N- and s-substituted Pyrazolopyrimidines: A promising new class of potent c-Src kinase inhibitors with prominent antitumor activity.

In this work, readily achievable synthetic pathways were utilized for construction of a library of N/S analogues based on the pyrazolopyrimidine scaffold with terminal alkyl or aryl fragments. Subsequently, we evaluated the anticancer effects of these novel analogs against the proliferation of various cancer cell lines, including breast, colon, and liver lines. The results were striking, most of the tested molecules exhibited strong and selective cytotoxic activity against the MDA-MB-231 cancer cell line; IC50 1.13 µM. Structure-activity relationship (SAR) analysis revealed that N-substituted derivatives generally enhanced the cytotoxic effect, particularly with aliphatic side chains that facilitated favorable target interactions. We also investigated apoptosis, DNA fragmentation, invasion assay, and anti-migration effects, and discussed their underlying molecular mechanisms for the most active compound 7c. We demonstrated that 7c N-propyl analogue could inhibit MDA-MB-231 TNBC cell proliferation by inducing apoptosis through the regulation of vital proteins, namely c-Src, p53, and Bax. In addition, our results also revealed the potential of these compounds against tumor metastasis by downregulating the invasion and migration modes. Moreover, the in vitro inhibitory effect of active analogs against c-Src kinase was studied and proved that might be the main cause of their antiproliferative effect. Overall, these compelling results point towards the therapeutic potential of these derivatives, particularly those with N-substitution as promising candidates for the treatment of TNBC type of breast cancer.

Development of Novel Class of Phenylpyrazolo[3,4-d]pyrimidine-Based Analogs with Potent Anticancer Activity and Multitarget Enzyme Inhibition Supported by Docking Studies.

Phenylpyrazolo[3,4-d]pyrimidine is considered a milestone scaffold known to possess various biological activities such as antiparasitic, antifungal, antimicrobial, and antiproliferative activities. In addition, the urgent need for selective and potent novel anticancer agents represents a major route in the drug discovery process. Herein, new aryl analogs were synthesized and evaluated for their anticancer effects on a panel of cancer cell lines: MCF-7, HCT116, and HePG-2. Some of these compounds showed potent cytotoxicity, with variable degrees of potency and cell line selectivity in antiproliferative assays with low resistance. As the analogs carry the pyrazolopyrimidine scaffold, which looks structurally very similar to tyrosine and receptor kinase inhibitors, the potent compounds were evaluated for their inhibitory effects on three essential cancer targets: EGFRWT, EGFRT790M, VGFR2, and Top-II. The data obtained revealed that most of these compounds were potent, with variable degrees of target selectivity and dual EGFR/VGFR2 inhibitors at the IC50 value range, i.e., 0.3-24 µM. Among these, compound 5i was the most potent non-selective dual EGFR/VGFR2 inhibitor, with inhibitory concentrations of 0.3 and 7.60 µM, respectively. When 5i was tested in an MCF-7 model, it effectively inhibited tumor growth, strongly induced cancer cell apoptosis, inhibited cell migration, and suppressed cell cycle progression leading to DNA fragmentation. Molecular docking studies were performed to explore the binding mode and mechanism of such compounds on protein targets and mapped with reference ligands. The results of our studies indicate that the newly discovered phenylpyrazolo[3,4-d]pyrimidine-based multitarget inhibitors have significant potential for anticancer treatment.

Design, synthesis, anticancer, and docking of some S- and/or N-heterocyclic derivatives as VEGFR-2 inhibitors.

Novel heterocyclic derivatives (4-22) were designed, synthesized, and evaluated against hepatocellular carcinoma type (HepG2) and breast cancer (MCF-7) cells, targeting the VEGFR-2 enzyme. Compounds 18, 10, 13, 11, and 14 were found to be the most potent derivatives against both the HepG2 and MCF-7 cancer cell lines, with GI50 = 2.11, 2.54 µM, 3.16, 3.64 µM, 3.24, 6.99 µM, 7.41, 6.49 µM and 8.08, 10.46 µM, respectively. Compounds 18 and 10 showed higher activities against both HepG2 and MCF-7 cells than sorafenib (GI50 = 9.18, 5.47 µM, respectively) and doxorubicin (GI50 = 7.94, 8.07 µM, respectively). Compounds 13, 11, and 14 showed higher activities than sorafenib against HepG2 cancer cells, but lower activities against MCF-7 cells. Compounds 18, 13, and 10 were more potent than sorafenib, inhibiting vascular endothelial growth factor receptor-2 (VEGFR-2) at GI50 values of 0.05, 0.06, and 0.08 µM, respectively. Compound 11 inhibited VEGFR-2 at an IC50 value of 0.10 µM, which is equipotent to sorafenib. Compound 14 inhibited VEGFR-2 at an IC50 value of 0.11 µM, which is nearly equipotent to sorafenib. The tested compounds have more selectivity against cancer cell lines. Compounds 18, 10, 13, 11, and 14 are, respectively, 16.76, 9.24, 6.06, 2.78, and 2.85 times more toxic in HePpG2 cancer cells than in VERO normal cells. Also, compounds 18, 10, 13, 11, and 14 are, respectively, 14.07, 8.02, 2.81, 3.18, and 2.20 times more toxic in MCF-7 than in VERO normal cells. The most active compounds, 10, 13, and 18, showed a good ADMET (absorption, distribution, metabolism, excretion, and toxicity) profile.

Design, synthesis, and molecular docking studies of new [1,2,4]triazolo[4,3-a]quinoxaline derivatives as potential A2B receptor antagonists.

Many shreds of evidence have recently correlated A2B receptor antagonism with anticancer activity. Hence, the search for an efficient A2B antagonist may help in the development of a new chemotherapeutic agent. In this article, 23 new derivatives of [1,2,4]triazolo[4,3-a]quinoxaline were designed and synthesized and its structures were confirmed by different spectral data and elemental analyses. The results of cytotoxic evaluation of these compounds showed six promising active derivatives with IC50 values ranging from 1.9 to 6.4 µM on MDA-MB 231 cell line. Additionally, molecular docking for all synthesized compounds was performed to predict their binding affinity toward the homology model of A2B receptor as a proposed mode of their cytotoxic activity. Results of molecular docking were strongly correlated with those of the cytotoxic study. Finally, structure activity relationship analyses of the new compounds were explored.

Design and discovery of new 1,2,4-triazolo[4,3-c]quinazolines as potential DNA intercalators and topoisomerase II inhibitors.

A new series of 1,2,4-triazolo[4,3-c]quinazoline derivatives was designed and synthesized as Topo II inhibitors and DNA intercalators. The cytotoxic effect of the new members was evaluated in vitro against a group of cancer cell lines including HCT-116, HepG-2, and MCF-7. Compounds 14c , 14d , 14e , 14e , 15b , 18b , 18c , and 19b exhibited the highest activities with IC50 values ranging from 5.22 to 24.24 µM. Furthermore, Topo II inhibitory activities and DNA intercalating affinities of the most promising candidates were evaluated as a possible mechanism for the antiproliferative effect. The results of the Topo II inhibition and DNA binding tests were coherent with that of in vitro cytotoxicity. Additionally, the most promising compound 18c was analyzed in HepG-2 cells for its apoptotic effect and cell cycle arrest. It was found that 18c can induce apoptosis and arrest the cell cycle at the G2-M phase. Finally, molecular docking studies were carried out for the designed compounds against the crystal structure of the DNA-Topo II complex as a potential target to explore their binding modes. On the basis of these studies, it was hypothesized that the DNA binding and/or Topo II inhibition would participate in the noted cytotoxicity of the synthesized compounds.

Antimicrobial screening and pharmacokinetic profiling of novel phenyl-[1,2,4]triazolo[4,3-a]quinoxaline analogues targeting DHFR and E. coli DNA gyrase B.

A novel series of [1,2,4]triazolo[4,3-a]quinoxaline derivatives of different heteroaromatization members were synthesized. The newly synthesized molecules were explored for their potential antimicrobial activities against a panel of pathogenic organisms. Among these derivatives, the chalcone compound 6e with a methoxy substituent exhibited broad potent antimicrobial activity against most of the bacterial and fungal strains. Furthermore, the analysis of the SAR disclosed that the linker and terminal aromatic fragments perform critical roles in exerting antibacterial activity. The molecular docking calculations were executed on two of the most bacterial targets, ATP-binding sites of DNA gyrase B, and the folate-binding site of DHFR enzymes. The results presented good binding data to the pockets of both enzymes showing different linkers contributions through the hydrogen-bonding and aromatic stacking interactions that stabilize the compounds in their pockets taking 6e compound as representative of most active analogs. In addition, good pharmacokinetic profiling data for the 6e compound was obtained and compared to reference drugs. Accordingly, our findings suggest that [1,2,4]triazolo[4,3-a]quinoxaline scaffold is an interesting precursor for the design of potent antimicrobial agents with multitarget inhibition.

5-(4-Methoxybenzylidene)thiazolidine-2,4-dione-derived VEGFR-2 inhibitors: Design, synthesis, molecular docking, and anticancer evaluations.

A novel series of 5-(4-methoxybenzylidene)thiazolidine-2,4-dione derivatives, 5a-g and 7a-f, was designed, synthesized, and evaluated for their anticancer activity against HepG2, HCT116, and MCF-7 cells. HepG2 and HCT116 were the most sensitive cell lines to the influence of the new derivatives. In particular, compounds 7f, 7e, 7d, and 7c were found to be the most potent derivatives of all the tested compounds against the HepG2, HCT116, and MCF-7 cancer cell lines. Compound 7f (IC50 = 6.19 ± 0.5, 5.47 ± 0.3, and 7.26 ± 0.3 µM, respectively) exhibited a higher activity than sorafenib (IC50 = 9.18 ± 0.6, 8.37 ± 0.7, and 5.10 ± 0.4 µM, respectively) against HepG2 and MCF-7, cells but a lower activity against HCT116 cancer cells, respectively. Also, this compound displayed a higher activity than doxorubicin (IC50 = 7.94 ± 0.6, 8.07 ± 0.8, and 6.75 ± 0.4 µM, respectively) against HepG2 and MCF-7 cells, but nearly the same activity against HCT116 cells, respectively. All derivatives, 5a-g and 7a-f, were evaluated for their inhibitory activities against vascular endothelial growth factor receptor-2 (VEGFR-2). Among them, compound 7f was found to be the most potent derivative that inhibited VEGFR-2 at an IC50 value of 0.12 ± 0.02 µM, which is nearly the same as that of sorafenib (IC50 = 0.10 ± 0.02 µM). Compounds 7e, 7d, 7c, and 7b exhibited the highest activity, with IC50 values of 0.13 ± 0.02, 0.14 ± 0.02, 0.14 ± 0.02, and 0.18 ± 0.03 µM, respectively, which are more than the half of that of sorafenib. Furthermore, molecular docking was performed to investigate their binding mode and affinities toward the VEGFR-2 receptor. The data obtained from the docking studies highly correlated with those obtained from the biological screening.

Design, Synthesis and Cytotoxic Evaluation of Novel Chalcone Derivatives Bearing Triazolo[4,3-a]-quinoxaline Moieties as Potent Anticancer Agents with Dual EGFR Kinase and Tubulin Polymerization Inhibitory Effects.

A series of hybrid of triazoloquinoxaline-chalcone derivatives 7a-k were designed, synthesized, fully characterized, and evaluated for their cytotoxic activity against three target cell lines: human breast adenocarcinoma (MCF-7), human colon carcinoma (HCT-116), and human hepatocellular carcinoma (HEPG-2). The preliminary results showed that some of these chalcones like 7b-c, and 7e-g exhibited significant antiproliferative effects against most of the cell lines, with selective or non-selective behavior, indicated by IC50 values in the 1.65 to 34.28 µM range. In order to investigate the mechanistic aspects of these active compounds, EGFR TK and tubulin inhibitory activities were measured as further biological assays. The EGFR TK assay results revealed that the derivatives 7a-c, 7e, and 7g could inhibit the EGFR TK in the submicromolar range (0.093 to 0.661 µM). Moreover, an antitubulin polymerization effect was noted for the active derivatives compared to the reference drug colchicine, with compounds 7e and 7g displaying 14.7 and 8.4 micromolar activity, respectively. Furthermore, a molecular docking study was carried out to explain the observed effects and the binding modes of these chalcones with the EGFR TK and tubulin targets.

Design, Synthesis, In Vitro, and In Silico Studies of New N5-Substituted-pyrazolo[3,4-d]pyrimidinone Derivatives as Anticancer CDK2 Inhibitors.

CDK2 is a key player in cell cycle processes. It has a crucial role in the progression of various cancers. Hepatocellular carcinoma (HCC) and colorectal cancer (CRC) are two common cancers that affect humans worldwide. The available therapeutic options suffer from many drawbacks including high toxicity and decreased specificity. Therefore, there is a need for more effective and safer therapeutic agents. A series of new pyrazolo[3,4-d]pyrimidine analogs was designed, synthesized, and evaluated as anticancer agents against the CRC and HCC cells, HCT116, and HepG2, respectively. Pyrazolo[3,4-d]pyrimidinone derivatives bearing N5-2-(4-halophenyl) acetamide substituents were identified as the most potent amongst evaluated compounds. Further evaluation of CDK2 kinase inhibition of two potential cytotoxic compounds 4a and 4b confirmed their CDK2 inhibitory activity. Compound 4a was more potent than the reference roscovitine regarding the CDK2 inhibitory activity (IC50 values: 0.21 and 0.25 µM, respectively). In silico molecular docking provided insights into the molecular interactions of compounds 4a and 4b with important amino acids within the ATP-binding site of CDK2 (Ile10, Leu83, and Leu134). Overall, compounds 4a and 4b were identified as interesting CDK2 inhibitors eliciting antiproliferative activity against the CRC and HCC cells, HCT116 and HepG2, respectively, for future further investigations and development.

Design, Molecular Docking, Synthesis, Anticancer and Anti-Hyperglycemic Assessments of Thiazolidine-2,4-diones Bearing Sulfonylthiourea Moieties as Potent VEGFR-2 Inhibitors and PPARγ Agonists.

Newly designed thiazolidine-2,4-diones 3-7a-c were synthesized, and their anticancer activities were screened against three cancer lines. They showed potent activities against HepG2 compared to the other HCT116 and MCF-7 tumor cell lines. Compounds 7c and 6c were detected as highly effective derivatives against MCF-7 (IC50 = 7.78 and 8.15 µM), HCT116 (IC50 = 5.77 and 7.11 µM) and HepG2 (IC50 = 8.82 and 8.99 µM). The highly effective derivatives 6a-c and 7a-c were tested against VERO normal cell lines. All derivatives were evaluated for their VEGFR-2 inhibitory actions and demonstrated high to low activities, with IC50 values varying from 0.08 to 0.93 µM. Moreover, derivatives 5a-c, 6a-c and 7a-c were assessed to verify their in vitro binding affinities to PPARγ and insulin-secreting activities. Finally, docking studies were performed to explore their affinities and binding modes toward both VEGFR-2 and PPARγ receptors.

From Phenylthiazoles to Phenylpyrazoles: Broadening the Antibacterial Spectrum toward Carbapenem-Resistant Bacteria.

The narrow antibacterial spectrum of phenylthiazole antibiotics was expanded by replacing central thiazole with a pyrazole ring while maintaining its other pharmacophoric features. The most promising derivative, compound 23, was more potent than vancomycin against multidrug-resistant Gram-positive clinical isolates, including vancomycin- and linezolid-resistant methicillin-resistant Staphylococcus aureus (MRSA), with a minimum inhibitory concentration (MIC) value as low as 0.5 µg/mL. Moreover, compound 23 was superior to imipenem and meropenem against highly pathogenic carbapenem-resistant strains, such as Acinetobacter baumannii, Klebsiella pneumoniae, and Escherichia coli. In addition to the notable biofilm inhibition activity, compound 23 outperformed both vancomycin and kanamycin in reducing the intracellular burden of both Gram-positive and Gram-negative pathogenic bacteria. Compound 23 cleared 90% of intracellular MRSA and 98% of Salmonella enteritidis at 2× the MIC. Moreover, preliminary pharmacokinetic investigations indicated that this class of novel antibacterial compounds is highly metabolically stable with a biological half-life of 10.5 h, suggesting a once-daily dosing regimen.

Synthesis and Biological Evaluation of Some [1,2,4]Triazolo[4,3-a]quinoxaline Derivatives as Novel Anticonvulsant Agents.

2-([1,2,4]Triazolo[4,3-a]quinoxalin-4-ylthio)acetic acid hydrazide (10) was used as a precursor for the syntheses of novel quinoxaline derivatives with potential anticonvulsant properties. The newly synthesized compounds have been characterized by IR, (1)H NMR, and mass spectral data followed by elemental analysis. The anticonvulsant evaluation was carried out for eleven of the synthesized compounds using metrazol induced convulsions model and phenobarbitone sodium as a standard. Among this set of tested compounds, two of them (14, and 15b) showed the best anticonvulsant activities.