and tumor necrosis factor alpha (TNF-α) in quantitative ATI extracts added to the human monocytic cell line THP-1. The current data suggest that sourdough fermentation can degrade ATI structure and bioactivity, and point to strategies to improve product development for wheat sensitivity patients.

Structural Dependence of Sulfated Polysaccharide for Diabetes Management: Fucoidan From Undaria pinnatifida Inhibiting α-Glucosidase More Strongly Than α-Amylase and Amyloglucosidase.

Abstract: Fucoidan refers to a group of sulfated polysaccharide that is commonly obtained from various species of brown seaweed. Fucoidan has gained increased popularity among researchers in the recent years due to its numerous biological activities, including its inhibitory effects against starch hydrolyzing enzymes such as α-amylase and α-glucosidase. This highlights the potential of fucoidan as an antidiabetic agent in the management and prevention of diabetes mellitus. In this study, the inhibitory effects of fucoidan isolated from the New Zeaweed Undaria pinnatifida seaweed species against three starch hydrolyzing enzymes – α-amylase, α-glucosidase and amyloglucosidase was investigated. It was demonstrated that while the fucoidan exhibited significant inhibitory effects against all the three starch hydrolases, it is an uncompetitive inhibitor of α-amylase and amyloglucosidase, and is a competitive inhibitor of α-glucosidase. Moreover, it exhibited significantly stronger inhibitory effects against α-glucosidase than α-amylase, thus having the desirable characteristics as an antidiabetic agent.

Impacts of Cellulase and Amylase on Enzymatic Hydrolysis and Methane Production in the Anaerobic Digestion of Corn Straw

Abstract: The impacts of enzyme pre-treatments on anaerobic digestion of lignocellulosic biomass were explored by using corn straw as a substrate for enzyme pre-treatment and anaerobic digestion and by utilizing starch and microcrystalline cellulose as substrates for comparative analysis. The cellulase pre-treatment effectively improved the enzymatic hydrolysis of cellulose, decreased the crystallinity, and consequently showed 33.2% increase in methane yield. The methane yield of starch increased by 16.0% through amylase pre-treatment. However, when the substrate was corn straw, both the efficiencies of enzymes and methane production were markedly reduced by the lignocellulosic structure. The corn straw’s methane yields were 277.6 and 242.4 mL·CH4/g·VS with cellulase and amylase pre-treatment, respectively, which was 11.7% and 27.9% higher than that of the untreated corn straw. It may imply that the lignocellulose should be broken up firstly, enzyme pre-treatments could have great potentials when combined with other methods.

Production of Highly Active Extracellular Amylase and Cellulase From Bacillus subtilis ZIM3 and a Recombinant Strain With a Potential Application in Tobacco Fermentation.

Abstract: In this study, a series of bacteria capable of degrading starch and cellulose were isolated from the aging flue-cured tobacco leaves. Remarkably, there was a thermophilic bacterium, Bacillus subtilis ZIM3, that can simultaneously degrade both starch and cellulose at a wide range of temperature and pH values. Genome sequencing, comparative genomics analyses, and enzymatic activity assays showed that the ZIM3 strain expressed a variety of highly active plant biomass-degrading enzymes, such as the amylase AmyE1 and cellulase CelE1. The in vitro and PhoA-fusion assays indicated that these enzymes degrading complex plant biomass into fermentable sugars were secreted into ambient environment to function. Besides, the amylase and cellulase activities were further increased by three- to five-folds by using overexpression. Furthermore, a fermentation strategy was developed and the biodegradation efficiency of the starch and cellulose in the tobacco leaves were improved by 30-48%. These results reveal that B. subtilis ZIM3 and the recombinant strain exhibited high amylase and cellulase activities for efficient biodegradation of starch and cellulose in tobacco and could potentially be applied for industrial tobacco fermentation.

Postprandial Hyperglycemia Lowering Effect of the Isolated Compounds from Olive Mill Wastes - An Inhibitory Activity and Kinetics Studies on α-Glucosidase and α-Amylase Enzymes.

Abstract: In the present study, we isolated seven compounds from olive mill wastes (OMW), one of them being novel, and investigated their antidiabetic potential through inhibition of α-glucosidase and α-amyl...

High amylose wheat starch structures display unique fermentability characteristics, microbial community shifts and enzyme degradation profiles

Abstract: A slower rate of starch digestion in the small intestine increases the amount of resistant starch (RS) entering the large intestine, which is associated with health benefits. Although increasing the amylose (AM) content of dietary starch intake is one way to increase RS, the processes involved in gut microbial hydrolysis and fermentation of high AM-RS substrates are poorly understood. In this study, five high AM wheat (HAW) starches ranging from 47% AM to 93% AM and a wild type (37% AM), in both native granular and cooked forms, were subjected to in vitro fermentation with a porcine faecal inoculum. Fermentation kinetics, temporal microbial changes, amylolytic enzyme activities and residual starch were determined. All granular starches showed similar fermentation characteristics, independent of AM level, whereas cooking accelerated fermentation of lower AM but slowed fermentation of high AM starches. HAW starches with a very high AM content (>85%) all had similar fermentation kinetics and short-chain fatty acid end-product profiles. Microbial α-amylase, β-amylase, pullulanase and amyloglucosidase enzymatic activities were all detected and followed fermentation kinetics. HAW starch promoted shifts in the microbial community, with increases of the family Lachnospiraceae and the genus Treponema observed, while the genera Prevotella and Streptococcus were reduced in comparison to 37% AM. Overall, these findings suggest that any HAW starch incorporated into high RS food products would be expected to have beneficial microbiota-mediated effects in terms of fermentation kinetics and end products.

Optimization and immobilization of amylase produced by Aspergillus terreus using pomegranate peel waste

Abstract: Amylases are amongst the most important hydrolytic enzymes that are used in numerous industrial uses reaching for food to pharmaceuticals Immobilization of enzymes can proposal several assistances as reusability and retrieval from their products improve strength under both operating and storing environments Marine fungal isolate was recovered from red sea water at Sharm El-Sheikh Province and was tested for amylase activity using different agricultural wastes as substrate It was found that pomegranate peel was the best substrate for amylase production (339 U/ml) Thus, it was subjected for identifying by 18S rDNA gene The phylogenetic analysis results indicated that this fungal isolate belonged to Aspergillus species with similarity of 99% and named as Aspergillus terrus SS_RS-NE Its nucleotide sequences were deposited in NCBI GenBank under accession no of MN901491 Some parameters affecting amylase activity using pomegranate peel as substrate were studied The results denoted that, the highest amylase activity of 34069 U/ml using 15% pomegranate peel at 30 °C, pH 60 on 5 days incubation time by Aspergillus terreus The produced crude enzyme was partially purified with 80% ammonium sulfate followed by dialysis The enzyme activity was 1246 U/ml and 2411 U/ml employing ammonium sulfate precipitation and dialysis respectively The partially purified amylase was immobilized with 2% sodium alginate and the results showed the highest immobilized enzyme yield was 928% The characterizations of immobilized amylase were studied and the results indicated that, the maximal immobilized amylase activity was 25225 U/ml with 2% starch as a substrate at optimum pH value of 65, temperature at 60 °C and 10 min reaction time in comparison to maximal free amylase enzyme at pH 5, 50 °C after 40 min The results also indicated the immobilized amylase was stable at 60 °C for 20 min Aspergillus terrus SS_RS-NE (MN901491) was isolated and genetically identified It has the ability to produce amylase enzyme using pomegranate peel waste with a yield of 339 U/ml The crude enzyme was partially purified by ammonium sulfate followed by dialysis The maximal immobilized amylase activity of 25225 U/ml was obtained under optimized some culture conditions and medium nutrient parameters