Novel 5-(Arylideneamino)-1H-Benzo[d]imidazole-2-thiols as Potent Anti-Diabetic Agents: Synthesis, In Vitro α-Glucosidase Inhibition, and Molecular Docking Studies

Antibacterial and antifungal pyrazoles based on different construction strategies

The growing prevalence of microbial infections, and antimicrobial resistance (AMR) stemming from the overuse and misuse of antibiotics, call for novel therapeutic agents, particularly ones targeting resistant microbial strains. Scientists are striving to develop innovative agents to tackle the rising microbial infections and abate the risk of AMR. Pyrazole, a five-membered heterocyclic compound belonging to the azole family, is a versatile scaffold and serves as a core structure in many drugs with antimicrobial and other therapeutic effects. In this review, we have updated pyrazole-based antibacterial and antifungal agents mainly developed between 2016 and 2024, by combining with diverse pharmacophores such as coumarin, thiazole, oxadiazole, isoxazole, indole, etc. Meanwhile, the various strategies (molecular hybridization, bioisosterism, scaffold hopping, multicomponent reactions, and catalyst-free synthesis) for integrating different functional groups with the pyrazole ring are discussed. Additionally, structure-activity relationships of these pyrazole derivatives, i.e., how structural modifications impact their selectivity and therapeutic potential against bacterial and fungal strains, are highlighted. This review provides insights into designing next-generation antimicrobials to combat AMR, and offers valuable perspectives to the scientists working on heterocyclic compounds with diverse bioactivities.

Identification of Antioxidant Methyl Derivatives of Ortho-Carbonyl Hydroquinones That Reduce Caco-2 Cell Energetic Metabolism and Alpha-Glucosidase Activity

α-glucosidase, a pharmacological target for type 2 diabetes mellitus (T2DM), is present in the intestinal brush border membrane and catalyzes the hydrolysis of sugar linkages during carbohydrate digestion. Since α-glucosidase inhibitors (AGIs) modulate intestinal metabolism, they may influence oxidative stress and glycolysis inhibition, potentially addressing intestinal dysfunction associated with T2DM. Herein, we report on a study of an ortho-carbonyl substituted hydroquinone series, whose members differ only in the number and position of methyl groups on a common scaffold, on radical-scavenging activities (ORAC assay) and correlate them with some parameters obtained by density functional theory (DFT) analysis. These compounds' effect on enzymatic activity, their molecular modeling on α-glucosidase, and their impact on the mitochondrial respiration and glycolysis of the intestinal Caco-2 cell line were evaluated. Three groups of compounds, according their effects on the Caco-2 cells metabolism, were characterized: group A (compounds 2, 3, 5, 8, 9, and 10) reduces the glycolysis, group B (compounds 1 and 6) reduces the basal mitochondrial oxygen consumption rate (OCR) and increases the extracellular acidification rate (ECAR), suggesting that it induces a metabolic remodeling toward glycolysis, and group C (compounds 4 and 7) increases the glycolysis lacking effect on OCR. Compounds 5 and 10 were more potent as α-glucosidase inhibitors (AGIs) than acarbose, a well-known AGI with clinical use. Moreover, compound 5 was an OCR/ECAR inhibitor, and compound 10 was a dual agent, increasing the proton leak-driven OCR and inhibiting the maximal electron transport flux. Additionally, menadione-induced ROS production was prevented by compound 5 in Caco-2 cells. These results reveal that slight structural variations in a hydroquinone scaffold led to diverse antioxidant capability, α-glucosidase inhibition, and the regulation of mitochondrial bioenergetics in Caco-2 cells, which may be useful in the design of new drugs for T2DM and metabolic syndrome.

Targeting α-amylase enzyme through multi-fold structure-based virtual screening and molecular dynamic simulation

α-Amylase play important role in hydrolyses of α-bonds of large α-linked polysaccharides; thus, it is a potential drug target in diabetes mellites (DM) and its inhibition is one of the therapeutic strategies in DM. With the aim to discover novel and safer therapeutic molecules to combat diabetes, a huge dataset of ∼0.69 billion compounds from ZINC20 database were screened against α-amylase using multi-fold structure-based virtual screening protocol. Based on receptor-based pharmacophore model, docking results, pharmacokinetic profile, molecular interactions with α-amylase, several compounds were retrieved as lead candidates to be further scrutinized in the in vitro assay and in vivo animal testing. Among the selected hits, CP26 exhibited the highest binding free energy in MMGB-SA analysis, followed by CP7 and CP9, which is higher than the binding free energy of acarbose. While CP20 and CP21 showed comparative binding free energy to acarbose. All the selected ligands showed acceptable binding energy range, therefore, several molecules with enhanced efficacy can be designed by derivatizing these molecules. The in-silico results indicates that the selected molecules could serve as potential selective α-amylase inhibitors and can be used for the treatment of diabetes.Communicated by Ramaswamy H. Sarma.

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.

Synthesis of novel hydrazide Schiff bases with anti-diabetic and anti-hyperlipidemic effects: in-vitro, in-vivo and in-silico approaches

The increasing global incidence of non-insulin-dependent diabetes mellitus (NIDDM) necessitates innovative therapeutic solutions. This study focuses on the design, synthesis and biological evaluation of Schiff base derivatives from 2-bromo-2-(2-chlorophenyl) acetic acid, particularly hydrazone compounds 4a and 4b. Both in-vitro and in-vivo assays demonstrate these derivatives' strong antidiabetic and anti-hyperlipidemic properties. In a 15-d experiment, we administered 4a and 4b at doses of 2.5 and 5 mg/kg body weight, which effectively improved symptoms of alloxan-induced diabetes in mice. These symptoms included weight loss, increased water consumption and high blood glucose levels. The compounds also normalized abnormal levels of total cholesterol (TC), triacylglycerol (TG) and low-density lipoprotein cholesterol (LDL-C), while raising the levels of high-density lipoprotein cholesterol (HDLC). Computational analysis showed that these compounds effectively inhibited the α-glucosidase enzyme by interacting with key catalytic residues, specifically Asp214 and Asp349. These computational results were confirmed through in-vitro tests, where 4a and 4b showed strong α-glucosidase inhibitory activity, with IC50 values of 0.70 ± 0.11 and 10.29 ± 0.30 µM, respectively. These compounds were more effective than the standard drug, acarbose, which had an IC50 value of 873.34 ± 1.67 µM. Mechanistic studies further indicated competitive inhibition, reinforcing the therapeutic potential of 4a and 4b for NIDDM treatment.Communicated by Ramaswamy H. Sarma.

Biochemical and computational inhibition of α-glucosidase by novel metronidazole-linked 1H-1,2,3-triazole and carboxylate moieties: kinetics and dynamic investigations

In the current study, metronidazole derivatives containing 1H-1,2,3-triazole and carboxylate moieties were evaluated in vitro and by computational methods for their anti-diabetic potential to insight into their medicinal use for the management of type II diabetes mellitus. Interestingly all 14 compounds displayed high to significant inhibitory capability against the key carbohydrate's digestive enzyme α-glucosidase with IC50 values in range of 9.73-56.39 μM, as compared to marketed drug acarbose (IC50 = 873.34 ± 1.67 μM). Compounds 5i and 7c exhibited the highest inhibition, therefore, these two compounds were further evaluated for their mechanistic studies to explore its type of inhibition. Compounds 5i and 7c both displayed a concentration-dependent (competitive type of inhibition) with Ki values 7.14 ± 0.01, 6.15 ± 0.02 μM, respectively, which conclude their favourable interactions with the active site residues of the α-glucosidase. Interestingly all compounds are non-cytotoxic against BJ cell line. To further validate our findings, in-silico approaches like molecular docking, and molecular dynamic simulations were applied to investigate the mode of bindings of compounds with the enzyme and identifies their inhibition mechanism, which strongly complements our experimental findings.Communicated by Ramaswamy H. Sarma.

Synthesis, Structural Elucidation, In Silico and In Vitro Studies of New Class of Methylenedioxyphenyl-Based Amide Derivatives as Potential Myeloperoxidase Inhibitors for Cardiovascular Protection

Novel methylenedioxyphenyl-based amides, especially N-(4-methoxybenzyl)-6-nitrobenzo-[1,3]-dioxole-5-carboxamide (MDC) and N-(3-acetylphenyl)-6-nitrobenzo-[1,3]-dioxole-5-carboxamide (ADC), potential cardiovascular preventive agents, are successfully synthesized, and their chemical structures are verified by 1H and 13C NMR, Fourier transform infrared (FT-IR), high-resolution mass spectrometry (HRMS), and single-crystal X-ray diffraction (SC-XRD) analyses. Data obtained from SC-XRD reveal that MDC and ADC are both monoclinic molecules with Z = 2 and 4, respectively. From density functional theory (DFT) calculations, 3.54 and 3.96 eV are the energy gaps of the optimized MDC and ADC structures, respectively. MDC and ADC exhibit an electrophilicity index value of more than 1.5 eV, suggesting that they can act as an electrophile, facilitating bond formation with biomolecules. Hirshfeld surface analysis demonstrates that more than 25% of atomic interactions in both MDC and ADC are from H···H interactions. Based on pharmacokinetic predictions, MDC and ADC exhibit drug-like properties, and molecular docking simulations revealed favorable interactions with active site pockets. Both MDC and ADC achieved higher docking scores of -7.74 and -7.79 kcal/mol, respectively, with myeloperoxidase (MPO) protein. From docking results, MPO was found to be most favorable followed by dipeptidyl peptidase-4 (DPP-4) and α-glucosidase (α-GD). Antioxidant, anti-inflammatory, and in vitro enzymatic studies of MDC and ADC indicate that MDC is more selective toward MPO and more potent than ADC. The application of MDC to inhibit myeloperoxidase could be ascertained to reduce the cardiovascular risk factor. This can be supported from the results of computational docking (based on hydrogen bonding and docking score), in vitro antioxidant and anti-inflammatory properties, and MPO enzymatic inhibition (based on the percentage of inhibition and IC50 values).

In vitro and in vivo anti-pigmentation effects of 2-mercaptobenzimidazoles as nanomolar tyrosinase inhibitors on mammalian cells and zebrafish embryos: Preparation of pigment-free zebrafish embryos

Recently, 10 2-mercaptobenzo[d]imidazole (2-MBI) compounds (1-10) were synthesized. Although all 2-MBI compounds are tyrosinase inhibitors that inhibit mushroom tyrosinase at extremely low concentrations (IC50 values: 20-740 nM) and effectively inhibit the browning of apples, to our knowledge, no studies have determined whether 2-MBI compounds inhibit mammalian tyrosinase. Mammalian tyrosinase is different from mushroom tyrosinase in its distribution within the cell and has structural characteristics that are different from mushroom tyrosinase in amino acid sequence and in the presence of a quaternary structure. Thus, the effect of the 10 2-MBI compounds on mammalian tyrosinase activity was investigated in B16F10 cells. Six compounds (1-6) exhibited stronger intracellular tyrosinase inhibition than that of kojic acid and phenylthiourea (PTU), which are known to be the most potent tyrosinase inhibitors; their strong tyrosinase inhibitory activity robustly inhibited intracellular melanin production in B16F10 cells. None of the tested 2-MBI compounds exhibited appreciable cytotoxicity in HaCaT and B16F10 cells. To confirm the anti-melanogenic efficacy of the 2-MBI compounds in vivo, a zebrafish embryo model was used. At concentrations 100 times lower than kojic acid, most 2-MBI compounds demonstrated much stronger depigmentation efficacy than that of kojic acid, and three 2-MBI compounds (2-4) showed depigmentation activity similar to or more potent than that of PTU, resulting in nearly pigment-free zebrafish embryos. These results suggest that 2-MBI compounds may be potential therapeutic agents for hyperpigmentation-related disorders.

In-silico based Designing of benzo[d]thiazol-2-amine Derivatives as Analgesic and Anti-inflammatory Agents

BACKGROUND

Benzo[d]thiazoles represent a significant class of heterocyclic compounds renowned for their diverse pharmacological activities, including analgesic and antiinflammatory properties. This molecular scaffold holds substantial interest among medicinal chemists owing to its structural versatility and therapeutic potential. Incorporating the benzo[d]thiazole moiety into drug molecules has been extensively investigated as a strategy to craft novel therapeutics with heightened efficacy and minimized adverse effects.

AIMS

The aim of the present research work was to design, synthesize and characterize the new benzo[d]thiazol-2-amine derivatives as potent analgesic and anti-inflammatory agents.

MATERIALS AND METHODS

The synthesis of the presented benzo[d]thiazol-2-amine derivatives was performed by condensing-(4-chlorobenzylidene) benzo[d]thiazol-2-amine with a number of substituted phenols in the presence of potassium iodide and anhydrous potassium carbonate in dry acetone. IR spectroscopy, 1HNMR spectroscopy, 13CNMR spectroscopy and Mass spectroscopy methods were used to characterize the structural properties of all 13 newly synthesized derivatives. The molecular properties of these newly synthesized derivatives were estimated to study the attributes of drug-like candidates. Benzo[d]thiazol-2-amine derivatives were molecularly docked with selective enzymes COX-1 and COX-2. Analgesic and anti-inflammatory activities of synthesized compounds were evaluated by using albino rats.

RESULTS

Findings of the research suggested that compounds G3, G4, G6, G8 and G11 possess higher binding affinity than diclofenac sodium, when docking was performed with enzyme COX-1. Compounds G1, G3, G6, G8 and G10 showed lower binding affinity than Indomethacin when docking was performed with enzyme COX-2. In vitro evaluation of the COX-1 and COX-2 enzyme inhibitory activities was performed for synthesized compounds.

DISCUSSION

Compounds G10 and G11 exhibited significant COX-1 and COX-2 enzyme inhibitory action with an IC50 value of 5.0 and 10 μM, respectively. Using the hot plate method and the carrageenan-induced rat paw edema model, the synthesized compounds were screened for their biological activities, including analgesic and anti-inflammatory activities. Highest analgesic action was exhibited by derivative G11 and the compound G10 showed the highest anti-inflammatory response. Inhibition of COX may be considered as a mechanism of action of these compounds.

CONCLUSION

It was concluded that synthesized derivatives G10 and G11 exhibited significant analgesic and anti-inflammatory effect; therefore, the said compounds may be subjected to further clinical investigation for establishing these as future compounds for the treatment of pain and inflammation.

Synthesis of novel coumarin-hydrazone hybrids as α-glucosidase inhibitors and their molecular docking studies

Diabetes mellitus is a metabolic disorder and more than 90% of diabetic patients suffer from type-2 diabetes, which is characterized by hyperglycemia. α-Glucosidase inhibition has become an appropriate approach to tackle high blood glucose levels. The current study was focused on synthesizing coumarin-hydrazone hybrids (7a-i) by using facile chemical reactions. The synthesized compounds were characterized by using 1H-NMR, 13C-NMR, and IR. To evaluate their anti-diabetic capability, all of the conjugates were screened for in vitro α-glucosidase inhibitory activity to reveal their therapeutic importance. All of the compounds (except 7b) demonstrated significant enzyme inhibitory potential with IC50 values ranging between 2.39-57.52 μM, as compared to the standard inhibitor, acarbose (IC50 = 873.34 ± 1.67 μM). Among them, compound 7c is the most potent α-glucosidase inhibitor (IC50 = 2.39 ± 0.05 μM). Additionally, molecular docking was employed to scrutinize the binding pattern of active compounds within the α-glucosidase binding site. The in silico analysis reflects that hydrazone moiety is an essential pharmacophore for the binding of compounds with the active site residues of the enzyme. This study demonstrates that compounds 7c and 7f deserve further molecular optimization for potential application in diabetic management.

Structure-based identification of potential substrate antagonists for isethionate sulfite-lyase enzyme of Bilophila Wadsworthia: Towards novel therapeutic intervention to curb gut-associated illness

Bilophila wadsworthia is one of the prominent sources of hydrogen sulfide (H₂S) production in appendices, excessive levels of which can result in a weaker colonic mucus barrier, inflammatory bowel disease, and colorectal cancer. Isethionate sulfite-lyase (IslA) enzyme catalyzes H2S production by cleaving CS bond in isethionate, producing acetaldehyde and sulfite. In this study, we aimed to identify potential substrate antagonists for IsIA using a structure-based drug design. Initially, pharmacophore-based computational screening of the ZINC20 database yielded 66 hits that were subjected to molecular docking targeting the isethionate binding site of IsIA. Based on striking docking scores, nine compounds showed strong interaction with critical IsIA residues (Arg189, Gln193, Glu470, Cys468, and Arg678), drug-like features, appropriate adsorption, metabolism, excretion, and excretion profile with non-toxicity. Molecular dynamics simulations uncovered the significant impact of binding the compounds on protein conformational dynamics. Finally, binding free energies revealed substantial binding affinity (ranging from -35.23 to -53.88 kcal/mol) of compounds (ZINC913876497, ZINC913856647, ZINC914263733, ZINC914137795, ZINC915757996, ZINC914357083, ZINC913934833, ZINC9143362047, and ZINC913854740) for IsIA. The compounds proposed herein through a multi-faceted computational strategy can be experimentally validated as potential substrate antagonists of B. wadsworthia's IsIA for developing new medications to curb gut-associated illness in the future.