Design, synthesis, and biological activity of non-amidine factor Xa inhibitors containing pyridine N-oxide and 2-carbamoylthiazole units

A Therapeutic Journey of Pyridine-Based Heterocyclic Compounds as Potent Anticancer Agents: A Review (From 2017 to 2021)

Pyridine derivatives are the most common and significant heterocyclic compounds, which show their fundamental characteristics to various pharmaceutical agents and natural products. Pyridine derivatives possess several pharmacological properties and a broad degree of structural diversity that is considered most valuable to explore the novel therapeutic agents. These compounds have an extensive range of biological activities such as antifungal, antibacterial, anticancer, anti-obesity, anti-inflammatory, antitubercular, antihypertensive, antineuropathic, antihistaminic, antiviral activities, and antiparasitic. The potent therapeutic properties of pyridine derivatives allow medicinal chemists to synthesize novel and effective chemotherapeutic agents. Consequently, the imperative objective of this comprehensive review is to summarize and investigate the literature regarding recent advancements in pyridine-based heterocycles to treat several kinds of cancer. Furthermore, the performances of pyridine derivatives were compared with some standard drugs including etoposide, sorafenib, cisplatin, and triclosan against different cancer cell lines. We hope this study will support the new thoughts to pursue the most active and less toxic rational designs.

Pegylated triarylmethanes: Synthesis, antimicrobial activity, anti-proliferative behavior and in silico studies

We describe herein the synthesis, characterization and biological studies of novel PEGylated triarylmethanes. Non-symmetrical and symmetrical triarylmethanes series have been synthesized by Friedel-Crafts hydroxyalkylation or directly from bisacodyl respectively followed by a functionalization with PEG fragments in order to increase bioavailability and biological effectiveness. The antimicrobial activity was investigated against Gram-positive and Gram-negative foodborne pathogens and against Candida albicans, an opportunistic pathogenic yeast. The anti-biocidal activity was also studied using Staphylococcus aureus as a reference bacterium. Almost all PEGylated molecules displayed an antifungal activity comparable with fusidic acid with MIC values ranging from 6.25 to 50 μg/mL. Compounds also revealed a promising antibiofilm activity with biofilm eradication percentages values above 80% for the best molecules (compounds 4d and 7). Compounds 7 and 8b showed a modest antiproliferative activity against human colorectal cancer cell lines HT-29. Finally, in silico molecular docking studies revealed DHFR and DNA gyrase B as potential anti-bacterial targets and in silico predictions of ADME suggested adequate drug-likeness profiles for the synthetized triarylmethanes.

The conversion of [(4-chloro-5H-1,2,3-dithiazol-5-ylidene)amino]azines into azine fused thiazole-2-carbonitriles

The thermolysis of several N-(4-chloro-5H-1,2,3-dithiazol-5-ylidene)pyridin-n-amines (where n = 2, 3 and 4) gives a mixture of thiazolopyridine-2-carbonitriles in low to moderate yields. Introduction, by design, of a chlorine substituent at the C2 or C4 position of N-(4-chloro-5H-1,2,3-dithiazol-5-ylidene)pyridin-3-amine and other selected azines enables a BnEt(3)NI mediated ANRORC style ring transformation that provides fourteen heteroazine fused thiazole-2-carbonitriles in moderate to near quantitative yields. The synthesis described herein therefore provides a facile high yielding two-step route to heteroazine fused thiazole-2-carbonitriles starting from 4,5-dichloro-1,2,3-dithiazolium chloride (Appel salt) and ortho- or para-chloro substituted meta-aminoazines.

DU-176b, a potent and orally active factor Xa inhibitor: in vitro and in vivo pharmacological profiles

BACKGROUND

Factor Xa (FXa), a key serine protease that converts prothrombin to thrombin in the coagulation cascade, is a promising target enzyme for the prophylaxis and treatment of thromboembolic diseases. DU-176b is a novel antithrombotic agent that directly inhibits FXa activity.

OBJECTIVE

To evaluate the in vitro pharmacological profiles and in vivo effects of DU-176b in animal models of thrombosis and bleeding.

METHODS

In vitro, FXa inhibition, specificity and anticoagulant activities were examined. Oral absorption was studied in rats and cynomolgus monkeys. In vivo effects were studied in rat and rabbit models of venous thrombosis and tail bleeding.

RESULTS

DU-176b inhibited FXa with Ki values of 0.561 nm for free FXa, 2.98 nm for prothrombinase, and exhibited >10 000-fold selectivity for FXa. In human plasma, DU-176b doubled prothrombin time and activated partial thromboplastin time at concentrations of 0.256 and 0.508 microm, respectively. DU-176b did not impair platelet aggregation by ADP, collagen or U46619. DU-176b was highly absorbed in rats and monkeys, as demonstrated by more potent anti-Xa activity and higher drug concentration in plasma following oral administration than a prototype FXa inhibitor, DX-9065a. In vivo, DU-176b dose-dependently inhibited thrombus formation in rat and rabbit thrombosis models, although bleeding time in rats was not significantly prolonged at an antithrombotic dose.

CONCLUSIONS

DU-176b is a more potent and selective FXa inhibitor with high oral bioavailability compared with its prototype, DX-9065a. DU-176b represents a promising new anticoagulant for the prophylaxis and treatment of thromboembolic diseases.

Amino(methyl) pyrrolidines as novel scaffolds for factor Xa inhibitors

The design and synthesis of a novel class of amino(methyl) pyrrolidine-based sulfonamides as potent and selective FXa inhibitors is reported. The amino(methyl) pyrrolidine scaffolds were designed based on the proposed bioisosterism to the piperazine core in known FXa inhibitors. The SAR study led to compound 15 as the most potent FXa inhibitor in this series, with an IC(50) of 5.5 nM and PT EC(2x) of 1.7 microM. The proposed binding models show that the pyrrolidine cores are in van der Waals contact with the enzyme surface, and the flexibility of amino(methyl) pyrrolidines allows the two nitrogen atoms to anchor both the P1 and P4 groups to fit similarly in the S1 and S4 pockets.

Antitumor studies -- part 2: structure-activity relationship study for flavin analogs including investigations on their in vitro antitumor assay and docking simulation into protein tyrosine kinase

Various analogs of flavins, 5-deazaflavins, and flavin-5-oxides were docked into the binding site of protein tyrosine kinase pp60(c-src), and some of them were assayed for their potential antitumor and PKC (protein kinase C) inhibitory activities in vitro. The results considering SAR (structure-activity relationship) revealed that the higher binding affinities obtained include compounds with the structure modifications on the flavin or 5-deazaflavin skeleton, namely, NH(2) or Ph (phenyl-) group at the C-2 position and so on. Computationally designed compounds 4a, 6a, b, 7, 11b, c, 12, 15, and 22c exhibited good docking results suggesting that they are potentially active antitumor agents. These compounds have 1-3 phenyl moieties, which are thought to be responsible for the planar aromatic fitting or electrostatic attraction onto the groove of the binding pocket.

Prediction of factor Xa inhibitors by machine learning methods

Factor Xa (FXa) inhibitors have been explored as anticoagulants for treatment and prevention of thrombotic diseases. Molecular docking, pharmacophore, quantitative structure-activity relationships, and support vector machines (SVM) have been used for computer prediction of FXa inhibitors. These methods achieve promising prediction accuracies of 69-80% for FXa inhibitors and 85-99% for non-inhibitors. Prediction performance, particularly for inhibitors, may be further improved by exploring methods applicable to more diverse range of compounds and by using more appropriate set of molecular descriptors. We tested the capability of several machine learning methods (C4.5 decision tree, k-nearest neighbor, probabilistic neural network, and support vector machine) by using a much more diverse set of 1098 compounds (360 inhibitors and 738 non-inhibitors) than those in other studies. A feature selection method was used for selecting molecular descriptors appropriate for distinguishing FXa inhibitors and non-inhibitors. The prediction accuracies of these methods are 89.1-97.5% for FXa inhibitors and 92.3-98.1% for non-inhibitors. In particular, compared to other studies, support vector machine gives a substantially improved accuracy of 94.6% for FXa non-inhibitors and maintains a comparable accuracy of 98.1% for inhibitors, based-on a more rigorous test with more diverse range of compounds. Our study suggests that machine learning methods such as SVM are useful for facilitating the prediction of FXa inhibitors.

Thiophene-anthranilamides as highly potent and orally available factor Xa inhibitors

There remains a high unmet medical need for a safe oral therapy for thrombotic disorders. The serine protease factor Xa (fXa), with its central role in the coagulation cascade, is among the more promising targets for anticoagulant therapy and has been the subject of intensive drug discovery efforts. Investigation of a hit from high-throughput screening identified a series of thiophene-substituted anthranilamides as potent nonamidine fXa inhibitors. Lead optimization by incorporation of hydrophilic groups led to the discovery of compounds with picomolar inhibitory potency and micromolar in vitro anticoagulant activity. Based on their high potency, selectivity, oral pharmacokinetics, and efficacy in a rat venous stasis model of thrombosis, compounds ZK 814048 (10b), ZK 810388 (13a), and ZK 813039 (17m) were advanced into development.

Design, synthesis, and biological activity of novel factor Xa inhibitors: Improving metabolic stability by S1 and S4 ligand modification

Serine protease factor xa (fXa) inhibitor 1 showed good ex vivo anti-fXa activity upon oral administration in rats. However, it has been revealed that 1 had low metabolic stability against human liver microsomes. To improve the metabolic stability, we attempted to modify the S1 and S4 ligands of 1. These modifications resulted in compound 34b, which exhibited selective anti-fXa activity and excellent anti-coagulation activity.