Antisolvent precipitation for the synergistic preparation of ultrafine particles of nobiletin under ultrasonication-homogenization and evaluation of the inhibitory effects of α-glucosidase and porcine pancreatic lipase in vitro.

To further enhance the application of nobiletin (an important active ingredient in Citrus fruits), we used ultrasonic homogenization-assisted antisolvent precipitation to create ultrafine particles of nobiletin (UPN). DMSO was used as the solvent, and deionized water was used as the antisolvent. When ultrasonication (670 W) and homogenization (16000 r/min) were synergistic, the solution concentration was 57 mg/mL, and the minimum particle size of UPN was 521.02 nm. The UPN samples outperformed the RN samples in terms of the inhibition of porcine pancreatic lipase, which was inhibited (by 500 mg/mL) by 68.41 % in the raw sample, 90.34 % in the ultrafine sample, and 83.59 % in the positive control, according to the data. Fourier transform infrared spectroscopy analysis revealed no chemical changes in the samples before or after preparation. However, the crystallinity of the processed ultrafine nobiletin particles decreased. Thus, this work offers significant relevance for applications in the realm of food chemistry and indirectly illustrates the expanded application potential of nobiletin.

Efficient biotransformation of naringenin to naringenin α-glucoside, a novel α-glucosidase inhibitor, by amylosucrase from Deinococcus wulumuquiensis.

Amylosucrase (ASase) efficiently biosynthesizes α-glucoside using flavonoids as acceptor molecules and sucrose as a donor molecule. Here, ASase from Deinococcus wulumuqiensis (DwAS) biosynthesized more naringenin α-glucoside (NαG) with sucrose and naringenin as donor and acceptor molecules, respectively, than other ASases from Deinococcus sp. The biotransformation rate of DwAS to NαG was 21.3% compared to 7.1-16.2% for other ASases. Docking simulations showed that the active site of DwAS was more accessible to naringenin than those of others. The 217th valine in DwAS corresponded to the 221st isoleucine in Deinococcus geothermalis AS (DgAS), and the isoleucine possibly prevented naringenin from accessing the active site. The DwAS-V217I mutant had a significantly lower biosynthetic rate of NαG than DwAS. The kcat/Km value of DwAS with naringenin as the donor was significantly higher than that of DgAS and DwAS-V217I. In addition, NαG inhibited human intestinal α-glucosidase more efficiently than naringenin.

The antihyperglycemic potential of pyrazolobenzothiazine 1, 1-dioxide novel derivative in mice using integrated molecular pharmacological approach.

Diabetes Mellitus is a metabolic disease characterized by elevated blood sugar levels caused by inadequate insulin production, which subsequently leads to hyperglycemia. This study was aimed to investigate the antidiabetic potential of pyrazolobenzothiazine derivatives in silico, in vitro, and in vivo. Molecular docking of pyrazolobenzothiazine derivatives was performed against α-glucosidase and α-amylase and compounds were selected based on docking score, bonding interactions and low root mean square deviation (RMSD). Enzyme inhibition assay against α-glucosidase and α-amylase was performed in vitro using p-nitrophenyl-α-D-glucopyranoside (PNPG) and starch substrate. Synthetic compound pyrazolobenzothiazine (S1) exhibited minimal conformational changes during the 100 ns MD simulation run. S1 also revealed effective IC50 values for α-glucosidase (3.91 µM) and α-amylase (8.89 µM) and an enzyme kinetic study showed low ki (- 0.186 µM, - 1.267 µM) and ki' (- 0.691 µM, - 1.78 µM) values with the competitive type of inhibition for both enzymes α-glucosidase and α-amylase, respectively. Moreover, studies were conducted to check the effect of the synthetic compound in a mouse model. A low necrosis rate was observed in the liver, kidney, and pancreas through histology analysis performed on mice. Compound S1 also exhibited a good biochemical profile with lower sugar level (110-115 mg/dL), increased insulin level (25-30 µM/L), and low level of cholesterol (85 mg/dL) and creatinine (0.6 mg/dL) in blood. The treated mice group also exhibited a low % of glycated haemoglobin (3%). This study concludes that S1 is a new antidiabetic-agent that helps lower blood glucose levels and minimizes the complications associated with type-II diabetes.

GAA/(Au-Au/IrO2)@Cu(PABA) reactor with cascade catalytic activity for α-glucosidase inhibitor screening.

BACKGROUND: In vitro screening strategies based on the inhibition of α-glucosidase (GAA) activity have been widely used for the discovery of potential antidiabetic drugs, but they still face some challenges, such as poor enzyme stability, non-reusability and narrow range of applicability. To overcome these limitations, an in vitro screening method based on GAA@GOx@Cu-MOF reactor was developed in our previous study. However, the method was still not satisfactory enough in terms of construction cost, pH stability, organic solvent resistance and reusability. Thence, there is still a great need for the development of in vitro screening methods with lower cost and wider applicability. RESULTS: A colorimetric sensing strategy based on GAA/(Au-Au/IrO2)@Cu(PABA) cascade catalytic reactor, which constructed through simultaneous encapsulating Au-Au/IrO2 nanozyme with glucose oxidase-mimicking and peroxidase-mimicking activities and GAA in Cu(PABA) carrier with peroxidase-mimicking activity, was innovatively developed for in vitro screening of GAA inhibitors in this work. It was found that the reactor not only exhibited excellent thermal stability, pH stability, organic solvent resistance, room temperature storage stability, and reusability, but also possessed cascade catalytic performance, with approximately 12.36-fold increased catalytic activity compared to the free system (GAA + Au-Au/IrO2). Moreover, the in vitro GAA inhibitors screening method based on this reactor demonstrated considerable anti-interference performance and detection sensitivity, with a detection limit of 4.79 nM for acarbose. Meanwhile, the method owned good reliability and accuracy, and has been successfully applied to the in vitro screening of oleanolic acid derivatives as potential GAA inhibitors. SIGNIFICANCE: This method not only more effectively solved the shortcomings of poor stability, narrow scope of application, and non-reusability of natural enzymes in the classical method compared with our previous work, but also broaden the application scope of Au-Au/IrO2 nanozyme with glucose oxidase and peroxidase mimicking activities, and Cu(PABA) carrier with peroxidase mimicking activity, which was expected to be a new generation candidate method for GAA inhibitor screening.

Synthesis and Biological Evaluation of New Dihydrofuro[3,2-b]piperidine Derivatives as Potent α-Glucosidase Inhibitors.

Inhibition of glycoside hydrolases has widespread application in the treatment of diabetes. Based on our previous findings, a series of dihydrofuro[3,2-b]piperidine derivatives was designed and synthesized from D- and L-arabinose. Compounds 32 (IC50 = 0.07 µM) and 28 (IC50 = 0.5 µM) showed significantly stronger inhibitory potency against α-glucosidase than positive control acarbose. The study of the structure-activity relationship of these compounds provides a new clue for the development of new α-glucosidase inhibitors.

Globunoids A-D, undescribed bichalconoid and biflavanoids with α-glucosidase and α-amylase inhibitory activities from Knema globularia stems.

A bichalconoid, globunoid A (1) and three biflavanones, globunoids B-D (2-4), previously undescribed, were isolated from the stems of Knema globularia, along with fourteen known analogues 5-18. The chemical structures of 1-4 were elucidated by the comprehensive spectroscopic analysis including UV, IR, HRESIMS, and NMR; the absolute configurations were determined based on their NOESY data, DP4+ statistical analysis, and ECD calculation. Up to now, compounds 2 and 3 represent the first 3,3″-linked biflavanone structures. Among the isolated compounds, 2, 3, and 2,3-dihydrocalodenin B (6) potently inhibited α-glucosidase and α-amylase activities, with IC50 values in the range 1.1-7.5 µM. Furthermore, the most active compound 6 was found to be a non-competitive inhibitor against these two enzymes.

Evaluation of novel 2-(quinoline-2-ylthio)acetamide derivatives linked to diphenyl-imidazole as α-glucosidase inhibitors: Insights from in silico, in vitro, and in vivo studies on their anti-diabetic properties.

The inhibition of the α-glucosidase enzyme is crucial for targeting type 2 diabetes mellitus (DM). This study introduces a series of synthetic analogs based on thiomethylacetamide-quinoline derivatives linked to diphenyl-imidazole as highly potential α-glucosidase inhibitors. Twenty derivatives were synthesized and screened in vitro against α-glucosidase, revealing IC50 values ranging from 0.18 ± 0.00 to 2.10 ± 0.07 µM, in comparison to the positive control, acarbose. Among these derivatives, compound 10c (IC50 = 0.180 µM) demonstrated the highest potency and revealed a competitive inhibitory mechanism in kinetic studies (Ki = 0.15 µM). Docking and molecular dynamic evaluations elucidated the binding mode of 10c with the active site residues of the α-glucosidase enzyme. Moreover, in vivo assessments on a rat model of DM affirmed the anti-diabetic efficacy of 10c, evidenced by reduced fasting and overall blood glucose levels. The histopathological evaluation enhanced pancreatic islet architecture and hepatocytes in liver sections. In conclusion, novel 2-(quinoline-2-ylthio)acetamide derivatives as potent α-glucosidase inhibitors were developed. Compound 10c emerged as a promising candidate for diabetes management, warranting further investigation for potential clinical applications and mechanistic insights.

Deciphering the binding behavior and interaction mechanism of apigenin and α-glucosidase based on multi-spectroscopic and molecular simulation studies.

This study investigated the molecular mechanism underlying the binding interaction between apigenin (API) and α-glucosidase (α-glu) by a combination of experimental techniques and computational simulation strategies. The spontaneously formation of stable API-α-glu complex was mainly driven by hydrogen bonds and hydrophobic forces, leading to a static fluorescence quenching of α-glu. The binding of API induced secondary structure and conformation changes of α-glu, decreasing the surface hydrophobicity of protein. Computational simulation results demonstrated that API could bind into the active cavity of α-glu via its interaction with active residues at the binding site. The important roles of key residues responsible for the binding stability and affinity between API and α-glu were further revealed by MM/PBSA results. In addition, it can be found that the entrance of active site tended to close after API binding as a result of its interaction with gate keeping residues. Furthermore, the structural basis for the binding interaction behavior of API was revealed and visualized by weak interaction analysis. The findings of our study revealed atomic-level mechanism of the interaction between API, which might shed light on the development of better inhibitors.

Coumarin linked to 2-phenylbenzimidazole derivatives as potent α-glucosidase inhibitors.

α-Glucosidase inhibitors have emerged as crucial agents in the management of type 2 diabetes mellitus. In the present study, a new series of coumarin-linked 2-phenylbenzimidazole derivatives 5a-m was designed, synthesized, and evaluated as anti-α-glucosidase agents. Among these derivatives, compound 5k (IC50 = 10.8 µM) exhibited a significant inhibitory activity in comparison to the positive control acarbose (IC50 = 750.0 µM). Through kinetic analysis, it was revealed that compound 5k exhibited a competitive inhibition pattern against α-glucosidase. To gain insights into the interactions between the title compounds and α-glucosidase molecular docking was employed. The obtained results highlighted crucial interactions that contribute to the inhibitory activities of the compounds against α-glucosidase. These derivatives show immense potential as promising starting points for developing novel α-glucosidase inhibitors.

Design, synthesis, α-amylase and glucose diffusion inhibition, and molecular docking studies of new indenopyrazolones bearing benzothiazole derivatives.

An eco-friendly facile synthesis of a series of twenty 1-(4/6-substitutedbenzo[d]thiazol-2-yl)-3-(phenyl/substitutedphenyl)indeno[1,2-c]pyrazol-4(1H)-ones 7a-t was achieved by the reaction of 2-(benzoyl/substitutedbenzoyl)-(1H)-indene-1,3(2H)-dione 3a-t and 2-hydrazinyl-4/6-substitutedbenzo[d]thiazole 6a-t in presence of freshly dried ethanol and glacial acetic acid under reflux conditions in good yields. The newly synthesized derivatives were well characterized using different physical and spectral techniques (FTIR, 1H NMR & 13C NMR, and HRMS). All the compounds were subjected to assess their in vitro α-amylase and glucose diffusion inhibitory activity. Amongst them, the compounds 7i and 7l showed better α-amylase inhibitory activity demonstrating IC50 values of 92.99±1.94 µg/mL and 95.41±3.92 µg/mL, respectively in comparison to the standard drug acarbose (IC50 value of 103.60±2.15 µg/mL). The derivatives 7d and 7k exhibited good glucose diffusion inhibition with values of 2.25±1.16 µg/mL and 2.63±1.45 µg/mL, respectively with standard reference acarbose (2.76±0.55 µg/mL). The observed α-amylase inhibitory activity findings were corroborated through molecular docking investigations, particularly for the highly active compounds 7i (binding energy -8.0 kcal/mol) and 7l (binding energy -8.2 kcal/mol) respectively, in comparison to acarbose with a value of binding energy -6.9 kcal/mol for α-amylase.

Establishment and application of a screening method for α-glucosidase inhibitors based on dual sensing and affinity chromatography.

α-Glucosidase plays a direct role in the metabolic pathways of starch and glycogen, any dysfunction in its activity could result in metabolic disease. Concurrently, this enzyme serves as a target for diverse drugs and inhibitors, contributing to the regulation of glucose metabolism in the human body. Here, an integrated analytical method was established to screen inhibitors of α-glucosidase. This step-by-step screening model was accomplished through the biosensing and affinity chromatography techniques. The newly proposed sensing program had a good linear relationship within the enzyme activity range of 0.25 U mL-1 to 1.25 U mL-1, which can quickly identify active ingredients in complex samples. Then the potential active ingredients can be captured, separated, and identified by an affinity chromatography model. The combination of the two parts was achieved by an immobilized enzyme technology and a microdevice for reaction, and the combination not only ensured efficiency and accuracy for inhibitor screening but also eliminated the occurrence of false positive results in the past. The emodin, with a notable inhibitory effect on α-glucosidase, was successfully screened from five traditional Chinese medicines using this method. The molecular docking results also demonstrated that emodin was well embedded into the active pocket of α-glucosidase. In summary, the strategy provided an efficient method for developing new enzyme inhibitors from natural products.

Amphiphilic α-Peptoid-deoxynojirimycin Conjugate-based Multivalent Glycosidase Inhibitor for Hypoglycemic Effect and Fluorescence Imaging.

Multivalent glycosidase inhibitors based on 1-deoxynojirimycin derivatives against α-glucosidases have been rapidly developed. Nonetheless, the mechanism based on self-assembled multivalent glucosidase inhibitors in living systems needs to be further studied. It remains to be determined whether the self-assembly possesses sufficient stability to endure transit through the small intestine and subsequently bind to the glycosidases located therein. In this paper, two amphiphilic compounds, 1-deoxynojirimycin and α-peptoid conjugates (LP-4DNJ-3C and LP-4DNJ-6C), were designed. Their self-assembling behaviors, multivalent α-glucosidase inhibition effect, and fluorescence imaging on living organs were studied. LP-4DNJ-6C exhibited better multivalent α-glucosidase inhibition activities in vitro. Moreover, the self-assembly of LP-4DNJ-6C could effectively form a complex with Nile red. The complex showed fluorescence quenching effect upon binding with α-glucosidases and exhibited potent fluorescence imaging in the small intestine. This result suggests that a multivalent hypoglycemic effect achieved through self-assembly in the intestine is a viable approach, enabling the rational design of multivalent hypoglycemic drugs.

Studies on α-amylase inhibition by acarbose and quercetin using fluorescence, circular dichroism, docking, and dynamics simulations.

This study looked at the effects of acarbose (ACA) and quercetin (QUE) on α-amylase activity, employing QUE and ACA to measure enzyme activity. The study observed that both drugs suppressed α-amylase activity, with greater inhibition reported at higher concentrations. The use of tryptophan residues as an intrinsic fluorescence probe permitted the observation of conformational changes in α-amylase, with CD measurements utilized to explore the secondary structure in the presence of QUE and ACA. Docking studies revealed an effective interaction between α-amylase, quercetin and acarbose, with a higher binding energy. Finally, a trajectory analysis was done to establish the stability and volatility of these complexes. These findings have potential significance for the development of new α-amylase-related therapeutics.

Chemical constituents from the leaves of Sindora siamensis var. maritima and their antimicrobial and α-glucosidase inhibitory activities.

Two new glycosides, sindosides A-B (1-2), along with 11 previously identified metabolites (3-13), were isolated from an ethanolic extract of the leaves of Sindora siamensis var. maritima. The structures of the purified phytochemicals were elucidated by interpreting their spectroscopic data (IR, NMR, and HRMS). The absolute configuration of compound 1 was established by experimental and calculated ECD spectra. The antimicrobial results revealed that compound 8 selectively inhibited C. albicans fungal with a MIC value of 64 µg/mL, whereas 11 presented a weak inhibition toward E. faecalis, S. aureus, and B. cereus bacterial strains with the same MIC value of 128 µg/mL. Interestingly, compounds 1, 2, 8, 9, and 11 showed α-glucosidase inhibitory activity with IC50 values ranging from 14.42 ± 0.21 to 30.62 ± 0.18 µM, which were more active than the positive control (acarbose, with an IC50 value of 46.78 ± 1.37 µM). Enzyme kinetic analysis revealed that compounds 1, 2, and 11 behaved as uncompetitive inhibitors with Ki values of 8.60 ± 1.04, 5.16 ± 0.73, and 7.17 ± 0.98 µM, respectively.

Synthesis and bio-evaluation of newer dihydropyridines and tetrahydropyridines based glycomimetic azasugars.

This study presents the synthesis and bio-evaluation of new triazolylated dihydropyridine and tetrahydropyridine azasugar scaffolds (F1-14). Azasugar glycomimetics are the synthetic substances that mimic the structural and functional characteristics of natural carbohydrates showcasing promising potential as therapeutic agents for diabetes. The α-glucosidase inhibitory activity of synthesized final compounds were evaluated against the commercially available α-glucosidase enzyme. Majority of the screened compounds displayed excellent inhibition with IC50 values ranging from 2.12 to 75.11 µM, when compared to the standard drug Acarbose. Particularly, compound F5 with IC50 value of 2.12 µM was found to be the most active compound among the series. Further molecular docking studies of selected ligands were performed to investigate the binding interactions with enzyme active sites. Their specific binding patterns have been analysed with the binding sites of Saccharomyces cerevisiae α-glucosidase. These findings suggest these candidates as the potential leads for the anti-diabetic activity.

Pyrano[2,3-b]chromone derivatives as novel dual inhibitors of α-glucosidase and α-amylase: Design, synthesis, biological evaluation, and in silico studies.

Inhibition of α-glucosidase and α-amylase is an important target for treatment of type 2 diabetes. In this work, a novel series of pyrano[2,3-b]chromene derivatives 5a-m was designed based on potent α-glucosidase and α-amylase inhibitors and synthesized by simple chemical reactions. These compounds were evaluated against the latter enzymes. Most of the title compounds exhibited high inhibitory activity against α-glucosidase and α-amylase in comparison to standard inhibitor (acarbose). Representatively, the most potent compound, 4-methoxy derivative 5d, was 30.4 fold more potent than acarbose against α-glucosidase and 6.1 fold more potent than this drug against α-amylase. In silico molecular modeling demonstrated that compound 5d attached to the active sites of α-glucosidase and α-amylase with a favorable binding energies and established interactions with important amino acids. Dynamics of compound 5d also showed that this compound formed a stable complex with the α-glucosidase active site. In silicodrug-likeness as well as ADMET prediction of this compound was also performed and satisfactory results were obtained.

Aporphine alkaloids and a naphthoquinone derivative from the leaves of Phaeanthus lucidus Oliv. and their α-glucosidase inhibitory activity.

Three previously undescribed aporphine alkaloids, phaeanthuslucidines E-G, one previously undescribed naphthoquinone derivative, phaeanthusnaphthoquinone, and three known compounds were isolated from an EtOAc extract of the leaves of Phaeanthus lucidus Oliv. The structures of all previously undescribed compounds were established through extensive spectroscopic investigations and high-resolution mass spectroscopy. The 6aR configuration of phaeanthuslucidines E-G was assigned by comparing their ECD spectra and specific rotation values with the reported known compounds. Some isolated compounds were evaluated for their α-glucosidase inhibitory activity. Among these compounds, phaeanthuslucidine E showed the highest α-glucosidase inhibitory activity with an IC50 value of 17.9 ± 0.4 µM. The molecular docking of phaeanthuslucidine E was further studied.

Phenolic Glycosides from Viburnum chinshanense Leaves and their α-Amylase and α-Glucosidase Inhibitory Activity.

The phytochemical investigation of Viburnum chinshanense leaves led to the isolation and identification of four new phenolic glycosides, viburninsides A-D (1-4), and eight known analogues (5-12). The structures of the four undescribed compounds were determined by spectroscopic techniques, including 1D NMR, 2D NMR, and HRESIMS, and their containing sugar units were confirmed by acid hydrolysis and HPLC analysis of the monosaccharide's chiral derivatives. Additionally, the α-amylase and α-glucosidase inhibitory activities of the isolated compounds were assessed. Compounds 1, 2, 4, 9, and 10 exhibited potential inhibitory activities against α-amylase and α-glucosidase with IC50 values ranging from 35.07 µM to 47.42 µM and 18.27 µM to 43.65 µM, respectively. Molecular docking analysis of compound 4 with the strongest inhibition against the target enzymes was also conducted.

Novel molecular hybrids of EGCG and quinoxaline: Potent multi-targeting antidiabetic agents that inhibit α-glucosidase, α-amylase, and oxidative stress.

Diabetes mellitus is a multifactorial disease and its effective therapy often demands several drugs with different modes of action. Herein, we report a rational design and synthesis of multi-targeting novel molecular hybrids comprised of EGCG and quinoxaline derivatives that can effectively inhibit α-glucosidase, α-amylase as well as control oxidative stress by scavenging ROS. The hybrids showed superior inhibition of α-glucosidase along with similar α-amylase inhibition as compared to standard drug, acarbose. Most potent compound, 15c showed an IC50 of 0.50 µM (IC50 of acarbose 190 µM) against α-glucosidase. Kinetics studies with 15c revealed a competitive inhibition against α-glucosidase. Binding affinity of 15c (-9.5 kcal/mol) towards α-glucosidase was significantly higher than acarbose (-7.7 kcal/mol). 15c exhibited remarkably high antioxidant activity (IC50 = 18.84 µM), much better than vitamin C (IC50 = 33.04 µM). Of note, acarbose shows no antioxidant activity. Furthermore, α-amylase activity was effectively inhibited by 15c with an IC50 value of 16.35 µM. No cytotoxicity was observed for 15c (up to 40 µM) in MCF-7 cells. Taken together, we report a series of multi-targeting molecular hybrids capable of inhibiting carbohydrate hydrolysing enzymes as well as reducing oxidative stress, thus representing an advancement towards effective and novel therapeutic approaches for diabetes.

Natural Sweetener, Glycyrrhetinic Acid 3-O-Mono-beta-d-glucuronide, for Postprandial Hyperglycemia Management.

This study examines the inhibitory effects of a range of sweeteners on α-glucosidase. Our findings revealed that only one natural sweetener, namely, glycyrrhetinic acid 3-O-mono-beta-d-glucuronide (GAMG), derived from licorice, exhibited a mixed-type inhibition against α-glucosidase with a IC50 value of 0.73 ± 0.05 mg/mL. The fluorescence intensity of α-glucosidase was quenched by GAMG in the formation of an α-glucosidase-GAMG complex. GAMG has been shown to induce conformational changes in α-glucosidase, likely through hydrogen bonding, van der Waals force, and alkyl-alkyl interactions with amino acid residues, including Arg 281, Leu 283, Trp 376, Asp 404, Asp 443, Trp 481, Asp 518, Phe 525, Ala 555, and Asp 616. Additional animal validation experiments demonstrated that GAMG slowed starch digestion, thereby attenuating the postprandial glycemic response. Taken together, these findings provide evidence that GAMG is a natural sweetener with potent inhibitory activity that selectively targets α-glucosidase. This study supports the use of GAMG as a natural sweetener, which holds a high biological value and may be beneficial for managing postprandial hyperglycemia.