Tailored quinoline hybrids as promising COX-2/15-LOX dual inhibitors endowed with diverse safety profile: Design, synthesis, SAR, and histopathological study.

Complications of the worldwide use of non-steroidal anti-inflammatory drugs (NSAIDs) sparked scientists to design novel harmless alternatives as an urgent need. So, a unique hybridization tactic of quinoline/pyrazole/thioamide (4a-c) has been rationalized and synthesized as potential COX-2/15-LOX dual inhibitors, utilizing relevant reported studies on these pharmacophores. Moreover, we extended these preceding hybrids into more varied functionality, bearing crucial thiazole scaffolds(5a-l). All the synthesized hybrids were evaluatedin vitroas COX-2/15-LOX dual inhibitors. Initially, series4a-cexhibited significant potency towards 15-LOX inhibition (IC50 = 5.454-4.509 µM) compared to meclofenamate sodium (IC50 = 3.837 µM). Moreover, they revealed reasonable inhibitory activities against the COX-2 enzyme in comparison to celecoxib.Otherwise, conjugates 5a-ldisclosed marked inhibitory activity against 15-LOX and strong inhibitory to COX-2. In particular, hybrids5d(IC50 = 0.239 µM, SI = 8.95), 5h(IC50 = 0.234 µM, SI = 20.35) and 5l (IC50 = 0.201 µM, SI = 14.42) revealed more potency and selectivity outperforming celecoxib (IC50 = 0.512 µM, SI = 4.28). In addition, the most potentcompounds, 4a, 5d, 5h, and 5l have been elected for further in vivoevaluation and displayed potent inhibition of edema in the carrageenan-induced rat paw edema test that surpassed indomethacin. Further, compounds5d, 5h, and 5l decreased serum inflammatory markers including oxidative biomarkersiNO, and pro-inflammatory mediators cytokines like TNF-α, IL-6, and PGE. Ulcerogenic liability for tested compounds demonstrated obvious gastric mucosal safety. Furthermore, a histopathological study for compound 5l suggested a confirmatory comprehensive safety profile for stomach, kidney, and heart tissues. Docking and drug-likeness studies offered a good convention with the obtained biological investigation.

From triazolophthalazines to triazoloquinazolines: A bioisosterism-guided approach toward the identification of novel PCAF inhibitors with potential anticancer activity.

Inhibition of PCAF bromodomain has been validated as a promising strategy for the treatment of cancer. In this study, we report the bioisosteric modification of the first reported potent PCAF bromodomain inhibitor, L-45 to its triazoloquinazoline bioisosteres. Accordingly, three new series of triazoloquinazoline derivatives were designed, synthesized, and assessed for their anticancer activity against a panel of four human cancer cells. Three derivatives demonstrated comparable cytotoxic activity with the reference drug doxorubicin. Among them, compound 22 showed the most potent activity with IC50 values of 15.07, 9.86, 5.75, and 10.79 µM against Hep-G2, MCF-7, PC3, and HCT-116 respectively. Also, compound 24 exhibited remarkable cytotoxicity effects against the selected cancer cell lines with IC50 values of 20.49, 12.56, 17.18, and 11.50 µM. Compounds 22 and 25 were the most potent PCAF inhibitors (IC50, 2.88 and 3.19 µM, respectively) compared with bromosporine (IC50, 2.10 µM). Follow up apoptosis induction and cell cycle analysis studies revealed that the bioisostere 22 could induce apoptotic cell death and arrest the cell cycle of PC3 at the G2/M phase. The in silico molecular docking studies were additionally performed to rationalize the PCAF inhibitory effects of new triazoloquinazoline bioisosteres.

In vivo- and in silico-driven identification of novel synthetic quinoxalines as anticonvulsants and AMPA inhibitors.

The lack of effective therapies for epileptic patients and the potentially harmful consequences of untreated seizure incidents have made epileptic disorders in humans a major health concern. Therefore, new and more potent anticonvulsant drugs are continually sought after, to combat epilepsy. On the basis of the pharmacophoric structural specifications of effective α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) antagonists with an efficient anticonvulsant activity, the present work reports the design and synthesis of two novel sets of quinoxaline derivatives. The anticonvulsant activity of the synthesized compounds was evaluated in vivo according to the pentylenetetrazol-induced seizure protocol, and the results were compared with those of perampanel as a reference drug. Among the synthesized compounds, 24, 28, 32, and 33 showed promising activities with ED50 values of 37.50, 23.02, 29.16, and 23.86 mg/kg, respectively. Docking studies of these compounds suggested that AMPA binding could be the mechanism of action of these derivatives. Overall, the pharmacophore-based structural optimization, in vivo and in silico docking, and druglikeness studies indicated that the designed compounds could serve as promising candidates for the development of effective anticonvulsant agents with good pharmacokinetic profiles.

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, synthesis, and antitumor activity of novel compounds based on 1,2,4-triazolophthalazine scaffold: Apoptosis-inductive and PCAF-inhibitory effects.

The antitumor activity of newly synthesised triazolophthalazines (L-45 analogues) 10-32 was evaluated in human hepatocellular carcinoma (HePG-2), breast cancer (MCF-7), prostate cancer (PC3), and colorectal carcinoma (HCT-116) cells. Compounds 17, 18, 25, and 32 showed potent antitumor activity (IC50, 2.83-13.97 µM), similar to doxorubicin (IC50, 4.17-8.87 µM) and afatinib (IC50, 5.4-11.4 µM). HePG2 was inhibited by compounds 10, 17, 18, 25, 26, and 32 (IC50, 3.06-10.5 µM), similar to doxorubicin (IC50, 4.50 µM) and afatinib (IC50, 5.4 µM). HCT-116 and MCF-7 were susceptible to compounds 10, 17, 18, 25, and 32 (IC50, 2.83-10.36 and 5.69-11.36 µM, respectively), similar to doxorubicin and afatinib (IC50 = 5.23 and 4.17, and 11.4 and 7.1 µM, respectively). Compounds 17, 25, and 32 exerted potent activities against PC3 (IC50, 7.56-12.28 µM) compared with doxorubicin (IC50, 8.87 µM) and afatinib (IC50 7.7 µM). Compounds 17 and 32 were the strongest PCAF inhibitors (IC50, 5.31 and 10.30 µM, respectively) and compounds 18 and 25 exhibited modest IC50 values (17.09 and 32.96 µM, respectively) compared with bromosporine (IC50, 5.00 µM). Compound 17 was cytotoxic to HePG2 cells (IC50, 3.06 µM), inducing apoptosis in the pre-G phase and arresting the cell cycle in the G2/M phase. Molecular docking for the most active PCAF inhibitors (17 and 32) was performed.

Novel triazolophthalazine-hydrazone hybrids as potential PCAF inhibitors: Design, synthesis, in vitro anticancer evaluation, apoptosis, and molecular docking studies.

Three novel series of triazolophthalazine derivatives bearing hydrazone moiety were designed, synthesized, and evaluated for their anticancer activity against four human cancer cell lines by MTT assay. Six derivatives demonstrated comparable activity with Doxorubicin reference drug against the selected cancer cells. Especially, compound 16 showed the most potent activity with IC50 values of 5.70, 8.04, 11.15, and 4.25, µM against HePG2, MCF-7, PC3, and HCT-116 respectively. Also, compound 26 exhibited comparable inhibitory effect with that of Doxorubicin against the selected cancer cell lines with IC50 values of 6.45, 8.63, 12.28, and 7.03 µM against HePG2, MCF-7, PC3, and HCT-116 respectively. Investigation of the apoptotic activity of the two most active compounds revealed that compounds 16 and 26 could induce both the early and the late apoptosis of HePG2. Further mechanistic study of the HePG2 cell cycle confirmed the spectacular cytotoxic and apoptotic effects of both compounds. Compounds 16 and 26 showed a pronounced increase in cells in G2/M and Pre G1 phases with a concomitant reduction of cells in G0-G1 and S phases. A follow up enzymatic assay indicated that these two compounds have comparable activities with that of bromosporine as PCAF inhibitors with IC50 values of 8.13 and 5.31 µM respectively. Moreover, molecular docking study for all the synthesized compounds was performed to predict their binding affinities toward the active site of histone acetyltransferase GCN5. Results of molecular docking were strongly correlated with that of the cytotoxicity study.

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.

tert-Butylphenylthiazoles with an oxadiazole linker: a novel orally bioavailable class of antibiotics exhibiting antibiofilm activity.

The structure-activity and structure-kinetic relationships of a new tert-butylphenylthiazole series with oxadiazole linkers were conducted with the objective of obtaining a new orally available antibacterial compounds. Twenty-two new compounds were prepared, purified and identified. Their activity against methicillin-resistant Staphylococcus aureus were examined. Compound 20 with 3-hydroxyazetidine as a nitrogenous side chain showed promising activity against twenty-four clinical isolates, including vancomycin-resistant staphylococcal and enterococcal species with MIC values ranging from 4-8 µg mL-1. Additional advantages of this compound include an ability to eradicate staphylococcal biofilm mass in a dose-dependent manner as well as high metabolic stability after an oral dose of 25 mg kg-1 with a biological half-life that exceeds 5 hours and a plasma concentration (C max) that exceeds the MIC values.

4-Substituted benzenesulfonamides featuring cyclic imides moieties exhibit potent and isoform-selective carbonic anhydrase II/IX inhibition.

The synthesis, characterization and biological evaluation of series of cyclic imides incorporating the 4-sulfamoylbenzamide scaffold (16-29) is disclosed. The compounds were designed by application of the "tail approach" to the aromatic sulfonamide scaffold and prepared by reacting the proper acid anhydride with 4-(hydrazinecarbonyl)benzenesulfonamide (15). Phtalimides and cyclic imides are biologically privileged scaffolds, endowed with versatile biological activity, such as an anti-proliferative action. The compounds were investigated for the inhibition of four human (h) isoforms of zinc enzyme carbonic anhydrase (CA, EC 4.2.1.1), and more specifically against the cytosolic hCA I and II and the transmembrane hCA IV and IX. Most screened sulfonamides exhibited great potency in inhibiting CA isoforms II, widely involved in glaucoma and other pathologies (KIs in the range of 0.7-62.3 nM), and IX, that is a validated anti-tumor target (KIs in the range of 3.0-50.9 nM), whereas interesting hydrophilicity-dependent inhibitory profiles were measured against isoform CA IV (KIs in the range of 3.9-428.6 nM). In silico studies were carried out to assess the binding mode of selected derivatives to hCA II, IV and IX.

Phenylthiazoles with tert-Butyl side chain: Metabolically stable with anti-biofilm activity.

A new series of phenylthiazoles with t-butyl lipophilic component was synthesized and their antibacterial activity against a panel of multidrug-resistant bacterial pathogens was evaluated. Five compounds demonstrated promising antibacterial activity against methicillin-resistant staphylococcal strains and several vancomycin-resistant staphylococcal and enterococcal species. Additionally, three derivatives 19, 23 and 26 exhibited rapid bactericidal activity, and remarkable ability to disrupt mature biofilm produced by MRSA USA300. More importantly, a resistant mutant to 19 couldn't be isolated after subjecting MRSA to sub-lethal doses for 14 days. Lastly, this new series of phenylthiazoles possesses an advantageous attribute over the first-generation compounds in their stability to hepatic metabolism, with a biological half-life of more than 9 h.

Alkynyl-containing phenylthiazoles: Systemically active antibacterial agents effective against methicillin-resistant Staphylococcus aureus (MRSA).

The promising activity of phenylthiazoles against multidrug-resistant bacterial pathogens, in particular MRSA, has been hampered by their limited systemic applicability, due to their rapid metabolism by hepatic microsomal enzymes, resulting in short half-lives. Here, we investigated a series of phenylthiazoles with alkynyl side-chains that were synthesized with the objective of improving stability to hepatic metabolism, extending the utility of phenylthiazoles from topical applications to treatment of a more invasive, systemic MRSA infections. The most promising compounds inhibited the growth of clinically-relevant isolates of MRSA in vitro at concentrations as low as 0.5 µg/mL, and exerted their antibacterial effect by interfering with bacterial cell wall synthesis via inhibition of undecaprenyl diphosphate synthase and undecaprenyl diphosphate phosphatase. We also identified two phenylthiazoles that successfully eradicated MRSA inside infected macrophages. In vivo PK analysis of compound 9 revealed promising stability to hepatic metabolism with a biological half-life of ∼4.5 h. In mice, compound 9 demonstrated comparable potency to vancomycin, and at a lower dose (20 mg/kg versus 50 mg/kg), in reducing the burden of MRSA in a systemic, deep-tissue infection, using the neutropenic mouse thigh-infection model. Compound 9 thus represents a new phenylthiazole lead for the treatment of MRSA infections that warrants further development.

Biphenylthiazole antibiotics with an oxadiazole linker: An approach to improve physicochemical properties and oral bioavailability.

A new series of oxadiazolylbiphenylthiazoles was prepared with the objective of improving the limited solubility of first-generation derivatives while maintaining antibacterial activity against drug-resistant Staphylococcus aureus. Studying the structure-activity relationship at the cationic part provided the piperazine-1-carboximidamide derivative 27 with a MIC (MRSA) value of 1.1 µg/mL, bactericidal mode of action, and a 50-fold improvement in aqueous solubility. Additionally, 27 exhibited a wider safety margin against mammalian cells, and most importantly, a significant improvement in oral bioavailability.

Investigating the Antibacterial Activity of Biphenylthiazoles against Methicillin- and Vancomycin-Resistant Staphylococcus aureus (MRSA and VRSA).

Phenylthiazoles were reported previously as a new scaffold with antibacterial activity against an array of multidrug-resistant staphylococci. However, their promising antibacterial activity was hampered in large part by their short half-life due to excessive hepatic clearance. Close inspection of the structure-activity-relationships (SARs) of the phenylthiazoles revealed two important structural features necessary for antibacterial activity (a nitrogenous and a lipophilic component). Incorporating the nitrogenous part within a pyrimidine ring resulted in analogues with a prolonged half-life, while the biphenyl moiety revealed the most potent analogue 1b. In this study, advantageous moieties have been combined to generate a new hybrid scaffold of 5-pyrimidinylbiphenylthiazole with the objective of enhancing both anti-MRSA activity and drug-like properties. Among the 37 tested biphenylthiazoles, piperazinyl-containing derivatives 10, 30, and 36 were the most potent analogues with MIC values as low as 0.39 µg/mL. Additionally, 36 exhibited significant improvement in stability to hepatic metabolism.

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.

Synthesis and antiproliferative effects of 5,6-disubstituted Pyridazin-3(2H)-ones designed as conformationally constrained combretastatin A-4 Analogues.

Novel 5,6-disubstituted pyridazin-3(2H)-one derivatives were designed and synthesized as combretastatin A-4 analogues. Our objective was to overcome the spontaneous cis to trans isomerization of the compound. We therefore replaced the cis-double bond with a pyridazine ring. The antiproliferative activity of the novel analogues was evaluated against four human cancer cell lines (HL-60, MDAMB- 435, SF-295 and HCT-8). We found that the analogues had little activity either against selected cell lines or against purified tubulin. Molecular modeling studies may account for their inactivity.

Design, synthesis, and molecular modelling of pyridazinone and phthalazinone derivatives as protein kinases inhibitors.

The design and synthesis of pyridazinone and phthalazinone derivatives are described. Newly synthesized compounds were tested on a panel of four kinases in order to evaluate their activity and potential selectivity. In addition, the promising compounds were tested on four cancer cell lines to examine cytotoxic effects. The compounds inhibited DYRK1A and GSK3 with different activity. SAR analysis and docking calculations were carried out to aid in the interpretation of the results. Taken together, our findings suggest that pyridazinone and phthalazinone scaffolds are interesting starting points for design of potent GSK3 and DYRK1A inhibitors.