Synthesis and biological evaluation of novel 2,4,5-substituted pyrimidine derivatives for anticancer activity

Design, synthesis, and biological evaluation of tetrahydropyrimidine analogue as GSK-3β/Aβ aggregation inhibitor and anti-Alzheimer's agent

The complex nature of Alzheimer's disease (AD) etiopathology is among the principal hurdles to developing effective anti-Alzheimer agents. Tau pathology and Amyloid-β (Aβ) accumulation are hallmarks and validated therapeutic strategies of AD. GSK-3β is a serine/threonine kinase involved in tau phosphorylation. Its excessive activity also contributes to the production of Aβ plaques, making GSK-3β an attractive AD target. Taking this into account, In this article, we outline the design, synthesis, and biological validation of a focused library of 1,2,3,4-tetrahydropyrimidine based derivatives as inhibitors of GSK-3β, tau phosphorylation, and Aβ accumulation. The inhibitory activity of forty nine synthetic compounds was tested against GSK-3β and other AD-relevant kinases. The kinetic experiments revealed the mode of GSK-3β inhibition by the most potent compound 44. The in- vitro drug metabolism and pharmacokinetic studies were thereafter performed. The anti-aggregation activity of the most potent GSK-3β inhibitor was tested using AD transgenic Caenorhabditis elegans (C. elegans) strain CL2006 for quantification of Aβ plaques and BR5706 C. elegans strain for tau pathology evaluation. We then evaluated the blood-brain barrier permeability and got promising results. Therefore, we present compound 44 as a potential ATP-competitive GSK-3β inhibitor with good metabolism and pharmacokinetic profile, anti-aggregation properties for amyloid beta protein, and reduction in tau-phosphorylation levels. We recommend more investigation into compound 44-based small molecules as possible targets for AD disease-modifying treatments.

Design, synthesis, and bioevaluation of diarylpyrimidine derivatives as novel microtubule destabilizers

In this work, a series of new diarylpyrimidine derivatives as microtubule destabilizers were designed, synthesized, and evaluated for anticancer activities. Based on restriction configuration strategy, we introduced the pyrimidine moiety containing the hydrogen-bond acceptors as cis-olefin bond of CA-4 analogs to improve structural stability. Compounds 11a-t exerted antiproliferative activities against three human cancer cell lines (SGC-7901, HeLa, and MCF-7), due to tubulin polymerization inhibition, showing high selectivity toward cancer cells in comparison with non-tumoral HSF cells, as evidenced by MTT assays. In mechanistic investigations, compound 11s remarkably inhibited tubulin polymerization and disorganized microtubule in SGC-7901 cells by binding to tubulin. Moreover, 11s caused G2/M phase cell cycle arrest in SGC-7901 cells in a concentration-dependent manner. Furthermore, molecular modeling analysis revealed that 11s interacts with tubulin through binding to the colchicine site. In addition, the prediction of physicochemical properties disclosed that 11s conformed well to the Lipinski's rule of five. This work offered a fresh viewpoint for the discovery of new tubulin-targeting anticancer drugs.

Computational Design, Synthesis, and Bioevaluation of 2-(Pyrimidin-4-yl)oxazole-4-carboxamide Derivatives: Dual Inhibition of EGFRWT and EGFRT790M with ADMET Profiling

The ongoing research in cancer treatment underscores the significance of dual epidermal growth factor receptor (EGFR) kinase inhibitors targeting both mutant and wild-type variants. In this study, employing in silico fragment-based drug design (FBDD) and computational analysis, we have successfully developed a novel chemical series of 2-(pyrimidin-4-yl)oxazole-4-carboxamide (16a-j) derivatives designed as dual EGFR kinase inhibitors. A comparative in vitro anticancer profile of the newly synthesized compounds (16a-j) was tested against a panel of five human cancer cell lines like prostate cancer (PC3 & DU-145), lung cancer (A549), human liver cancer (HEPG2), and breast cancer (MDA-MB-468) by employing MTT method. In this experiment a well-known anticancer agent, Etoposide was used as positive control. Most of the derivatives demonstrated significant cytotoxicity, ranging from excellent to moderate levels. The IC50 values for the synthesized compounds observed between 0.10 ± 0.052 to 9.83 ± 5.96 µM, while the positive control exhibited a range of 1.97 ± 0.45 µM to 3.08 ± 0.135 µM. These results indicate that the synthesized compounds demonstrate higher cytotoxic potency in comparison to the reference compound. Furthermore, all these compounds underwent screening against normal Vero cell lines to assess their cytotoxicity. In each case, the observed cytotoxicity values (IC50) were higher than 22 µM, affirming the compounds selectivity for cancer cell lines. Among the compounds investigated, three compounds (16a, 16e, and 16i) exhibited notable cytotoxicity, while two compounds (16g and 16h) demonstrated exceptional cytotoxicity. The selectivity index of the tested compounds indicates a pronounced preference for targeting cancer cell lines over normal cells. Furthermore, all the compounds 16a-j underwent assessment for their EGFR kinase inhibitory activity against both EGFRWT and mutated EGFRT790M. The results unveiled the potential eligibility of this new series of compounds as effective EGFR inhibitors. Moreover, compound 16h underwent additional testing for cell cycle analysis, revealing its capability to arrest the cell cycle in the G2/M phase and induce apoptosis at the IC50 concentration.

Design, Docking, Characterisation, and Synthesis of Pyrimidine Derivatives for Antidepressant Activity

BACKGROUND

According to the report, in 2022, the prevalence rate of depression in India was 4.50%, and the cases stood at 56,675,969. The development of antidepressant agents has reduced the number of depressant and suicidal cases. Many researchers have found that pyrimidine possesses antidepressant activity. With this background, we thought of synthesizing pyrimidine derivatives.

OBJECTIVE

The objective of this study is to carry out molecular docking, synthesis, characterization, and evaluation of 2-((4,6-diphenylpyrimidin-2-yl)oxy)-N-phenylacetamide derivatives (17-26) as in vivo antidepressant agent.

METHOD

The designed compounds were checked for their activity using Molegro virtual docker (MVD) and were further synthesized. Benzaldehyde reacted with acetophenone to give compound (3), which gave compound (4) upon reaction with urea. In another reaction, substituted anilines (5) were reacted with chloroacetyl chloride (6) to yield compounds (7-16), which upon further reaction with compound (4) yielded the final derivatives (17-26). The synthesized compounds were characterized by spectral analysis and checked for their antidepressant activity.

RESULT

The MolDock scores of the derivatives ranged from -147.097 to -182.095, whereas of active ligand IXX_801 was -115.566. All the synthesized pyrimidine derivatives showed better affinity towards the Cryo-EM structure of the wild-type human serotonin transporter complexed with vilazodone, imipramine, and 15B8 Fab protein (PDB ID: 7LWD) as compared to standard drug clomipramine (-101.064). All the synthesized derivatives were screened for antidepressant activity at a 100mg/kg dose level compared to the standard clomipramine HCl at a dose level of 20mg/kg. Among all the synthesized derivatives, compound 24 showed the most potent antidepressant activity, and Compound 20 showed moderate antidepressant activity, which reduced the duration of immobility times to 35.42% and 31.97% at 100mg/kg dose level when compared to the control, respectively.

CONCLUSION

Compound 24 showed the highest MolDock score as well as found to be the most potent antidepressant agent.

4-amino-2-phenyl-6-(p-fluorophenyl)-5-carbonitrile-pyrimidine-bis-substituted-loaded liposomes as promising system for cancer treatment

The aim of the present study was to perform in vitro and in vivo assessments of the antineoplastic action of 4-amino-pyrimidine encapsulated in liposomes. Liposomes were prepared and characterized for particle size and drug encapsulation and submitted to long-term stability tests. Cytotoxicity assays were performed in HeLa cells. Antineoplastic activity was investigated using the experimental sarcoma 180 tumor in Swiss albino mice. Encapsulation efficiency was 82.93 ± 0.04% and no significant changes were found with respect to particle size or pH after centrifugation and mechanical agitation tests. The in vitro results at concentration of 20 μg/mL indicated a considerable reduction in cell viability after treatment with encapsulated pyrimidine (75.91%). The in vivo assays using the compounds in encapsulated and free forms and 5-fluorouracil achieved tumor inhibition rates of 66.47 ± 26.8%, 50.46 ± 16.24% and 14.47 ± 9.22%, respectively. Mitotic counts demonstrated a greater reduction in the number of mitoses in animals treated with liposomal pyrimidine (32.15%) compared to those treated with the pyrimidine free (87.69%) and 5-fluorouracil (71.39%). This study demonstrated that the development of liposome formulations containing 4-amino-pyrimidine is a promising alternative for overcoming limitations related to the toxicity of current cancer treatment, ensuring greater therapeutic efficacy.

Experimental and theoretical study on the regioselective bis- or polyalkylation of 6-amino-2-mercapto-3H-pyrimidin-4-one using zeolite nano-gold catalyst and a quantum hybrid computational method

The synthetic utility of 6-amino-2-mercapto-3H-pyrimidin-4-one 3 as building blocks for new poly (pyrimidine) by alkylation using the bis(halo) compounds and zeolite nano-gold as a catalyst was investigated. Furthermore, the experimental findings by the theoretical Density functional theory (DFT) computations at the DFT/B3LYP level of theory, utilizing the 6-311++G (d,p) basis set in the gas phase, were used to investigate the distinct phases for Regio isomer 11a & 12a and 11b & 12b compounds was fair and of good quality. The stability of the 12a and 12b phases is higher than the other Regio isomer 11a and 11b phases, according to DFT modelling. By computing HOMO and LUMO pictures, the electronic parameters: dipole moment of these compounds in the ground state were theoretically investigated. Non-linear optical (NLO) characteristics and quantum chemical parameters were examined using frontier molecular orbital (FMO) analysis. Natural bond orbital analysis was used to characterize the charge transfer of the electron density in the investigated compounds (NBO). The molecular electrostatic potential surfaces (MEPS) plots have been generated, and absorption spectral analysis in different solvents has been theoretically and experimentally examined to better understand the reactivity spots. At the B3LYP/6-311G (d,p) level of theory, thermodynamic properties were also calculated. Finally, DFT calculations were used to connect the structure-activity relationship (SAR) with real antibacterial results for compounds 12a and 12b.

High-fat diet-induced obesity augments the deleterious effects of estrogen deficiency on bone: Evidence from ovariectomized mice

Several epidemiological studies have suggested that obesity complicated with insulin resistance and type 2 diabetes exerts deleterious effects on the skeleton. While obesity coexists with estrogen deficiency in postmenopausal women, their combined effects on the skeleton are poorly studied. Thus, we investigated the impact of high-fat diet (HFD) on bone and metabolism of ovariectomized (OVX) female mice (C57BL/6J). OVX or sham operated mice were fed either HFD (60%fat) or normal diet (10%fat) for 12 weeks. HFD-OVX group exhibited pronounced increase in body weight (~86% in HFD and ~122% in HFD-OVX, p < 0.0005) and impaired glucose tolerance. Bone microCT-scanning revealed a pronounced decrease in trabecular bone volume/total volume (BV/TV) (-15.6 ± 0.48% in HFD and -37.5 ± 0.235% in HFD-OVX, p < 0.005) and expansion of bone marrow adipose tissue (BMAT; +60.7 ± 9.9% in HFD vs. +79.5 ± 5.86% in HFD-OVX, p < 0.005). Mechanistically, HFD-OVX treatment led to upregulation of genes markers of senescence, bone resorption, adipogenesis, inflammation, downregulation of gene markers of bone formation and bone development. Similarly, HFD-OVX treatment resulted in significant changes in bone tissue levels of purine/pyrimidine and Glutamate metabolisms, known to play a regulatory role in bone metabolism. Obesity and estrogen deficiency exert combined deleterious effects on bone resulting in accelerated cellular senescence, expansion of BMAT and impaired bone formation leading to decreased bone mass. Our results suggest that obesity may increase bone fragility in postmenopausal women.

Hantzsch-Like Synthesis, DNA Photocleavage, DNA/BSA Binding, and Molecular Docking Studies of Bis(sulfanediyl)bis(tetrahydro-5-deazaflavin) Analogs Linked to Naphthalene Core

The cyclocondensation reaction of aldehydes with dimedone and bis(6-aminopyrimidin-4-one) in acetic acid led to the formation of the corresponding bis(pyrimido[4,5-b]quinoline-4,6-diones) which are known as bis(sulfanediyl)bis(tetrahydro-5-deazaflavin) analogs in a single step. Also, bis(pyrimido[4,5-b]quinoline-4,6-diones) which are linked to naphthyl core via phenoxymethyl linkage is prepared. The interactions of the synthesized compounds with DNA and bovine serum albumin (BSA) were studied. Gel electrophoresis assay was used to show the capability of the compounds to photocleave the supercoiled pBR322 plasmid DNA in UV-A (365 nm). Besides, the most photocleavable compound, bis(tetrahydropyrimido[4,5-b]quinoline-4,6-dione) linked to pyridin-3-yl at position-5 exhibits good binding affinities toward CT-DNA and BSA as supported by UV/VIS spectral studies. In addition to the experimental findings, a molecular docking simulation was performed to collect detailed binding data for this compound to both biomolecules.

Indole derivatives as tubulin polymerization inhibitors for the development of promising anticancer agents

The α- and β-tubulins are the major polypeptide components of microtubules (MTs), which are attractive targets for anticancer drug development. Indole derivatives display a variety of biological activities including antitumor activity. In recent years, a great number of indole derivatives as tubulin polymerization inhibitors have sprung up, which encourages medicinal chemists to pursue promising inhibitors with improved antitumor activities, excellent physicochemical, pharmacokinetic and pharmacodynamic properties. In this review, the recent progress from 2010 to present in the development of indole derivatives as tubulin polymerization inhibitors was summarized and reviewed, which would provide useful clues and inspirations for further design of outstanding tubulin polymerization inhibitors.

Metal Free Access to Polysubstituted Pyrimidines via Nitrile Activation and [2+2+2] Cycloaddition

Tf₂ O mediated intermolecular / intramolecular [2+2+2] cycloaddition between alkynes and nitriles has been developed for efficient construction of polysubstituted pyrimidines and bicyclopyrimidines. In presence of Tf₂ O, aza-allene species were generated in situ through nitrile activation and subsequently participated in the [2+2+2] cycloaddition, which was fully supported by deuteration experiments. The reaction had good substrate extensibility with moderate to excellent yield including trimethylsilylalkynes. The method was utilized as a synthetic tool in the preparation of a luminescent metal complex.

Innovative antimicrobial substances based on uracil S-derivatives

The problem of antimicrobial resistance is an important global public health challenge. We propose that a development of new antibiotic compounds around known natural substances is a solution to this problem. We investigate reengineer natural products into potent antibiotics. Uracil fragment is abundant in nature and significant to treat infectious diseases due to its affection to the replication of the bacterial chromosome. 12 new uracil S-derivatives were obtained and tested for their in vitro antimicrobial properties. N³ -(thietan-3-yl)- and N³ -(1,1-dioxothietan-3-yl)uracils derivatives were synthesized by thietanylation of 6-methyluracil with 2-chloromethylthiirane and subsequent oxidation of the thietan ring. A method of their alkylation with ethyl-2-chloroacetate was developed and acetohydrazides containing 3-(thietan-3-yl)- and 3-(1,1-dioxothietan-3-yl)uracilyls fragments in the acetyl group were obtained by hydrazinolysis of 2-(thietanyluracil-1-yl)acetic acid ethyl esters. Their interaction with β-dicarbonyl compounds, anhydride of mono- and dicarboxylic acids was studied. Antimicrobial activity was determined by the agar diffusion method on test organisms: S. aureus, E. coli, P. vulgaris, K. pneumoniae, C. diversus, E. aerogenes, P. aeruginosa, S. abosit. N-acyl-5-hydroxypyrazolines and N,N'-diacylhydrazines of 6-methyluracil thietanyl- and dioxothietanyl derivatives showed high antimicrobial activity, which is consistent with the results of structure activity relationship analysis (MIC 0.1-10 μg/ml).

Light-induced one-pot synthesis of pyrimidine derivatives from vinyl azides

A one-pot procedure for the synthesis of tetrasubstituted dihydropyrimidine and pyrimidine derivatives from α-azidocinnamates was developed. The synthesis is based on the finding that the outcome of LED photolysis of α-azidocinnamates depends on the light wavelength employed. Blue light (455 nm) leads to the formation of 2H-azirines only, but violet light (395 nm), UV-A light (365 nm), or sunlight result in the transformation of the in situ formed 2H-azirines to 1,3-diazabicyclo[3.1.0]hex-3-enes. Under basic catalysis (DBU), the latter were isomerized to 1,6-dihydropyrimidines which were oxidized to pyrimidines using DDQ. A successful use of Cs2CO3 as a base and air as an oxidant was also demonstrated.

Novel Pyrimidine Derivatives as Potential Anticancer Agents: Synthesis, Biological Evaluation and Molecular Docking Study

In the present paper, new pyrimidine derivatives were designed, synthesized and analyzed in terms of their anticancer properties. The tested compounds were evaluated in vitro for their antitumor activity. The cytotoxic effect on normal human dermal fibroblasts (NHDF) was also determined. According to the results, all the tested compounds exhibited inhibitory activity on the proliferation of all lines of cancer cells (colon adenocarcinoma (LoVo), resistant colon adenocarcinoma (LoVo/DX), breast cancer (MCF-7), lung cancer (A549), cervical cancer (HeLa), human leukemic lymphoblasts (CCRF-CEM) and human monocytic (THP-1)). In particular, their feature stronger influence on the activity of P-glycoprotein of cell cultures resistant to doxorubicin than doxorubicin. Tested compounds have more lipophilic character than doxorubicin, which determines their affinity for the molecular target and passive transport through biological membranes. Moreover, the inhibitory potential against topoisomerase II and DNA intercalating properties of synthesized compounds were analyzed via molecular docking.

Structural and theoretical studies of 4-chloro-2-methyl-6-oxo-3,6-dideuteropyrimidin-1-ium chloride (d 6)

The title compound, C5D6ClN2O+·Cl-, crystallizes in the ortho-rhom-bic space group, Pbcm, and consists of a 4-chloro-2-methyl-6-oxo-3,6-di-hydro-pyrimidin-1-ium cation and a chloride anion where both moieties lie on a crystallographic mirror. The cation is disordered and was refined as two equivalent forms with occupancies of 0.750 (4)/0.250 (4), while the chloride anion is triply disordered with occupancies of 0.774 (12), 0.12 (2), and 0.11 (2). Unusually, the bond angles around the C=O unit range from 127.2 (6) to 115.2 (3)° and similar angles have been found in other structures containing a 6-oxo-3,6-di-hydro-pyrimidin-1-ium cation, including the monclinic polymorph of the title compound, which crystallizes in the monoclinic space group P21/c [Kawai et al. (1973 ▸). Cryst. Struct. Comm. 2, 663-666]. The cations and anions pack into sheets in the ab plane linked by N-H⋯Cl hydrogen bonds as well as C-H⋯O and Cl⋯O inter-actions. In graph-set notation, these form R 3 3(11) and R 3 2(9) rings. Theoretical calculations seem to indicate that the reason for the unusual angles at the sp 2 C is the electrostatic inter-action between the oxygen atom and the adjacent N-H hydrogen.

Design, Synthesis, Molecular Modeling and Antitumor Evaluation of Novel Indolyl-Pyrimidine Derivatives with EGFR Inhibitory Activity

Scaffolds hybridization is a well-known drug design strategy for antitumor agents. Herein, series of novel indolyl-pyrimidine hybrids were synthesized and evaluated in vitro and in vivo for their antitumor activity. The in vitro antiproliferative activity of all compounds was obtained against MCF-7, HepG2, and HCT-116 cancer cell lines, as well as against WI38 normal cells using the resazurin assay. Compounds 1-4 showed broad spectrum cytotoxic activity against all these cancer cell lines compared to normal cells. Compound 4g showed potent antiproliferative activity against these cell lines (IC₅₀ = 5.1, 5.02, and 6.6 μM, respectively) comparable to the standard treatment (5-FU and erlotinib). In addition, the most promising group of compounds was further evaluated for their in vivo antitumor efficacy against EAC tumor bearing mice. Notably, compound 4g showed the most potent in vivo antitumor activity. The most active compounds were evaluated for their EGFR inhibitory (range 53-79%) activity. Compound 4g was found to be the most active compound against EGFR (IC₅₀ = 0.25 µM) showing equipotency as the reference treatment (erlotinib). Molecular modeling study was performed on compound 4g revealed a proper binding of this compound inside the EGFR active site comparable to erlotinib. The data suggest that compound 4g could be used as a potential anticancer agent.

Green catalyst Cu(II)-enzyme-mediated eco-friendly synthesis of 2-pyrimidinamines as potential larvicides against Culex quinquefasciatus mosquito and toxicity investigation against non-target aquatic species

Novel one-pot multicomponent synthesis of 2-pyrimidinamine derivatives can be achieved via green chemistry, using Cu(II)-tyrosinase enzyme (Cu-Tyr) as a catalyst. This method offers mild reaction conditions and a high yield of derivatives. We synthesised several compounds in this manner and evaluated their larvicidal, and antifeedant activities. Out of the synthesised derivatives, compound 3, with a median lethal dose (LD₅₀) of 21.43 µg/mL, was highly active against Culex quinquefasciatus, compared to compounds 1a-m and 2, and the control, hydantocidin. Compounds 1j, 1d, and 1e were low active against C. quinquefasciatus with LD₅₀ values of 78.46, 78.59, and 79.54 µg/mL, respectively. In antifeedant screening, compounds 1j, 1l, and 2 generated 100% mortality within 24 h against Oreochromis mossambicus at 100 µg/mL, where toxicity was determined as the ratio of the number of dead and live fingerlings (%) at 24 h. In contrast, compounds 1a-f, 1i, 1m, and 3 were less toxic to O. mossambicus as compared to the control, dibromoisophakellin. Therefore, compound 3 had high larvicidal activity against C. quinquefasciatus and was less toxic to non-target aquatic species. Molecular docking studies also supported the finding that compound 3 was an effective larvicide with more inhibition ability than the control hydantocidin (-9.6 vs. -6.1 kcal/mol).

Modified-amino acid/peptide pyrimidine analogs: synthesis, structural characterization and DFT studies of N-(pyrimidyl)gabapentine and N-(pyrimidyl)baclofen

H-Bonding networks and π–π and halogen bonding interactions in the crystal structures of N-modified amino acid pyrimidine analogs are investigated using DFT calculations and X-ray crystallography analysis.

Suzuki–Miyaura Reactions of (4-bromophenyl)-4,6-dichloropyrimidine through Commercially Available Palladium Catalyst: Synthesis, Optimization and Their Structural Aspects Identification through Computational Studies

5-(4-bromophenyl)-4,6-dichloropyrimidine was arylated with several aryl/heteroaryl boronic acids via the Suzuki cross-coupling reaction by using Pd(0) catalyst to yield novel pyrimidine analogs (3a-h). It was optimized so that good yields were obtained when 5 mol % Pd(PPh3)4 was used along with K3PO4 and 1,4-Dioxane. Electron-rich boronic acids were succeeded to produce good yields of products. Density functional theory (DFT) calculations were also applied on these new compounds to analyze their reactivity descriptors and electronic and structural relationship. According to DFT studies, compound 3f is the most reactive one, while 3g is the most stable one. As per DFT studies, the hyperpolarizability (β) values of these compounds do not show them as very good non-linear optical (NLO) materials. Compound 3f has the highest β value among all the compounds under study but still it is not high enough to render it a potent NLO material.

DESIGN, In silico Modeling, Toxicity study and Synthesis of Novel Substituted Semicarbazide Derivatives of Pyrimidine: An Antitubercular Agent

Background:

A series of 1-(2-(2-amino-5-carbamoyl-6-(1-(substitutedphenyl) prop-1-enyl) pyrimidin-4-yloxy)acetyl) semicarbazide (4a-i) derivatives was synthesized from substituted aromatic aldehydes, ethyl cyanoacetate and guanidine hydrochloride and characterized by analytical and spectral data, FTIR, 1H-NMR and Mass spectroscopy data.

Methods:

The antiTB action of the synthesized compounds was screened in comparison with the standard drug Rifampicin using MABA assay method. The SAR of substituted aromatic aldehydes with modification at ortho, meta and para positions with electron withdrawing group.

Results:

The compounds 1-(2-(2-amino-5- carbamoyl-6-(1-(2-fluorophenyl) prop-1-enyl) pyrimidin-4- yloxy) acetyl) semicarbazide and 1-(2-(2-amino- 5-carbamoyl-6-(1-(3-chlorophenyl) prop-1-enyl) pyrimidin-4-yloxy) acetyl) semicarbazide showed equal MIC values against Mycobacterium tuberculosis H37Ra with the value of 3.90μg/ml.

Conclusion:

The SAR study revealed that the antiTB activity of the synthesized compounds were affected by lipophilicity of the substituent.

Pyrimidine: A promising scaffold for optimization to develop the inhibitors of ABC transporters

The multidrug resistance (MDR) phenomenon in cancer cells is the major obstacle leading to failure of chemotherapy accompanied by the feature of intractable and recurrence of cancers. As significant contributors that cause MDR, ABC superfamily proteins can transport the chemotherapeutic drugs out of the tumor cells by the energy of adenosine triphosphate (ATP) hydrolysis, thereby reducing their intracellular accumulation. The ABC transports like ABCB1, ABCC1 and ABCG2 have been extensively studied to develop modulators for overcoming MDR. To date, no reversal agents have been successfully marketed for clinical application, and little information about the ABC proteins bound to specific inhibitors is known, which make the design of MDR inhibitors with potency, selectivity and low toxicity a major challenge. In recent years, it has been increasingly recognized that pyrimidine-based derivatives have the potential for reversing ABC-mediated MDR. In this review, we summarized the pyrimidine-based inhibitors of ABC transporters, and mainly focused on their structure optimizations, development strategies and structure-activity relationship studies in hope of providing a reference for medicinal chemists to develop new modulators of MDR with highly potency and fewer side effects.

QSAR modelling and molecular docking studies for anti-cancer compounds against melanoma cell line SK-MEL-2

A dataset of seventy-two (72) cytotoxic compounds of the National Cancer Institute (NCI) was studied by QSAR and docking approaches to gain deeper insights into ligands selectivity on SK-MEL-2 cell line. The QSAR model was built using fifty (50) molecules and the best-generated model based on multiple linear regression showed, respectively good quality of fits (R 2 (0.864),R a d j u s t e d 2 (0.845), Q2 cv (0.799) andR p r e d 2 (0.706)). The model's predictive ability was determined by a test set of twenty-two (22) compounds. Compounds 30 and 41 were selected as templates for in silico design because they had high pGI50 activity and are in the model's applicability domain. The obtained information from the model was explored to design novel molecules by introducing various modifications. Moreover, the designed compounds with better-predicted activity (pGI50) values were selected and docked on the active site of the protein (PDB-CODE: 3OG7) which is responsible for melanoma cancer to elucidate their binding mode. AN2 (-12.1kcalmol-1) and AC4 (-12.4kcalmol-1) showed a better binding score for the target when compared with (vemurafenib, -11.3kcalmol-1) the known inhibitor of the target (V600E-BRAF). These findings may be very helpful in early anti-cancer drug development.

In Vitro Biological Estimation of 1,2,3-Triazolo[4,5-d]pyrimidine Derivatives as Anti-breast Cancer Agent: DFT, QSAR and Docking Studies

Background & Objective:

Series of synthesized molecular compounds were considered as anti-breast cancer. The molecular descriptors which describe the microbial activities of the studied compounds were calculated using theoretical approach.

Methods:

The calculated parameters obtained EHOMO (eV), ELUMO (eV), dipole moment (Debye), log P, molecular weight (amu), HBA, HBD, Vol and Ovality were screened. The obtained calculated descriptors were used to develop QSAR model for prediction of experimental inhibition concentration (IC50) using SPSS and Gretl software packages for multiple linear regression (MLR) and MATLAB for the artificial neural network (ANN).

Results:

From this statistical analysis, MLR and ANN were observed to be predictive, however, ANNQSAR model predicted more efficiently than MLR.

Conclusion:

Furthermore, molecular docking study was executed with breast cancer cell line (PDB ID: 1hi7); it was observed that BS20 with binding energy of -7.0 kcal/mol bounded more efficiently than other compounds also, it inhibited more than the standard used (5-FU).

Synthesis and transformation of 6-aminomethyl derivatives of 7-hydroxy-2'-fluoroisoflavones

Mannich aminomethylation of 8-methyl-7-hydroxy-2'-fluoroisoflavones applying bis-(N,N-dimethylamino)methane afforded C-6 substituted N,N-dimethylaminomethyl derivatives. Subsequent acetylation of these compounds in acetic anhydride in the presence of potassium acetate provided access to the corresponding acetoxymethyl derivatives that were converted to hydroxymethyl- and alkoxymethyl-substituted 7-hydroxyisoflavonoids. Addition of 3-(N,N-dimethylamino)-5,5-dimethyl-2-cyclohexen-1-one or 1,3-dimethyl-5-aminopyrazole with thermally generated ortho-quinone methides led to hetero-Diels–Alder or Michael adducts.

Synthesis, spectroscopic (FT–IR and UV–Vis), crystallographic and theoretical studies, and a molecular docking simulation of an imatinib-like template

The aim of the present study was to report the crystal structure and spectroscopic, electronic, supramolecular and electrostatic properties of a new polymorph of 4-(pyridin-2-yl)pyrimidin-2-amine (C9H8N4). The compound was synthesized under microwave irradiation. The single-crystal X-ray structure analysis revealed an angle of 13.36 (8)° between the planes of the rings, as well as molecules linked by Nsp 2—H...N hydrogen bonds forming dimers along the crystal. The material was analyzed by FT–IR vibrational spectroscopy, while a computational approach was used to elucidate the vibrational frequency couplings. The existence of Nsp 2—H...N hydrogen bonds in the crystal was confirmed spectroscopically by the IR peaks from the N—H stretching vibration shifting to lower wavenumbers in the solid state relative to those in the gas phase. The supramolecular studies confirmed the formation of centrosymmetric R 2 2(8) rings, which correspond to the formation of dimers that stack parallel to the b direction. Other weak C—H...π interactions, essential for crystal growth, were found. The UV–Vis spectroscopic analysis showed a donor–acceptor process, where the amino group acts as a donor and the pyridine and pyrimidine rings act as acceptors. The reactive sites of the molecule were identified and their quantitative values were defined using the electrostatic potential model proposed in the multifunctional wave function analyzer multiwfn. The calculated interaction energies between pairs of molecules were used to visualize the electrostatic terms as the leading factors against the dispersion factors in the crystal-growth process. The docking results showed that the amino group of the pyrimidine moiety was simultaneously anchored by hydrogen-bonding interactions with the Asp427 and His407 protein residues. This compound could be key for the realization of a series of syntheses of molecules that could be used as possible inhibitors of chronic myelogenous leukemia.

Novel Tetrahydroquinazolinamines as Selective Histamine 3 Receptor Antagonists for the Treatment of Obesity

The histamine 3 receptor (H3R) is a presynaptic receptor, which modulates several neurotransmitters including histamine and various essential physiological processes, such as feeding, arousal, cognition, and pain. The H3R is considered as a drug target for the treatment of several central nervous system disorders. We have synthesized and identified a novel series of 4-aryl-6-methyl-5,6,7,8-tetrahydroquinazolinamines that act as selective H3R antagonists. Among all the synthesized compounds, in vitro and docking studies suggested that the 4-methoxy-phenyl-substituted tetrahydroquinazolinamine compound 4c has potent and selective H3R antagonist activity (IC₅₀ < 0.04 μM). Compound 4c did not exhibit any activity on the hERG ion channel and pan-assay interference compounds liability. Pharmacokinetic studies showed that 4c crosses the blood brain barrier, and in vivo studies demonstrated that 4c induces anorexia and weight loss in obese, but not in lean mice. These data reveal the therapeutic potential of 4c as an anti-obesity candidate drug via antagonizing the H3R.

Synthesis and Characterization of Novel Thiazolo[3,2-a]pyrimidine Derivatives and Evaluation of Antioxidant and Cytotoxic Activities

A series of novel thiazolo[3,2-a]pyrimidines were synthesized and characterized by FT-IR, ¹ H, ¹³ C-NMR and mass techniques. Their antioxidant activities were investigated by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay and the results showed that all the synthesized compounds exhibit good antioxidant activity. In addition, it was found that any substituent on the aromatic ring of the products plays an important role in their antioxidant activity. In vitro cytotoxicity of compounds 4a-4j was investigated using MTT cell viability assay. Among these compounds, 6-ethyl 2,3-dimethyl 5-(4-chlorophenyl)-7-methyl-2,3-dihydro-5H-[1,3]thiazolo[3,2-a]pyrimidine-2,3,6-tricarboxylate (4e) bearing a chlorine substituent displayed the highest cytotoxic effect (IC₅₀ =6.26±0.6 μm) in comparison with doxorubicin (IC₅₀ =0.68±0.1 μm) as a standard after 72 h. Therefore, it is assumed that these compounds could be used as effective antioxidant and cytotoxic agents.

NitroketeneN,S-acetals: synergistic building blocks for the synthesis of heterocycles

The development of novel heterocyclic compounds from simple and easily accessible starting components is of significant importance in medicinal chemistry. Due to the presence of active chromophores and potent pharmacological activities, nitroketene N,S-acetals have emerged as a fascinating building block in organic synthesis. The synergistic skeleton of these acetals and the presence of electron-donating as well as electron-withdrawing groups lead to the generation of distinctive structural features and are highly useful for building diverse heterocyclic rings. This review highlights the preparation of different nitroketene N,S-acetals and their applications in the synthesis of diverse heterocyclic compounds.

This review highlights the synthesis of several kinds of nitroketene N,S-acetals and their applications in the synthesis of different kinds of heterocyclic compounds.

Synthesis of Pyrimidine- and Quinazoline-Fused Benzimidazole-4,7-diones Using Combinatorial Cyclocondensation and Oxidation

β-Bromo-α,β-unsaturated aldehydes and 2-bromobenzaldehydes react with 4,7-dimethoxy-1H-benzo[d]imidazole-2-amine by microwave irradiation in dimethylformamide in the presence of a base to give the corresponding dimethoxy-substituted benzo[4,5]imidazo[1,2-a]pyrimidines and benzo[4,5]imidazo[1,2-a]quinazolines, respectively, in moderate to good yields. Oxidation of such N-fused hybrid scaffolds by aqueous ceric ammonium nitrate affords pyrimidine- and quinazoline-fused benzimidazole-4,7-diones in high yields.

Integrative Bone Metabolomics-Lipidomics Strategy for Pathological Mechanism of Postmenopausal Osteoporosis Mouse Model

Osteoporosis, characterized by bone mass reduction and increased fractures, has become a global health problem that seriously affects the health of people, especially postmenopausal women; however, the current pathogenesis of postmenopausal osteoporosis (PMOP) has not been thoroughly elucidated to date. In this study, bilateral ovariectomy was performed to establish an OVX mouse model of osteoporosis. UPLC-Q-TOF-MS-based lipidomics in combination with metabolomics were used to analyze the femur tissue of osteoporosis mice. We found that 11 polar metabolites and 93 lipid metabolites were significantly changed and were involved in amino acid metabolism, nucleotide metabolism and lipid metabolism. Among the lipids, fatty acyls, glycerolipids, glycerophospholipids, sphingolipids and sterols showed robust changes. These results revealed that several metabolic disorders caused by changes in the hormone levels in OVX, especially disordered lipid metabolism, are closely related to the imbalance between bone resorption and formation and may underlie the development of PMOP. The data generated via lipidomics and metabolomics presented in this study shows good applicability and wide coverage in the construction of the metabolic profile of bone tissue. Therefore, this approach may provide the pathway focusing and data support at the metabolite level for the in-depth mechanism of PMOP.

Synthesis and biological evaluation of new 2,4,6-trisubstituted pyrimidines and their N-alkyl derivatives

A series of new 2,4,6-trisubstituted pyrimidines and their N-alkyl bromide derivatives were prepared based upon methoxy substituted azachalcones as the starting materials. All newly synthesized compounds were screened for their anti-proliferative, cytotoxic, antibacterial activities and DNA/protein binding affinity. In vitro cell proliferation inhibitory and cell cytotoxic effects of 2,4,6-trisubstituted pyrimidines (1-9) and their N-alkyl bromide derivatives (2a-c, 3a-c,5a-c,6a-c, 8a-c, 9a-c) were obtained with the help of the 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) cell proliferation, LDH cytotoxicity detection, and microdilution assays. The antimicrobial activity for these compounds was also evaluated following the European Pharmacopoeia 8.0 protocol. The interactions of these compounds with DNA or bovine serum albumin were investigated by the spectrophotometric titration method. When the cytotoxic analysis and anticancer properties of the compounds were examined, most of the compounds significantly exhibited an anti-proliferative potency on cancer cells (IC₅₀ ∼ 2-10 µg/mL) and caused a cytotoxic effect as low as control drugs, 5-fluorouracil, and cisplatin (∼7-15%). Because the compound-DNA adducts are hyperchromic or hypochromic, they caused variations in their spectra. This situation shows they can be linked to DNA by the groove binding mode at a binding constant range of 2.0 × 104 and 2.4 × 105 M^-1. The antimicrobial screening results revealed that our new compounds for some human Gram(+) and Gram(-) pathogen bacteria showed remarkable activity with MIC values between <7.81 and 125 µg/mL. Overall, incorporation of alkyl chain to pyrimidines in the generation of N-alkyl bromides has resulted in showing differences in DNA/protein binding affinity, along with anti-proliferative and cytotoxic activity in favor of new compounds.