Quinoline-2-carboxylic acid isolated from Ephedra pachyclada and its structural derivatives show inhibitory effects against α-glucosidase and α-amylase

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.

Alpha-glucosidase inhibitory and hypoglycemic effects of imidazole-bearing thioquinoline derivatives with different substituents: In silico, in vitro, and in vivo evaluations

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disorder characterized by high blood sugar levels. It was shown that modulating the activity of α-glucosidase, an enzyme involved in carbohydrate digestion and absorption, can improve blood sugar control and overall metabolic health in individuals with T2DM. As a result, in the current study, a series of imidazole bearing different substituted thioquinolines were designed and synthesized as α-glucosidase inhibitors. All derivatives exhibited significantly better potency (IC50 = 12.1 ± 0.2 to 102.1 ± 4.9 µM) compared to the standard drug acarbose (IC50 = 750.0 ± 5.0 µM). 8g as the most potent analog, indicating a competitive inhibition with Ki = 9.66 µM. Also, the most potent derivative was subjected to molecular docking and molecular dynamic simulation against α-glucosidase to determine its mode of action in the enzyme and study the complex's behavior over time. In vivo studies showed that 8g did not cause acute toxicity at 2000 mg/kg doses. Additionally, in a diabetic rat model, treatment with 8g significantly reduced fasting blood glucose levels and decreased blood glucose levels following sucrose loading compared to acarbose, a standard drug used for blood sugar control. The findings suggest that the synthesized compound 8g holds promise as an α-glucosidase inhibitor for improving blood sugar control and metabolic health.

Glycosidase-targeting small molecules for biological and therapeutic applications

Glycosidases are ubiquitous enzymes that catalyze the hydrolysis of glycosidic linkages in oligosaccharides and glycoconjugates. These enzymes play a vital role in a wide variety of biological events, such as digestion of nutritional carbohydrates, lysosomal catabolism of glycoconjugates, and posttranslational modifications of glycoproteins. Abnormal glycosidase activities are associated with a variety of diseases, particularly cancer and lysosomal storage disorders. Owing to the physiological and pathological significance of glycosidases, the development of small molecules that target these enzymes is an active area in glycoscience and medicinal chemistry. Research efforts carried out thus far have led to the discovery of numerous glycosidase-targeting small molecules that have been utilized to elucidate biological processes as well as to develop effective chemotherapeutic agents. In this review, we describe the results of research studies reported since 2018, giving particular emphasis to the use of fluorescent probes for detection and imaging of glycosidases, activity-based probes for covalent labelling of these enzymes, glycosidase inhibitors, and glycosidase-activatable prodrugs.

Synthesis of Quinoline-2-Carboxylic Acid Aryl Ester and Its Apoptotic Action on PC3 Prostate Cancer Cell Line

The aim of the present study is to synthesise an aryl ester compound from quinoline-2-carboxylic acid to evaluate its apoptotic, cell cycle blockade, and antiproliferative activity on the prostate cancer cell lines (PC3). Chromatographic and spectroscopic analysis was used to identify the synthesised carboxylic acid compound. The synthesised compound was treated with a PC3 cell line for 24 h with control. The cells were treated at various concentration ranges of 0, 3.91, 7.81, 15.63, 31.25, 62.5, 125, 250, 500, and 1000 µg/mL each. The cytotoxicity effect was studied by MTT assay, and their anticancer activity was further evaluated using cell cycle analysis, DNA fragmentation assay, acridine orange-ethidium bromide staining, and Western blot analysis. The end antiproliferative result showed that PC3 cell viability decreases in a concentration-dependent manner and the synthesised compound exhibited potent cytotoxicity against PC3 cells with an IC50 value of 26 µg/mL at the concentration of 125 µg. The increase in the number of apoptotic cells was observed after treating PC3 cells with the sample in double-staining methods. S phase of the cell cycle was significantly blocked by the test sample, and a typical ladder pattern of internucleosomal fragmentation was observed. A decrease in the live cells was observed with the sample in AO/ET-BR. A significant increase in the Bax expression and a decrease in Bcl-2 expression observed enhance the activity of caspases-7 and -9. The synthesised compound had shown to possess excellent cytotoxic effect through inducing apoptosis, especially causing cell cycle arrest at the S phase.

Novel Pyrano[3,2-c]quinoline-1,2,3-triazole Hybrids as Potential Anti-Diabetic Agents: In Vitro α-Glucosidase Inhibition, Kinetic, and Molecular Dynamics Simulation

In this study, a novel series of pyrano[3,2-c]quinoline-1,2,3-triazole hybrids 8a-o were synthesized and evaluated against the α-glucosidase enzyme. All compounds showed significant in vitro inhibitory activity (IC₅₀ values of 1.19 ± 0.05 to 20.01 ± 0.02 μM) compared to the standard drug acarbose (IC₅₀ = 750.0 μM). Among them, 2-amino-4-(3-((1-benzyl-1H-1,2,3-triazol-4-yl)methoxy)phenyl)-5-oxo-5,6-dihydro-4H-pyrano[3,2-c]quinoline-3-carbonitrile (compound 8k) demonstrated the best inhibitory effect toward α-glucosidase (IC₅₀ = 1.19 ± 0.05 μM) with a competitive pattern of inhibition. Since compound 8k was synthesized as a racemic mixture, molecular docking and dynamics simulations were performed on R- and S-enantiomers of compound 8k. Based on the molecular docking results, both R- and S-enantiomers of compound 8k displayed significant interactions with key residues including catalytic triad (Asp214, Glu276, and Asp349) in the enzyme active site. However, an in silico study indicated that S- and R-enantiomers were inversely located in the enzyme active site. The R-enantiomer formed a more stable complex with a higher binding affinity to the active site of α-glucosidase than that of the S- enantiomer. The benzyl ring in the most stable complex ((R)-compound 8k) was located in the bottom of the binding site and interacted with the enzyme active site, while the pyrano[3,2-c]quinoline moiety occupied the high solvent accessible entrance of the active site. Thus, the synthesized pyrano[3,2-c]quinoline-1,2,3-triazole hybrids seem to be promising scaffolds for the development of novel α-glucosidase inhibitors.

Synthesis, ADMT prediction, and in vitro and in silico α-glucosidase inhibition evaluations of new quinoline-quinazolinone-thioacetamides

In this work, a new series of quinoline-quinazolinone-thioacetamide derivatives 9a-p were designed using a combination of effective pharmacophores of the potent α-glucosidase inhibitors. These compounds were synthesized by simple chemical reactions and evaluated for their anti-α-glucosidase activity. Among the tested compounds, compounds 9a, 9f, 9g, 9j, 9k, and 9m demonstrated significant inhibition effects in comparison to the positive control acarbose. Particularly, compound 9g with inhibitory activity around 83-fold more than acarbose exhibited the best anti-α-glucosidase activity. Compound 9g showed a competitive type of inhibition in the kinetic study, and the molecular simulation studies demonstrated that this compound with a favorable binding energy occupied the active site of α-glucosidase. Furthermore, in silico ADMET studies of the most potent compounds 9g, 9a, and 9f were performed to predict their drug-likeness, pharmacokinetic, and toxicity properties.

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.

Naturally-occurring carboxylic acids from traditional antidiabetic plants as potential pancreatic islet FABP3 inhibitors. A molecular docking-aided study

The antidiabetic action of traditional plants is mostly attributed to their antioxidant and anti-inflammatory properties. These plants are still having some secrets, making them an attractive source that allows for investigating new drugs or uncovering precise pharmacologic antidiabetic functions of their constituents. In diabetes, which is a lipid disease, long-term exposure of pancreatic islet beta cells to fatty acids (FAs) increases basal insulin release, reduces glucose-stimulated insulin secretion, causes islet beta cell inflammation, failure and apoptosis. Pancreatic islet beta cells express fatty acid binding protein 3 (FABP3) that receives long-chain FAs and traffics them throughout different cellular compartments to be metabolized and render their effects. Inhibition of this FABP3 may retard FA metabolism and protect islet beta cells. Since FAs interact with FABPs by their carboxylic group, some traditionally-known antidiabetic plants were reviewed in the present study, searching for their components that have common features of FABP ligands, namely carboxylic group and hydrophobic tail. Many of these carboxylic acids were computationally introduced into the ligand-binding pocket of FABP3 and some of them exhibited FABP3 ligand possibilities. Among others, the naturally occurring ferulic, cleomaldeic, caffeic, sinapic, hydroxycinnamic, 4-p-coumaroylquinic, quinoline-2-carboxylic, chlorogenic, 6-hydroxykynurenic, and rosmarinic acids in many plants are promising candidates for being FABP3-specific inhibitors. The study shed light on repurposing these phyto-carboxylic acids to function as FABP inhibitors. However, more in-depth biological and pharmacological studies to broaden the understanding of this function are needed.

Natural Sympathomimetic Drugs: From Pharmacology to Toxicology

Sympathomimetic agents are a group of chemical compounds that are able to activate the sympathetic nervous system either directly via adrenergic receptors or indirectly by increasing endogenous catecholamine levels or mimicking their intracellular signaling pathways. Compounds from this group, both used therapeutically or abused, comprise endogenous catecholamines (such as adrenaline and noradrenaline), synthetic amines (e.g., isoproterenol and dobutamine), trace amines (e.g., tyramine, tryptamine, histamine and octopamine), illicit drugs (e.g., ephedrine, cathinone, and cocaine), or even caffeine and synephrine. In addition to the effects triggered by stimulation of the sympathetic system, the discovery of trace amine associated receptors (TAARs) in humans brought new insights about their sympathomimetic pharmacology and toxicology. Although synthetic sympathomimetic agents are mostly seen as toxic, natural sympathomimetic agents are considered more complacently in the terms of safety in the vision of the lay public. Here, we aim to discuss the pharmacological and mainly toxicological aspects related to sympathomimetic natural agents, in particular of trace amines, compounds derived from plants like ephedra and khat, and finally cocaine. The main purpose of this review is to give a scientific and updated view of those agents and serve as a reminder on the safety issues of natural sympathomimetic agents most used in the community.

Design, synthesis, and in silico studies of quinoline-based-benzo[d]imidazole bearing different acetamide derivatives as potent α-glucosidase inhibitors

In this study, 18 novel quinoline-based-benzo[d]imidazole derivatives were synthesized and screened for their α-glucosidase inhibitory potential. All compounds in the series except 9q showed a significant α-glucosidase inhibition with IC₅₀ values in the range of 3.2 ± 0.3–185.0 ± 0.3 µM, as compared to the standard drug acarbose (IC₅₀ = 750.0 ± 5.0 µM). A kinetic study indicated that compound 9d as the most potent derivative against α-glucosidase was a competitive type inhibitor. Furthermore, the molecular docking study revealed the effective binding interactions of 9d with the active site of the α-glucosidase enzyme. The results indicate that the designed compounds have the potential to be further studied as new anti-diabetic agents.

Antioxidant and Antihyperglycemic Effects of Ephedra foeminea Aqueous Extract in Streptozotocin-Induced Diabetic Rats

Background: Ephedra foeminea is known in Jordan as Alanda and traditionally. It is used to treat respiratory symptoms such as asthma and skin rashes as an infusion in boiling water. The purpose of this study was to determine the antidiabetic property of Ephedra foeminea aqueous extract in streptozotocin-induced diabetic rats. Methods: The aqueous extract of Ephedra foeminea plant was used to determine the potential of its efficacy in the treatment of diabetes, and this extract was tested on diabetic rats as a model. The chemical composition of Ephedra foeminea aqueous extract was determined using liquid chromatography–mass spectrometry (LC-MS). Antioxidant activity was assessed using two classical assays (ABTS and DPPH). Results: The most abundant compounds in the Ephedra foeminea extract were limonene (6.3%), kaempferol (6.2%), stearic acid (5.9%), β-sitosterol (5.5%), thiamine (4.1%), riboflavin (3.1%), naringenin (2.8%), kaempferol-3-rhamnoside (2.3%), quercetin (2.2%), and ferulic acid (2.0%). The antioxidant activity of Ephedra foeminea aqueous extract was remarkable, as evidenced by radical scavenging capacities of 12.28 mg Trolox/g in ABTS and 72.8 mg GAE/g in DPPH. In comparison to control, induced diabetic rats treated with Ephedra foeminea extract showed significant improvement in blood glucose levels, lipid profile, liver, and kidney functions. Interleukin 1 and glutathione peroxidase levels in the spleen, pancreas, kidney, and liver of induced diabetic rats treated with Ephedra foeminea extract were significantly lower than in untreated diabetic rats. Conclusions: Ephedra foeminea aqueous extract appears to protect diabetic rats against oxidative stress and improve blood parameters. In addition, it has antioxidant properties that might be very beneficial medicinally.

Synthesis of new clioquinol derivatives as potent α-glucosidase inhibitors; molecular docking, kinetic and structure-activity relationship studies

Diabetes mellitus is a chronic metabolic disorder with increasing prevalence and long-term complications. The aim of this study was to identify α-glucosidase inhibitory compounds with potential anti-hyperglycemic activity. For this purpose, a series of new clioquinol derivatives 2a-11a was synthesized, and characterized by various spectroscopic techniques. The enzyme inhibitory activities of the resulting derivatives were assessed using an in-vitro mechanism-based assay. All the tested compounds 2a-11a of the series showed a significant α-glucosidase inhibition with IC₅₀ values 43.86-325.81 µM, as compared to the standard drug acarbose 1C₅₀: 875.75 ± 2.08 µM. Among them, compounds 4a, 5a, 10a, and 11a showed IC₅₀ values of 105.51 ± 2.41, 119.24 ± 2.37, 99.15 ± 2.06, and 43.86 ± 2.71 µM, respectively. Kinetic study of the active analogues showed competitive, non-competitive, and mixed-type inhibitions. Furthermore, the molecular docking study was performed to elucidate the binding interactions of most active analogues with the various sites of α-glucosidase enzyme. The results indicate that these compounds have the potential to be further studied as new anti-diabetic agents.

Metal-Free Chemoselective Oxidation of 4-Methylquinolines into Quinoline-4-Carbaldehydes

A convenient protocol for the synthesis of quinoline-4-carbaldehydes via chemoselective oxidation of 4-methylquinolines using hypervalent iodine(III) reagents as oxidant is described. This method highlights metal-free and mild reaction conditions, nice yield, good functional group tolerance, and high chemoselectivity.

Metabolome Exploration by High-Resolution Mass Spectrometry Methodologies of Two New Yeast Species: Starmerella reginensis and Starmerella kourouensis

Nature is harnessed since ancient times to fulfill human needs, and yeast culture has been mastered for bakery, brewery, or the preparation of beverages. In this context, the two recently discovered yeast species Starmerella reginensis and Starmerella kourouensis, belonging to a genus related to fermentative activities in the literature, were explored via untargeted metabolomics approaches. Ultrahigh-performance liquid chromatography hyphenated with tandem mass spectrometry and a deep investigation of molecular networks and spectral data allowed the annotation of, respectively, 439 and 513 metabolites for S. reginensis and S. kourouensis, with approximatively 30% compound annotations and 40% chemical class annotations for both yeast strains. These analyses and Fourier transform ion cyclotron resonance mass spectrometry accurate metabolic profiles unveiled a rich content of alkaloids, lipids, amino acids, and terpenoids for S. reginensis. S. kourouensis presents a similar profile with more sulfated compounds. In short, these results enrich the current knowledge about Starmerella yeast secondary metabolites and reveal their significant structural diversity of small molecules.

Synthesis, Docking, in silico ADMET and Pharmacological Evaluation of Some N-acetyl Pyrazole and Quinoline Conjugates

Background:

Pyrazolines are reported having anti-inflammatory, anti-oxidant and antidiabetic activities in the literature. Drugs like celecoxib, antipyrine, etc. are structurally similar to the designed compounds.

Objectives:

To synthesize and characterize N-acetyl pyrazole and quinoline conjugates and test them for Anti-inflammatory, Antioxidant, Antibacterial, Antiamylase and Antimalarial activities.

Methods:

A series of methoxy substituted quinoline based pyrazoline derivatives (2a-2j) were synthesized in good to excellent yield from corresponding quinoline chalcones (1a-1j). The synthesized compounds were characterized and screened for their in vitro anti-inflammatory, antioxidant, antiamylase, antibacterial and antimalarial activities. Docking and in silico ADMET studies were performed with PDB: 3LN1.

Results:

Compounds 2b, 2i and 2j showed significant anti-inflammatory activity as compared to standard sodium diclofenac. All compounds (2a-2j) showed excellent antioxidant activity for DPPH even more than standard ascorbic acid. Compounds 2e, 2f, 2h and 2i showed excellent antioxidant activity for NO. as compared to standard ascorbic acid. Compound 2f showed significant antioxidant activity for SOR. Almost all the compounds showed significant antibacterial as well as anti-amylase activity with few exceptions, whereas compounds 2f, 2h and 2j showed potent antimalarial activity.

Conclusion:

Compounds have shown good anti-inflammatory activities as compared with diclofenac. All the synthesized pyrazoline derivatives showed excellent anti-amylase activity as compared to standard acarbose. Also, compounds have shown good antioxidant antibacterial and antimalarial activities.

A Review of the Ephedra genus: Distribution, Ecology, Ethnobotany, Phytochemistry and Pharmacological Properties

Ephedra is one of the largest genera of the Ephedraceae family, which is distributed in arid and semiarid regions of the world. In the traditional medicine from several countries some species from the genus are commonly used to treat asthma, cold, flu, chills, fever, headache, nasal congestion, and cough. The chemical constituents of Ephedra species have been of research interest for decades due to their contents of ephedrine-type alkaloids and its pharmacological properties. Other chemical constituents such as phenolic and amino acid derivatives also have resulted attractive and have provided evidence-based supporting of the ethnomedical uses of the Ephedra species. In recent years, research has been expanded to explore the endophytic fungal diversity associated to Ephedra species, as well as, the chemical constituents derived from these fungi and their pharmacological bioprospecting. Two additional aspects that illustrate the chemical diversity of Ephedra genus are the chemotaxonomy approaches and the use of ephedrine-type alkaloids as building blocks in organic synthesis. American Ephedra species, especially those that exist in Mexico, are considered to lack ephedrine type alkaloids. In this sense, the phytochemical study of Mexican Ephedra species is a promising area of research to corroborate their ephedrine-type alkaloids content and, in turn, discover new chemical compounds with potential biological activity. Therefore, the present review represents a key compilation of all the relevant information for the Ephedra genus, in particular the American species, the species distribution, their ecological interactions, its ethnobotany, its phytochemistry and their pharmacological activities and toxicities, in order to promote clear directions for future research.

Efficient Synthesis and in Silico Studies of the Benzimidazole Hybrid Scaffold with the Quinolinyloxadiazole Skeleton with Potential α-Glucosidase Inhibitory, Anticoagulant, and Antiplatelet Activities for Type-II Diabetes Mellitus Management and Treating Thrombotic Disorders

The current study evaluates antidiabetic, anticoagulant, and antiplatelet activity of novel benzimidazole-containing quinolinyl oxadiazoles. These derivatives are synthesized and characterized using spectroscopy (FT-IR, ¹H NMR, and mass spectroscopy) and single-crystal X-ray diffraction methods. The inhibitory effects of these compounds were evaluated by the α-glucosidase inhibitory assay and shows the activity in the range of IC₅₀ = 0.66 ± 0.05 to 3.79 ± 0.46 μg/mL. In addition, molecular docking studies revealed that benzimidazole-containing quinolinyl oxadiazoles can correctly dock into the target receptor protein of the human intestinal α-glucosidase, while their bioavailability/drug-likeness was predicted to be acceptable but requires further optimization. On the other hand, compound 8a and 8d showed anticoagulant activity as they enhanced the clotting time from control 180-410 and 180-390 s, respectively, in platelet rich plasma and 230-460 and 230-545 s in platelet poor plasma. Furthermore, only 8a showed antiplatelet activity by inhibiting epinephrine-induced platelet aggregation, and the observed aggregation inhibition was found to be 93.4%. Compounds 8a-f show nontoxic properties because of the non-hydrolyzing properties in the RBC cells. In addition, 8a and 8d show anti-edema and anti-hemorrhagic properties in the experimental mice. These findings reveal that benzimidazole-containing quinolinyl oxadiazoles act as α-glucosidase inhibitors to develop novel therapeutics for treating type-II diabetes mellitus and can act as lead molecules in drug discovery as potential antidiabetic and antithrombotic agents.

Novel quinoline derivatives as potent in vitro α-glucosidase inhibitors: in silico studies and SAR predictions

A new series of exceptionally potent quinoline derivatives 6–30 as α-glucosidase inhibitors was identified.