Human Pancreatic Α-amylase Research Articles

Inhibition of Human Salivary and Pancreatic α-Amylase by Resveratrol Oligomers.

A key strategy to mitigate postprandial hyperglycemia involves inhibiting α-amylases, which commence the starch digestion process in the gut. This study examined the inhibitory effects of resveratrol and stilbenoid tetramers, vaticanol B, (-)-hopeaphenol, and vatalbinoside A on human salivary and pancreatic α-amylases experimentally and through molecular docking studies. Vaticanol B demonstrated the most potent inhibition with IC50 values of 5.3 ± 0.3 μM for salivary and 6.1 ± 0.5 μM for pancreatic α-amylase (compared to acarbose with IC50 values of 1.2 ± 0.1 μM and 0.5 ± 0.0 μM, respectively). Kinetic analysis suggested a competitive inhibition mode for vaticanol B. Resveratrol and vatalbinoside A were poor inhibitors of human α-amylases, while (-)-hopeaphenol exhibited moderate inhibition. Molecular docking supported the inhibition data, and several aspects of the structural configurations explained the stronger inhibition exerted by vaticanol B. Overall, vaticanol B shows promise as a natural alternative to acarbose for inhibiting α-amylase.

Design and synthesis of new coumarin-1,2,3-triazole hybrids as new antidiabetic agents: In vitro α-amylase, α-glucosidase inhibition, anti-inflammatory, and docking study

The current study focuses on the synthesis of coumarin-triazole hybrids (7i-t) starting from 4-hydroxy benzaldehyde or 4-hydroxyacetophenone (1a-b) and propargyl bromide. On the other hand, coumarin derivatives (5c-h) were prepared by Pechmann cyclization and treated with sodium azide to give the corresponding 3-azido methyl coumarins (6c-h). Finally, 1,3-dipolar cycloaddition between compounds 6c-h and terminal alkyne 2a-b produces coumarin-triazole hybrids (7i-t) utilizing click chemistry approaches that are high yielding, wide in scope and simple to perform. The structural proofs of the newly synthesized coumarin-triazole hybrids (7i-t) are proved by various spectroscopic techniques, including IR, 1H NMR, 13C NMR, and LC-MS. The synthesized new coumarin triazole hybrids (7i-t) were explored for their antihyperglycemic potential and therefore evaluated for α-glucosidase and α-amylase inhibitory activities along with anti-inflammatory. The results suggest that among the series, compound 7l showed excellent activity with an IC50 value of 0.67±0.014 mg/mL and 0.72±0.012 mg/mL for α-amylase, and α-glucosidase inhibitory potential while compound 7o showed promising anti-inflammatory activity with IC50 value of 0.54±0.003 mg/mL. To support the above findings, molecular docking studies were performed, which confirmed the interaction of the synthesized molecules 7i-t with an effective binding energy of -9.0 to -10.6 kcal/mol at the active site of the enzyme human pancreatic α-amylase (PDB ID: 1B2Y). Therefore, these scaffolds have the potential to function as lead candidates for antidiabetic and anti-inflammatory activities.

Ultrasound-assisted synthesis of 4-thiazolidinone Schiff bases and their antioxidant, α-glucosidase, α-amylase inhibition, mode of inhibition and computational studies

AbstractDiabetes mellitus (DM) has become a growing concern to global public health, being at the forefront of acute disorders and causes of mortality across the globe. Clinically approved drugs that are currently being used are faced with severe side effects, consequently necessitating the development of new drugs with no/fewer side effects and improved pharmacological potency. Herein, we report a rapid and efficient synthesis of thiazolidinone Schiff bases (2a-2t) from benzylidenehydrazines and thioglycolic acid under neat conditions through ultra-sonication. All the synthesized compounds were obtained in exceptional yields (89–95%) and confirmed by 1D and 2D nuclear magnetic resonance (NMR) spectroscopy, as well as High-resolution mass spectrometry (HRMS). The synthesized compounds were then evaluated for their antidiabetic activity through α-glucosidase and α-amylase inhibitory potentials and their antioxidant activity through Nitric Oxide (NO), 2,2′-diphenyl-1-picrylhydrazyl (DPPH), and Ferric reducing antioxidant power (FRAP) assays. Among them, 2q (IC50 = 96.63 μM) and 2h (IC50 = 125.27 μM) emerged as the most potent derivatives against α-amylase relative to reference drug acarbose (IC50 = 131.63 µM), respectively. Antioxidant evaluation further revealed that the synthesized derivatives were excellent NO scavengers disclosing 2n (IC50 = 44.95 µM) as the most potent derivative. Moreover, in silico ADME calculations predicted these compounds to have excellent drug-like properties. Kinetic studies disclosed the mode of α-amylase inhibition as competitive while molecular docking studies of the most active derivatives performed into the binding active site of human pancreatic α-amylase enzyme deciphered their ligand-protein interactions that explicated their observed experimental potencies.

Virtual screening, ADME prediction, drug-likeness, and molecular docking analysis of Fagonia indica chemical constituents against antidiabetic targets.

Fagonia indica from Zygophyllaceae family is a medicinal specie with significant antidiabetic potential. The present study aimed to investigate the in vitro antidiabetic activity of Fagonia indica crude extract followed by an in silico screening of its phytoconstituents. For this purpose, crude extract of Fagonia indica was prepared and divided in three different parts, i.e., n-hexane, ethyl acetate, and methanolic fraction. Based on in vitro outcomes, the phytochemical substances of Fagonia indica were virtually screened through a literature survey and a screening library of compounds (1-13) was prepared. The clinical potential of these novel drug candidates was assessed by applying an ADME screening profile. Findings of SwissADME indicators (Absorption, Distribution, Metabolism, and Excretion) for the compounds (1-13) presented relatively optimal physicochemical characteristics, drug-likeness, and medicinal chemistry. The antidiabetic action of these leading drug candidates was optimized through molecular docking analysis against 3 different human pancreatic α-amylase macromolecular targets with (PDB ID 1B2Y), (PDB ID 3BAJ), and (PDB ID: 3OLI) by applying Virtual Docker (Molegro MVD). Metformin was taken as a reference standard for the sake of comparison. In vitro antidiabetic evaluation gave good results with promising α-amylase inhibitory action in the form of IC50 values, as for n-hexane extract = 206.3µM, ethyl acetate = 41.64µM, and methanolic extract = 9.61µM. According to in silico outcomes, all 13 phytoconstituents possess the best binding affinity with successful MolDock scores ranging from - 97.2003 to - 65.6877kcal/mol and show a great number of binding interactions than native drug metformin. Therefore, the current work concluded that the diabetic inhibition prospective of extract and the compounds of Fagonia indica may contribute to being investigated as a new class of antidiabetic drug or drug-like candidate for further studies.

Design, Synthesis of 3-(Aryl)-1-(2-p-tolylthiazol-4-yl)prop-2-en-1-ones as Alpha(α)-Amylase Inhibitors.

α-Amylase inhibition is vital in controlling diabetic complications. Herein, we have synthesized a hybrid scaffold based on thiazole-chalcone to access α-amylase inhbition. The proposed structures were verified with spectroscopic techniques (UV-Vis., FT-IR, 1H-, 13C-NMR, and elemental analysis). The synthesized compounds were evaluated for their α-amylase and antioxidant potential. In vitro hemolytic assay was performed to test biocompatibility of all compounds. Among tested compounds, 4 c (IC50=3.8 μM), 4 g (IC50=14.5 μM), and 4 f (IC50=17.1 μM) were found excellent α-amylase inhibitors. However, none of the tested compounds exhibited significant antioxidant activity. All compounds showed less lysis than Triton X-100, but compounds 4 f and 4 h had the least lysis at all tested concentrations and were found to be safe for human erythrocytes. Molecular docking study was performed to evaluate the binding interactions of ligands with human pancreatic α-amylase (HPA). The binding score -8.09 to -8.507 kcal/mol revealed strong binding interactions in the ligand-protein complex. The docking results supplemented the observed α-amylase inhibition and hence augment the scaffold to serve as leads for the antidiabetic drug development.

Investigation into the Phytochemical Composition, Antioxidant Properties, and In-Vitro Anti-Diabetic Efficacy of Ulva lactuca Extracts.

In this research, the chemical compositions of various extracts obtained from Ulva lactuca, a type of green seaweed collected from the Nador lagoon in the northern region of Morocco, were compared. Their antioxidant and anti-diabetic properties were also studied. Using GC-MS technology, the fatty acid content of the samples was analyzed, revealing that palmitic acid, eicosenoic acid, and linoleic acid were the most abundant unsaturated fatty acids present in all samples. The HPLC analysis indicated that sinapic acid, naringin, rutin, quercetin, cinnamic acid, salicylic acid, apigenin, flavone, and flavanone were the most prevalent phenolic compounds. The aqueous extract obtained by maceration showed high levels of polyphenols and flavonoids, with values of 379.67 ± 0.09 mg GAE/g and 212.11 ± 0.11 mg QE/g, respectively. This extract also exhibited an impressive ability to scavenge DPPH radicals, as indicated by its IC50 value of 0.095 ± 0.12 mg/mL. Additionally, the methanolic extract obtained using the Soxhlet method demonstrated antioxidant properties by preventing β-carotene discoloration, with an IC50 of 0.087 ± 0.14 mg/mL. Results from in-vitro studies showed that extracts from U. lactuca were able to significantly inhibit the enzymatic activity of α-amylase and α-glucosidase. Among the various extracts, methanolic extract (S) has been identified as the most potent inhibitor, exhibiting a statistically similar effect to that of acarbose. Furthermore, molecular docking models were used to evaluate the interaction between the primary phytochemicals found in these extracts and the human pancreatic α-amylase and α-glucosidase enzymes. These findings suggest that U. lactuca extracts contain bioactive substances that are capable of reducing enzyme activity more effectively than the commercially available drug, acarbose.

Two rare flavonoid glycosides from Litsea glutinosa (Lour.) C. B. Rob.: experimental and computational approaches endorse antidiabetic potentiality

BackgroundLitsea glutinosa (Lour.) C. B. Rob. belongs to the Litsea genus and is categorized under the family of Lauraceae. The study aimed to investigate the phytoconstituents and pharmacological properties of methanol extract of leaves of Litsea glutinosa, focusing on antidiabetic activity via in vivo and in silico techniques.MethodsExtensive chromatographic and spectroscopic techniques were applied to isolate and characterize the constituents from the L. glutinosa plant species. The antidiabetic activity was studied in streptozotocin-induced diabetes mice, and the computational study of the isolated compounds was carried out by utilizing AutoDock Vina programs. In addition, the pharmacokinetic properties in terms of absorption, distribution, metabolism and excretion (ADME) and toxicological profiles of the isolated compounds were examined via in silico techniques.ResultsIn the present study, two flavonoid glycosides 4΄-O-methyl (2 ̋,4 ̋-di-E-p-coumaroyl) afzelin (1) and quercetin 3-O-(2 ̋,4 ̋-di-E-p-coumaroyl)-α-L-rhamnopyranoside (2) were isolated from the leaves of L. glutinosa and characterized by 1H and 13C NMR, COSY, HSQC, HMBC, and mass spectral data. Although compounds 1 and 2 have been reported twice from Machilis litseifolia and Lindera akoensis, and Machilis litseifolia and Mammea longifolia, respectively, this is the first report of this isolation from a Litsea species. Administering the methanolic extract of L. glutinosa at doses of 300 and 500 mg/kg/day to mice with diabetes induced by streptozotocin led to a significant decrease in fasting blood glucose levels (p < 0.05) starting from the 7th day of treatment. Besides, the computational study and PASS analysis endorsed the current in vivo findings that the both isolated compounds exerted higher binding affinities to human pancreatic α-amylase and aldose reductase than the conventional drugs. The in silico ADMET analysis revealed that the both isolated compounds have a favorable pharmacokinetic and safety profile suitable for human consumption.ConclusionAccording to the current outcomes obtained from in vivo and in silico techniques, the leaf extract of L. glutinosa could be a natural remedy for treating diabetes, and the isolated phytoconstituents could be applied against various illnesses, mainly hyperglycemia. However, more investigations are required for extensive phytochemical isolation and pharmacological activities of these phytoconstituents against broader targets with exact mechanisms of action.

The substitution sites of hydroxyl and galloyl groups determine the inhibitory activity of human pancreatic α-amylase in twelve tea polyphenol monomers

Tea polyphenols have been reported as potential α-amylase inhibitors. However, the quantitative structure–activity relationship (QSAR) between tea polyphenols and human pancreas α-amylase (HPA) is not well understood. Herein, the inhibitory effect of twelve tea polyphenol monomers on HPA was investigated in terms of inhibitory activity, as well as QSAR analysis and interaction mechanism. The results revealed that the HPA inhibitory activity of theaflavins (TFs), especially theaflavin-3′-gallate (TF-3′-G, IC50: 0.313 mg/mL), was much stronger than that of catechins (IC50: 18.387–458.932 mg/mL). The QSAR analysis demonstrated that the determinant for the inhibitory activity of HPA was not the number of hydroxyl and galloyl groups in tea polyphenol monomers, while the substitution sites of these groups potentially might play a more important role in modulating the inhibitory activity. The inhibition kinetics and molecular docking revealed that TF-3′-G as a mixed-type inhibitor had the lowest inhibition constant and bound to the active sites of HPA with the lowest binding energy (−7.74 kcal/mol). These findings could provide valuable insights into the structures-activity relationships between tea polyphenols and the HPA inhibitors.

Exploration of Anti-Diabetic Potential of Rubus ellipticus smith through Molecular Docking, Molecular Dynamics Simulation, and MMPBSA Calculation

Diabetes is a chronic metabolic disorder affecting a majority of the population worldwide. Hyperglycemia leading to diabetes mellitus could be managed through the inhibition of human pancreatic α-amylase enzyme. Phytochemicals are frequently reported to possess anti-diabetic activity through inhibition of normal functioning of α-amylase. This study aims to find potential α-amylase inhibitors from Rubus ellipticus Smith with molecular-level understanding using different computational tools. From the molecular docking calculations, rubuside F and rubuside D possessed good binding affinity of -10.0 kcal/mol and -9.9 kcal/mol, respectively better than the reference drugs (acarbose, miglitol, voglibose and metformin). Both the compounds showed good geometrical stability from molecular dynamics simulation accessed in terms of RMSD, hydrogen bond count, SASA, Rg and RMSF. Binding free energy changes of -27.92±4.15 kcal/mol and -28.75±4.15 kcal/mol, respectively for the two ligands indicated sustained thermodynamic spontaneity present in the adducts. The two phytochemicals could be proposed as potential inhibitors of human pancreatic α-amylase for the treatment of diabetes. Further, in vitro and in vivo experiments are recommended for the verification of computational insights in the course of drug design and discovery process.

In Silico and In Vitro Analyses to Repurpose Quercetin as a Human Pancreatic α-Amylase Inhibitor.

Human pancreatic α-amylase (HPA), situated at the apex of the starch digestion hierarchy, is an attractive therapeutic approach to precisely regulate blood glucose levels, thereby efficiently managing diabetes. Polyphenols offer a natural and multifaceted approach to moderate postprandial sugar spikes, with their slight modulation in carbohydrate digestion and potential secondary benefits, such as antioxidant and anti-inflammatory effects. Taking into consideration the unfavorable side effects of currently available commercial medications, we aimed to study a library of polyphenols attributed to their remarkable antidiabetic properties and screened the most potent HPA inhibitor via a comprehensive in silico study encompassing molecular docking, molecular mechanics with generalized Born and surface area solvation (MM/GBSA) calculation, molecular dynamics (MD) simulation, density functional theory (DFT) study, and pharmacokinetic properties followed by an in vitro assay. Significant hydrogen bonding with the catalytic triad residues of HPA, prominent MM/GBSA binding energy of -27.03 kcal/mol, and the stable nature of the protein-ligand complex with regard to 100 ns MD simulation screened quercetin as the best HPA inhibitor. Additionally, quercetin showed strong reactivity in the substrate-binding pocket of HPA and exhibited favorable pharmacokinetic properties with a considerable inhibitory concentration (IC50) of 57.37 ± 0.9 μg/mL against α-amylase. This study holds prospects for HPA inhibition and suggests quercetin as an approach to therapy for diabetes; however, it is imperative to conduct further research.

Control of postprandial hyperglycemia by oral administration of the sea anemone mucus-derived α-amylase inhibitor (magnificamide)

Diabetes mellitus is a serious threat to human health in both developed and developing countries. Optimal disease control requires the use of a diet and a combination of several medications, including oral hypoglycemic agents such as α-glucosidase inhibitors. Currently, the arsenal of available drugs is insufficient, which determines the relevance of studying new potent α-amylase inhibitors. We implemented the recombinant production of sea anemone derived α-amylase inhibitor magnificamide in Escherichia coli. Peptide was isolated by a combination of liquid chromatography techniques. Its folding and molecular weight was proved by 1H NMR and mass spectrometry. The Ki value of magnificamide against human pancreatic α-amylase is 3.1 nM according to Morrison equation for tight binding inhibitors. Our study of the thermodynamic characteristics of binding of magnificamide to human salivary and pancreatic α-amylases by isothermal titration calorimetry showed the presence of different binding mechanisms with Kd equal to 0.11 µM and 0.1 nM, respectively. Experiments in mice with streptozotocin-induced diabetes mimicking diabetes mellitus type 1 were used to study the efficiency of magnificamide against postprandial hyperglycemia. It was found that at a dose of 0.005 mg kg–1, magnificamide effectively blocks starch breakdown and prevents the development of postprandial hyperglycemia in T1D mice. Our results demonstrated the therapeutic potential of magnificamide for the control of postprandial hyperglycemia.

Hypoglycemic activity of Syzygium cumini (L.) Skeels seed extracts: an approach to in vitro, in vivo, and in silico studies

This research is carried out to explore the hypoglycemic activity of Syzygium cumini seed extracts by in vitro, in vivo, and in silico methods. For in vitro studies the α-amylase and α-glucosidase enzyme inhibition assays were employed. For in vivo studies 30 alloxan induced Wistar rats were used. They were orally administered with glibenclamide and low/high dose of the extracts and were monitored regularly for the change in blood glucose levels for about 28 days. The in silico molecular docking was conducted to evaluate the binding interaction of 1,2,3-Benzenetriol with human pancreatic α-amylase and α-glucosidase. It was found that all the extracts were able to inhibit the α-amylase and α-glucosidase enzymes. Among which the acetone extract showed greater inhibition with 72.52 ± 0.51% and 63.02 ± 0.73% for both the enzymes, respectively. There was significant (p < 0.05) reduction in blood glucose levels in the rats administered with glibenclamide and extracts. In silico docking results revealed that the compound 1,2,3-Benzenetriol exhibited the highest binding affinity for human pancreatic α-amylase with binding energy −7.7 kcal/mol. Thus suggesting the utilization of S. cumini seeds in the management of diabetes mellitus. Communicated by Ramaswamy H. Sarma

In silico docking studies of alpha-amylase inhibitors from the methanol extract of Aloe vera

In the current study, potent inhibitors of a-amylase, one of the significant regulating enzymes in diabetes, were identified from the methanolic extract of Aloe barbadensis miller (Aloe vera), an indigenous herbal plant used to treat carbohydrate absorption problems such as diabetes and obesity. The Aloe vera gel extract was dried, ground, macerated with methanol and subjected to phytochemical screening, which was characterized by gas chromatography. Since there is a rapid increase in computational methods to predict the association between two molecules, molecular docking studies assessed the effect of AVM (Aloe vera methanol) extract in inhibiting the enzyme alpha-amylase. The molecules derived from GC-MS analysis were employed as ligands for the receptor α-amylase in molecular docking experiments. The protein target used in this study was the human pancreatic α-amylase with PDB-ID -2QV4. The protein target and ligand structures were obtained from PDB and Pubchem databases respectively and docking studies were performed using PyRx. In this study, we intended to find distinct phytochemical substances from the Aloe vera plant as α-amylase inhibitors with an objective that the molecular docking studies provided in this study might result in the discovery of effective α-amylase inhibitors for diabetic management.

Plant-Based Bioactive Phthalates Derived from Hibiscus rosa-sinensis: As In Vitro and In Silico Enzyme Inhibition.

Hibiscus rosa-sinensis is an attractive, ever-blossoming, and effortlessly available plant around the globe. The fabulous flowers of H. rosa-sinensis enjoy a significant status in folk medicine throughout the world and comprise a range of phyto constituents due to which this splendid flower owns numerous biological and pharmaceutical activities like antioxidant, antifungal, antimicrobial, anti-inflammatory, antipyretic, antidiabetic, and antifertility activity. Considering this, column chromatographic isolation of the phytoconstituents of ethyl acetate fraction of the flowers of H. rosa-sinensis was performed. A series of five phthalates including Di-n-octyl phthalate (HR1), ditridecyl phthalate (HR2), 1-allyl 2-ethyl phthalate (HR3), diethyl phthalate (HR4), and bis (6-methylheptyl) phthalate (HR5) were isolated. The structures of the isolated phthalates were elucidated by gas chromatography-mass spectrometry, 1H NMR, and 13C NMR. In silico and in vitro antidiabetic and antioxidant potential and DFT studies of isolated phthalates were carried out. In our study, isolated ligands were explored as potent antidiabetic as well as antioxidant agents as they exhibited good binding affinity (in in vitro and in silico experiments) against all selected protein targets. Compounds HR1-HR5 showed that the binding affinity value ranged from -5.9 to -5.2 kcal/mol, -5.5 to -4.3 kcal/mol, and -5.0 to -4.1 kcal/mol for target proteins 1HNY, 2I3Y, and 5O40, respectively. Among all isolated phthalates, HR5 can be a lead compound as it showed the best binding affinity with human pancreatic α-amylase (ΔG = -5.9 kcal/mol) and displayed a minimum inhibition concentration (IC50) of 11.69 μM among all phthalates. Compound HR1 was the best docked and scored compound for inhibiting glutathione peroxidase; however, HR2 possessed the lowest binding score of -5.0 kcal/mol, thus indicating the highest potential among isolated phthalates for inhibiting the superoxide dismutase. Furthermore, the top-ranked docked ligand-protein complex for each protein was assessed for stability of protein and complex mobility by molecular dynamics simulation using the IMOD server.

Exploration of human pancreatic alpha-amylase inhibitors from Physalis peruviana for the treatment of type 2 diabetes

Type 2 Diabetes (T2D), a chronic metabolic disorder characterized by persistent hyperglycemia, accounts for ∼90% of all types of diabetes. Pancreatic α-amylase is a potential drug target for preventing postprandial hyperglycemia and inhibiting T2D in humans. Although many synthetic drugs have been identified against pancreatic α-amylase, however, reported several side effects, and plant-derived natural products are less explored against T2D. This study tested 34 flavonoids derived from the plant Physalis peruviana against the human pancreatic α-amylase (HPA) using in silico computational approaches such as molecular docking and molecular dynamics simulation approaches. Schrödinger, a drug discovery package with modules applicable for molecular docking, protein-ligand interaction analysis, molecular dynamics, post-dynamics simulation, and binding free energy calculation, was employed for all computational studies. Four flavonoids, namely, Chlorogenic acid, Withaperuvin F, Withaperuvin H, and Rutin, were picked based on their docking score ranging between −7.03 kcal/mol and −11.35 kcal/mol compared to the docking score −7.3 kcal/mol of reference ligand, i.e. Myricetin. The molecular dynamics analysis suggested that all flavonoids showed considerable stability within the protein’s catalytic pocket, except chlorogenic acid, which showed high deviation during the last 15 ns. However, the interactions observed in initial docking and extracted from the simulation trajectory involved > 90% identical residues, indicating the affinity and stability of the docked flavonoids with the protein. Therefore, all four compounds identified in this study are proposed as promising antidiabetic candidates and should be further considered for their in vitro and in vivo validation. Communicated by Ramaswamy H. Sarma

Study of the Phytochemical Composition, Antioxidant Properties, and In Vitro Anti-Diabetic Efficacy of Gracilaria bursa-pastoris Extracts.

In this study, a comparison was made of the chemical makeup of different extracts obtained from Gracilaria bursa-pastoris, a type of red seaweed that was gathered from the Nador lagoon situated in the northern part of Morocco. Additionally, their anti-diabetic and antioxidant properties were investigated. The application of GC-MS technology to analyze the fatty acid content of the samples revealed that linoleic acid and eicosenoic acid were the most abundant unsaturated fatty acids across all samples, with palmitic acid and oleic acid following in frequency. The HPLC analysis indicated that ascorbic and kojic acids were the most prevalent phenolic compounds, while apigenin was the most common flavonoid molecule. The aqueous extract exhibited significant levels of polyphenols and flavonoids, registering values of 381.31 ± 0.33 mg GAE/g and 201.80 ± 0.21 mg QE/g, respectively. Furthermore, this particular extract demonstrated a remarkable ability to scavenge DPPH radicals, as evidenced by its IC50 value of 0.17 ± 0.67 mg/mL. In addition, the methanolic extract was found to possess antioxidant properties, as evidenced by its ability to prevent β-carotene discoloration, with an IC50 ranging from 0.062 ± 0.02 mg/mL to 0.070 ± 0.06 mg/mL. In vitro study showed that all extracts significantly inhibited the enzymatic activity of α-amylase and α-glucosidase. Finally, molecular docking models were applied to assess the interaction between the primary phytochemicals identified in G. bursa-pastoris extracts and the human pancreatic α-amylase and α-glucosidase enzymes. The findings suggest that these extracts contain bioactive substances capable of reducing enzyme activity more effectively than the commercially available drug acarbose.

How and When Does an Enzyme React? Unraveling α-Amylase Catalytic Activity with Enhanced Sampling Techniques

Enzymatic catalysis is a complex process that can involve multiple conformations of the enzyme:substrate complex and several competitive reaction pathways, resulting in a multi-dimensional free energy landscape. The study of enzymatic activity often requires deep knowledge of the system to establish the catalytic mechanism and identify the possible reactive conformations of the complex. Here, we present an enhanced sampling and machine learning-based approach to explore the catalytic reaction space and characterize the transformation from reactive to non-reactive conformations with minimal a priori knowledge of the system. We applied this approach to study the rate-determining step of the glycolysis reaction of maltopentose catalyzed by human pancreatic α-amylase, an important enzyme in glucose production as well as a major drug target for the treatment of type-II diabetes. We unravel the complexity of the enzymatic reaction, reveal three binding modes of the substrate within the active site, and highlight the role of water in the catalytic process and in the stepwise conversion of reaction-ready to non-reactive conformations. Overall, these insights offer atomistic details on the catalytic mechanism and dynamics of the active site, allowing one to shed light on two fundamental questions in enzymatic catalysis, that is how and when does an enzyme react?

Insights on the Hypoglycemic Potential of Crocus sativus Tepal Polyphenols: An In Vitro and In Silico Study.

Post-prandial hyperglycemia typical of diabetes mellitus could be alleviated using plant-derived compounds such as polyphenols, which could influence the activities of enzymes involved in carbohydrate digestion and of intestinal glucose transporters. Here, we report on the potential anti-hyperglycemic effect of Crocus sativus tepals compared to stigmas, within the framework of valorizing these by-products of the saffron industry, since the anti-diabetic properties of saffron are well-known, but not those of its tepals. In vitro assays showed that tepal extracts (TE) had a greater inhibitory action than stigma extracts (SE) on α-amylase activity (IC50: TE = 0.60 ± 0.09 mg/mL; SE = 1.10 ± 0.08 mg/mL; acarbose = 0.051 ± 0.07) and on glucose absorption in Caco-2 differentiated cells (TE = 1.20 ± 0.02 mg/mL; SE = 2.30 ± 0.02 mg/mL; phlorizin = 0.23 ± 0.01). Virtual screening performed with principal compounds from stigma and tepals of C. sativus and human pancreatic α-amylase, glucose transporter 2 (GLUT2) and sodium glucose co-transporter-1 (SGLT1) were validated via molecular docking, e.g., for human pancreatic α-amylase, epicatechin 3-o-gallate and catechin-3-o-gallate were the best scored ligands from tepals (-9.5 kcal/mol and -9.4 kcal/mol, respectively), while sesamin and episesamin were the best scored ones from stigmas (-10.1 kcal/mol). Overall, the results point to the potential of C. sativus tepal extracts in the prevention/management of diabetes, likely due to the rich pool of phytocompounds characterized using high-resolution mass spectrometry, some of which are capable of binding and interacting with proteins involved in starch digestion and intestinal glucose transport.

Macromolecular α-glucans with α-1,3/α-1,4 branching structures produced using dual glycosyltransferases: Elucidation of physicochemical and slowly digestible properties

Amylosucrase from Neisseria polysaccharea (NpAS) produces the linear amylose-like α-glucans by the elongation property from sucrose, and 4,3-α-glucanotransferase from Lactobacillus fermentum NCC 2970 (4,3-αGT) newly synthesizes the α-1,3 linkages after cleaving the α-1,4 linkages by the glycosyltransferring property. This study focused on the synthesis of high molecular α-1,3/α-1,4-linked glucans by combining NpAS and 4,3-αGT and analyzed their structural and digestive properties. The enzymatically synthesized α-glucans have a molecular weight of >1.6 × 107 g mol−1, and the α-4,3 branching ratios on the structures increased as the amount of 4,3-αGT increased. The synthesized α-glucans were hydrolyzed to linear maltooligosaccharides and α-4,3 branched α-limit dextrins (α-LDx) by human pancreatic α-amylase, and the amounts of produced α-LDx were increased depending on the ratio of synthesized α-1,3 linkages. In addition, approximately 80 % of the synthesized products were partially hydrolyzed by mammalian α-glucosidases, and the glucose generation rates decelerated as the amounts of α-1,3 linkages increased. In conclusion, new types of α-glucans with α-1,4 and α-1,3 linkages were successfully synthesized by a dual enzyme reaction. These can be utilized as slowly digestible and prebiotic ingredients in the gastrointestinal tract due to their novel linkage patterns and high molecular weights.

Synthesis of Thiazole‐Chalcone Hybrid Molecules: Antioxidant, Alpha(α)‐Amylase Inhibition and Docking Studies

The molecular hybrid approach is very significant to combat various drug-resistant disorders. A simple, convenient, and cost-effective synthesis of thiazole-based chalcones is accomplished, using a molecular hybrid approach, in two steps. The compound 1-(2-phenylthiazol-4-yl)ethanone (3) was used as the main intermediate for the synthesis of 3-(arylidene)-1-(2-phenylthiazol-4-yl)prop-2-en-1-ones (4a-f). Thin layer chromatography was used to testify the formation and purity of all synthesized compounds. Further structural confirmation of all compounds was achieved via different spectroscopic techniques (UV, FT-IR, 1 H- and 13 C-NMR) and elemental analysis. All synthesized compounds were tested for their α-amylase inhibition and antioxidant potential. The cytotoxic property of compounds was also tested with in vitro haemolytic assay. All tested compounds showed moderate to excellent α-amylase inhibition and antioxidant activity. All tested compounds are found safe to use due to their less toxicity when compared to the standard Triton X. The molecular docking simulation study of all synthesized compounds was also conducted to examine the best binding interactions with human pancreatic α-amylase (pdb: 4 W93) using AutodockVina. The molecular docking results authenticated the in vitro amylase inhibition results, i.e., 3-(3-Methoxyphenyl)-1-(2-phenylthiazol-4-yl)prop-2-en-1-one (4e) exhibited lowest IC50 value 54.09±0.11 μM with a binding energy of -7.898 kcal/mol.