Fructose-1,6-bisphosphatase Inhibitors. 2. Design, synthesis, and structure-activity relationship of a series of phosphonic acid containing benzimidazoles that function as 5'-adenosinemonophosphate (AMP) mimics

Deamination of 1-Aminoalkylphosphonic Acids: Reaction Intermediates and Selectivity

Deamination of 1-aminoalkylphosphonic acids in the reaction with HNO₂ (generated "in situ" from NaNO₂) yields a mixture of substitution products (1-hydroxyalkylphosphonic acids), elimination products (vinylphosphonic acid derivatives), rearrangement and substitution products (2-hydroxylkylphosphonic acids) as well as H₃PO₄. The variety of formed reaction products suggests that 1-phosphonoalkylium ions may be intermediates in such deamination reactions.

A detailed review on the phytochemical profiles and anti-diabetic mechanisms of Momordica charantia

Diabetes mellitus is the most well-known endocrine dilemma suffered by hundreds of million people globally, with an annual mortality of more than one million people. This high mortality rate highlights the need for in-depth study of anti-diabetic agents. This review explores the phytochemical contents and anti-diabetic mechanisms of M. charantia (cucurbitaceae). Studies show that M. charantia contains several phytochemicals that have hypoglycemic effects, thus, the plant may be effective in the treatment/management of diabetes mellitus. Also, the biochemical and physiological basis of M. charantia anti-diabetic actions is explained. M. charantia exhibits its anti-diabetic effects via the suppression of MAPKs and NF-κβin pancreatic cells, promoting glucose and fatty acids catabolism, stimulating fatty acids absorption, inducing insulin production, ameliorating insulin resistance, activating AMPK pathway, and inhibiting glucose metabolism enzymes (fructose-1,6-bisphosphate and glucose-6-phosphatase). Reviewed literature was obtained from credible sources such as PubMed, Scopus, and Web of Science.

Excited-state cobaloxime catalysis enabled scalable oxidant-free dehydrogenative C–H phosphinoylation of undirected heterocycles

Visible-light-induced excited-state cobalt catalysis enables C(sp2)–H/C(sp3)–H phosphinoylation accompanied by H2 evolution. The reaction achieves the late-stage modification of more than 10 distinct classes of heterocycles and arenes.

Modeling the metabolic interplay between a parasitic worm and its bacterial endosymbiont allows the identification of novel drug targets

The filarial nematode Brugia malayi represents a leading cause of disability in the developing world, causing lymphatic filariasis in nearly 40 million people. Currently available drugs are not well-suited to mass drug administration efforts, so new treatments are urgently required. One potential vulnerability is the endosymbiotic bacteria Wolbachia-present in many filariae-which is vital to the worm. Genome scale metabolic networks have been used to study prokaryotes and protists and have proven valuable in identifying therapeutic targets, but have only been applied to multicellular eukaryotic organisms more recently. Here, we present iDC625, the first compartmentalized metabolic model of a parasitic worm. We used this model to show how metabolic pathway usage allows the worm to adapt to different environments, and predict a set of 102 reactions essential to the survival of B. malayi. We validated three of those reactions with drug tests and demonstrated novel antifilarial properties for all three compounds.

Development of disulfide-derived fructose-1,6-bisphosphatase (FBPase) covalent inhibitors for the treatment of type 2 diabetes

Fructose-1,6-bisphosphatase (FBPase), as a key rate-limiting enzyme in the gluconeogenesis (GNG) pathway, represents a practical therapeutic strategy for type 2 diabetes (T2D). Our previous work first identified cysteine residue 128 (C128) was an important allosteric site in the structure of FBPase, while pharmacologically targeting C128 attenuated the catalytic ability of FBPase. Herein, ten approved cysteine covalent drugs were selected for exploring FBPase inhibitory activities, and the alcohol deterrent disulfiram displayed superior inhibitory efficacy among those drugs. Based on the structure of lead compound disulfiram, 58 disulfide-derived compounds were designed and synthesized for investigating FBPase inhibitory activities. Optimal compound 3a exhibited significant FBPase inhibition and glucose-lowering efficacy in vitro and in vivo. Furthermore, 3a covalently modified the C128 site, and then regulated the N125-S124-S123 allosteric pathway of FBPase in mechanism. In summary, 3a has the potential to be a novel FBPase inhibitor for T2D therapy.

Fructose-1,6-bisphosphatase Inhibitors: A Review of Recent (2000- 2017) Advances and Structure-Activity Relationship Studies

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Diabetes mellitus, commonly referred to as diabetes, is the 8th leading cause of death worldwide. As of 2015, approximately 415 million people were estimated to be diabetic worldwide, type 2 diabetes being the most common accounting for approximately 90-95% of all diagnosed cases with increasing prevalence. Fructose-1,6-bisphosphatase is one of the important therapeutic targets recently discovered to treat this chronic disease. In this focused review, we have highlighted recent advances and structure-activity relationship studies in the discovery and development of different fructose-1,6-bisphosphatase inhibitors reported since the year 2000.

Synthesis, Characterization and Evaluation of Cytotoxic Activities of Novel Aziridinyl Phosphonic Acid Derivatives

New aziridine 2-phosphonic acids were prepared by monohydrolysis of the aziridine 2-phosphonates that were obtained by the modified Gabriel-Cromwell reaction of vinyl phosphonate or α-tosylvinyl phosphonate with a primary amine or a chiral amine. The cellular cytotoxicity of these compounds was tested against the HCT-116 colorectal cancer cell lines and the CCD-18Co normal colon fibroblast lines using the MTT assay. Three of the synthesized phosphonic acid derivatives 2e (ethyl hydrogen {(2S)-1-[(1S)-1-(naphthalen-2-yl)ethyl]aziridin-2-yl}phosphonate), 2h (ethyl hydrogen (1-benzylaziridin-2-yl)phosphonate), and 2i (ethyl hydrogen (1-cyclohexylaziridin-2-yl)phosphonate) showed higher cytotoxicity than the reference cancer treatment agent etoposide. Cell death was through a robust induction of apoptosis even more effectively than etoposide, a well-known apoptosis inducing agent.

Fructose 1,6-bisphosphatase: getting the message across

Fructose 1,6-bisphosphatase (FBPase) is a key enzyme in gluconeogenesis. It is a potential drug target in the treatment of type II diabetes. The protein is also associated with a rare inherited metabolic disease and some cancer cells lack FBPase activity which promotes glycolysis facilitating the Warburg effect. Thus, there is interest in both inhibiting the enzyme (for diabetes treatment) and restoring its activity (in relevant cancers). The mammalian enzyme is tetrameric, competitively inhibited by Fructose 2,6-bisphosphate and negatively allosterically regulated by AMP. This allosteric regulation requires information transmission between the AMP binding site and the active site of the enzyme. A recent paper by Topaz et al. (Bioscience Reports (2019) 39, pii:BSR20180960) has added additional detail to our understanding of this information transmission process. Two residues in the AMP binding site (Lys¹¹² and Tyr¹¹³) were shown to be involved in initiating the message between the two sites. This tyrosine residue has recently be shown to be important with protein’s interaction with the antidiabetic drug metformin. A variant designed to increase metal ion affinity (M248D) resulted in a five-fold increase in enzymatic activity. Interestingly alterations of two residues at the subunit interfaces (Tyr¹⁶⁴ and Met¹⁷⁷) resulted in increased responsiveness to AMP. Overall, these findings may have implications in the design of novel FBPase inhibitors or activators.

Development of prediction model for fructose- 1,6- bisphosphatase inhibitors using the Monte Carlo method

Fructose-1,6-bisphosphatase (FBPase) is an enzyme important for regulation of gluconeogenesis, which is a major process in the liver responsible for glucose production. Inhibition of FBPase enzyme causing blockage of the gluconeogenesis process represents a newer scheme in the progress of anti-diabetic drugs. The current research describes the development of hybrid optimal descriptors-based quantitative structure-activity relationship (QSAR) models intended for a set of 62 FBPase inhibitors with the Monte Carlo method. The molecular structures were expressed by the simplified molecular input line entry system (SMILES) notation. Three splits were prepared by random division of the molecules into training set, calibration set and validation set. Statistical parameters obtained from QSAR modelling were good for various designed splits. The best QSAR model showed the following parameters: the values of r² for calibration set and validation set of the best model were 0.6837 and 0.8623 and of Q² were 0.6114 and 0.8036, respectively. Based on the results obtained for correlation weights, different structural attributes were described as promoter of the endpoint. Further, these structural attributes were used in designing of new FBPase inhibitors and a molecular docking study was completed for the determination of interactions of the designed molecules with the enzyme.

Developments towards synthesis of N-heterocycles from amidines via C–N/C–C bond formation

This review focuses on the synthesis of N-heterocycles using amidines as starting materials, with an emphasis on the mechanisms of these reactions via C–N/C–C bond formation.

Synthesis and biological evaluation of imidazo[2,1-b]thiazole-benzimidazole conjugates as microtubule-targeting agents

A series of imidazo[2,1-b]thiazole-benzimidazole conjugates were synthesized and evaluated for their antiproliferative activity against four human cancer cell lines i.e.; HeLa (cervical), A549 (lung), MCF-7 (breast) and DU-145 (prostate) along with normal HEK-293 cell line. Amongst them, conjugate 6d displayed significant cytotoxicity against human lung cancer cell line, A549 with IC₅₀ value 1.08 µM. Further, cell cycle analysis revealed that this compound arrested the cell cycle at G2/M phase in A549 cells. Furthermore, the tubulin polymerization assay results suggest that this conjugate (6d) exhibits significant inhibitory effect on the tubulin assembly with an IC50 value of 1.68 µM. Moreover, the apoptotic inducing properties of compound 6d was confirmed by Hoechst staining, measurement of mitochondrial membrane potential (ΔΨm) and annexin V-FITC assay. Further, molecular docking studies revealed that compound 6d occupied the colchicine binding site.

Targeting hepatic glucose metabolism in the treatment of type 2 diabetes

Type 2 diabetes mellitus is characterized by the dysregulation of glucose homeostasis, resulting in hyperglycaemia. Although current diabetes treatments have exhibited some success in lowering blood glucose levels, their effect is not always sustained and their use may be associated with undesirable side effects, such as hypoglycaemia. Novel antidiabetic drugs, which may be used in combination with existing therapies, are therefore needed. The potential of specifically targeting the liver to normalize blood glucose levels has not been fully exploited. Here, we review the molecular mechanisms controlling hepatic gluconeogenesis and glycogen storage, and assess the prospect of therapeutically targeting associated pathways to treat type 2 diabetes.

Accessing Benzimidazoles via a Ring Distortion Strategy: An Oxone Mediated Tandem Reaction of 2-Aminobenzylamines

An exceptional oxone mediated tandem transformation of 2-aminobenzylamines to 2-substituted benzimidazoles is reported. It occurs at room temperature with aromatic, heteroaromatic, and aliphatic aldehydes. In this reaction initial condensation of 2-aminobenzylamine with appropriate aldehydes afforded a tetrahydroquinazoline intermediate which underwent oxone-mediated ring distortion to afford the desired compounds in moderate to excellent yields.

Catalytic transfer hydrogenation of azobenzene by low-valent nickel complexes: a route to 1,2-disubstituted benzimidazoles and 2,4,5-trisubstituted imidazolines

The one-pot synthesis of 1,2-disubstituted benzimidazoles by the transfer hydrogenation of azobenzene, using benzylamine as a hydrogen donor is reported, catalyzed by 2 mol% of [Ni(COD)₂] : dippe.

Synthesis of new α-aminophosphonate derivatives incorporating benzimidazole, theophylline and adenine nucleobases using l-cysteine functionalized magnetic nanoparticles (LCMNP) as magnetic reusable catalyst: evaluation of their anticancer properties

A new class of α-aminophosphonate derivatives incorporating benzimidazole, theophylline and adenine nucleobases were synthesized in a three-step process and the anticancer activities of selected ligands were evaluated.

Synthesis of novel polybrominated benzimidazole derivatives-potential CK2 inhibitors with anticancer and proapoptotic activity

The efficient method for the synthesis of novel cell permeable inhibitors of protein kinase CK2 with anticancer and proapoptotic activity has been developed. A series of polybrominated benzimiadazole derivatives substituted by various cyanoalkyl groups have been synthesized. Cyanoethyl derivatives were obtained by Michael type addition of 4,5,6,7-tetrabromo-1H-benzimidazole (TBBi) and 4,5,6,7-tetrabromo-2-methyl-1H-benzimidazole to acrylonitrile, whilst cyanomethyl, cyanopropyl and cyanobutyl analogs by N-alkylation of 4,5,6,7-tetrabromo-1H-benzimidazole and 4,5,6,7-tetrabromo-2-methyl-1H-benzimidazole with appropriate cyanoalkyl halides. The inhibitory activity against protein kinase rhCK2α catalytic subunit and cytotoxicity against two human cancer cell lines: acute lymphocytic leukemia (CCRF-CEM) and breast (MCF-7) were evaluated for all newly synthesized compounds. Additionally, the proapoptotic activity toward leukemia cells and intracellular inhibition of CK2 for the most cytotoxic derivatives have been performed, demonstrating 4,5,6,7-tetrabromo-2-methyl-1H-benzimidazole as a new selective inhibitor of rhCK2 with twenty-fold better proapoptotic activity than parental compound (TBBi).

Discovery of novel indole derivatives as allosteric inhibitors of fructose-1,6-bisphosphatase

A series of novel indole derivatives was designed and synthesized as inhibitors of fructose-1,6-bisphosphatase (FBPase). The most potent compound 14c was identified with an IC50 value of 0.10 μM by testing the inhibitory activity against recombinant human FBPase. The structure-activity relationships were investigated on the substitution at 4- and 5-position of the indole scaffold. The binding interactions of the title compounds at AMP binding site of FBPase were predicted using CDOCKER algorithm.

Toward the prediction of FBPase inhibitory activity using chemoinformatic methods

Currently, Chemoinformatic methods are used to perform the prediction for FBPase inhibitory activity. A genetic algorithm-random forest coupled method (GA-RF) was proposed to predict fructose 1,6-bisphosphatase (FBPase) inhibitors to treat type 2 diabetes mellitus using the Mold² molecular descriptors. A data set of 126 oxazole and thiazole analogs was used to derive the GA-RF model, yielding the significant non-cross-validated correlation coefficient r²_ncv and cross-validated r²_cv values of 0.96 and 0.67 for the training set, respectively. The statistically significant model was validated by a test set of 64 compounds, producing the prediction correlation coefficient r²_pred of 0.90. More importantly, the building GA-RF model also passed through various criteria suggested by Tropsha and Roy with r²_o and r²_m values of 0.90 and 0.83, respectively. In order to compare with the GA-RF model, a pure RF model developed based on the full descriptors was performed as well for the same data set. The resulting GA-RF model with significantly internal and external prediction capacities is beneficial to the prediction of potential oxazole and thiazole series of FBPase inhibitors prior to chemical synthesis in drug discovery programs.

In silico identification of structure requirement for novel thiazole and oxazole derivatives as potent fructose 1,6-bisphosphatase inhibitors

Fructose 1,6-bisphosphatase (FBPase) has been identified as a drug discovery target for lowering glucose in type 2 diabetes mellitus. In this study, a large series of 105 FBPase inhibitors were studied using a combinational method by 3D-QSAR, molecular docking and molecular dynamics simulations for a further improvement in potency. The optimal 3D models exhibit high statistical significance of the results, especially for the CoMFA results with r_ncv², q² values of 0.986, 0.514 for internal validation, and r_pred², r_m² statistics of 0.902, 0.828 statistics for external validation. Graphic representation of the results, as contoured 3D coefficient plots, also provides a clue to the reasonable modification of molecules. (1) Substituents with a proper length and size at the C5 position of the thiazole core are required to enhance the potency; (2) A small and electron-withdrawing group at the C2 position linked to the thiazole core is likely to help increase the FBPase inhibition; (3) Substituent groups as hydrogen bond acceptors at the C2 position of the furan ring are favored. In addition, the agreement between 3D-QSAR, molecular docking and molecular dynamics simulation proves the rationality of the developed models. These results, we hope, may be helpful in designing novel and potential FBPase inhibitors.

Oxazole phosphonic acids as fructose 1,6-bisphosphatase inhibitors with potent glucose-lowering activity

Phosphonic acid-containing oxazoles were discovered as potent inhibitors of fructose 1,6-bisphosphatase. Several oxazoles demonstrated significant glucose-lowering activity in rats after intravenous dosing.

Discovery of a series of phosphonic acid-containing thiazoles and orally bioavailable diamide prodrugs that lower glucose in diabetic animals through inhibition of fructose-1,6-bisphosphatase

Oral delivery of previously disclosed purine and benzimidazole fructose-1,6-bisphosphatase (FBPase) inhibitors via prodrugs failed, which was likely due to their high molecular weight (>600). Therefore, a smaller scaffold was desired, and a series of phosphonic acid-containing thiazoles, which exhibited high potency against human liver FBPase (IC(50) of 10-30 nM) and high selectivity relative to other 5'-adenosinemonophosphate (AMP)-binding enzymes, were discovered using a structure-guided drug design approach. The initial lead compound (30j) produced profound glucose lowering in rodent models of type 2 diabetes mellitus (T2DM) after parenteral administration. Various phosphonate prodrugs were explored without success, until a novel phosphonic diamide prodrug approach was implemented, which delivered compound 30j with good oral bioavailability (OBAV) (22-47%). Extensive lead optimization of both the thiazole FBPase inhibitors and their prodrugs culminated in the discovery of compound 35n (MB06322) as the first oral FBPase inhibitor advancing to human clinical trials as a potential treatment for T2DM.