Discovery of a new class of potent pyrrolo[3,4-c]quinoline-1,3-diones based inhibitors of human dihydroorotate dehydrogenase: Synthesis, pharmacological and toxicological evaluation.

Twenty N-substituted pyrrolo[3,4-c]quinoline-1,3-diones 3a-t were synthesized by a cyclization reaction of Pfitzinger's quinoline ester precursor with the selected aromatic, heteroaromatic and aliphatic amines. The structures of all derivatives were confirmed by IR, 1H NMR, 13C NMR and HRMS spectra, while their purity was determined using HPLC techniques. Almost all compounds were identified as a new class ofpotent inhibitors against hDHODH among which 3a and 3t were the most active ones with the same IC50 values of 0.11 µM, about seven times better than reference drug leflunomide. These two derivatives also exhibited very low cytotoxic effects toward healthy HaCaT cells and the optimal lipophilic properties with logP value of 1.12 and 2.07 respectively, obtained experimentally at physiological pH. We further evaluated the comparative differences in toxicological impact of the three most active compounds 3a, 3n and 3t and reference drug leflunomide. The rats were divided into five groups and were treated intraperitoneally, control group (group I) with a single dose of leflunomide (20 mg/kg) group II and the other three groups, III, IV and V were treated with 3a, 3n and 3t (20 mg/kg bw) separately. The investigation was performed in liver, kidney and blood by examining serum biochemical parameters and parameters of oxidative stress.

Synthesis and biological evaluation of new quinoline-4-carboxylic acid-chalcone hybrids as dihydroorotate dehydrogenase inhibitors.

Fourteen novel quinoline-4-carboxylic acid-chalcone hybrids were obtained via Claisen-Schmidt condensation and evaluated as potential human dihydroorotate dehydrogenase (hDHODH) inhibitors. The ketone precursor 2 was synthesized by the Pfitzinger reaction and used for further derivatization at position 3 of the quinoline ring for the first time. Six compounds showed better hDHODH inhibitory activity than the reference drug leflunomide, with IC50 values ranging from 0.12 to 0.58 µM. The bioactive conformations of the compounds within hDHODH were resolved by means of molecular docking, revealing their tendency to occupy the narrow tunnel of hDHODH within the N-terminus and to prevent ubiquinone as the second cofactor from easily approaching the flavin mononucleotide as a cofactor for the redox reaction within the redox site. The results of the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay revealed that 4d and 4h demonstrated the highest cytotoxic activity against the A375 cell line, with IC50 values of 5.0 and 6.8 µM, respectively. The lipophilicity of the synthesized hybrids was obtained experimentally and expressed as logD7.4 values at physiologicalpH while the solubility assay was conducted to define physicochemical characteristics influencing the ADMET properties.

Low cytotoxic quinoline-4-carboxylic acids derived from vanillin precursors as potential human dihydroorotate dehydrogenase inhibitors.

Twenty novel 2-substituted quinoline-4-carboxylic acids bearing amide moiety were designed and synthesized by Doebner reaction. Human dihydroorotate dehydrogenase (hDHODH) was recognized as a biological target and all compounds were screened as potential hDHODH inhibitors in an enzyme inhibition assay. The prepared heterocycles were also evaluated for their cytotoxic effects on the healthy HaCaT cell line while lipophilic properties were considered on the basis of experimentally determined logD values at physiological pH. The most promising compound 5j, with chlorine at para-position of terminal phenyl ring, showed good hDHODH inhibitory activity, low cytotoxicity, and optimal lipophilicity. The bioactive conformation of 5j on the hDHODH, determined by means of molecular docking, revealed the compound's pharmacology and provide guidelines for further lead optimization.

Potent human dihydroorotate dehydrogenase inhibitory activity of new quinoline-4-carboxylic acids derived from phenolic aldehydes: Synthesis, cytotoxicity, lipophilicity and molecular docking studies.

A series of novel 2-substituted quinoline-4-carboxylic acids was synthesized by Doebner reaction starting from freely available protocatechuic aldehyde and vanillin precursors. Human dihydroorotate dehydrogenase (hDHODH) was recognised as a clear molecular target for these heterocycles. All compounds were also tested for their antiproliferative potential against three cancer cells (MCF-7, A549, A375) and one normal cell line (HaCaT) to evaluate the selective cytotoxicity. Quinoline derivatives 3f and 3g were identified as potent hDHODH inhibitors while 3k and 3l demonstrated high cytotoxic activity against MCF-7 and A375 cells and good selectivity. In addition, the logD7.4 values obtained by the experimental method were found to be in the range from -1.15 to 1.69. The chemical structures of all compounds were confirmed by IR, NMR and elemental analysis. The compounds pharmacology on the molecular level was revealed by means of molecular docking, highlighting the structural differences that distinguish highly active from medium and low active hDHODH inhibitors.

Highly selective anthraquinone-chalcone hybrids as potential antileukemia agents.

A series of 23 novel anthraquinone-chalcone hybrids containing amide function was synthesized and structurally characterized. Sixteen compounds exerted strong cytotoxic activities against K562, Jurkat and HL-60 leukemia cell lines and significantly lower cytotoxic effects against normal MRC-5 cells, indicating very high selectivity in their anticancer action. The compounds 6g, 6u and 6v activate apoptosis in K562 cells through the extrinsic and intrinsic apoptotic pathway. The compound 6e triggered apoptosis in K562 cells only through the extrinsic apoptotic pathway. Treatment of K562 cells with each of these four compounds caused decrease in the expression levels of MMP2, MMP9, and VEGF, suggesting their anti-invasive, antimetastatic and antiangiogenic properties. The compounds 6g and 6v downregulated expression levels of miR-155 in K562 cells, while compounds 6e and 6u upregulated miR-155 levels in treated cells, in comparison with control cells. The structure-based 3-D QSAR models for 6f, 6e, 6i and 6l describe pro-apoptotic activity against caspase-3.

Synthesis, antioxidant and antiproliferative activities of 1,3,4-thiadiazoles derived from phenolic acids.

Two 2-amino-1,3,4-thiadiazoles containing phenolic hydroxyl groups were combined with different carboxylic acid chlorides giving sixteen amide derivatives with good antioxidant and antiproliferative potential. The compound 3'c with an adamantane ring displayed excellent DPPH radical scavenging activity and good cytotoxic activity against human acute promyelocytic leukemia HL-60 cells, while 1,3,4-thiadiazole 3'h with 4-chlorophenyl moiety was found to be the most effective in inhibition of survival of lung carcinoma A549 cells. All examined thiadiazoles except 3a and 3'a exerted higher cytotoxic activities on A549 and HL-60 cancer cells when compared with normal fibroblasts MRC-5, pointing to selectivity in their antiproliferative action. Some of the most active novel compounds 3c, 3'c, 3'g and 3'h induced significant increase in the percentage of HL-60 cells in the subG1 cell cycle phase in comparison with the control cells. The induction of cell death in HL-60 cells by these compounds was at least partially dependent on activation of caspase-3 and caspase-8. The compounds 3c and 3'c exerted strong antiangiogenic activity. Furthermore, compounds 3c, 3'c, 3'g and 3'h showed the ability to down-regulate the MMP2 and VEGFA expression levels in the treated HL-60 cells when compared with the control cell samples.

Novel anthraquinone based chalcone analogues containing an imine fragment: synthesis, cytotoxicity and anti-angiogenic activity.

A new class of imine derivatives of hybrid chalcone analogues containing anthraquinone scaffold was synthesized and evaluated for their in vitro cytotoxic activity against HeLa, LS174, and A549 cancer cells. The compound 5n with furan ring linked to imino group showed potent activity against all target cells with IC50 values ranging from 1.76 to 6.11µM. A mode of action study suggested that compounds induced changes typical for apoptosis in HeLa cells. The most active compounds inhibited tubulogenesis and 5h was found to exhibit a strong anti-angiogenic effect.

Antiproliferative activity and QSAR studies of a series of new 4-aminomethylidene derivatives of some pyrazol-5-ones.

Twenty five 4-aminomethylidene derivatives obtained from 3-phenyl-2-pyrazolin-5-one and 1,3-diphenyl-2-pyrazolin-5-one were synthesized and tested for their antiproliferative activity against human breast cancer MDA-MB-361 and MDA-MB-453 cell lines. The compounds derived from 1,3-diphenyl-2-pyrazolin-5-one exhibited the most remarkable activity in the treatment of both cell lines. In vitro antiproliferative activities were accompanied by an important apoptotic fraction of both cell lines; also, compounds inhibited key endothelial cell functions implicated in invasion and angiogenesis. QSAR methods were performed in order to analyze the influence of structural features of the compounds investigated on the antiproliferative potential on MDA-MB-361 and MDA-MB-453 cancer cells. One-parameter heuristic analysis was performed and different whole molecule and fragmental descriptors were considered for rationalization of mechanism of interaction of these compounds with active place of hypothetical target included in tumorigenesis.

Synthesis, antitumor activity and QSAR studies of some 4-aminomethylidene derivatives of edaravone.

A series of aminomethylidene derivatives obtained from 4-formyledaravone were synthesized and characterized by IR, NMR and elemental analysis. All the compounds were screened for their antitumor activity. The compound containing 5-phenylpyrazole moiety (3q) exhibited remarkable antitumor activity in in vitro assays, especially against human breast cancer MDA-MB-361 and MDA-MB-453 cell lines. The most important whole-molecule descriptors for antitumor activity on MDA-MB-453 cells belong to the group of quantum-chemical descriptors.

Synthesis, characterization, electrochemical studies and antitumor activity of some new chalcone analogues containing ferrocenyl pyrazole moiety.

A series of new alpha,beta-unsaturated conjugated ketones containing ferrocenyl pyrazole unit were synthesized and fully characterized by IR and NMR spectroscopy. Electrochemical characterization of subject compounds was performed by means of cyclic voltametry. The in vitro cytotoxic activity of all the synthesized compounds was studied against cervix adenocarcinoma HeLa, melanoma Fem-x and myelogenous leukemia K562 cell lines by the MTT method. Derivative 1l containing 3-pyridyl moiety exhibited a better cytotoxic activity in the cell growth inhibition of K562 cell lines in comparison with cisplatin as a reference compound.

Synthesis and antimicrobial activity of some new pyrazole derivatives containing a ferrocene unit.

A series of new imines and amines have been synthesized by condensation of 1H-3-ferrocenyl-1-phenylpyrazole-4-carboxaldehyde with the corresponding amines, followed by reduction with sodium borohydride. The synthesized compounds have been screened for their in vitro antimicrobial activity against 11 bacteria and three fungal/yeast strains, using disc diffusion and broth microdilution susceptibility assays. They have shown a wide range of activities, from completely inactive to the highly active compounds.

Novel 1,3,4-thiadiazole-chalcone hybrids containing catechol moiety: synthesis, antioxidant activity, cytotoxicity and DNA interaction studies.

Hybrid compounds that combine the 1,3,4-thiadiazole-containing catechol moiety with a chalcone motif were synthesized and examined for their antioxidant activity, cytotoxicity, and DNA-binding activity. A series of thirteen compounds showed strong antioxidant and cytotoxic effects on human acute promyelocytic leukemia HL-60 cells. Several compounds exerted good cytotoxic activities on cervical adenocarcinoma HeLa cells. The treatment of HeLa cells with IC50 and double IC50 concentrations of the compounds 5a, 5c, 5f, and 5m induced a statistically significant increase in the percentage of cells within a subG1 cell cycle phase. The examined compounds caused G2/M cell cycle arrest in HeLa cells. Each of these compounds triggered apoptosis in HeLa cells through activation of caspase-3, the main effector caspase, caspase-8, which is involved in the extrinsic apoptotic pathway, and caspase-9, which is involved in the intrinsic apoptotic pathway. All of the examined compounds decreased the expression levels of MMP2 in HeLa cells and levels of protumorigenic miR-133b. Compounds 5a and 5m lowered the expression level of oncogenic miR-21 in HeLa cells. In addition, compounds 5a, 5f, and 5m decreased the expression levels of oncogenic miR-155 while the treatment of HeLa cells with compounds 5a, 5c, and 5f increased expression of tumor-suppressive miR-206. Observed effects of these compounds on expression levels of four examined miRNAs suggest their prominent cancer-suppressive activity. An investigation by absorption and fluorescence spectroscopy showed more efficient calf thymus DNA binding activity of the compound 5m in comparison to other tested compounds. Results of a pUC19 plasmid cleavage study and comet assay showed DNA damaging activities of compounds 5a and 5c.

Synthesis, spectroscopic and X-ray characterization of a copper(II) complex with the Schiff base derived from pyridoxal and aminoguanidine: NMR spectral studies of the ligand.

A copper(II) complex with the pyridoxal-aminoguanidine (PL-AG) Schiff base adduct, as an organic compound of the very potent biological activity and promising pharmacological importance in the treatment of diabetic complications, has been prepared and characterized. The X-ray structural analysis of the [CuCl2(PL-AG)] complex showed that it has a distorted pseudo-square-pyramidal (4+1) structure with the tridentate ONN Schiff base in the equatorial plane, with the Cu-O(1), Cu-N(1) and Cu-N(3) bond lengths of 1.917(2)A, 1.930(2)A and 1.984(2)A, respectively. The bond length of the equatorial Cu-Cl(1) is 2.279(1)A, while that of the apical Cu-Cl(2) is 2.792(1)A. Pyridoxal fragment is coordinated in its zwitterionic form. In addition to the X-ray structural analysis, the complex was characterized by IR spectrometric, conductometric and magnetic techniques, and the ligand itself by IR, 1H and 13C NMR spectra.

Mannich bases of 1,2,4-triazole-3-thione containing adamantane moiety: Synthesis, preliminary anticancer evaluation, and molecular modeling studies.

A series of 18 novel N-Mannich bases derived from 5-adamantyl-1,2,4-triazole-3-thione was synthesized and characterized using NMR spectroscopy and X-ray diffraction technique. All derivatives were evaluated for their anticancer potential against four human cancer cell lines. Several tested compounds exerted good cytotoxic activities on K562 and HL-60 cell lines, along with pronounced selectivity, showing lower cytotoxicity against normal fibroblasts MRC-5 compared to cancer cells. The effects of compounds 5b, 5e, and 5j on the cell cycle were investigated by flow cytometric analysis. It was found that these compounds cause the accumulation of cells in the subG1 and G1 phases of the cell cycle and induce caspase-dependent apoptosis, while the anti-angiogenic effects of 5b, 5e, and 5j have been confirmed in EA.hy926 cells using a tube formation assay. Further, the interaction of Bax protein with compound 5b was investigated by means of molecular modeling, applying the combined molecular docking/molecular dynamics approach.

Synthesis, characterization, cytotoxicity and antiangiogenic activity of copper(II) complexes with 1-adamantoyl hydrazone bearing pyridine rings.

Three novel copper complexes with tridentate N2O ligand di(2-pyridil) ketone 1-adamantoyl hydrazone (Addpy) of the formula [Cu(II)2Cu(I)2(Addpy)2Br2(µ-Br4)] (1), catena-poly[CuCl(µ-Addpy)(µ-Cl)CuCl2]n (2) and [Cu(Addpy)(NCS)2] (3) were synthesized. Complexes are characterized by X-ray crystallography, spectral (UV-Vis, FTIR), electrochemical (CV) analyses, and magnetochemical measurements. Investigation of anticancer potential of Cu(II) complexes, mode of cell death, apoptosis, and inhibition of angiogenesis were performed. All tested malignant cell lines (HeLa, LS174, A549, K562, and MDA-MB-231) showed high sensitivity to the examined Cu(II) complexes. It has been shown that the complexes induce apoptosis in the caspase 3-dependent manner, whereas the anti-angiogenic effects of 1, 2, and 3 have been confirmed in EA.hy926 cells using a tube formation assay.

Anthraquinone-chalcone hybrids: synthesis, preliminary antiproliferative evaluation and DNA-interaction studies.

Novel anthraquinone based chalcone compounds were synthesized starting from 1-acetylanthraquinone in a Claisen-Schmidt reaction and evaluated for their anticancer potential against three human cancer cell lines. Compounds 4a, 4b and 4j showed promising activity in inhibition of HeLa cells with IC50 values ranging from 2.36 to 2.73 µM and low cytotoxicity against healthy MRC-5 cell lines. The effects that compounds produces on the cell cycle were investigated by flow cytometry. It was found that 4a, 4b and 4j cause the accumulation of cells in the S and G2/M phases in a dose-dependent manner and induce caspase-dependent apoptosis. All of three compounds exhibit calf thymus DNA-binding activity. The determined binding constants by absorption titrations (2.65 × 10(3) M(-1), 1.36 × 10(3) M(-1)and 2.51 × 10(3) M(-1) of 4a/CT-DNA, 4b/CT-DNA and 4j/CT-DNA, respectively) together with fluorescence displacement analysis designate 4a, 4b and 4j as strong minor groove binders, but no cleavage of plasmid DNA was observed.

Synthesis, cytotoxic activity and DNA-interaction studies of novel anthraquinone-thiosemicarbazones with tautomerizable methylene group.

A series of novel anthraquinone-thiosemicarbazone derivatives in a tautomerizable keto-imine form was synthesized and tested for their in vitro cytotoxic activity against human cancer cells (HeLa, MDA-MB-361, MDA-MB-453, K562, A549) and human normal MRC-5 cells. Several compounds efficiently inhibited cancer cell growth at micromolar concentrations, especially against K562 and HeLa cells. As determined by flow cytometric analysis, anthraquinone-thiosemicarbazone caused significant increase in the number of sub-G1 phase of HeLa cells and apoptosis in a concentration-dependent manner. Also, inhibition of caspase-3, -8, and -9 with specific caspase inhibitors reduced the apoptosis mediated by the tested compounds in HeLa cells. All anthraquinone-thiosemicarbazones exhibit calf thymus DNA-binding activity, but no cleavage of plasmid DNA was observed.

Synthesis, characterization and antitumor activity of polymeric copper(II) complexes with thiosemicarbazones of 3-methyl-5-oxo-1-phenyl-3-pyrazolin-4-carboxaldehyde and 5-oxo-3-phenyl-3-pyrazolin-4-carboxaldehyde.

New polymeric copper(II) complexes with two tridentate ONS thiosemicarbazone ligands containing substituted pyrazolone moiety were synthesized and characterized by means of spectroscopic, electrochemical and crystallographic techniques. While both ligands exist as different tautomers in the solid state and DMSO-d(6) solution, Cu(II) ion coordinates the ligands from the same tautomeric form with square-pyramidal geometry around each Cu atom. In the crystal structures, the copper(II) complex cation forms polymeric chains {[Cu(L)Cl](+)}(n) with a bridging chlorine atom. One of the complexes was found to have a significantly higher cytotoxic potential in comparison with cisplatin in inhibition of several cell lines (HL60, REH, C6, L929 and B16). The results obtained on the basis of flow cytometry indicated that apoptosis could be possible mechanism of cell death.