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Background: Synthesis of new heterocyclic drugs in short reaction time with sufficient quantity is considered as a target for several pharmaceutical scientists. Thus, organic reactions proceeded on the surface of nano-sized catalysts to speed up the stimulation process. Objective: we aimed in this research to synthesize a new series of heterocyclic compounds carrying pyrazole moiety in the presence of ZnO nano-catalyst to investigate their anti-tubercular activity. Methods: ZnO(NPs) was used in synthesis of novel series of thienylpyrazolopyrimidines bearing arylazo group by reaction of thiophene-enaminone and the amino-arylazopyrazoles in excellent yield. On the other hand, another series of theinyl-pyrazoles was synthesized through the reaction of the same enaminone with hydrazonoyl chlorides but the usage of ZnO(NPs) failed in such reactions. Results: The proposed structures of the products and the mechanistic pathways of the reactions were assured based on the spectral data and chemical evidences. Thienylpyrazole derivatives were assessed for their activity as Mycobacterium tuberculosis inhibitor and their results revealed that two thienylpyrazole derivatives 24d & 24f showed the most significant anti-mycobacterial activity with MIC values 0.70 & 1.29 µM/mL, respectively comparing with the MIC value = 0.60 µM/mL of the standard drug Rifampicin. Furthermore, the most active thienylpyrazole derivatives were investigated for their cytotoxic impact versus normal cells WI-38 (Normal human Lung fibroblast cells) using MTT assay. These thienylpyrazole derivatives exhibited good selective index profile. Moreover, 1,3,4-trisubstituted pyrazole analogues showed good interaction with the active site of enoyl-acyl carrier protein reductase (Mt InhA) through the molecular docking studies. Conclusion: We succeeded to synthesis a new series of heterocyclic compounds carrying pyrazole moiety in the presence of ZnO nano-catalyst as anti-tubercular agents.

Inhibition of membrane‐bound pyrophosphatase (mPPase) with small molecules offer a new approach in the fight against pathogenic protozoan parasites. mPPases are absent in humans, but essential for many protists as they couple pyrophosphate hydrolysis to the active transport of protons or sodium ions across acidocalcisomal membranes. So far, only few nonphosphorus inhibitors have been reported. Here, we explore the chemical space around previous hits using a combination of screening and synthetic medicinal chemistry, identifying compounds with low micromolar inhibitory activities in the Thermotoga maritima mPPase test system. We furthermore provide early structure‐activity relationships around a new scaffold having a pyrazolo[1,5‐a]pyrimidine core. The most promising pyrazolo[1,5‐a]pyrimidine congener was further investigated and found to inhibit Plasmodium falciparum mPPase in membranes as well as the growth of P. falciparum in an ex vivo survival assay., Chemical space exploration: Novel low micromolar membrane‐bound pyrophosphatase (mPPase) inhibitors based on an exploratory screening against Thermotoga maritima mPPase followed by early SARs around a pyrazolo[1,5‐a]pyrimidine scaffold. Compound 17 a retained activity against Plasmodium falciparum mPPase in membranes, and inhibited parasite growth ex vivo.

Biofilms are multicellular communities of microorganisms that generally attach to surfaces in a self-produced matrix. Unlike planktonic cells, biofilms can withstand conventional antibiotics, causing significant challenges in the healthcare system. Currently, new chemical entities are urgently needed to develop novel anti-biofilm agents. In this study, we designed and synthesized a set of 2,4,5,6-tetrasubstituted pyrimidines and assessed their antibacterial activity against planktonic cells and biofilms formed by Staphylococcus aureus. Compounds 9e, 10d, and 10e displayed potent activity for inhibiting the onset of biofilm formation as well as for killing pre-formed biofilms of S. aureus ATCC 25923 and Newman strains, with half-maximal inhibitory concentration (IC50) values ranging from 11.6 to 62.0 µM. These pyrimidines, at 100 µM, not only decreased the number of viable bacteria within the pre-formed biofilm by 2–3 log10 but also reduced the amount of total biomass by 30–50%. Furthermore, these compounds were effective against planktonic cells with minimum inhibitory concentration (MIC) values lower than 60 µM for both staphylococcal strains. Compound 10d inhibited the growth of S. aureus ATCC 25923 in a concentration-dependent manner and displayed a bactericidal anti-staphylococcal activity. Taken together, our study highlights the value of multisubstituted pyrimidines to develop novel anti-biofilm agents.

A series of novel pyrazolo[3,4-d]pyrimidines was synthesised. Twelve synthesised compounds were evaluated for their anticancer activity against 60 human tumour cell lines by NCI (USA). Compound 7d proved prominent anticancer activity. It showed 1.6-fold more potent anti-proliferative activity against OVCAR-4 cell line with IC50 = 1.74 μM. It also exhibited promising potent anticancer activity against ACHN cell line with IC50 value 5.53 μM, representing 2.2-fold more potency than Erlotinib. Regarding NCI-H460 cell line, compound 7d (IC50 = 4.44 μM) was 1.9-fold more potent than Erlotinib. It inhibited EGFR and ErbB2 kinases at sub-micromolar level (IC50 = 0.18 and 0.25 µM, respectively). Dual inhibition of EGFR and ErbB2 caused induction of apoptosis which was confirmed by a significant increase in the level of active caspase-3 (11-fold). It showed accumulation of cells in pre-G1 phase and cell cycle arrest at G2/M phase.

In the search for new anti-influenza virus (IV) compounds, we have identified the 1,2,4-triazolo[1,5-a]pyrimidine (TZP) as a very suitable scaffold to obtain compounds able to disrupt IV RNA-dependent RNA polymerase (RdRP) PA-PB1 subunits heterodimerization. In this work, in order to acquire further SAR insights for this class of compounds and identify more potent derivatives, we designed and synthesized additional series of analogues to investigate the role of the substituents around the TZP core. To this aim, we developed four facile and efficient one-step procedures for the synthesis of 5-phenyl-, 6-phenyl- and 7-phenyl-2-amino-[1,2,4]triazolo[1,5-a]pyrimidines, and 2-amino-5-phenyl-[1,2,4]triazolo[1,5-a]pyrimidin-7-ol. Two analogues having the ethyl carboxylate moiety at the C-2 position of the TZP were also prepared in good yields. Then, the scaffolds herein synthesized and two previous scaffolds were functionalized and evaluated for their anti-IAV activity, leading to the identification of compound 22 that showed both anti-PA-PB1 (IC50 = 19.5 μM) and anti-IAV activity (EC50 = 16 μM) at non-toxic concentrations, thus resulting among the most active TZP derivatives reported to date by us. A selection of the synthesized compounds, along with a set of in-house available analogues, was also tested against SARS-CoV-2. The most promising compound 49 from this series displayed an EC50 value of 34.47 μM, highlighting the potential of the TPZ scaffold in the search for anti-CoV agents. ispartof: EUROPEAN JOURNAL OF MEDICINAL CHEMISTRY vol:221 ispartof: location:France status: published

A novel series of 6-substituted pyrrolo[2,3-d]pyrimidines with reversed amide moieties from the lead compound 1a were designed and synthesized as nonclassical antifolates and as potential antitumor agents. Target compounds 1–9 were successfully obtained through two sequential condensation reactions from the key intermediate 2-amino-6-(2-aminoethyl)-3,7-dihydro-4H-pyrrolo[2,3-d]pyrimidin-4-one. In preliminary antiproliferation assay, all compounds demonstrated submicromolar to nanomolar inhibitory effects against KB tumor cells, whereas compounds 1–3 also exhibited nanomolar antiproliferative activities toward SW620 and A549 cells. In particular, compounds 1–3 were significantly more potent than the positive control methotrexate (MTX) and pemetrexed (PMX) to A549 cells. The growth inhibition induced cell cycle arrest at G1-phase with S-phase suppression. Along with the results of nucleoside protection assays, inhibition assays of dihydrofolate reductase (DHFR) clearly elucidated that the intracellular target of the designed compounds was DHFR. Molecular modeling studies suggested two binding modes of the target compounds with DHFR.

Pneumocystis pneumonia (PCP) caused by Pneumocystis jirovecii (pj) can lead to serious health consequences in patients with an immunocompromised system. Trimethoprim (TMP), used as first-line therapy in combination with sulfamethoxazole, is a selective but only moderately potent pj dihydrofolate reductase (pjDHFR) inhibitor, whereas non-clinical pjDHFR inhibitors, such as, piritrexim and trimetrexate are potent but non-selective pjDHFR inhibitors. To meet the clinical needs for a potent and selective pjDHFR inhibitor for PCP treatment, fourteen 6-substituted pyrido[3,2-d]pyrimidines were developed. Comparison of the amino acid residues in the active site of pjDHFR and human DHFR (hDHFR) revealed prominent amino acid differences which could be exploited to structurally design potent and selective pjDHFR inhibitors. Molecular modeling followed by enzyme assays of the compounds revealed 15 as the best compound of the series with an IC50 of 80 nM and 28-fold selectivity for inhibiting pjDHFR over hDHFR. Compound 15 serves as the lead analog for further structural variations to afford more potent and selective pjDHFR inhibitors.

To find novel effective Aurora kinases inhibitors, a series of structurally interesting nitroxide labeled pyrimidines were synthesized and evaluated their anti-proliferative and Aurora kinases inhibitory activities. Among them, butyl 2-(3-((5-fluoro-2-((4-((1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)carbamoyl) phenyl) amino)pyrimidin-4-yl)amino)-1H-pyrazol-5-yl)acetate (22) possessed the most potent anti-proliferative effects against four carcinoma cell lines with IC50 values in range of 0.89–11.41 μM, and kinases inhibition against Aurora A and B with the IC50 values were 9.3 and 2.8 nM, respectively. Furthermore, compound 22 blocked the phosphorylation of Aurora A (T288), Aurora B (Thr232) and HisH3, decreased the expression of proteins TPX2, Eg5 and Bora, as well as disrupted the mitotic spindle formation in HeLa cells. Molecular docking studies indicated that compound 22 well interact with both Aurora A and B. The results showed that compound 22 is a potential anticancer agent as promising pan-Aurora kinase inhibitor.

Background: Phosphatidylinositol-3-kinase α (PI3Kα) is a ubiquitous intracellular enzyme, mainly involved in intracellular signaling pathways, promotes cellular growth, proliferation, and differentiation. Therefore, inhibition of PI3K can be a hotspot in molecular targeted therapy for the treatment of cancer. Methods: The present research work involves molecular docking studies performed to screen derivatives of urea and thiourea bearing thieno [3,2-d]-pyrimidines against the active site of PI3K enzyme using MOE.2008.10. The designed structures (6a-f) and (7a-j) were synthesized by the facile synthetic methods and evaluated for their anticancer activity against HT-29 and MCF-7 cell lines and inhibitory activity against PI3Kα enzyme. Results: Among the tested compounds, 4-(4-(2-(3-(pyrimidin-2-yl)thioureido)ethyl)piperazin-1-yl)thieno[3,2- d]pyrimidine-6-carboxamide (7f) showed the highest anticancer activity against HT-29 and MCF-7 cell lines with IC50 values of 2.18 µM and 4.25 µM, respectively. Further, the same compound also exhibited potent PI3Kα inhibitory activity with IC50 value of 1.26 µM. Conclusion: Docking studies supported the initial pharmacophoric hypothesis and suggested a mode of interaction at the active binding site of PI3Kα, demonstrating that the target compounds were potential inhibitory agents for cancer therapy.

Pyrazolo[1,5-a]pyrimidines 5a&ndash, c, 9a&ndash, c and 13a&ndash, i were synthesized for evaluation of their in vitro antimicrobial properties against some microorganisms and their immunomodulatory activity. The biological activities of pyrazolo[1,5-a]pyrimidines showed that the pyrazolo[1,5-a]pyrimidines (5c, 9a, 9c, 13a, 13c, 13d, 13e and 13h) displayed promising antimicrobial and immunomodulatory activities. Studying the in silico predicted physicochemical, pharmacokinetic, ADMET and drug-likeness properties for the pyrazolo[1,5-a]pyrimidines 5a&ndash, i confirmed that most of the compounds (i) were within the range set by Lipinski&rsquo, s rule of five, (ii) show higher gastrointestinal absorption and inhibition of some CYP isoforms, and (iii) have a carcinogenicity test that was predicted as negative and hERG test that presented medium risk. Moreover, the molecular docking study demonstrated that the compounds 5c, 9a, 9c, 13a, 13c, 13d, 13e and 13h are potent inhibitors of 14-alpha demethylase, transpeptidase and alkaline phosphatase enzymes. This study could be valuable in the discovery of a new series of drugs.

Meaningful words in English need vowels to break up the sounds that consonants make. The Nature has encoded her messages in RNA molecules using only four alphabets A, U, C and G in which the nine member double-ring bases (adenine (A) and Guanine (G)) are purines, while the six member single-ring bases (cytosine (C) and uracil (U)) are pyrimidines. Four bases A, U, C and G of RNA sequences are divided into three kinds of classifications according to their chemical properties. One of the three classifications, the purine-pyrimidine class is important. In understanding the distribution (organization) of purines and pyrimidines over some of the non-coding RNAs, all miRNAs of the three species (human, gorilla and chimpanzee) of Hominidae family and two species (mouse and rat) from of Muridae family are considered. The distribution of purines and pyrimidines over miRNA shows deviation from randomness. Based on the quantitative metrics (fractal dimension, Hurst exponent, Hamming distance, distance pattern of purine-pyrimidine, density distribution of purine-pyrimidine and Shannon entropy) five different clusters have been made for the five species. We have observed some couple of results including the closeness of different clusters among the five species.

Pancreatic cancer is a highly malignant tumor, and more effective treatment is urgently needed to lengthen the life of patients. In this paper a class of new 2,6,7-substituted pyrrolo[2,3-d]pyrimidine derivatives of CDK 4/6 inhibitor ribociclib (1) was designed and synthesized to investigate their effect on the proliferation of pancreatic cancer cells. The structure-activity relationship (SAR) of synthetic compounds was analyzed based on both their in vitro anti-proliferative activity and the CDK4 inhibitory activity. A series of 6-anilinocarbonyl-substituted pyrrolo[2,3-d]pyrimidine derivatives (25, 41-48) showed the significantly increased potency against two proliferating cancer cell lines (MIA PaCa-2 and BxPC-3) in MTT assay though their CDK4 inhibitory activity were lower in a varying range compared to 1. The most potent compound 41 was identified as a highly selective and potent CDK 4/6 inhibitor in the human kinases profiling assay, it also exhibited the favorable in vitro pharmacokinetic properties for further in vivo evaluation. Meanwhile, 41 exhibited the potential as a combination partner with mTOR inhibitor to treat pancreatic cancer. Alternatively, introducing of sulfonamide fragment into C2-substituent of pyrrolo[2,3-d]pyrimidine provided the clue for future optimization to afford new CDK9 inhibitors.

We review developments in fluorine chemistry contributing to the more precise use of fluorinated pyrimidines (FPs) to treat cancer. 5-Fluorouracil (5-FU) is the most widely used FP and is used to treat > 2 million cancer patients each year. We review methods for 5-FU synthesis, including the incorporation of radioactive and stable isotopes to study 5-FU metabolism and biodistribution. We also review methods for preparing RNA and DNA substituted with FPs for biophysical and mechanistic studies. New insights into how FPs perturb nucleic acid structure and dynamics has resulted from both computational and experimental studies, and we summarize recent results. Beyond the well-established role for inhibiting thymidylate synthase (TS) by the 5-FU metabolite 5-fluoro-2′-deoxyuridine-5′-O-monophosphate (FdUMP), recent studies have implicated new roles for RNA modifying enzymes that are inhibited by 5-FU substitution including tRNA methyltransferase 2 homolog A (TRMT2A) and pseudouridylate synthase in 5-FU cytotoxicity. Furthermore, enzymes not previously implicated in FP activity, including DNA topoisomerase 1 (Top1), were established as mediating FP anti-tumor activity. We review recent literature summarizing the mechanisms by which 5-FU inhibits RNA- and DNA-modifying enzymes and describe the use of polymeric FPs that may enable the more precise use of FPs for cancer treatment in the era of personalized medicine.

To combine the potency of trimetrexate (TMQ) or piritrexim (PTX) with the species selectivity of trimethoprim (TMP), target based design was carried out with the X-ray crystal structure of human dihydrofolate reductase (hDHFR) and the homology model of Pneumocystis jirovecii DHFR (pjDHFR). Using variation of amino acids such as Met33/Phe31 (in pjDHFR/hDHFR) that affect the binding of inhibitors due to their distinct positive or negative steric effect at the active binding site of the inhibitor, we designed a series of substituted-pyrrolo[2,3-d]pyrimidines. The best analogs displayed better potency (IC(50)) than PTX and high selectivity for pjDHFR versus hDHFR, with 4 exhibiting a selectivity for pjDHFR of 24-fold.

We report the design, synthesis, and biological evaluation of heterocyclic-fused pyrimidines as tubulin polymerization inhibitors targeting the colchicine binding site with significantly improved therapeutic index. Additionally, for the first time, we report high-resolution X-ray crystal structures for the best compounds in this scaffold, 4a, 4b, 6a, and 8b. These structures not only confirm their direct binding to the colchicine site in tubulin and reveal their detailed molecular interactions but also contrast the previously published proposed binding mode. Compounds 4a and 6a significantly inhibited tumor growth in an A375 melanoma xenograft model and were accompanied by elevated levels of apoptosis and disruption of tumor vasculature. Finally, we demonstrated that compound 4a significantly overcame clinically relevant multidrug resistance in a paclitaxel resistant PC-3/TxR prostate cancer xenograft model. Collectively, these studies provide preclinical and structural proof of concept to support the continued development of this scaffold as a new generation of tubulin inhibitors.

A novel series of 6-substituted benzoyl and non-benzoyl straight chain pyrrolo[2,3-d]pyrimidines were designed and synthesized as potential antitumor agents targeting both thymidylate and purine nucleotide biosynthesis. Starting from the key intermediate 2-amino-4-oxo-pyrrolo[2,3-d]pyrimidin-6-yl-acetic acid, target compounds 1–6 were successfully obtained through two sequential condensation and saponification reactions in decent yield. The newly synthesized compounds showed antiproliferative potencies against a panel of tumor cell lines including KB, SW620 and MCF7. In particular, most compounds of this series exhibited nanomolar to subnanomolar inhibitory activities toward KB tumor cells, significantly more potent than the positive control methotrexate (MTX) and pemetrexed (PMX). Along with the results of nucleoside protection assays, molecular modeling studies suggested that the antitumor activity of compound 6 could be attributed to multitargeted inhibition of folate-dependent enzymes thymidylate synthase (TS), glycinamide ribonucleotide formyltransferase (GARFTase) and 5-aminoimidazole-4-carboxamide ribonucleotide formyltransferase (AICARFTase). Growth inhibition by compound 6 also induced distinct early apoptosis and cell cycle arrest at S-phase, which resulted in cell death.

Despite great efforts have been made in the prevention and therapy of human immunodeficiency virus (HIV-1) infection, however the difficulty to eradicate latent viral reservoirs together with the emergence of multi-drug-resistant strains require the search for innovative agents, possibly exploiting novel mechanisms of action. In this context, the HIV-1 reverse transcriptase (RT)-associated ribonuclease H (RNase H), which is one of the few HIV-1 encoded enzymatic function still not targeted by any current drug, can be considered as an appealing target. In this work, we repurposed in-house anti-influenza derivatives based on the 1,2,4-triazolo[1,5-a]-pyrimidine (TZP) scaffold for their ability to inhibit HIV-1 RNase H function. Based on the results, a successive multi-step structural exploration around the TZP core was performed leading to identify catechol derivatives that inhibited RNase H in the low micromolar range without showing RT-associated polymerase inhibitory activity. The antiviral evaluation of the compounds in the MT4 cells showed any activity against HIV-1 (IIIB strain). Molecular modelling and mutagenesis analysis suggested key interactions with an unexplored allosteric site providing insights for the future optimization of this class of RNase H inhibitors. ispartof: MOLECULES vol:25 issue:5 ispartof: location:Switzerland status: published

The new steroidal pyrimidine derivatives (4-6) were synthesized by the reaction of steroidal thiosemicarbazones with (2-methyl) diethyl malonate in absolute ethanol. After characterization by spectral and analytical data, the DNA interaction studies of compounds (4-6) were carried out by UV-vis, fluorescence spectroscopy, hydrodynamic measurements, molecular docking and gel electrophoresis. The compounds bind to DNA preferentially through electrostatic and hydrophobic interactions with K-b; 2.31 x 10(3) M-1, 1.93 x 10(3) M-1 and 2.05 x 10(3) M-1, respectively indicating the higher binding affinity of compound 4 towards DNA. Gel electrophoresis demonstrated that compound 4 showed a strong interaction during the concentration dependent cleavage activity with pBR322 DNA. The molecular docking study suggested the intercalation of steroidal pyrimidine moiety in the minor groove of DNA. During in vitro cytotoxicity, compounds (4-6) revealed potential toxicity against the different human cancer cells (MTT assay). During DAPI staining, the nuclear fragmentations on cells occurred after treatment with compounds 4 and 5. Western blotting analysis clearly indicates that compound 4 causes apoptosis in MCF-7 cancer cells. The results revealed that compound 4 has better prospectus to act as a cancer chemotherapeutic candidate, which warrants further in vivo anticancer investigations. (C) 2017 Published by Elsevier B.V.

We report for the first time a small series of compounds endowed in vitro with inhibitory properties for the human (h) expressed Carbonic Anhydrase (CAs, E.C. 4.2.1.1) enzymes of physiological interest (i.e. I, II, VA, IX and XII) and bearing the pyrazolo[1,5-a]pyrimidine (PP) scaffold at the tail section. Among the series reported, 1a-3a, 7a, 8a, 1b and 2b resulted effective ligands and with good selectivities for the hCAs II, IX or XII. In consideration of the nearly matching KI values of 7a for both the hCA II and IX (i.e. 26.4 and 23.0 nM respectively) we explored its binding mode within the CA IX mimic isoform by means of X-ray crystal experiments on the corresponding adduct.

By removing 5-methyl and 6-acetyl groups in our previously reported compound 3, we designed a series of novel 2,7-diaryl-[1,2,4]triazolo[1,5-a]pyrimidine derivatives as potential tubulin polymerization inhibitors. Among them, compound 5e displayed low nanomolar antiproliferative efficacy on HeLa cells which was 166-fold higher than the lead analogue 3. Interestingly, 5e displayed significant selectivity in inhibiting cancer cells over HEK-293 (normal human embryonic kidney cells). In addition, 5e dose-dependently arrested HeLa in G2/M phase through the alterations of the expression levels of p-cdc2 and cyclin B1, and caused HeLa cells apoptosis by regulation of expressions of cleaved PARP. Further evidence demonstrated that 5e effectively inhibited tubulin polymerization and was 3-fold more powerful than positive control CA-4. Moreover, molecular docking analysis indicated that 5e overlapped well with CA-4 in the colchicine-binding site. These studies demonstrated that 2,7-diaryl-[1,2,4]triazolo[1,5-a]pyrimidine skeleton might be used as the leading unit to develop novel tubulin polymerization inhibitors as potential anticancer agents.

Dihydrofolate reductase (DHFR) has been a well-recognized target for the treatment of many diseases. Based on 8,10-dideazaminopterins, which are classical antifolates that potently inhibit DHFR, we have designed a series of novel 2,4-diamino-6-substituted pyrido[3,2-d]pyrimidines. By removing the glutamate moiety and introducing lipophilic groups, we hoped to improve passive diffuse through the cell membranes. The target compounds were efficiently synthesized using one-pot procedure and evaluated in vitro for DHFR inhibition and antitumor activity. Compounds 5e, 5h, 5i and 5k were the most potent inhibitors of recombinant human DHFR (rhDHFR) with IC50 values in the range 0.2–1.0 μM. Analysis using flow cytometric indicated that the effect of compound 5k on cell cycle progression was linked to induction of S phase arrest. Compounds 5g, 5h, 5i and 5k showed broad spectrum antitumor activity against four different tumor cell lines, with IC50 values in the range 0.07–23 μM. Molecular docking investigations showed that the trimethoyphenyl ring of compound 5k occupied a position near the cofactor-binding site in the rhDHFR-inhibitor complex, with close intermolecular contacts with Asp21, Phe31, Ser59, Ile60 and Pro61.

Tyrosine kinases are one of the most critical mediators in the signaling path way. Late studies have proved the part of tyrosine kinases in the pathophysiology of cancer diseases. This current research paper has focused on investigating the novel Pyrazolo[1,5-a]pyrimidines and Pyrido[2,3-d]pyrimidines as a small molecules that can inhibit tyrosine kinase in cancer cells. NCI protocol was applied to test the antitumor activity of such compounds. Leukemia and renal cancer cell lines proved to be sensitive to some derivatives such as 6b–d, 9a and 11 with GI% values ranging from 30.4 to 41.3%. In addition, compound 11 proved to be the most active against MCF-7 with GI% 62.5. The synthesized compounds were also evaluated for their inhibitory effects against EGFR kinase enzyme. Compound 9b proved to be the most active one among the synthesized series with inhibition % value of 81.72 at 25 nM concentration and IC50 8.4 nM which is very close to the reference drug Sorafenib. In vitro cytotoxicity test was also performed using the MCF-7 breast cell line. Computer modeling using the active site of tyrosine kinase as a template and the most active tyrosine kinase inhibitors were calculated. Docking studies of the synthesized compounds into the active site of EGFR kinase domain showed good agreement with the obtained biological results.

The development of biologically active molecules based on molecular recognition is an attractive and challenging task in medicinal chemistry and the molecules that can activate/deactivate certain receptors are of great medical interest. In this contribution, selected pyrimidine/piperidine derivatives were synthesized and tested for the ability to activate/deactivate Aryl hydrocarbon receptor (AhR) and Glucocorticoid receptor (GR). Tested compounds are shown to activate the receptors but to much lesser extent than positive controls, dioxin and dexamethasone for Ahr and GR, respectively. However, some of them antagonized the positive controls action. Although further in vivo studies are needed to fully characterize the bioactivities of these compounds, the reported in vitro evidences demonstrate that they might be used as the modulators of AhR and GR activities.

Focal adhesion kinase (FAK) is considered as an attractive target for oncology. A series of F-18 labeled 5-bromo-N 2 -(4-(2-fluoro-pegylated (FPEG))-3,5-dimethoxyphenyl)-N 4 -(4-methoxyphenyl)pyrimidine-2,4-diamine derivatives were prepared and evaluated as the FAK targeted radiotracers for the early diagnoses of tumor. For the study of the FAK targeted drug molecules, this was the first attempt to develop the tumor diagnostic imaging agents on the radiopharmaceutical level. They inhibited the activity of FAK with IC 50 in the range of 91.4–425.7 nM, and among which the result of the [ 19 F] 2 was relatively good and had a modest IC 50 of 91.4 nM. The [ 19 F] 2 was also profiled in vitro against some other kinds of cancer-related kinases (including two kinds of non-receptor tyrosine kinase: PYK2 and JAK2, and three kinds of receptor tyrosine kinase: IGF-1R, EGFR and PDGFRβ). It displayed 25.2 folds selectivity against PYK2, 35.1 folds selectivity against EGFR, and more than 100 folds selectivity against IGF-1R, JAK2 and PDGFRβ. For the biodistribution in S180 bearing mice, the corresponding [ 18 F] 2 were also relatively good, with modest tumor uptake of 5.47 ± 0.19 and 5.80 ± 0.06 %ID/g at 15 and 30 min post-injection, respectively. Furthermore, its tumor/muscle, tumor/bone and tumor/blood ratio at 15 min post-injection were 3.16, 2.53 and 4.52, respectively. And its tumor/muscle, tumor/bone and tumor/blood ratio at 30 min post-injection were 3.14, 2.76 and 4.43, respectively. In addition, coronal micro-PET/CT images of a mouse bearing S180 tumor clearly confirmed that [ 18 F] 2 could be accumulated in tumor, especially at 30 min post-injection. Besides, for the [ 18 F] 2 , both the biodistribution data and the micro-PET/CT imaging study showed significantly reduced uptake of the radiotracer in the tumor tissue at 30 min post-injection in mice that received PF-562,271 (one of the reported best selective FAK inhibitor which was developed by Pfitzer Inc. and inhibited the activity of FAK with IC 50 value of 1.5 nM) at 1 h before the injection of radiotracer. In combination with the above kinase profiling assay, it could be indicated that the uptake of [ 18 F] 2 in tumor of the mouse model was due to FAK expression, and that [ 18 F] 2 might be a kind of selectively FAK targeted tumor imaging agents. What's more, the results of the MD (molecular dynamics) simulations were in agreement with the changing trends of the interaction between the different F-19 standards and the FAK (expressed as the in vitro inhibitory abilities of enzymatic activities of FAK in this article), which was also in agreement with and had great effect on the changing trends of the uptake of the corresponding F-18 labeled tracers in tumor and some of theirs target/non-target ratios.

A novel series of heat shock protein 90 (Hsp90) inhibitors was identified by X-ray crystal analysis of complex structures at solvent-exposed exit pocket C. The 2-amino-pyrrolo[2,3-d]pyrimidine derivatives, 7-deazapurines substituted with a benzyl moiety at C5, showed potent Hsp90 inhibition and broad-spectrum antiproliferative activity against NCI-60 cancer cell lines. The most potent compound, 6a, inhibited Hsp90 with an IC50 of 36nM and showed a submicromolar mean GI50 value against NCI-60 cell lines. The interaction of 6a at the ATP-binding pocket of Hsp90 was confirmed by X-ray crystallography and Western blot analysis.

Based on the recent observation that the antiplatelet agent ticagrelor and one of its metabolite exert bactericidal activity against gram-positive bacteria, a series of 1,2,3-triazolo[4,5-d]pyrimidines structurally related to ticagrelor were synthesized and examined as putative antiplatelet and antibacterial agents. The aim was to assess the possibility of dissociating the two biological properties and to find novel 1,2,3-triazolo[4,5-d]pyrimidines expressing antiplatelet activity and devoid of in vitro antibacterial activity. The new compounds synthesized were known metabolites of ticagrelor as well as structurally simplified analogues. Some of them were found to express antiplatelet activity and to lose the antibacterial activity, supporting the view that the two activities were not necessarily linked.

Aim: Cyclooxygenase-2 (COX-2) inhibition and scavenging-free radicals are important targets in cancer treatment. Materials & methods: Sulfanylpyrimidines and triazolopyrimidines were synthesized and evaluated as anticancer and antioxidant COX-1/2 inhibitors. Results: Compound 7 showed the same growth inhibitory activity as 5-fluorouracil against MCF-7. Compound 6f displayed broad-spectrum anticancer activity against the four tested cancer cell lines. Compounds 5b, 6a, 6c, 6d and 8 were found to be more active antioxidants than trolox. Compounds 6a, 6c, 6f and 8 revealed high COX-2 inhibitory activity and selectivity, which was confirmed by docking studies. Conclusion: Compound 6f could be considered as promising anticancer and antioxidant structural lead with COX-2 inhibition that deserve further derivatization and investigation.

A series of 2-phenyl-7-(aryl)pyrazolo[1,5-a]pyrimidine-3-carbonitriles 11a–j and 2-phenyl-7-(aryl)pyrazolo[1,5-a]pyrimidine-3,6-dicarbonitriles 16a–c was synthesized by the reaction of 5-amino-3-phenyl-1H-pyrazole-4-carbonitrile (5) with 3-(dimethylamino)-1-arylprop-2-en-1-ones 6a–j or 2-aryl-3-(dimethylamino)acrylonitriles 12a–c, respectively. In addition, 7-amino-5-oxo-2-phenyl-4,5-dihydropyrazolo[1,5-a]pyrimidine-3-carbonitrile (22) was prepared from the reaction of compound 5 with ethyl cyanoacetate. The anticancer activity of the newly synthesized compounds against Huh-7, HeLa, MCF-7 and MDA-MB231 cell lines showed moderate activity of compound 11f as anti-proliferative agent against Huh-7 cell line with IC50 = 6.3 µM when compared with doxorubicin (IC50 = 3.2 µM). On the other hand, compound 16b revealed potent anti-proliferative activity against HeLa cell line with IC50 = 7.8 µM when compared with doxorubicin (IC50 = 8.1 µM). Also compound 11i exhibited a promising anti-proliferative activity against MCF-7 cell line (IC50 = 3.0 µM) whereas IC50 of doxorubicin = 5.9 µM, finally compounds 11i and 16b have potent activity as anti-proliferative agents against MDA-MB231 cell line with IC50 = 4.32 and 5.74 µM, respectively when compared with doxorubicin (IC50 = 6.0 µM).

With the worldwide number of human immunodeficiency virus positive patients stagnant and the increasing emergence of viral strains resistant to current treatment, the development of novel anti-human immunodeficiency virus drug candidates is a perpetual quest of medicinal chemists. Herein, we report a novel group of diarylpyrimidines, non-nucleoside reverse transcriptase inhibitors, which represents an important class of current anti-human immunodeficiency virus therapy. Series of diarylpyrimidines containing o, o-difluorophenyl (A-arm), 4-cyanophenylamino (B-arm), and a small substituent (e.g. NH2, OMe) at positions 2, 4, and 6 of the pyrimidine ring were prepared. The A-arm was modified in the para position (F or OMe) and linked to the central pyrimidine core with a variable spacer (CO, O, NH). Antiviral activities of 20 compounds were measured against wild type human immunodeficiency virus-1 and mutant reverse transcriptase strains (K103N, Y181C) using a cytoprotection assay. To the most promising structural motives belong the o, o-difluoro- p-methoxy A-arm in position 4, and the amino group in position 6 of pyrimidine. Single digit nanomolar activities with no significant toxicity (CC50 > 17,000 nM) were found for compounds 35 (EC50 = 2 nM), 37 (EC50 = 3 nM), and 13 (EC50 = 4 nM) having O, NH, and CO linkers, respectively.

Nucleic acid aptamers can be chemically modified to enhance function, but modifying previously selected aptamers can have nontrivial structural and functional consequences. We present a reselection strategy to evaluate the impact of several modifications on preexisting aptamer pools. RNA aptamer libraries with affinity to HIV-1 reverse transcriptase (RT) were retranscribed with 2′-F, 2′-OMe, or 2′-NH2 pyrimidines and subjected to three additional selection cycles. RT inhibition was observed for representative aptamers from several structural families identified by high-throughput sequencing when transcribed with their corresponding modifications. Thus, reselection identified specialized subsets of aptamers that tolerated chemical modifications from unmodified preenriched libraries. Inhibition was the strongest with the 2′-F-pyrimidine (2′-FY) RNAs, as compared to inhibition by the 2′-OMeY and 2′-NH2Y RNAs. Unexpectedly, a diverse panel of retroviral RTs were strongly inhibited by all 2′-FY-modified transcripts, including sequences that do not inhibit those RTs as unmodified RNA. The magnitude of promiscuous RT inhibition was proportional to mole fraction 2′-FY in the transcript. RT binding affinity by 2′-FY transcripts was more sensitive to salt concentration than binding by unmodified transcripts, indicating that interaction with retroviral RTs is more ionic in character for 2′-FY RNA than for unmodified 2′-OH RNA. These surprising features of 2′-FY-modified RNA may have general implications for applied aptamer technologies.

Cyclooxygenase 2 (COX-2) is an inducible enzyme responsible for the conversion of arachidonic acid into the prostaglandins, PGG2 and PGH2. Expression of this enzyme increases in inflammation. Therefore, the development of probes for imaging COX-2 with positron emission tomography (PET) has gained interest because they could be useful for the study of inflammation in vivo, and for aiding anti-inflammatory drug development targeting COX-2. Nonetheless, effective PET radioligands are still lacking. We synthesized eleven COX-2 inhibitors based on a 2(4-methylsulfonylphenyl)pyrimidine core from which we selected three as prospective PET radioligands based on desirable factors, such as high inhibitory potency for COX-2, very low inhibitory potency for COX-1, moderate lipophilicity, and amenability to labeling with a positron-emitter. These inhibitors, namely 6-methoxy-2-(4-(methylsulfonyl)phenyl-N-(thiophen-2ylmethyl)pyrimidin-4-amine (17), the 6-fluoromethyl analogue (20), and the 6-(2-fluoroethoxy) analogue (27), were labeled in useful yields and with high molar activities by treating the 6-hydroxy analogue (26) with [11C]iodomethane, [18F]2-fluorobromoethane, and [d2-18F]fluorobromomethane, respectively. [11C]17, [18F]20, and [d2-18F]27 were readily purified with HPLC and formulated for intravenous injection. These methods allow these radioligands to be produced for comparative evaluation as PET radioligands for measuring COX-2 in healthy rhesus monkey and for assessing their abilities to detect inflammation.

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

Oxidative stress in cells can lead to the accumulation of reactive oxygen species and oxidation of DNA precursors. Oxidized nucleotides such as 2&rsquo, deoxyribo-5-hydroxyuridin (HdU) and 2&rsquo, deoxyribo-5-hydroxymethyluridin (HMdU) can be inserted into DNA during replication and repair. HdU and HMdU have attracted particular interest because they have different effects on damaged-DNA processing enzymes that control the downstream effects of the lesions. Herein, we studied the chemically simulated translesion DNA synthesis (TLS) across the lesions formed by HdU or HMdU using microscale thermophoresis (MST). The thermodynamic changes associated with replication across HdU or HMdU show that the HdU paired with the mismatched deoxyribonucleoside triphosphates disturbs DNA duplexes considerably less than thymidine (dT) or HMdU. Moreover, we also demonstrate that TLS by DNA polymerases across the lesion derived from HdU was markedly less extensive and potentially more mutagenic than that across the lesion formed by HMdU. Thus, DNA polymerization by DNA polymerase &eta, (pol&eta, ), the exonuclease-deficient Klenow fragment of DNA polymerase I (KF&ndash, ), and reverse transcriptase from human immunodeficiency virus type 1 (HIV-1 RT) across these pyrimidine lesions correlated with the different stabilization effects of the HdU and HMdU in DNA duplexes revealed by MST. The equilibrium thermodynamic data obtained by MST can explain the influence of the thermodynamic alterations on the ability of DNA polymerases to bypass lesions induced by oxidative products of pyrimidines. The results also highlighted the usefulness of MST in evaluating the impact of oxidative products of pyrimidines on the processing of these lesions by damaged DNA processing enzymes.

The design, synthesis, and biological evaluations of eight 4-substituted 5-methyl-furo[2,3-d]pyrimidines are reported. Synthesis involved N(4)-alkylation of N-aryl-5-methylfuro[2,3-d]pyrimidin-4-amines, obtained from Ullmann coupling of 4-amino-5-methylfuro[2,3-d]pyrimidine and appropriate aryl iodides. Compounds 3, 4, and 9 showed potent microtubule depolymerizing activities, while compounds 6-8 had slightly lower potency. Compounds 4, 6, 7, and 9 inhibited tubulin assembly with IC50 values comparable to that of combretastatin A-4 (CA-4). Compounds 3, 4, and 6-9 circumvented Pgp and βIII-tubulin mediated drug resistance, mechanisms that can limit the efficacy of paclitaxel, docetaxel, and the vinca alkaloids. In the NCI 60-cell line panel, compound 3 exhibited GI50 values less than 10 nM in 47 of the cell lines. In an MDA-MB-435 xenograft model, compound 3 had statistically significant antitumor effects. The biological effects of 3 identify it as a novel, potent microtubule depolymerizing agent with antitumor activity.

A new series of 2-amino-4-oxo-6-substituted pyrrolo[2,3-d]pyrimidines, with an isosteric replacement of the side chain amide moiety to a sulfur atom, were designed and synthesized as multitargeted antifolates as well as potential antitumor agents. Starting from previously synthesized 2-amino-4-oxo-pyrrolo[2,3-d]pyrimidin-6-yl-acetic acid, a reduction by lithium triethylborohydride and successive mesylation afforded the key mesylate. Nucleophilic substitution by mercaptoacetic or mercaptopropionic acid methyl esters, followed by hydrolysis and condensation with pyridinyl-methylamines provided the nonclassical compounds 1-6, whereas condensation with glutamic acid diethyl ester hydrochloride and saponification afforded the classical analogs 7-8. All target compounds exhibited inhibitory activities toward KB, SW620 and A549 tumor cell lines. The most potent compounds of this series, 7 and 8, are better inhibitors against A549 cells than methotrexate (MTX) and pemetrexed (PMX). Nucleoside protection assays establish compound 8 a dual inhibitor of thymidylate synthase (TS) and 5-aminoimidazole-4-carboxamide ribonucleotide formyltransferase (AICARFTase) targeting both de novo thymidylate and purine nucleotide biosynthesis, which is further verified by the molecular modeling studies. Analogous to PMX, target compound 8 alternates the cell cycle of SW620 cells with S-phase accumulation and induces apoptosis, leading to cell death.

The [1,2,4]triazolo[1,5-a]pyrimidines comprise a promising class of non-naturally occurring microtubule (MT)-active compounds. Prior studies revealed that different triazolopyrimidine substitutions can yield molecules that either promote MT stabilization or disrupt MT integrity. These differences can have important ramifications in the therapeutic applications of triazolopyrimidines and suggest that different analogues may exhibit different binding modes within the same site or possibly interact with tubulin/MTs at alternative binding sites. To help discern these possibilities, a series of photoactivatable triazolopyrimidine congeners was designed, synthesized and evaluated in cellular assays with the goal of identifying candidate probes for photoaffinity labeling experiments. These studies led to the identification of different derivatives that incorporate a diazirine ring in the amine substituent at position 7 of the triazolopyrimidine heterocycle, resulting in molecules that either promote stabilization of MTs or disrupt MT integrity. These photoactivatable candidate probes hold promise to investigate the mode of action of MT-active triazolopyrimidines.

Mycobacterium tuberculosis infection is responsible for a global pandemic. New drugs are needed that do not show cross-resistance with the existing front-line therapeutics. A triazine antitubercular hit led to the design of a related pyrimidine family. The synthesis of a focused series of these analogs facilitated exploration of their in vitro activity, in vitro cytotoxicity, and physiochemical and absorption-distribution-metabolism-excretion properties. Select pyrimidines were then evaluated for their pharmacokinetic profiles in mice. The findings suggest a rationale for the further evolution of this promising series of antitubercular small molecules, which appear to share some similarities with the clinical compound PA-824 in terms of activation, while highlighting more general guidelines for the optimization of small-molecule antitubercular agents.

A novel series of 4,6-disubstituted pyrazolo[3,4-d]pyrimidines (7-43) bearing various anilines at C-4 position and thiophenethyl or thiopentane moieties at C-6 position have been designed and synthesized by molecular hybridization approach. All the synthesized compounds were evaluated for in vitro CDK2/cyclin E and Abl kinase inhibitory activity as well as anti-proliferative activity against K-562 (chronic myelogeneous leukemia), and MCF-7 (breast adenocarcinoma) cell lines. The structure-activity relationship (SAR) studies revealed that compounds with thiophenethyl group at C-6 with mono-substituted anilines at C-4 exhibited better CDK2 inhibitory activity compared to alkyl group (thiopentane) at C-6 and di-substituted anilines at C-4 of the scaffold. In particular, compounds having 2-chloro, 3-nitro and 4-methylthio aniline groups at C-4 displayed significant enzymatic inhibitory activity against CDK2 with single digit micromolar IC50 values. The in silico molecular docking studies suggested possible binding orientation and the binding energies were in agreement with the observed SAR as well as experimental results. In addition, some of the synthesized compounds showed anti-proliferative effects against K-562 and MCF-7 cancer cell lines with IC50 values in a micromolar range. Thus, the synthesized compounds could be considered as new anticancer hits for further lead optimization.

Rapid emergence of antibiotic resistance is one of the most challenging global public health concerns. In particular, vancomycin-resistant Enterococcus faecium infections have been increasing in frequency, representing 25% of enterococci infections in intensive care units. A novel class of 1,2,4-triazolo[1,5-a]pyrimidines active against E. faecium is reported herein. We used a three-component Biginelli-like heterocyclization reaction for the synthesis of a series of these derivatives based on reactions of aldehydes, β-dicarbonyl compounds, and 3-alkylthio-5-amino-1,2,4-triazoles. The resulting compounds were assayed for antimicrobial activity against the ESKAPE panel of bacteria, followed by investigation of their in vitro activities. These analyses identified a subset of 1,2,4-triazolo[1,5-a]pyrimidines that had good narrow-spectrum antibacterial activity against E. faecium and exhibited metabolic stability with low intrinsic clearance. Macromolecular synthesis assays revealed cell-wall biosynthesis as the target of these antibiotics.

A new series of 5-substituted thiopheneyl pyrrolo[2,3-d]pyrimidines 6–11 with varying chain lengths (n = 1–6) were designed and synthesized as hybrids of the clinically used anticancer drug pemetrexed (PMX) and our 6-substituted thiopheneyl pyrrolo[2,3-d]pyrimidines 2c and 2d with folate receptor (FR) α and proton-coupled folate transporter (PCFT) uptake specificity over the reduced folate carrier (RFC) and inhibition of de novo purine nucleotide biosynthesis at glycinamide ribonucleotide formyltransferase (GARFTase). Compounds 6–11 inhibited KB human tumor cells in the order 9 = 10 > 8 > 7 > 6 = 11. Compounds 8–10 were variously transported by FRα, PCFT, and RFC and, unlike PMX, inhibited de novo purine nucleotide rather than thymidylate biosynthesis. The antiproliferative effects of 8 and 9 appeared to be due to their dual inhibitions of both GARFTase and 5-aminoimidazole-4-carboxamide ribonucleotide formyltransferase. Our studies identify a unique structure–activity relationship for transport and dual target inhibition.

Corticotropin-releasing factor (CRF) is a neurohormone that plays a crucial role in integrating the body’s overall response to stress. It appears necessary and sufficient for the organism to mount functional, physiological and endocrine responses to stressors. CRF is released in response to various triggers such as chronic stress. The role of CRF and its involvement in these neurological disorders suggest that new drugs that can target the CRF function or bind to its receptors may represent a new development of neuropsychiatric medicines to treat various stress-related disorders including depression, anxiety and addictive disorders. Based on pharmacophore of the CRF 1 receptor antagonists, a new series of thiazolo[4,5-d] pyrimidines were synthesized as Corticotropin-releasing factor (CRF) receptor modulators and the prepared compounds carry groups shown to produce optimum binding affinity to CRF receptors. Twenty two compounds were evaluated for their CRF 1 receptor binding affinity in HEK 293 cell lines and two compounds 5o and 5s showed approximately 25% binding affinity to CRF 1 receptors. Selected compounds (5c and 5f) were also evaluated for their effect on expression of genes associated with depression and anxiety disorders such as CRF1, CREB1, MAO-A, SERT, NPY, DatSLC6a3, and DBH and significant upregulation of CRF1 mRNA has been observed with compound 5c.

A series of 5-substituted 3-isopropyl-7-[4-(2-pyridyl)benzyl]amino-1(2)H-pyrazolo[4,3-d]pyrimidine derivatives was synthesized and evaluated for their cyclin-dependent kinase (CDK) inhibition activity. The most potent compounds contained various hydroxyalkylamines at the 5 position and possessed low nanomolar IC50 values for CDK2 and CDK5. Preliminary profiling of one of the most active compounds on a panel of 50 protein kinases revealed its high selectivity for CDKs. The compounds arrested cells in S and G2/M phases, and induced apoptosis in various cancer cell lines. Significant dephosphorylation of the C-terminus of RNA polymerase II and focal adhesion kinase (FAK), well-established substrates of CDKs, has been found in treated cells. Cleavage of PARP-1, down-regulation of Mcl-1 and activation of caspases correlated well with CDK inhibition and confirmed apoptosis as the primary type of cell death induced in cancer cells treated with the compounds in vitro. A comparison of known purine-based CDK inhibitor CR8 with its pyrazolo[4,3-d]pyrimidine bioisosteres confirmed that the novel compounds are more potent in cellular assays than purines. Therefore, pyrazolo[4,3-d]pyrimidine may emerge as a novel scaffold in medicinal chemistry and as a source of potent CDK inhibitors.

Pyrimidine ring is the building unit of DNA and RNA and thus pyrimidine based chemical architectures exhibit diverse pharmacological activities. Among the reported medicinal attributes of pyrimidines, anticancer activity is the most extensively reported. The anticancer potential of pyrimidines in fused scaffolds has also been evidenced through number of research article and patent literature. The pyrimidines based scaffolds have exerted their cell killing effects through varied mechanisms which indicate their potential to interact with diverse enzymes/ targets/receptors. This review article strictly focuses on the patent literature from 2009 onwards. The structure of the potent compounds, their IC50 values, models/assays used for the anticancer evaluation and the enzymes/ receptors/ targets involved have been presented in this compilation. Significant number of patents i.e. 59 have been published on pyrimidine based anticancer agents from 2009-2014 (from 2009 through the present date) which clearly indicate that this heterocycle is an area of focus at present for researchers all over the globe. Moreover, out of the 59 patents published during this period, 32 have been published from 2012 onwards which further highlights the present interest of the researcher towards pyrimidine based anticancer agents. The promising activity displayed by these pyrimidine based scaffolds clearly places them in forefront as potential future drug candidates. The present compilation can be extremely beneficial for the medicinal chemists working on design and synthesis of anticancer drugs.

The serine-threonine kinase CDK9 is a target of emerging interest for the development of anti-cancer drugs. There are multiple lines of evidence linking CDK9 activity to cancer, including the essential role this kinase plays in transcriptional regulation through phosphorylation of the C-terminal domain (CTD) of RNA polymerase II. Indeed, inhibition of CDK9 has been shown to result in a reduction of short-lived proteins such as the pro-survival protein Mcl-1 in malignant cells leading to the induction of apoptosis. In this work we report our initial studies towards the discovery of selective CDK9 inhibitors, starting from the known multi-kinase inhibitor PIK-75 which possesses potent CDK9 activity. Our series is based on a pyrazolo[1,5-a]pyrimidine nucleus and, importantly, the resultant lead compound 18b is devoid of the structural liabilities present in PIK-75 and possesses greater selectivity.

Pancreatic cancer is one of the most challenging diseases with seven months only as median survival time due to its poor prognosis. Several enzymes are blamed for the progress of pancreatic cancer especially, platelet-derived growth factor receptors (PDGFRs) , this in turn makes them promising targets for its treatment. In this study, twenty eight new compounds based on thieno[2,3-d]pyrimidine scaffold were synthesized as anti-pancreatic cancer agents mimicking the benzofuro[3,2-d]pyrimidine derivative, amuvatinib. Various linkers including amides, esters, ketones, urea and thiourea derivatives were utilized to study their effect on the anti-proliferative activity of these compounds. Most of the tested compounds revealed good cytotoxic activities against pancreatic carcinoma cell line PANC-1. Compound 9d showed the highest cytotoxicity with an IC50 value of 5.4 µM. Furthermore, 9d showed excellent platelet derived growth factor receptor (PDGFR-α) inhibitory activity, with IC50 value 0.155 µM. Docking study was carried out into PDGFR-α active site which showed comparable binding mode to that of FDA approved PDGFR-α inhibitor, imatinib. 3D-Quantitative structure activity relationship (QSAR) model was built up with five-featured pharmacophore which could be implemented for emerging effective lead structures. These compounds could serve as a new chemotype for discovering new agents for pancreatic cancer therapy.

The discovery, synthesis and biological evaluations of a series of nine N5-substituted-pyrrolo[3,2-d]pyrimidin-4-amines are reported. Novel compounds with microtubule depolymerizing activity were identified. Some of these compounds also circumvent clinically relevant drug resistance mechanisms (expression of P-glycoprotein and βIII tubulin). Compounds 4, 5, and 8–13 were one to two-digit nanomolar (IC50) inhibitors of cancer cells in culture. Contrary to recent reports (Banerjee et al. J. Med. Chem. 2018, 61, 1704–1718), the conformation of the most active compounds determined by 1H NMR and molecular modeling are similar to that reported previously and in keeping with recently reported X-ray crystal structures. Compound 11, freely water soluble as the HCl salt, afforded statistically significant inhibition of tumor growth in three xenograft models [MDA-MB-435, MDA-MB-231 and NCI/ADR-RES] compared with controls. Compound 11 did not display indications of animal toxicity and is currently slated for further preclinical development.

Bridge homologation of the previously reported nonclassical two-carbon-bridged antifolate, 2,4-diamino-6- phenethylpyrido[3,2-d]pyrimidine (wm-5a), afforded the three-, four- and five-carbon-bridged antifolate analogues 3.1-3.5, 4.1-4.2 and 5.1-5.5. The target compounds, with substituents at various positions on the carbon bridges, were efficiently synthesized by aldol condensation or Wittig reaction and followed by reduction. Elongation of the two-carbon bridge to three-, four-or five-carbon bridges, and also saturation of the carbon bridges, provided compounds with good inhibitory activity against recombinant human DHFR (rhDHFR). Analogue 3.5, which has a three-carbon bridge, inhibited the proliferation of HL-60 and HCT116 cells to a greater extent than the other analogues. Compound 3.5 was also the most potent inhibitor of rhDHFR (IC50 = 0.06 mu M), and was approximately 38-fold more potent than the two-carbon-bridged lead compound. Docking studies revealed that both the length and flexibility of the saturated carbon bridge in 3.5 were important for high potency. Flow cytometry studies indicated that compound 3.5 arrested HL-60 cells in the S-phase and induced apoptosis. Western blot analysis of HL-60 cells treated with 3.5 showed a dose-dependent upregulation of DHFR protein levels. (C) 2018 Elsevier Ltd. All rights reserved.

A series of eleven conformationally restricted, 4-substituted 2,6-dimethylfuro[2,3-d]pyrimidines was designed to explore the bioactive conformation required for dual inhibition of microtubule assembly and receptor tyrosine kinases (RTKs), and their biological activities are reported. All three rotatable single bonds in the lead compound 1 were sequentially restricted to address the role of each in SAR for microtubule and RTK inhibitory effects. Compounds 2, 3, 7 and 10 showed microtubule depolymerizing activity comparable to or better than the lead 1, some with nanomolar EC50 values. While compound 8 had no effect on microtubules, 8 and 10 both showed potent RTK inhibition with nanomolar IC50s. These compounds confirm that the bioactive conformation for RTK inhibition is different from that for tubulin inhibition. The tetrahydroquinoline analog 10 showed the most potent dual tubulin and RTK inhibitory activities (low nanomolar inhibition of EGFR, VEGFR2 and PDGFR-β). Compound 10 has highly potent activity against many NCI cancer cell lines, including several chemo-resistant cell lines, and could serve as a lead for further preclinical studies.

Abnormal signalling from the Protein tyrosine kinases (PTKs) like receptor tyrosine kinases and intracellular tyrosine kinases can lead to diseases such as cancer especially non-small cell lung cancer, chronic myeloid leukaemia and gastrointestinal stromal tumours. Various Protein tyrosine kinase inhibitors are available but face poor bioavailability, severe toxicities and recent cases of drug-resistant cancers prompts for development of better drug molecules. In this study we report the design and development of a novel Protein Tyrosine Kinase (PTK) inhibitor on the basis of pharmacophore modelling. Compound 2-(benzo[ d ]oxazol-2-ylamino)- N -(2-chloro-4-fluorophenyl)-4-methyl-6-(3-nitrophenyl) pyrimidine-5-carboxamide 31 was obtained containing essential pharmacophore structural features. This compound exhibited highest activity against leukaemia cell line (RPMI-8226) at 0.7244 µM, renal cancer cell line (A498) at 0.8511 µM and prostate cancer cell line (PC-3) at 0.7932 µM on the NCI five dose assay test. The PTK assay provides promising activity at IC 50 of 0.07 µM in the human breast cancer cell line MDA-MB-468. Compound 31 had good intermolecular interaction with PTK in the molecular docking studies, this ligand-enzyme complex was found to stable in the MM-PBSA study over 100 ns. It had 54.22% oral bioavailability with T max of 0.60 h which is higher compared to the dasatinib with bioavailability and T max of 14–34% and 1–1.42 h respectively. Anticancer action of 31 was found to be impressive in pharmacokinetic studies making it a potential lead molecule.

Btk is a tyrosine kinase dysregulated in several B-cell malignancies and autoimmune diseases, and this has given rise to a search for Btk inhibitors. Nevertheless, only one Btk inhibitor, ibrutinib, has been approved to date, although other compounds are currently being evaluated in clinical trials or in preclinal stages. Area covered: This review, after a brief introduction on Btk and its inhibitors already in clinical trials, focusses on pyrrolo[2,3-d]pyrimidine derivatives patented in the last five years as Btk inhibitors. Indeed, the pyrrolo[2,3-d]pyrimidine scaffold, being a deaza-isostere of adenine, the nitrogenous base of ATP, is an actively pursued target for Btk inhibitors. The patent literature since 2012 have been extensively investigated, pointing out the general features of the patented compounds and, when it is possible, their mechanism of action. Expert opinion: The recently patented pyrrolo[2,3-d]pyrimidines, acting as reversible or irreversible inhibitors, showed a very interesting in vitro activity. For this reason, the development of compounds endowed with this scaffold could afford a significant impact in the search for drug candidates for the treatment of immune diseases or B-cell malignancies.