Kinetics and molecular modeling studies on the inhibition mechanism of GH13 α-glycosidases by small molecule ligands

Alpha-glucosidase inhibitors play an important role in Diabetes Mellitus (DM) treatment since they prevent postprandial hyperglycemia. The Glycoside Hydrolase family 13 (GH13) is the major family of enzymes acting on substrates containing α-glucoside linkages, such as maltose and amylose/amylopectin chains in starch. Previously, our group identified glycoconjugate 1H-1,2,3-triazoles (GCTs) inhibiting two GH13 α-glycosidases: yeast maltase (MAL12) and porcine pancreatic amylase (PPA). Here, we combined kinetic studies and computational methods on nine GCTs to characterize their inhibitory mechanism. They all behaved as reversible inhibitors, and kinetic models encompassed noncompetitive and various mechanisms of mixed-type inhibition for both enzymes. Most potent inhibitors displayed Ki values of 30 μM for MAL12 (GPESB16) and 37 μM for PPA (GPESB15). Molecular dynamics and docking simulations indicated that on MAL12, GPESB15 and GPESB16 bind in a cavity adjacent to the active site, while on the PPA, GPESB15 was predicted to bind at the entrance of the catalytic site. Notably, despite its putative location within the active site, the binding of GPESB15 does not obstruct the substrate's access to the cleavage site. Our study contributes to paving the way for developing novel therapeutic strategies for managing DM-2 through GH13 α-glycosidases inhibition.

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.

Antioxidant, α-Glucosidase, and α-Amylase Inhibition Activities of Erythropalum scandens Blume

Diabetes is a major health problem worldwide, which is increasing day by day. Since ancient times, medicinal plants have been a key source of medicinal agents, and many of them have been authorized as strong medications or drug candidates. This study evaluated the antioxidant, α-glucosidase, and α-amylase inhibition activities of Erythropalum scandens Blume. The plant revealed the significant antioxidant and in vitro antidiabetic activity. The crude methanolic extract reported the highest antioxidant activity with an IC50 of 59.35 ± 5.47 μg/mL, followed by its dichloromethane (DCM) and ethyl acetate (EA) fractions with an IC50 of 66.45 ± 2.46 μg/mL and 80.46 ± 2.69 μg/mL, respectively, as compared to the standard quercetin’s IC50 value of 6.29 ± 1.02 μg/mL. Among the crude extract and its fractions, the EA fraction disclosed the significant inhibiting activity against α-glucosidase and α-amylase with an IC50 value of 17.92 ± 0.88 μg/mL and 44.51 ± 0.12 μg/mL, respectively. This research work has scientifically validated the traditional use of this plant.

Synthesis, in silico, in vitro and in vivo studies of novel natural-based arylidenes curcumin as potential glycohydrolase digestive enzymes inhibitors

Diabetes is one of the most common metabolic diseases in humans and the use of herbal medicines is of great clinical importance to inhibit carbohydrate-hydrolyzing enzymes and reduce blood glucose levels in diabetic patients. Inhibition of glycosidase activity is an effective way to treat and prevent diabetes. Therefore, in this study, curcumin-based benzaldehyde derivatives were synthesized and used as influential agents in the treatment of diabetes with inhibitory properties against two carbohydrate-hydrolyzing enzymes α-glucosidase (α-Glu) and α-amylase (α-Amy) as significant therapeutic targets for reducing postprandial hyperglycemia. Overall, the findings showed that due to the specific inhibitory activity against α-Glu in comparison with α-Amy, as well as more stability and antioxidant activity than curcumin, C5 and C8 derivatives are potentially important anti-diabetic drugs, not only to decrease glycemic index but also to limit the activity of the main production pathways of reactive oxygen species (ROS) in diabetic patients.Communicated by Ramaswamy H. Sarma.

Design, Synthesis, α-Amylase/α-Glucosidase Inhibition Assay, Induced Fit Docking Study of New Hybrid Compounds Containing 4H-Pyrano[2,3-d]pyrimidine, 1H-1,2,3-Triazole and D-Glucose Components

In this study, the click chemistry between N-propargyl derivatives of substituted 4H-pyrano[2,3-d]pyrimidines and tetra-O-acetyl-α-d-glucopyranosyl azide carried out under catalytic conditions using catalyst CuI@Montmorillonite and additive N,N-diisopropylethylamine (DIPEA). The yields of obtained hybrid compounds having 4H-pyrano[2,3-d]pyrimidine connected to 1H-1,2,3-triazole rings were about 85-94 %. All these synthesized hybrid compounds were examined for in vitro α-amylase (with IC₅₀ values in the range of 103.63±1.13 μM to 295.45±1.11 μM) and α-glucosidase (with IC₅₀ values in the range of 45.63±1.14 μM to 184.52±1.15) inhibitory activity. Amongst this series, ethyl ester 8m showed the best inhibitory activity against α-amylase with IC₅₀ of 103.63±1.13 μM, while ethyl ester 8t exhibited the highest activity against α-glucosidase with IC₅₀ of 45.63±1.14 μM. The kinetics of the inhibition of compound 8t showed the competitive α-glucosidase inhibitor property of this compound. Furthermore, the most potent compounds had any cytotoxicity against human normal cells. Induced fit docking and molecular dynamics simulation calculations indicated that the inhibition potential compounds 8m and 8t had the active interactions with the residues in receptors of corresponding tested enzymes. The calculated binding free energy from MM-GBSA approach showed that the major energy components contributed to the active binding of these studied inhibitors, including Coulomb, lipophilic and van der Waals energy. Further, 300 ns MD simulation showed that studied ligand-protein complexes were stable and indicated the structural observations into mode of binding in these complexes.

Microwave assisted regioselective synthesis of quinoline appended triazoles as potent anti-tubercular and antifungal agents via copper (I) catalyzed cycloaddition

Quinolin-3-yl-methyl-1,2,3-triazolyl-1,2,4-triazol-3(4H)-ones 8j-v were synthesized by click chemistry as an ultimate tactic where [3 + 2] cycloaddition of azides with terminal alkynes has been evolved. Herein, we are inclined to divulge the implication and prevalence of CuSO₄·5H₂O and THF/water promoted [3 + 2] cycloaddition reactions. The foremost supremacy of this method are transitory reaction times, facile workup, excellent yields (88-92%) with exorbitant purity and regioselective single product formation both under conventional and microwave method. Docking studies illustrated strong binding interactions with enzyme InhA-D148G (PDB ID: 4DQU) by means of high C-score values. The anti-tubercular and antifungal screening of synthesized compounds proclaimed promising activity. The in vitro and in silico studies imply that these triazoles appended quinolines may acquire the ideal structural prerequisites for auxiliary expansion of novel therapeutic agents.

Bioactive 1,2,3-Triazoles: An Account on their Synthesis, Structural Diversity and Biological Applications

The triazole heterocycle is a privileged scaffold in medicinal chemistry, since its structure is present in a large number of biologically active molecules, including several drugs currently in the market. Due to their vast applications, a wide variety of methods are described for their preparation, such as the 1,3-dipolar cycloaddition and processes involving diazo compounds and diazo transfer reactions. Considering the significant number of contributions from our research group to this chemistry in recent decades, in this account we discuss both the development of new methods for the synthesis of 1,2,3-triazoles and the preparation of new triazole-functionalized biologically active molecules using classical approaches.

Curcumin-based Antioxidant and Glycohydrolase Inhibitor Compounds: Synthesis and In Vitro Appraisal of the Dual Activity Against Diabetes

BACKGROUND

Curcumin, as the substantial constituent of the turmeric plant (Curcuma longa), plays a significant role in the prevention of various diseases, including diabetes. It possesses ideal structure features as an enzyme inhibitor, including a flexible backbone, hydrophobic nature, and several available hydrogen bond (H-bond) donors and acceptors.

OBJECTIVE

The present study aimed at synthesizing several novel curcumin derivatives and further evaluation of these compounds for possible antioxidant and anti-diabetic properties along with inhibitory effect against two carbohydrate-hydrolyzing enzymes, α-amylase and α-glucosidase, as these enzymes are therapeutic targets for attenuation of postprandial hyperglycemia.

METHODS

Therefore, curcumin-based pyrido[2,3-d]pyrimidine derivatives were synthesized and identified using an instrumental technique like NMR spectroscopy and then screened for antioxidant and enzyme inhibitory potential. Total antioxidant activity, reducing power assay and 1,1-diphenyl-2- picrylhydrazyl (DPPH•) radical scavenging activity were done to appraise the antioxidant potential of these compounds in vitro.

RESULTS

Compounds L6-L9 showed higher antioxidant activity while L4, L9, L12 and especially L8 exhibited the best selectivity index (lowest α-amylase/α-glucosidase inhibition ratio).

CONCLUSION

These antioxidant inhibitors may be potential anti-diabetic drugs, not only to reduce glycemic index but also to limit the activity of the major reactive oxygen species (ROS) producing pathways.

Design and synthesis of new indanol-1,2,3-triazole derivatives as potent antitubercular and antimicrobial agents

In a search of new antitubercular agents, herein we have reported a series of new thirty-two indanol-1,2,3-triazole derivatives. The synthesized compounds were screened for their in vitro antitubercular and antimicrobial activities. Among the screened compounds, most of the compounds have displayed good antitubercular activity against Mycobacterium tuberculosis H37Rv. The compound 5g has been identified as potent antitubercular agent with MIC value 1.56 µM. The most active compounds of the series were further studied for their cytotoxicity against HEK 293 cells using MTT assay and found to be nontoxic. In addition, ten compounds were shown good antimicrobial activities against both antibacterial and antifungal pathogens. A molecular docking study against Mycobacterial enoyl-ACP-reductase (InhA) was performed to gain an insight into the molecular mechanism of antitubercular action. The pharmacokinetic parameters of these compounds were studied and displayed acceptable drug-likeness score.

Evaluation of the alpha-amylase inhibitory activity of Nepalese medicinal plants used in the treatment of diabetes mellitus

Background

α-Amylase catalyses the hydrolysis of starch and ultimately producing glucose. Controlling the catalytic activity of this enzyme reduces glucose production in the postprandial stage, which could be a therapeutic benefit for people with diabetes. This study was conducted to evaluate α-amylase inhibition for utilizing the crude extracts of some medicinal plants traditionally used in Nepal for the treatment of diabetes and its related complications.

Methods

Microtiter plate approach has been used to assess inhibitory activities of in vitro α-amylase of methanolic extracts of thirty-two medicinal plants. A starch tolerance test was used in rats to investigate the in vivo study of the methanolic extract concerning glibenclamide as the positive control.

Results

Acacia catechu, Dioscorea bulbifera, and Swertia chirata exhibited inhibitory activity against α-amylase and with IC50 values; 49.9, 296.1, and 413.5 μg/mL, respectively. Kinetics study revealed that all the extracts displayed a mixed type of inhibition pattern, with Ki values ranging from 26.6–204.2 μg/mL. Free radical scavenging activity was again re-examined and found prominent in extracts of A. catechu. Likewise, A. catechu and S. chirata showed significant reduction of blood glucose concentration up to 30 min after oral dose of 250 mg/kg (F (4, 20) = 4.1, p = .048), and (F (4, 20) = 4.1, p = .036), respectively.

Conclusions

Enzymatic assay for α-amylase inhibition using extracts was successfully evaluated. Also, the in-vitro and in-vivo study model revealed that medicinal plants could be a potent source of α-amylase inhibition. So, they could serve as potential candidates for future drug development strategies for curing diabetes with minimal or no adverse side effects.

Hypoglycaemic activity of Bauhinia holophylla through GSK3-β inhibition and glycogenesis activation

CONTEXT

Bauhinia L. species, including Bauhinia holophylla (Bong.) Steud. (Fabaceae), have traditionally been used to treat diabetes. Bauhinia is a complex botanical genus, and the indiscriminate use of the diverse Bauhinia species is reflected in the experimental divergence of their medicinal potential.

OBJECTIVE

The hypoglycaemic and hypolipidaemic effects, molecular mechanism of action and phytochemical properties of an authentic extract of B. holophylla leaves were evaluated.

MATERIALS AND METHODS

A phytochemical study of a 70% EtOH extract was performed using FIA-ESI-IT-MS/MSn and HPLC-PAD-ESI-IT-MS. The extract (200 or 400 mg/kg b.w.) was administered for 14 days to streptozotocin-induced diabetic Swiss mice. Glucose tolerance and insulin sensitivity, blood parameters, gene and protein expression, and the in vivo and in vitro inhibition of intestinal glucosidases were assessed.

RESULTS

HPLC-PAD-ESI-IT-MS analysis identified flavonoid derivatives of quercetin, myricetin, luteolin and kaempferol. Treatment with 400 mg/kg of the extract reduced blood glucose (269.0 ± 32.4 mg/dL vs. 468.0 ± 32.2 mg/dL for diabetic animals), improved glucose tolerance, decreased cholesterol and triglyceride levels, and increased the mRNA expression of proteins involved in glucogenesis in the liver and muscle, such as PI3-K/Akt, GS, GSK3-β (ser-9), AMPK and Glut4. The activity of intestinal maltase was inhibited in vitro (IC50: 43.0 µg/mL for the extract compared to 516.4 µg/mL for acarbose) and in vivo.

DISCUSSION AND CONCLUSIONS

Treatment with B. holophylla was associated with a marked hypoglycaemic effect through the stimulation of glycogenesis and inhibition of gluconeogenesis and intestinal glucose absorption, without increasing basal insulinaemia.

Novel Benzylidenehydrazide-1,2,3-Triazole Conjugates as Antitubercular Agents: Synthesis and Molecular Docking

Background & Objectives:

Novel 1,2,3-triazole based benzylidenehydrazide derivatives were synthesized and evaluated for antitubercular activity against Mycobacterium tuberculosis (MTB) H37Ra, M. bovis BCG and cytotoxic activity. Most of the derivatives exhibited promising in vitro potency against MTB characterized by lower MIC values.

Methods:

Among all the synthesized derivatives, compound 6a and 6j were the most active against active and dormant MTB H37Ra, respectively. Compound 6d was significantly active against dormant and active M. bovis BCG.

Results:

The structure activity relationship has been explored on the basis of anti-tubercular activity data. The active compounds were also tested against THP-1, A549 and Panc-1 cell lines and showed no significant cytotoxicity. Further, the synthesized compounds were found to have potential antioxidant with IC50 range = 11.19-56.64 µg/mL. The molecular docking study of synthesized compounds was performed against DprE1 enzyme of MTB to understand the binding interactions.

Conclusion:

Furthermore, synthesized compounds were also analysed for ADME properties and the potency of compounds indicated that, this series can be considered as a starting point for the developement of novel and more potent anti-tubercular agents in future.

Triazole-diindolylmethane conjugates as new antitubercular agents: synthesis, bioevaluation, and molecular docking

We describe the synthesis of novel triazole-incorporated diindolylmethanes (DIMs) using a molecular hybridization approach. The in vitro antitubercular activity of the DIMs against Mycobacterium tuberculosis H37Ra (ATCC 25177) was tested in the active and dormant state. Among all the synthesized conjugates, the compounds 6b, 6f, 6l, 6n, 6q, 6r, and 6s displayed good antitubercular activity against both the active and dormant Mtb H37Ra strain. The compound 6l exhibited good antitubercular activity against dormant Mtb H37Ra with an IC₅₀ value of 1 μg mL^-1 and IC₉₀ (MIC) value of 3 μg mL^-1. The compounds 6b, 6l, and 6r displayed good antitubercular activity against active Mtb H37Ra with IC₅₀ values of 2.19, 1.52, and 0.22 μg mL^-1, respectively. The compounds 6b, 6h, 6l, and 6s displayed more than 70% inhibition against the Gram-positive Bacillus subtilus strain at 3 μg mL^-1. The molecular docking study showed the binding modes of the titled compounds in the active site of the DprE1 enzyme and assisted with elucidating a structural basis for the inhibition of Mycobacteria.

A facile water-stable MOF-based “off–on” fluorescent switch for label-free detection of dopamine in biological fluid

An Abtz–CdI₂–MOF was developed as an “off–on” fluorescent switch for label-free detection of dopamine without any surface modification or functionalization.

Synthesis and bioactivity of novel triazole incorporated benzothiazinone derivatives as antitubercular and antioxidant agent

In search of new active molecules against Mycobacterium tuberculosis (MTB) H37Ra and M. bovis BCG, a small focused library of benzothiazinone based 1,2,3-triazoles has been efficiently prepared via click chemistry approach. Several derivatives were found to be promising inhibitors of MTB and M. bovis BCG characterized by lower MIC values (27.34-29.37μg/mL). Among all the synthesized compounds, 6c and 6e is the most active compound against MTB and M. bovis BCG. The compounds were further tested for anti-proliferative activity against HeLa, A549 and A431 cell lines using MTT assay and showed no significant cytotoxic activity at the maximum concentration evaluated. Further, the synthesized compounds were found to have potential antioxidant activity with IC50 range=14.14-47.11μg/mL. Furthermore, to rationalize the observed biological activity data, the molecular docking study also been carried out against a potential target MTB DprE1, which revealed a significant correlation between the binding score and biological activity for these compounds. The results of the in vitro and in silico study suggest that the triazole incorporated benzothiazinone may possess the ideal structural requirements for further development of novel therapeutic agents.

Thioflavin T effect in diabetic Wistar rats: reporting the antihyperglycemic property of an amyloid probing dye

BACKGROUND

Thioflavin T (ThT) is a well-known probe of amyloid fibrils with a benzothiazole core structure. As a compound with partial inhibitory effect on alpha-amylase, the results of oral ThT administration were investigated on a streptozotocin (STZ)-induced rat model of diabetes.

METHODS

STZ was administered intraperitoneally for induction of diabetes. Afterwards, doses of 2, 8, 16, and 32 mg/kg of ThT were used in diabetic and non-diabetic rats. Blood glucose levels, lipid profiles, alpha-amylase activity, food and water intake and urine volume were assessed. Docking was also performed to evaluate the inhibitory effect of ThT on alpha-amylase.

RESULTS

Upon treatment with ThT, blood glucose levels and lipid profile of diabetic rats improved significantly. Furthermore, alpha-amylase serum levels of treated animals decreased compared to the control group, suggesting a possible effect of ThT on this digestive enzyme. On the other hand, the food intake of treated animals showed a decrease. ThT effects were also seen to some extent in the non-diabetic group.

CONCLUSION

ThT is suggested to be a potentially useful compound in treatment and prevention of diabetes and associated complications.

1,2,3-Triazole derivatives as antitubercular agents: synthesis, biological evaluation and molecular docking study

A library of thirty one 1,2,3-triazole derivatives efficiently preparedviaclick chemistry and evaluated for their antitubercular, antioxidant, and cytotoxic activities.

1-Phenyl-1H- and 2-phenyl-2H-1,2,3-triazol derivatives: design, synthesis and inhibitory effect on alpha-glycosidases

Due to aging and increasingly overweight in human population, the incidence of non-insulin dependent diabetes mellitus (NIDDM or Type 2 DM) is increasing considerably. Therefore, searching for new α-glycosidase inhibitors (GIs) capable of slowing down carbohydrate assimilation by humans is an important strategy towards control of NIDDM. In this report, we disclose the search for new easily accessible synthetic triazoles as anti-diabetic compounds. Two series of non-glycosid triazoles were synthesized (series A and B) and screened against baker's yeast α-glucosidase (MAL12) and porcine pancreatic α-amylase activity (PPA). Of the 60 compounds tested at 500 μM, were considered hits (≥60% inhibition) six triazoles against MAL12 and three against PPA, with the inhibition reaching up to 99.4% on MAL12 and 88.6% on PPA. The IC₅₀ values were calculated for both enzymes and ranged from 54 to 482 μM for MAL12 and 145 to 282 μM for PPA. These results demonstrated the potential activity of simple and non-glycosidic triazoles as an important novel class of GIs for the development of drugs to treat Type 2 DM.