Development of Stable Amino-Pyrimidine-Curcumin Analogs: Synthesis, Equilibria in Solution, and Potential Anti-Proliferative Activity

With the clear need for better cancer treatment, naturally occurring molecules represent a powerful inspiration. Recently, curcumin has attracted attention for its pleiotropic anticancer activity in vitro, especially against colorectal and prostate cancer cells. Unfortunately, these encouraging results were disappointing in vivo due to curcumin's low stability and poor bioavailability. To overcome these issues, herein, the synthesis of eight new pyrimidine-curcumin derivatives is reported. The compounds were fully characterized (1H/13C NMR (Nuclear Magnetic Resonance), LC-MS (Liquid Chromatography-Mass Spectrometri), UV-Vis spectroscopy), particularly their acid/base behavior; overall protonation constants were estimated, and species distribution, as a function of pH, was predicted, suggesting that all the compounds are in their neutral form at pH 7.4. All the compounds were extremely stable in simulated physiological media (phosphate-buffered saline and simulated plasma). The compounds were tested in vitro (48 h incubation treatment) to assess their effect on cell viability in prostate cancer (LNCaP and PC3) and colorectal cancer (HT29 and HCT116) cell lines. Two compounds showed the same anti-proliferative activity as curcumin against HCT116 cells and improved cytotoxicity against PC3 cells.

Novel Pyrimidine Derivatives as Antioxidant and Anticancer Agents: Design, Synthesis and Molecular Modeling Studies

The heterocyclic ring system of pyrido [2,3-d]pyrimidines is a privileged scaffold in medicinal chemistry, possessing several biological activities. The synthesis of the pyrimidine derivatives was performed via the condensation of a suitable α,β-unsaturated ketone with 4-amino-6-hydroxy-2-mercaptopyrimidine monohydrate in glacial acetic acid. Chalcones were synthesized, as starting materials, via the Claisen-Schmidt condensation of an appropriately substituted ketone and an appropriately substituted aldehyde in the presence of aqueous KOH 40% w/v in ethanol. All the synthesized compounds were characterized using IR, ¹H-NMR, ¹³C-NMR, LC-MS and elemental analysis. The synthesized compounds were evaluated for their antioxidant (DPPH assay), anti-lipid peroxidation (AAPH), anti-LOX activities and ability to interact with glutathione. The compounds do not interact significantly with DPPH but strongly inhibit lipid peroxidation. Pyrimidine derivatives 2a (IC₅₀ = 42 μΜ), 2f (IC₅₀ = 47.5 μΜ) and chalcone 1g (IC₅₀ = 17 μM) were the most potent lipoxygenase inhibitors. All the tested compounds were found to interact with glutathione, apart from 1h. Cell viability and cytotoxicity assays were performed with the HaCaT and A549 cell lines, respectively. In the MTT assay towards the HaCaT cell line, none of the compounds presented viability at 100 μM. On the contrary, in the MTT assay towards the A549 cell line, the tested compounds showed strong cytotoxicity at 100 μM, with derivative 2d presenting the strongest cytotoxic effects at the concentration of 50 μΜ.

Computational Design of Phosphatidylinositol 3-Kinase Inhibitors

One of the most sought-after therapeutic targets for treating human cancers is the phosphoinositide 3-kinase; PI3k is an integral part of the PI3K/protein kinase B signaling arcade. This pathway is frequently activated in malignancies. Drug resistance and dose-limiting adverse effects are currently associated challenges with the existing anticancer chemotherapy. Therefore, in this research, a series of pyrimidine derivatives were designed and evaluated against human PI3K by using molecular docking analysis. The docking results were further verified by molecular dynamic simulation, which analyzed the strength of the macromolecular complex with respect to time. Compounds IV and XIV were found to be the most potent inhibitors of the human PI3K receptor with a high degree of stability within the active site of the target receptor for a timeframe of 50 ns. Thus, both of these compounds could be important drug candidates for the development of PI3K inhibitors as a prospective anticancer agent.

Investigation of fragmentation pathways of protonated 2-methoxypyrimidine derivatives

Several representative pyrimidine derivatives were selected to undergo electrospray ionization (ESI) followed by collision-induced dissociation tandem mass spectrometry (CID MS/MS) experiments. Two competitive pathways were found to govern the formation of major fragment ions from protonated species of these molecules. The pathways were largely affected by the 2-O-methyl group but not significantly influenced by the substitution on C-5 site of the pyrimidine ring. These findings were supported by both deuterium labeling CID MS/MS experiments and theoretical calculations. The deuterium labeled pyrimidine ion molecules were generated in-source in ESI from the fully deuterated hydrazinyl pyrimidines, which were readily obtained through hydrogen/deuterium (H/D) exchange when dissolved in deuterium oxide (D2 O).

Integrated computational approach for in silico design of new purinyl pyridine derivatives as B-Raf kinase inhibitors

B-Raf is one among the most frequently mutating proto-oncogene which is associated with the serine/threonine Raf kinase family involved in the RAS-RAF-MEK-ERK pathway, which is the most deregulated pathway in human cancers. Mutant B-Raf ^V600E got an excellent scope for investigation in cancer as a potential therapeutic target. Formerly B-Raf^V600E is considered the molecular target for numerous antitumor compounds like purinyl pyridine and pyrimidine derivatives. In the current research work using molecular docking approach of Schrodinger Glide 5.6 version, ligand docking, pharmacophore-based virtual screening, binding free energy calculations of a series of 2-amino purinyl pyridine and pyrimidine derivatives were modeled, their docking values were predicted, that were considered to be potent against B-Raf ^V600E. A five-point hypothesis accompanied by a hydrogen bond acceptor(A), two hydrogen bond donors(D), and two aromatic rings (R) was built with a justifiable R² value of 0.91 and a Q² value of 0.64. Then by using Asinex Elite Synergy database, virtual screening was performed, and identified several potential hits. Subsequently, the molecules which had interactions with the target B-Raf kinase were determined by subjecting the obtained hits for SP and XP docking processes. Finally, for the top leads obtained, binding free energies were accomplished. About 16 new purinyl pyridine molecules were also designed. Almost nine molecules manifested crucial ligand interactions and binding free energies. At the outset, this research paved the way for us in spotting new molecules with B-Raf inhibitory activity, which can further be explored to design molecules with enhanced pharmacokinetic profiles.

Structural Aspects of mTOR Inhibitors: In Progress to Search Potential Compounds

mTOR (mammalian target of rapamycin) is a catalytic subunit composed of two multi-protein complexes that indicate mTORC1, mTORC2. It plays a crucial role in various fundamental cell processes like cell proliferation, metabolism, survival, cell growth, etc. Various first line mTOR inhibitors such as Rapamycin, Temsirolimus, Everolimus, Ridaforolimus, Umirolimus, Zotarolimus have been used popularly. Whereas, several mTOR inhibitors such as Gedatolisib (PF-05212384) are under phase 2 clinical trials studies for the treatment of triple-negative breast cancer. The mTOR inhibitors bearing heterocyclic moieties such as quinazoline, thiophene, morpholine, imidazole, pyrazine, furan, quinoline are under investigation against various cancer cell lines (U87MG, PC-3, MCF-7, A549, MDA-231). In this review, we summarized updated research related to mTOR inhibitors, their structure-activity relationship which may help scientists for the development of potent inhibitors against cancer.

Promising Antidiabetic and Antimicrobial Agents Based on Fused Pyrimidine Derivatives: Molecular Modeling and Biological Evaluation with Histopathological Effect

Diabetes is the most common metabolic disorder in both developing and non-developing countries, and a well-recognized global health problem. The WHO anticipates an increase in cases from 171 million in 2000 to 366 million by 2030. In the present study, we focus on the preparation of pyrimidine derivatives as potential antidiabetic and antimicrobial agents. Thein vivoeffect on total serum glucose concentration, cholesterol and antioxidant activity was assessed in adult male albino Wister rats and compared to the reference drug glimperide. Promising results were observed for compound 5. The histopathological study confirms that compound 5 results in significant activity with liver maintenance. The antimicrobial activities were evaluated against several bacterial strains such as Salmonella typhimurium ATCC 25566, Bacillus cereus, Escherichia coli NRRN 3008, Pseudomonas aeruginosa ATCC 10145, Staphylococcus aureus ATCC 6538and fungi such as Rhizopus oligosporus, Mucor miehei and Asperillus niger. Compounds 4 and 5 showed a good inhibition of the bacterial zone compared to the reference drug cephradine. Finally, we suggest protein targets for these drugs based on computational analysis, and infer their activities from their predicted modes of binding using molecular modeling. The molecular modeling for compounds 4 and 5 resulted in improved docking scores and hydrogen bonding. The docking studies are in good agreement with the in vitro and in vivo studies.

Targeting virus-host interaction by novel pyrimidine derivative: an in silico approach towards discovery of potential drug against COVID-19

The entire human population over the globe is currently facing appalling conditions due to the spread of infection from coronavirus disease-2019 (COVID-19). The spike glycoprotein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) present on the surface of the virion mediates the virus entry into the host cells and therefore is targeted by several scientific groups as a novel drug target site. The spike glycoprotein binds to the human angiotensin-converting enzyme-2 (hACE2) cell surface receptor abundantly expressed in lung tissues, and this binding phenomenon is a primary determinant of cell tropism and pathogenesis. The binding and internalization of the virus is the primary and most crucial step in the process of infection, and therefore the molecules targeting the inhibition of this process certainly hold a significant therapeutic value. Thus, we systematically applied the computational techniques to identify the plausible inhibitor from a chosen set of well characterized diaryl pyrimidine analogues which may disrupt interfacial interaction of spike glycoprotein (S) at the surface of hACE2. Using molecular docking, molecular dynamics (MD) simulation and binding free energy calculation, we have identified AP-NP (2-(2-amino-5-(naphthalen-2-yl)pyrimidin-4-yl)phenol), AP-3-OMe-Ph (2-(2-amino-5-(3-methoxyphenyl)pyrimidin-4-yl)phenol) and AP-4-Me-Ph (2-(2-amino-5-(p-tolyl) pyrimidin-4-yl)phenol) from a group of diaryl pyrimidine derivatives which appears to bind at the interface of the hACE2-S complex with low binding free energy. Thus, pyrimidine derivative AP-NP may be explored as an effective inhibitor for hACE2-S complex. Furthermore, in vitro and in vivo studies will strengthen the use of these inhibitors as suitable drug candidates against SARS-COV-2.

Communicated by Ramaswamy H. Sarma

Non-Nucleoside Agonists of the Adenosine Receptors: An Overview

Potent and selective adenosine receptor (AR) agonists are of pharmacological interest for the treatment of a wide range of diseases and conditions. Among these derivatives, nucleoside-based agonists represent the great majority of molecules developed and reported to date. However, the limited availability of compounds selective for a specific AR subtype (i.e., A2BAR) and a generally long and complex synthetic route for largely substituted nucleosides are the main drawbacks of this category of molecules. Non-nucleoside agonists represent an alternative set of compounds able to stimulate the AR function and based on simplified structures. This review provides an updated overview on the structural classes of non-nucleoside AR agonists and their biological activities, with emphasis on the main derivatives reported in the literature. A focus is also given to the synthetic routes employed to develop these derivatives and on molecular modeling studies simulating their interaction with ARs.

The Administration of the New Pyrimidine Derivative-4-{2-[2-(3,4-Dimethoxyphenyl)-Vinyl]-6-Ethyl-4-Oxo-5-Phenyl-4H-Pyrimidine-1-Il}Benzsulfamide Restores the Activity of Brain Cells in Experimental Chronic Traumatic Encephalopathy by Maintaining Mitochondrial Function

Background and objectives: To evaluate the effect of a new pyrimidine derivative on the change of mitochondrial function in experimental chronic traumatic encephalopathy. Materials and methods: The study was performed on male mice of the BALB/c line (acute toxicity was assessed) and male rats of the Wistar line, which were modeled chronic traumatic encephalopathy by the method of free fall of the load (weight 150 g from a 50 cm height). The injury to rats was reproduced once a day for 7 days. Further, cognitive functions, changes in sensorimotor deficiency, cerebral blood flow, neuron-specific enolase(NSE), S100β, glial fibrillary acidic protein (GFAP) (in blood serum) and β-amyloid, adenosine triphosphate (ATP) (in brain tissue supernatant) were evaluated. Mitochondrial respiration was also measured. Choline alfoscerate (100 mg/kg) was used as a reference drug. Results: The study found that the use of a new pyrimidine derivative contributed to the preservation of the mitochondrial respirometric function and cognitive functions in rats. In addition, against the administration of test-object marked increase in the concentration of ATP, the velocity of cerebral blood flow was 4.2 times (p < 0.05) and 35.6% (p < 0.05), respectively, as well as reduced concentration and GFAP, NSE, S100β, β-amyloid and sensorimotor deficit at 2.7 (p < 0.05) times; 2 times (p < 0.05); 2.4 times (p < 0.05); of 30.4% (p < 0.05 and 46.5% (p < 0.05), respectively. The LD₅₀ (per os) for the test-object was 4973.56 ± 573.72 mg/kg. Conclusion: Based on the obtained data, high therapeutic efficacy and low systemic toxicity of the application are assumed 4-{2-[2-(3,4-dimethoxyphenyl)-vinyl]-6-ethyl-4-oxo-5-phenyl-4H-pyrimidine-1-Il}benzsulfamide in chronic traumatic encephalopathy.

Evaluation of novel pyrimidine derivatives as a new class of mushroom tyrosinase inhibitor

Background and aim

Tyrosinase (EC 1.14.18.1) is responsible for enzymatic browning in fruits and vegetables. Its inhibitors may be applied to efficiently treat hyperpigmentation and are widely used in pharmaceutical and cosmetic products, food supplements and insecticides. Previous studies have shown that heterocyclic compounds with an amino group can inhibit tyrosinase activity. The present study aims to evaluate the inhibitory effect of some novel 2,6-diamino-4-chloropyrimidine derivatives (1a-e) and 2,4,6-triaminopyrimidine (2a–e) including bioactive aniline moiety on the activity of the mushroom tyrosinase.

Methods

In practice, the azo salt was initially synthesized from aniline derivatives and combined subsequently with the 2,4,6-triaminopyrimidine and 2,6-diamino-4 chloropyrimidine followed by crystallization. The structures of resulting compounds were confirmed by FT-IR, ¹³C NMR, and ¹H NMR. The derivatives (0–100 µM) were evaluated for their inhibitory effect on tyrosinase activity using l-3,4-dihydroxyphenylalanine (l-DOPA) as substrate.

Results

All compounds showed inhibitory effects against the activity of the enzyme. About 23.72–55.08% inhibition was observed in the presence of 30 µM of each compound. The IC₅₀ values of the synthesized compounds were measured, and their inhibition properties were also visualized by zymography. Based on the results, the compounds 1a-e and 2a-e showed moderate inhibitory activities. Notably, pyrimidine derivatives 1a (IC₅₀=24.68) and 1d (IC₅₀=24.45) also exhibited similar inhibitory activities when compared with the positive control, kojic acid (IC₅₀=25.24 µM). Kinetic studies indicated that the type of inhibition was noncompetitive.

Conclusion

All results suggest that pyrimidine derivatives, especially 1d and 1a, can be considered as safe and efficient tyrosinase inhibitors.

Advances in the Solid-Phase Synthesis of Pyrimidine Derivatives

This Review describes the existing synthetic approaches for the solid-phase synthesis (SPS) of differently substituted and fused pyrimidine derivatives. These synthetic strategies are classified on the basis of the different synthetic routes leading to the particular type of pyrimidine heterocycle formed. The Review discusses the application of a variety of polystyrene derived supports for the construction of pyrimidine rings. The effect of microwave heating on the solid-phase synthesis is also addressed in the review.

Transient Sulfenic Acids in the Synthesis of Biologically Relevant Products

Sulfenic acids as small molecules are too unstable to be isolated and their transient nature offers the possibility to involve them in concerted processes that lead to the obtainment of functional groups such as sulfoxides, sulfones, and disulfides. All these functions are present in a number of natural and synthetic drugs and can represent structural motives inducing biologically relevant properties. In this small review the generation and reactions of sulfenic acid bearing naturally occurring residues are described. Carbohydrate and aminoacid-derived sulfenic acids have been used in concerted addition with triple bonds to obtain alliin derivatives and thiosugars in enantiomerically pure form. Glycoconjugates with sulfinyl, sulfonyl, and disulfane functional groups and pyridine-derived disulfides have been obtained from bis- and tris-sulfinyl precursors of sulfenic acids. Small families of such compounds have been subjected to preliminary biological tests. Starting from the evidence that the control of molecular architecture and the presence of suitable functional groups can play a significant role on the exhibition of biological properties, apoptotic effects on malignant cells by glycoconjugates and inhibitory activity against the important human pathogen S. aureus by pyrimidine-derived disulfides have been found.

Novel Multicomponent Synthesis of Pyridine-Pyrimidines and Their Bis-Derivatives Catalyzed by Triazine Diphosphonium Hydrogen Sulfate Ionic Liquid Supported on Functionalized Nanosilica

In this Research Article, we report an efficient synthesis of 1,3-dimethyl-5-aryl-7-(pyridine-3(2)(4)-yl)pyrimidine-2,4(1H,3H)-diones via a three-component reaction of aryl aldehydes, 1,3-dimethyl-6-aminouracil and carbonitriles in the presences of triazine diphosphonium hydrogen sulfate ionic liquid supported on functionalized nanosilica (APTADPHS-nSiO₂) as a reusable catalyst under microwave irradiation and solvent-free conditions. The bis-derivatives of pyridine-pyrimidines were also efficiently prepared from dialdehydes and dinitriles. In addition, 3-methyl-1H-pyrazole-5-amine was used successfully instead of 1,3-dimethyl-6-aminouracil under the same conditions to afford the corresponding products in high yields. The catalyst can be reused at least five times without any significant loss of its activity. The easy recovery, reusability and excellent activity of the catalyst as well as easy workup are other noteworthy advantages of this method.

Pharmacological activities of some triazinopyrazolothieno pyrimidine derivatives

Triazinopyrazolothieno pyrimidine derivatives 1-5 were evaluated for their anti-inflammatory, analgesic and anticancer activities and acute toxicity. Anti-inflammatory activity of the compounds was studied using the carrageenan test. All tested compounds showed analgesic activity, 3-methoxycarbonyl-4,6-dimethyl-8-[(N-methylindolyl)methyl] pyrimido [5',4':4,5]thieno [3',2'-3,4]pyrazolo [5,1-c]triazine (4) showed activity comparable to that of diclofenac. Compounds 1-5 were also screened for anticancer activity on a human lung cancer cell line (A549) and a human prostate cancer cell line (DU145) using the MTT micro-cultured tetrazolium assay method. Compound 4 showed also significant anticancer activity against both cancer cell lines, comparable to that of doxorubicin. The most active compounds were tested for their acute toxicity and median lethal doses were evaluated.

Synthesis and insecticidal activity of novel pyrimidine derivatives containing urea pharmacophore against Aedes aegypti

BACKGROUND

Aedes aegypti is a major mosquito vector for the transmission of serious diseases, especially dengue and yellow fever. More than 1 billion people in developing countries are at risk. The widespread and continual use of pesticides can lead to resistant mosquitoes. In order to maintain mosquito control gains, it is critical to develop and evaluate novel bioactive molecules that differ in mode of action from currently used products.

RESULTS

A series of novel pyrimidine derivatives were designed and synthesized. Their structures were elucidated by proton nuclear magnetic resonance spectroscopy and high-resolution mass spectrometry. The biological activities of these compounds were tested against Ae. aegypti. Many of them exhibited insecticidal activity against adult and larval mosquitoes. Compound 4d displayed relatively good activity to reach 70% mortality at 2 µg mL^-1 . Furthermore, density functional theory calculations were established to study the structure-activity relationship of these novel compounds.

CONCLUSION

A practical synthetic route for pyrimidine derivatives is presented. This study suggests that these pyrimidine derivatives exhibit some activity against the yellow fever mosquito and, with further structure modification, could be novel lead compounds for the development of insecticides against mosquitoes. © 2016 Society of Chemical Industry.

Study on 2-arylthio-5-iodo pyrimidine derivatives as novel nonnucleoside inhibitors against hepatitis B virus DNA replication

BACKGROUND

Novel nonnucleoside hepatitis B virus inhibitors have been recently developed for the reason of drug-resistant mutations and adverse effects of nucleoside analogs. In this study, two series of 2-arylthio-5-iodo pyrimidine analogs were firstly reported as potential anti-HBV agents.

METHODOLOGY

Target compounds were prepared according to two high-yielded synthetic routes, and their anti-HBV activities were evaluated on Hep2.2.15 and HepAD38 cell lines, respectively. To probe the mechanism of active agents, a cell-based (Huh-7) study of biochemical markers (e.g., HBeAg, HBsAg, intracellular HBV DNA and pgRNA) was performed. Furthermore, the pharmacophore models were constructed for future optimization of lead compounds.

CONCLUSION

2-Arylthio-5-iodo pyrimidine derivatives firstly proved to be effective against HBV, which paves the way for future development of nonnucleoside anti-HBV agents.

Crystal structure of 2-acetyl-5-(3,4-di-meth-oxy-phen-yl)-6-eth-oxy-carbonyl-3,7-dimethyl-5H-thia-zolo[3,2-a]pyrimidin-8-ium chloride

The title mol­ecular salt, C₂₁H₂₅N₂O₅S⁺·Cl⁻, crystallizes with two ion pairs in the asymmetric unit. The cations have similar conformations (r.m.s. overlay fit = 0.40 Å), with one of them showing disorder of the terminal methyl group of the ester in a 0.72 (2):0.28 (2) ratio. In the first cation, the 3,4-dimeth­oxy-substituted phenyl ring subtends a dihedral angle of 88.38 (7)° with the pyrimidine ring and 6.79 (8)° with the thia­zole ring. The equivalent data for the second cation are 89.97 (3) and 6.42 (7)°, respectively. The pyrimidine ring adopts a sofa conformation in each cation. In the crystal, the components are linked by N—H⋯Cl hydrogen bonds, generating isolated ion pairs. The ion pairs are are linked by C—H⋯O inter­actions, generating a three-dimensional network. In addition, a weak C—H⋯π inter­action is observed.

TBK1 inhibitors: a review of patent literature (2011 - 2014)

INTRODUCTION

TANK-binding kinase 1 (TBK1) is a noncanonical IκB kinase family member that regulates the innate immune response. Misregulation of TBK1 activity can promote inflammatory disorders and oncogenesis; therefore, TBK1 inhibitors are considered a promising therapy for inflammation and cancer.

AREAS COVERED

In this review, the authors provide information on the role of TBK1 in human health and on recently developed inhibitors from patents granted from 2011 to 2014. The reader will gain an understanding of the mechanisms of TBK1 function as well as the structure and biological activity of recently developed TBK1 inhibitors. Google and NCBI search engines were used to find relevant patents and clinical information using "TBK1 inhibitor" as the search term.

EXPERT OPINION

The role of TBK1 in various diseases has prompted the further investigation of significant targets. Although research on TBK1 inhibitors has increased over the last few years, only a few inhibitors of this kinase have been identified. In addition, almost all of the chemical inhibitors are modified from different scaffolds and/or chemotypes of pyrimidine. Specifically, compound BX795 is the representative one, which was first patented as a potent TBK1 inhibitor. Even though some compounds have displayed interesting potential inhibition and selectivity of TBK1 in vitro and in in vivo trials, the development of more efficient and selective TBK1 inhibitors is still required.

Design, synthesis, and preliminary activity evaluation of novel pyrimidine derivatives as acid pump antagonists

Acid-related diseases of the upper gastrointestinal tract, especially gastroesophageal reflux disease (GERD), remain a widespread problem worldwide. In this paper, we reported the design, synthesis, and preliminary gastric antisecretory activity evaluation of novel pyrimidine derivatives as acid pump antagonists. The gastric antisecretory activity assay results showed that all compounds displayed potent gastric antisecretory activity when gastric secretion was stimulated by histamine. The most potent compound 5g exhibited even similar gastric antisecretory activity compared with the control revaprazan, and the relative inhibition rate was 93.0%, which was worthy of further investigation.