Syntheses, in vitro evaluation and molecular docking studies of 5-bromo-2-aryl benzimidazoles as 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.

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.

Therapeutic Potential of Benzimidazoisoquinoline Derivatives in Alleviating Murine Hepatic Fibrosis

Short Title: Benzimidazoisoquinoline derivatives as potent antifibrotics Hepatic fibrosis is a pathological condition of liver disease with an increasing number of cases worldwide. Therapeutic strategies are warranted to target the activated hepatic stellate cells (HSCs), the collagen-producing cells, an effective strategy for controlling the disease progression. Benzimidazoisoquinoline derivatives were synthesized as hybrid molecules by the combination of benzimidazoles and isoquinolines to evaluate their anti-fibrotic potential using an in-vitro and in-vivo model of hepatic fibrosis. A small library of benzimidazoisoquinoline derivatives (1-17 and 18-21) was synthesized from 2-aryl benzimidazole and acetylene functionalities through C-H and N-H activation. Compounds (10 and its recently synthesized derivatives 18-21) depicted a significant decrease in PDGF-BB and/or TGFβ-induced proliferation (1.7-1.9 -fold), migration (3.5-5.0 -fold), and fibrosis-related gene expressions in HSCs. These compounds could revert the hepatic damage caused by chronic exposure to hepatotoxicants, ethanol, and/or carbon tetrachloride as evident from the histological, biochemical, and molecular analysis. Anti-fibrotic effect of the compounds was supported by the decrease in the malondialdehyde level, collagen deposition, and gene expression levels of fibrosis-related markers such as α-SMA, COL1α1, PDGFRβ, and TGFRIIβ in the preclinical models of hepatic fibrosis. In conclusion, the synthesized benzimidazoisoquinoline derivatives (compounds 18, 19, 20, and 21) possess anti-fibrotic therapeutic potential against liver fibrosis.

Synthesis of new bis(dimethylamino)benzophenone hydrazone for diabetic management: In-vitro and in-silico approach

Inhibiting α-glucosidase is a reliable method for reducing blood sugar levels in diabetic individuals. Bis(dimethylamino)benzophenone derivatives 1-27 were synthesized from bis(dimethylamino)benzophenone via two-step reaction. Different spectroscopic techniques, including EI-MS and 1H NMR, were employed to characterize all synthetic derivatives. The elemental composition of synthetic compounds was confirmed by elemental analysis and results were found in agreement with the calculated values. The synthetic compounds 1-27 were evaluated for α-glucosidase inhibitory activity, except five compounds all derivatives showed good to moderate inhibitory potential in the range of IC50 = 0.28 ± 2.65 - 0.94 ± 2.20 μM. Among them, the most active compounds were 5, 8, 9, and 12 with IC50 values of 0.29 ± 4.63, 0.29 ± 0.93, 0.28 ± 3.65, and 0.28 ± 2.65, respectively. Furthermore, all these compounds were found to be non-toxic on human fibroblast cell lines (BJ cell lines). Kinetics study of compounds 8 and 9 revealed competitive type of inhibition with Ki values 2.79 ± 0.011 and 3.64 ± 0.012 μM, respectively. The binding interactions of synthetic compounds were also confirmed through molecular docking studies that indicated that compounds fit well in the active site of enzyme. Furthermore, a total of 30ns MD simulation was carried out for the most potent complexes of the series. The molecular dynamics study revealed that compound-8 and compound-12 were stable during the MD simulation.

A Review on the Development of Novel Heterocycles as α-Glucosidase Inhibitors for the Treatment of Type-2 Diabetes Mellitus

One of the most effective therapeutic decencies in the treatment of Type 2 Diabetes Mellitus is the inhibition of α-glucosidase enzyme, which is present at the brush border of the intestine and plays an important role in carbohydrate digestion to form mono-, di-, and polysaccharides. Acarbose, Voglibose, Miglitol, and Erniglitate have been well-known α-glucosidase inhibitors in science since 1990. However, the long synthetic route and side effects of these inhibitors forced the researchers to move their focus to innovate simple and small heterocyclic scaffolds that work as excellent α-glucosidase inhibitors. Moreover, they are also effective against the postprandial hyperglycemic condition in Type 2 Diabetes Mellitus. In this aspect, this review summarizes recent progress in the discovery and development of heterocyclic molecules that have been appraised to show outstanding inhibition of α-glucosidase to yield positive effects against diabetes.

Imidazo[1,2-c]quinazolines as a novel and potent scaffold of α-glucosidase inhibitors: design, synthesis, biological evaluations, and in silico studies

α-Glucosidase inhibition is an approved treatment for type 2 diabetes mellitus (T2DM). In an attempt to develop novel anti-α-glucosidase agents, two series of substituted imidazo[1,2-c]quinazolines, namely 6a-c and 11a-o, were synthesized using a simple, straightforward synthetic routes. These compounds were thoroughly characterized by IR, 1H and 13C NMR spectroscopy, as well as mass spectrometry and elemental analysis. Subsequently, the inhibitory activities of these compounds were evaluated against Saccharomyces cerevisiae α-glucosidase. In present study, acarbose was utilized as a positive control. These imidazoquinazolines exhibited excellent to great inhibitory potencies with IC50 values ranging from 12.44 ± 0.38 μM to 308.33 ± 0.06 μM, which were several times more potent than standard drug with IC50 value of 750.0 ± 1.5 μM. Representatively, compound 11j showed remarkable anti-α-glucosidase potency with IC50 = 12.44 ± 0.38 μM, which was 60.3 times more potent than positive control acarbose. To explore the potential inhibition mechanism, further evaluations including kinetic analysis, circular dichroism, fluorescence spectroscopy, and thermodynamic profile were carried out for the most potent compound 11j. Moreover, molecular docking studies and in silico ADME prediction for all imidazoquinazolines 6a-c and 11a-o were performed to reveal their important binding interactions, as well as their physicochemical and drug-likeness properties, respectively.

Synthesis and structure-activity relationship studies of benzimidazole-thioquinoline derivatives as α-glucosidase inhibitors

In this article, different s-substituted benzimidazole-thioquinoline derivatives were designed, synthesized, and evaluated for their possible α-glucosidase inhibitory activities. The most active compound in this series, 6j (X = 4-bromobenzyl) exhibited significant potency with an IC₅₀ value of 28.0 ± 0.6 µM compared to acarbose as the positive control with an IC₅₀ value of 750.0 µM. The kinetic study showed a competitive inhibition pattern against α-glucosidase for the 6j derivative. Also, the molecular dynamic simulations were performed to determine key interactions between compounds and the targeted enzyme. The in silico pharmacodynamics and ADMET properties were executed to illustrate the druggability of the novel derivatives. In general, it can be concluded that these derivatives can serve as promising leads to the design of potential α-glucosidase inhibitors.

New benzimidazole-oxadiazole derivatives: Synthesis, α-glucosidase, α-amylase activity, and molecular modeling studies as potential antidiabetic agents

Benzimidazole-1,3,4-oxadiazole derivatives (5a-z) were synthesized and characterized with different spectroscopic techniques such as ¹ H NMR, ¹³ C NMR, and HRMS. The synthesized analogs were examined against α-glucosidase and α-amylase enzymes to determine their antidiabetic potential. Compounds 5g and 5q showed the most activity with 35.04 ± 1.28 and 47.60 ± 2.16 µg/mL when compared with the reference drug acarbose (IC₅₀  = 54.63 ± 1.95 µg/mL). Compounds 5g, 5o, 5s, and 5x were screened against the α-amylase enzyme and were found to show excellent potential, with IC₅₀ values ranging from 22.39 ± 1.40 to 32.07 ± 1.55 µg/mL, when compared with the standard acarbose (IC₅₀  = 46.21 ± 1.49 µg/mL). The antioxidant activities of the effective compounds (5o, 5g, 5s, 5x, and 5q) were evaluated by TAS methods. A molecular docking research study was conducted to identify the active site and explain the functions of the active chemicals. To investigate the most likely binding mode of the substances 5g, 5o, 5q, 5s, and 5x, a molecular dynamics simulation was also carried out.

Substituted Benzimidazole Analogues as Potential α-Amylase Inhibitors and Radical Scavengers

Benzimidazole scaffolds are known to have a diverse range of biological activities and found to be antidiabetic and antioxidant. In this study, a variety of arylated benzimidazoles 1-31 were synthesized. Except for compounds 1, 6, 7, and 8, all are new derivatives. All compounds were screened for α-amylase inhibitory, 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activities. In vitro screening results revealed that all molecules demonstrated significant α-amylase inhibition with IC50 values of 1.86 ± 0.08 to 3.16 ± 0.31 μM as compared to standard acarbose (IC50 = 1.46 ± 0.26 μM). However, compounds showed significant ABTS and DPPH radical scavenging potentials with IC50 values in the range of 1.37 ± 0.21 to 4.00 ± 0.10 μM for ABTS and 1.36 ± 0.09 to 3.60 ± 0.20 μM for DPPH radical scavenging activities when compared to ascorbic acid with IC50 values of 0.72 ± 0.21 and 0.73 ± 0.05 μM for ABTS and DPPH radical scavenging potentials, respectively. Structure-activity relationship (SAR) was established after critical analysis of varying substitution effects on α-amylase inhibitory and radical scavenging (ABTS and DPPH) potentials. However, molecular docking was also performed to figure out the active participation of different groups of synthetic molecules during binding with the active pocket of the α-amylase enzyme.

Diaryl azo derivatives as anti-diabetic and antimicrobial agents: synthesis, in vitro, kinetic and docking studies

In the present study, a series of azo derivatives (TR-1 to TR-9) have been synthesised via the diazo-coupling approach between substituted aromatic amines with phenol or naphthol derivatives. The compounds were evaluated for their therapeutic applications against alpha-glucosidase (anti-diabetic) and pathogenic bacterial strains E. coli (gram-negative), S. aureus (gram-positive), S. aureus (gram-positive) drug-resistant strain, P. aeruginosa (gram-negative), P. aeruginosa (gram-negative) drug-resistant strain and P. vulgaris (gram-negative). The IC₅₀ (µg/mL) of TR-1 was found to be most effective (15.70 ± 1.3 µg/mL) compared to the reference drug acarbose (21.59 ± 1.5 µg/mL), hence, it was further selected for the kinetic studies in order to illustrate the mechanism of inhibition. The enzyme inhibitory kinetics and mode of binding for the most active inhibitor (TR-1) was performed which showed that the compound is a non-competitive inhibitor and effectively inhibits the target enzyme by binding to its binuclear active site reversibly.

Design, synthesis, molecular docking, and in vitro α-glucosidase inhibitory activities of novel 3-amino-2,4-diarylbenzo[4,5]imidazo[1,2-a]pyrimidines against yeast and rat α-glucosidase

In an attempt to find novel, potent α-glucosidase inhibitors, a library of poly-substituted 3-amino-2,4-diarylbenzo[4,5]imidazo[1,2-a]pyrimidines 3a–ag have been synthesized through heating a mixture of 2-aminobenzimidazoles 1 and α-azidochalcone 2 under the mild conditions. This efficient, facile protocol has been resulted into the desirable compounds with a wide substrate scope in good to excellent yields. Afterwards, their inhibitory activities against yeast α-glucosidase enzyme were investigated. Showing IC₅₀ values ranging from 16.4 ± 0.36 µM to 297.0 ± 1.2 µM confirmed their excellent potency to inhibit α-glucosidase which encouraged us to perform further studies on α-glucosidase enzymes obtained from rat as a mammal source. Among various synthesized 3-amino-2,4-diarylbenzo[4,5]imidazo[1,2-a]pyrimidines, compound 3k exhibited the highest potency against both Saccharomyces cerevisiae α-glucosidase (IC₅₀ = 16.4 ± 0.36 μM) and rat small intestine α-glucosidase (IC₅₀ = 45.0 ± 8.2 μM). Moreover, the role of amine moiety on the observed activity was studied through substituting with chlorine and hydrogen resulted into a considerable deterioration on the inhibitory activity. Kinetic study and molecular docking study have confirmed the in-vitro results.

Apoptosis inducing properties of 3-biotinylate-6-benzimidazole B-nor-cholesterol analogues

In this work, a series of Biotin-substituted B-nor-cholesteryl benzimidazole compounds were synthesized. The antiproliferativeactivities of these compounds were evaluated in vitro using a series of human cancer cell lines, including HeLa (cervical cancer), SKOV3 (ovarian cancer), T-47D (thymus gland cancer), MCF-7 (human breast cancer) and HEK293T (normal renal epithelial) cells. These compounds displayed distinct antiproliferative activities against the currently tested cancer cells. The apoptotic properties induced by compound 6d were further investigated. Our results showed that compound 6d could induce the apoptosis of SKOV3 cells, blocking the cell growth in S-phase. Western blotting analyses revealed that compound 6d can induce cell apoptosis via the mitochondria-dependent pathway.

Biological Evaluation, Molecular Docking, and SAR Studies of Novel 2-(2,4-Dihydroxyphenyl)-1H- Benzimidazole Analogues

In the present study, new 4-(1H-benzimidazol-2-yl)-benzene-1,3-diols, modified in both rings, have been synthesized and their efficacies as acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) inhibitors have been determined. The modified Ellman’s spectrophotometric method was applied for the biological evaluation. The compounds showed strong (IC₅₀ 80–90 nM) AChE and moderate (IC₅₀ 5–0.2 µM) BuChE inhibition in vitro. Some compounds were effective toward AChE/BuChE, exhibiting high selectivity ratios versus BuChE, while the other compounds were active against both enzymes. The structure–activity relationships were discussed. The compounds inhibited also in vitro self-induced Aβ(1–42) aggregation and exhibited antioxidant properties. The docking simulations showed that the benzimidazoles under consideration interact mainly with the catalytic site of AChE and mimic the binding mode of tacrine.

Synthesis of new indazole based dual inhibitors of α-glucosidase and α-amylase enzymes, their in vitro, in silico and kinetics studies

The current study describes the discovery of novel inhibitors of α-glucosidase and α-amylase enzymes. For that purpose, new hybrid analogs of N-hydrazinecarbothioamide substituted indazoles 4-18 were synthesized and fully characterized by EI-MS, FAB-MS, HRFAB-MS, ¹H-, and ¹³C NMR spectroscopic techniques. Stereochemistry of the imine double bond was established by NOESY measurements. All derivatives 4-18 with their intermediates 1-3, were evaluated for in vitro α-glucosidase and α-amylase enzyme inhibition. It is worth mentioning that all synthetic compounds showed good inhibition potential in the range of 1.54 ± 0.02-4.89 ± 0.02 µM for α-glucosidase and for α-amylase 1.42 ± 0.04-4.5 ± 0.18 µM in comparison with the standard acarbose (IC₅₀ value of 1.36 ± 0.01 µM). In silico studies were carried out to rationalize the mode of binding interaction of ligands with the active site of enzymes. Moreover, enzyme inhibitory kinetic characterization was also performed to understand the mechanism of enzyme inhibition.

2-Mercapto Benzothiazole Derivatives: As Potential Leads for the Diabetic Management

BACKGROUND

Results of our previous studies on antiglycation activity, and the noncytotoxicity of 2-mercapto benzothiazoles, encouraged us to further widen our investigation towards the identification of leads against diabetes mellitus.

METHODS

33 derivatives of 2-mercapto benzothiazoles 1-33 were evaluated for in vitro α- glucosidase inhibitory activity. Mode of inhibition was deduced by kinetic studies. To predict the interactions of 2-mercapto benzothiazole derivatives 1-33 with the binding pocket of α-glucosidase enzyme, molecular docking studies were performed on the selected inhibitors.

RESULTS

Compounds 2-4, 6-7, 9-26, 28 and 30 showed many folds potent α-glucosidase inhibitory activity in the range of IC50 = 31.21-208.63 μM, as compared to the standard drug acarbose (IC50 = 875.75 ± 2.08 μM). It was important to note that except derivative 28, all other derivatives were also found previously to have antiglycating potential in the range of IC50 = 187.12-707.21 μM.

CONCLUSION

A number of compounds were identified as dual nature as antiglycating agent and α- glucosidase inhibitors. These compounds may serve as potential lead candidates for the management of diabetes mellitus.

New Hybrid Hydrazinyl Thiazole Substituted Chromones: As Potential α-Amylase Inhibitors and Radical (DPPH & ABTS) Scavengers

Current research is based on the identification of novel inhibitors of α-amylase enzyme. For that purpose, new hybrid molecules of hydrazinyl thiazole substituted chromones 5-27 were synthesized by multi-step reaction and fully characterized by various spectroscopic techniques such as EI-MS, HREI-MS, 1H-NMR and 13C-NMR. Stereochemistry of the iminic bond was confirmed by NOESY analysis of a representative molecule. All compounds 5-27 along with their intervening intermediates 1-4, were screened for in vitro α-amylase inhibitory, DPPH and ABTS radical scavenging activities. All compounds showed good inhibition potential in the range of IC50 = 2.186-3.405 µM as compared to standard acarbose having IC50 value of 1.9 ± 0.07 µM. It is worth mentioning that compounds were also demonstrated good DPPH (IC50 = 0.09-2.233 µM) and ABTS (IC50 = 0.584-3.738 µM) radical scavenging activities as compared to standard ascorbic acid having IC50 = 0.33 ± 0.18 µM for DPPH and IC50 = 0.53 ± 0.3 µM for ABTS radical scavenging activities. In addition to that cytotoxicity of the compounds were checked on NIH-3T3 mouse fibroblast cell line and found to be non-toxic. In silico studies were performed to rationalize the binding mode of compounds (ligands) with the active site of α-amylase enzyme.

A novel library of -arylketones as potential inhibitors of α-glucosidase: Their design, synthesis, in vitro and in vivo studies

α-glucosidase is an essential enzyme located at the brush border of intestines. It is an important therapeutic target for type II diabetes. Herein we have designed a library of novel α-arylketones as inhibitors of α-glucosidase (yeast origin) via scaffold hopping and bioisosteric modification of known inhibitors of α-glucosidase. The design was validated through molecular docking that revealed strong binding interactions of the newly designed compounds against α-glucosidase. A library comprising of 15 compounds was synthesized in a combinatorial fashion, where the advanced amide intermediates were accessed through “shot gun” synthesis. The final compounds were characterized by ¹H, ¹³C-NMR and with high resolution mass spectroscopy. In vitro screening of the compounds against yeast α-glucosidase revealed substantial inhibition with IC₅₀s in the range of 4–10 μM (the standard drug acarbose inhibits α-glucosidase with an IC₅₀ of 9.95 μM). Reaction kinetics suggested mixed type inhibition. Finally, in vivo studies of the most active compound 3c against Streptozotocin induced male albino Wistar rats revealed that its administration in the rats for about 4 weeks lead to a highly significant (P < 0.001) decrease in the fasting blood glucose (FBG) compared to the untreated diabetic rats. Moreover, lower dose of 3c had better control over FBG in contrast to high-dose.