Discovery, synthesis, and investigation of the antitumor activity of novel piperazinylpyrimidine derivatives

Design, Synthesis and Antitumor Activity of 1H-indazole-3-amine Derivatives

A series of indazole derivatives were designed and synthesized by molecular hybridization strategy, and these compounds were evaluated the inhibitory activities against human cancer cell lines of lung (A549), chronic myeloid leukemia (K562), prostate (PC-3), and hepatoma (Hep-G2) by methyl thiazolyl tetrazolium (MTT) colorimetric assay. Among these, compound 6o exhibited a promising inhibitory effect against the K562 cell line with the IC₅₀ (50% inhibition concentration) value of 5.15 µM, and this compound showed great selectivity for normal cell (HEK-293, IC₅₀ = 33.2 µM). Moreover, compound 6o was confirmed to affect apoptosis and cell cycle possibly by inhibiting Bcl2 family members and the p53/MDM2 pathway in a concentration-dependent manner. Overall, this study indicates that compound 6o could be a promising scaffold to develop an effective and low-toxic anticancer agent.

Transition-metal-free radical difluorobenzylation/cyclization of unactivated alkenes: access to ArCF2-substituted ring-fused quinazolinones

A mild and efficient transition-metal-free radical difluorobenzylation/cyclization of unactivated alkenes toward the synthesis of difluorobenzylated polycyclic quinazolinone derivatives with easily accessible α,α-difluoroarylacetic acids has been developed. This transformation has the advantages of wide functional group compatibility, a broad substrate scope, and operational simplicity. This methodology provided a highly attractive access to pharmaceutically valuable ArCF₂-containing polycyclic quinazolinones.

Access to Phosphine-Containing Quinazolinones Enabled by Photo-Induced Radical Phosphorylation/Cyclization of Unactivated Alkenes

A mild and facile photo-induced cascade radical addition/cyclization of unactivated alkenes has been reported, through which a variety of biologically valuable phosphine-containing quinazolinones could be obtained in moderate to good yields. The protocol was characterized by mild conditions, broad substrate scope, and high atomic economy.

Medicinal Chemistry Strategies for the Development of Bruton's Tyrosine Kinase Inhibitors against Resistance

Despite significant efficacy, one of the major limitations of small-molecule Bruton's tyrosine kinase (BTK) agents is the presence of clinically acquired resistance, which remains a major clinical challenge. This Perspective focuses on medicinal chemistry strategies for the development of BTK small-molecule inhibitors against resistance, including the structure-based design of BTK inhibitors targeting point mutations, e.g., (i) developing noncovalent inhibitors from covalent inhibitors, (ii) avoiding steric hindrance from mutated residues, (iii) making interactions with the mutated residue, (iv) modifying the solvent-accessible region, and (v) developing new scaffolds. Additionally, a comparative analysis of multi-inhibitions of BTK is presented based on cross-comparisons between 2916 unique BTK ligands and 283 other kinases that cover 7108 dual/multiple inhibitions. Finally, targeting the BTK allosteric site and uding proteolysis-targeting chimera (PROTAC) as two potential strategies are addressed briefly, while also illustrating the possibilities and challenges to find novel ligands of BTK.

Recent developments in the green synthesis of biologically relevant cinnolines and phthalazines

Both cinnolines and phthalazines are heterocyclic compounds which have a wide range of biological activities and pharmacological profiles. This work represents the recent advances in the green synthesis of cinnolines and phthalazines as 1,2 and 2,3-diazanaphalenes were cited. The docking studies and mode of action for key scaffolds were also reported.

The Aryl Hydrocarbon Receptor Undergoes Chaperone-Mediated Autophagy in Triple-Negative Breast Cancer Cells

The aryl hydrocarbon receptor (AHR) is a ligand-activated signaling molecule expressed in many cell types, including triple-negative and non-triple-negative breast cancer cells. It affects breast cancer growth and crosstalk with estrogen receptor signaling. Normally, this receptor is degraded shortly after ligand activation via the 26S proteasome. Here, we report that AHR undergoes chaperone-mediated autophagy in MDA-MB-468 triple-negative breast cancer cells. This lysosomal degradation of AHR exhibits the following characteristics: (1) it is triggered by 6 amino-nicotinamide, starvation, and piperazinylpyrimidine compound Q18; (2) it is not observed in non-triple-negative breast cancer cells (MCF-7, T47D, and MDA-MB-361); (3) it can be inhibited by progesterone receptor B but not estrogen receptor alpha; (4) it can be reversed by chloroquine but not MG132; (5) it requires LAMP2A; and (6) it involves AHR-HSC70 and AHR-LAMP2A interactions. The NEKFF sequence localized at amino acid 558 of human AHR appears to be a KFERQ-like motif of chaperone-mediated autophagy, responsible for the LAMP2A-mediated AHR protein degradation.

Investigation of biological activity of 2,3-disubstituted quinazolin-4(1H)-ones against Mycobacterium tuberculosis and DNA via docking, spectroscopy and DFT studies

Docking studies, structural data of DNA binding and molecular dynamics simulations of substituted quinazolin-4(1H)-ones.

Pharmacological Inhibition of CDK8 in Triple-Negative Breast Cancer Cell Line MDA-MB-468 Increases E2F1 Protein, Induces Phosphorylation of STAT3 and Apoptosis

Cyclin-dependent kinase 8 (CDK8) has been identified as a colon cancer oncogene. Since this initial observation, CDK8 has been implicated as a potential driver of other cancers including acute myelogenous leukemia (AML) and some breast cancers. Here, we observed different biological responses to CDK8 inhibition among colon cancer cell lines and the triple-negative breast cancer (TNBC) cell line MDA-MB-468. When treated with CDK8 inhibitor 4, all treated cell lines responded with decreased cell viability and increased apoptosis. In the MDA-MB-468 cell line, the decrease in cell viability was dependent on increased phosphorylation of signal transducer and activator of transcription 3 (STAT3), which is not observed in the colon cancer cell lines. Furthermore, increased STAT3 phosphorylation in 4 treated MDA-MB-468 cells was dependent on increased transcription factor E2F1 protein. These results are consistent with previous reports of exogenous expression of E2F1-induced apoptosis in MDA-MB-468 cells.

Efficient Synthesis of Novel 1,3,4-Oxadiazoles Bearing a 4-N,N-Dimethylaminoquinazoline Scaffold via Palladium-Catalyzed Suzuki Cross-Coupling Reactions

Two series of novel (symmetrical and unsymmetrical) quinazolinylphenyl-1,3,4-oxadiazole derivatives were synthesized using palladium-catalyzed Suzuki cross-coupling reactions. The presented synthetic methodology is based on the use of bromine-substituted 2-phenyl-4-N,N-dimethylaminoquinazolines and either a boronic acid pinacol ester or a diboronic acid bis(pinacol) ester of 2,5-diphenyl-1,3,4-oxadiazole. The reactions are conducted in a two-phase solvent system in the presence of catalytic amounts of [1,1′-bis(diphenylphosphino)ferrocene]-dichloropalladium(II), sodium carbonate, and tetrabutylammonium bromide, which plays the role of a phase-transfer catalyst. The luminescence properties of the obtained compounds are discussed in the context of applying these compounds in optoelectronics. Specifically, two highly-conjugated final products: N,N-dimethyl-2-phenyl-6-(4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl)quinazolin-4-amine (8f) and 6,6′-(4,4′-(1,3,4-oxadiazole-2,5-diyl)bis(4,1-phenylene))bis(N,N-dimethylquinazolin-4-amine (9f), which contain a 1,3,4-oxadiazole moiety connected to a quinazoline ring by a 1,4-phenylene linker at the 6 position, exhibit strong fluorescence emission and high quantum yields.

Elaborating piperazinyl-furopyrimidine based scaffolds as phosphoinositol-3-kinase enzyme alpha (PI3Kα) inhibitors to combat pancreatic cancer

Phosphoinositol-3-kinase enzyme (PI3K) plays a crucial role in driving oncogenic growth in various mammalian cells, particularly pancreatic cells. In the current study a series of novel furo[2,3-d]pyrimidine based-compounds were designed and synthesized as potential PI3K-α inhibitors. In accordance to the structure–activity relationship (SAR) studies of known PI3K-α inhibitors, different linkers including amide, urea and ether were attached to a piperazinyl furo[2,3-d]pyrimidine core. The synthesized compounds that revealed moderate PI3K-α inhibitory activity were tested for their anti-proliferative activities against pancreatic carcinoma on the PANC-1 cell line. Compounds 7b and 8a showed the highest anti-proliferative activity with IC₅₀ values of 4.5 μM and 6 μM, respectively and relatively, the best in vitro PI3K inhibition ability within the newly synthesized compounds. Additionally, all the newly synthesized final compounds were tested on 60 human cancer cell lines. A docking study was carried out on the PI3K-α active site showing a comparable binding mode to that of FDA approved PI3K-α inhibitors. These newly discovered lipid kinase inhibitors could be considered as potential candidates for the development of new targeted anticancer agents.

Phosphoinositol-3-kinase alpha (PI3K-α) enzyme inhibition to combat pancreatic cancer.

New CDK8 inhibitors as potential anti-leukemic agents - Design, synthesis and biological evaluation

Cyclin-dependent kinase 8 (CDK8) plays a vital role in regulating cell transcription either through its association with the mediator complex or by the phosphorylation of transcription factors. CDK8-mediated activation of oncogenes has proved to be important in a variety of cancer types including hematological malignancies. We have designed and synthesized a series of new synthetic steroids. The compounds were evaluated as CDK8 inhibitors in vitro. The three most potent compounds exhibit K_d-values towards CDK8 in the low nanomolar range (3.5-18 nM). Furthermore, the compounds displayed selectivity for CDK8 in a panel of 465 different kinases. The cell studies indicated a selectivity to kill AML-cancer cell lines compared to normal cell lines.

Design and synthesis of phthalazine-based compounds as potent anticancer agents with potential antiangiogenic activity via VEGFR-2 inhibition

In the designed compounds, either a biarylamide or biarylurea moiety or an N-substituted piperazine motif was linked to position 1 of the phthalazine core. The anti-proliferative activity of the synthesised compounds revealed that eight compounds (6b, 6e, 7b, 13a, 13c, 16a, 16d and 17a) exhibited excellent broad spectrum cytotoxic activity in NCI 5-log dose assays against the full 60 cell panel with GI₅₀ values ranging from 0.15 to 8.41 µM. Moreover, the enzymatic assessment of the synthesised compounds against VEGFR-2 tyrosine kinase showed the significant inhibitory activities of the biarylureas (12b, 12c and 13c) with IC₅₀s of 4.4, 2.7 and 2.5 μM, respectively, and with 79.83, 72.58 and 71.6% inhibition of HUVEC at 10 μM, respectively. Additionally, compounds (7b, 13c and 16a) were found to induce cell cycle arrest at S phase boundary. Compound 7b triggered a concurrent increase in cleaved caspase-3 expression level, indicating the apoptotic-induced cell death.

Preliminary in vitro and in vivo investigation of a potent platelet derived growth factor receptor (PDGFR) family kinase inhibitor

Aberrant expression of wild-type and mutant forms of the platelet-derived growth factor receptor (PDGFR) family of receptor tyrosine kinases has been implicated in various oncologic indications such as leukemias, gliomas, and soft tissue sarcomas. Clinically used kinase inhibitors imatinib and sunitinib are potent inhibitors of wild-type PDGFR family members, but show reduced binding to mutant forms. Here we describe compound 5 which binds to both wild-type and oncogenic mutant forms of PDGFR family members, and demonstrates both cellular and in vivo activity.

Palladium-catalyzed oxidative CC bond cleavage with molecular oxygen: one-pot synthesis of quinazolinones from 2-amino benzamides and alkenes

Palladium-catalyzed oxidative cleavage/cyclization has been disclosed for the concise synthesis of various quinazolinone derivatives from readily available 2-aminobenzamides and terminal alkenes with excellent functional group tolerance.

Photophysics of Dihydroquinazolinone Derivatives: Experimental and Theoretical Studies

Herein, we report the synthesis of two dihydroquinazolinone derivative 2-(2-Hydroxy-naphthalen-1-yl)-2, 3-dihydro-1H-quinazolin-4-one (1) and 2-(3-Methyl-thiophen-2-yl)-2,3-dihydro-1H-quinazolin-4-one (2) by using 2-aminobenzamide, 2-hydroxybenzaldehyde and 3-methyl thiophene-2-carboxaldehyde. The synthesized compounds were characterized by 1H NMR, 13C NMR, FT-IR and its spectral, photophysical, intramolecular charge transfer characteristics were studied by absorption and emission spectroscopy. The synthesized compound exhibits significant changes in their photophysical properties depending on the solvent polarity. The observed bathochromic emission band and difference in Stokes shift on changing the polarity of the solvents clearly demonstrate the highly polar character of the excited state. The synthesized compounds were also studied by density functional theory (DFT) and time-dependent density functional theory (TDDFT) to expose the reproducibility by computational means.

Synthesis of New Substituted 5-amino-8H-phthalazino[1,2-b]quinazolin-8-one Derivatives

A series of novel substituted 5-amino-8 H-phthalazino[1,2- b]quinazolin-8-one derivatives synthesised by condensation of different amines with 5-chloro-8 H-phthalazino[1,2- b]quinazolin-8-one, which was prepared from methyl 2-aminobenzoate by condensation with hydrazine hydrate and then cyclisation with a phthalic anhydride in N,N-dimethylacetamide at refluxing condition. The intermediate and target compounds were obtained in good yields and were easily purified by filtration or recrystallisation.

Synthesis and In Vitro Cytotoxic Properties of Polycarbo-Substituted 4-(Arylamino)quinazolines

Herein, we describe the synthesis of novel unsymmetrical polycarbo-substituted 4-anilinoquinazolines derived from the 2-aryl-6-bromo-8-iodoquinazolines via one-pot three-step reaction sequences involving initial amination and subsequent double cross-coupling (bis-Suzuki, Sonogashira/Stille or Sonogashira/Suzuki-Miyaura) reactions with different cross coupling partners for the two carbon–carbon bond formation steps. The 4-anilinoquinazolines were evaluated for potential cytotoxicity against three cancer cell lines, namely, human breast adenocarcinoma (MCF-7) cells, human cervical cancer (HeLa) and human lung cancer (A549) cells. The most active compounds, 2b, 2c, 3c, 4a, 4c and 5a, were found to be more selective against the MCF-7 and HeLa cell lines than the human lung carcinoma (A549) cells. We selected compounds 2c, 3c and 7a as representatives for further evaluation for potential to induce apoptosis and/or necrotic properties in the three cancer cell lines. Compound 2c induced apoptosis of MCF-7 cells through cell membrane alteration. Treatment of Hela and A549 cell lines with compounds 3c and 7a, respectively, led to caspase-3 activation in both cell lines. Compound 3c, on the other hand, caused more necrosis than apoptosis induction in the membrane alteration assay.

Quinazolines and quinazolinones as ubiquitous structural fragments in medicinal chemistry: An update on the development of synthetic methods and pharmacological diversification

Nitrogen-rich heterocycles, particularly quinazolines and quinazolinones, represent a unique class of diversified frameworks displaying a broad spectrum of biological functions. Over the past several years, intensive medicinal chemistry efforts have generated numerous structurally functionalized quinazoline and quinazolinone derivatives. Interest in expanding the biological effects, demonstrated by these motifs, is growing exponentially, as indicated by the large number of publications reporting the easy accessibility of these skeletons in addition to the diverse nature of synthetic as well as biological applications. Therefore, the main focus of the present review is to provide an ample but condensed overview on various synthetic approaches providing access to quinazoline and quinazolinone compounds with multifaceted biological activities. Furthermore, mechanistic insights, synthetic utilization, structure-activity relationships and molecular modeling inputs for the potent derivatives have also been discussed.

Piperazine scaffold: A remarkable tool in generation of diverse pharmacological agents

Piperazine is one of the most sought heterocyclics for the development of new drug candidates. This ring can be traced in a number of well established, commercially available drugs. Wide array of pharmacological activities exhibited by piperazine derivatives have made them indispensable anchors for the development of novel therapeutic agents. The review herein highlights the therapeutic significance of piperazine derivatives. Various therapeutically active piperazine derivatives developed by several chemists are reported here.

CDK8 kinase--An emerging target in targeted cancer therapy

Cyclin-dependent kinase (CDK) inhibitors have been developed as potential anticancer therapeutics and several nonselective compounds are currently in advanced clinical trials. This review is focused on the key biological roles of CDK8 kinase, which provide a proof-of-principle for continued efforts toward effective cancer treatment, targeting activity of this CDK family member. Among currently identified kinase inhibitors, several displayed significant selectivity for CDK8 and notably the effectiveness in targeting cancer specific gene expression programs. Structural features of CDK8 and available ligands were discussed from a perspective of the rational drug design process. Current state of the art confirms that further development of CDK8 inhibitors will translate into targeted therapies in oncology. This article is part of a Special Issue entitled:Inhibitors of Protein Kinases.

Synthetic approaches, functionalization and therapeutic potential of quinazoline and quinazolinone skeletons: the advances continue

The presence of N-heterocycles as an essential structural motif in a variety of biologically active substances has stimulated the development of new strategies and technologies for their synthesis. Among the various N-heterocyclic scaffolds, quinazolines and quinazolinones form a privileged class of compounds with their diverse spectrum of therapeutic potential. The easy generation of complex molecular diversity through broadly applicable, cost-effective, practical and sustainable synthetic methods in a straightforward fashion along with the importance of these motifs in medicinal chemistry, received significant attention from researchers engaged in drug design and heterocyclic methodology development. In this perspective, the current review article is an effort to recapitulate recent developments in the eco-friendly and green procedures for the construction of highly challenging and potentially bioactive quinazoline and quinazolinone compounds in order to help medicinal chemists in designing and synthesizing novel and potent compounds for the treatment of different disorders. The key mechanistic insights for the synthesis of these heterocycles along with potential applications and manipulations of the products have also been conferred. This article also aims to highlight the promising future directions for the easy access to these frameworks in addition to the identification of more potent and specific products for numerous biological targets.

Antimicrobial, anti-TB, anticancer and anti-HIV evaluation of new s-triazine-based heterocycles

BACKGROUND

The acquirement of resistance by microorganisms to the antimicrobial arsenal is a threat to public health. A recent WHO report estimated that 1.3 million HIV-negative people and 0.38 million HIV-positive people died from TB in 2009. Various forms of cancer account for a high percentage of deaths in both women (breast cancer) and men (prostate cancer).

RESULTS & DISCUSSION

In vitro activity assessment of newly constructed s-triazines against a panel of microorganisms including bacteria, fungi and Mycobacteria demonstrated that the compounds are of immense attraction for impending drug discovery. They were further examined for in vitro activity against breast cancer and prostate cancer cell lines, as well as HIV-1 (III(B)) and HIV-2 (ROD) viral strains. Proposed structural confirmation studies by IR, (1)H NMR, (13)C NMR, (19)F NMR spectroscopy and elemental analysis were in accordance.

CONCLUSION

Activity profiles of the products may contribute considerably to future drug-discovery studies.

Exploiting the MDM2-CK1α protein-protein interface to develop novel biologics that induce UBL-kinase-modification and inhibit cell growth

Protein-protein interactions forming dominant signalling events are providing ever-growing platforms for the development of novel Biologic tools for controlling cell growth. Casein Kinase 1 α (CK1α) forms a genetic and physical interaction with the murine double minute chromosome 2 (MDM2) oncoprotein resulting in degradation of the p53 tumour suppressor. Pharmacological inhibition of CK1 increases p53 protein level and induces cell death, whilst small interfering RNA-mediated depletion of CK1α stabilizes p53 and induces growth arrest. We mapped the dominant protein-protein interface that stabilizes the MDM2 and CK1α complex in order to determine whether a peptide derived from the core CK1α-MDM2 interface form novel Biologics that can be used to probe the contribution of the CK1-MDM2 protein-protein interaction to p53 activation and cell viability. Overlapping peptides derived from CK1α were screened for dominant MDM2 binding sites using (i) ELISA with recombinant MDM2; (ii) cell lysate pull-down towards endogenous MDM2; (iii) MDM2-CK1α complex-based competition ELISA; and (iv) MDM2-mediated ubiquitination. One dominant peptide, peptide 35 was bioactive in all four assays and its transfection induced cell death/growth arrest in a p53-independent manner. Ectopic expression of flag-tagged peptide 35 induced a novel ubiquitin and NEDD8 modification of CK1α, providing one of the first examples whereby NEDDylation of a protein kinase can be induced. These data identify an MDM2 binding motif in CK1α which when isolated as a small peptide can (i) function as a dominant negative inhibitor of the CK1α-MDM2 interface, (ii) be used as a tool to study NEDDylation of CK1α, and (iii) reduce cell growth. Further, this approach provides a technological blueprint, complementing siRNA and chemical biology approaches, by exploiting protein-protein interactions in order to develop Biologics to manipulate novel types of signalling pathways such as cross-talk between NEDDylation, protein kinase signalling, and cell survival.