New 2,4-bis[(substituted-aminomethyl)phenyl]phenylquinazoline and 2,4-bis[(substituted-aminomethyl)phenyl]phenylquinoline Derivatives: Synthesis and Biological Evaluation as Novel Anticancer Agents by Targeting G-Quadruplex.

The syntheses of novel 2,4-bis[(substituted-aminomethyl)phenyl]phenylquinazolines 12 and 2,4-bis[(substituted-aminomethyl)phenyl]phenylquinolines 13 are reported here in six steps starting from various halogeno-quinazoline-2,4-(1H,3H)-diones or substituted anilines. The antiproliferative activities of the products were determined in vitro against a panel of breast (MCF-7 and MDA-MB-231), human adherent cervical (HeLa and SiHa), and ovarian (A2780) cell lines. Disubstituted 6- and 7-phenyl-bis(3-dimethylaminopropyl)aminomethylphenyl-quinazolines 12b, 12f, and 12i displayed the most interesting antiproliferative activities against six human cancer cell lines. In the series of quinoline derivatives, 6-phenyl-bis(3-dimethylaminopropyl)aminomethylphenylquinoline 13a proved to be the most active. G-quadruplexes (G4) stacked non-canonical nucleic acid structures found in specific G-rich DNA, or RNA sequences in the human genome are considered as potential targets for the development of anticancer agents. Then, as small aza-organic heterocyclic derivatives are well known to target and stabilize G4 structures, their ability to bind G4 structures have been determined through FRET melting, circular dichroism, and native mass spectrometry assays. Finally, telomerase inhibition ability has been also assessed using the MCF-7 cell line.

Design, Synthesis, and Antiprotozoal Evaluation of New Promising 2,9-Bis[(substituted-aminomethyl)]-4,7-phenyl-1,10-phenanthroline Derivatives, a Potential Alternative Scaffold to Drug Efflux.

A series of novel 2,9-bis[(substituted-aminomethyl)]-4,7-phenyl-1,10-phenanthroline derivatives was designed, synthesized, and evaluated in vitro against three protozoan parasites (Plasmodium falciparum, Leishmania donovani and Trypanosoma brucei brucei). Pharmacological results showed antiprotozoal activity with IC50 values in the sub and µM range. In addition, the in vitro cytotoxicity of these original molecules was assessed with human HepG2 cells. The substituted diphenylphenanthroline 1l was identified as the most potent antimalarial derivative with a ratio of cytotoxic to antiparasitic activities of 505.7 against the P. falciparum CQ-resistant strain W2. Against the promastigote forms of L. donovani, the phenanthrolines 1h, 1j, 1n and 1o were the most active with IC50 from 2.52 to 4.50 µM. The phenanthroline derivative 1o was also identified as the most potent trypanosomal candidate with a selectivity index (SI) of 91 on T. brucei brucei strain. FRET melting and native mass spectrometry experiments evidenced that the nitrogen heterocyclic derivatives bind the telomeric G-quadruplexes of P. falciparum and Trypanosoma. Moreover, as the telomeres of the parasites P. falciparum and Trypanosoma could be considered to be possible targets of this kind of nitrogen heterocyclic derivatives, their potential ability to stabilize the parasitic telomeric G-quadruplexes have been determined through the FRET melting assay and by native mass spectrometry.

G-quadruplexes in helminth parasites.

Parasitic helminths infecting humans are highly prevalent infecting ∼2 billion people worldwide, causing inflammatory responses, malnutrition and anemia that are the primary cause of morbidity. In addition, helminth infections of cattle have a significant economic impact on livestock production, milk yield and fertility. The etiological agents of helminth infections are mainly Nematodes (roundworms) and Platyhelminths (flatworms). G-quadruplexes (G4) are unusual nucleic acid structures formed by G-rich sequences that can be recognized by specific G4 ligands. Here we used the G4Hunter Web Tool to identify and compare potential G4 sequences (PQS) in the nuclear and mitochondrial genomes of various helminths to identify G4 ligand targets. PQS are nonrandomly distributed in these genomes and often located in the proximity of genes. Unexpectedly, a Nematode, Ascaris lumbricoides, was found to be highly enriched in stable PQS. This species can tolerate high-stability G4 structures, which are not counter selected at all, in stark contrast to most other species. We experimentally confirmed G4 formation for sequences found in four different parasitic helminths. Small molecules able to selectively recognize G4 were found to bind to Schistosoma mansoni G4 motifs. Two of these ligands demonstrated potent activity both against larval and adult stages of this parasite.

Design, synthesis, and antiproliferative effect of 2,9-bis[4-(pyridinylalkylaminomethyl)phenyl]-1,10-phenanthroline derivatives on human leukemic cells by targeting G-quadruplex.

Current multiagent chemotherapy regimens have improved the cure rate in acute leukemia patients, but they are highly toxic and poorly efficient in relapsed patients. To improve the treatment approaches, new specific molecules are needed. The G-quadruplexes (G4s), which are noncanonical nucleic acid structures found in specific guanine-rich DNA or RNA, are involved in many cellular events, including control of gene expression. G4s are considered as targets for the development of anticancer agents. Heterocyclic molecules are well known to target and stabilize G4 structures. Thus, a new series of 2,9-bis[(substituted-aminomethyl)phenyl]-1,10-phenanthroline derivatives (1a-i) was designed, synthesized, and evaluated against five human myeloid leukemia cell lines (K562, KU812, MV4-11, HL60, and U937). Their ability to stabilize various oncogene promoter G4 structures (c-MYC, BCL-2, and K-RAS) as well as the telomeric G4 was also determined through the fluorescence resonance energy transfer melting assay and native mass spectrometry. In addition, the more bioactive ligands 1g-i were tested for telomerase activity in HuT78 and MV4-11 protein extracts.

Design, synthesis, and antiprotozoal evaluation of new 2,4-bis[(substituted-aminomethyl)phenyl]quinoline, 1,3-bis[(substituted-aminomethyl)phenyl]isoquinoline and 2,4-bis[(substituted-aminomethyl)phenyl]quinazoline derivatives.

A series of new 2,4-bis[(substituted-aminomethyl)phenyl]quinoline, 1,3-bis[(substituted-aminomethyl)phenyl]isoquinoline, and 2,4-bis[(substituted-aminomethyl)phenyl]quinazoline derivatives was designed, synthesised, and evaluated in vitro against three protozoan parasites (Plasmodium falciparum, Leishmania donovani, and Trypanosoma brucei brucei). Biological results showed antiprotozoal activity with IC50 values in the µM range. In addition, the in vitro cytotoxicity of these original molecules was assessed with human HepG2 cells. The quinoline 1c was identified as the most potent antimalarial candidate with a ratio of cytotoxic to antiparasitic activities of 97 against the P. falciparum CQ-sensitive strain 3D7. The quinazoline 3h was also identified as the most potent trypanosomal candidate with a selectivity index (SI) of 43 on T. brucei brucei strain. Moreover, as the telomeres of the parasites P. falciparum and Trypanosoma are possible targets of this kind of nitrogen heterocyclic compounds, we have also investigated stabilisation of the Plasmodium and Trypanosoma telomeric G-quadruplexes by our best compounds through FRET melting assays.

Synthesis of new piperazinyl-pyrrolo[1,2-a]quinoxaline derivatives as inhibitors of Candida albicans multidrug transporters by a Buchwald-Hartwig cross-coupling reaction.

Two series of piperazinyl-pyrrolo[1,2-a]quinoxaline derivatives were prepared via a Buchwald-Hartwig cross-coupling reaction and then evaluated for their ability to inhibit the drug efflux activity of CaCdr1p and CaMdr1p transporters of Candida albicans overexpressed in a Saccharomyces cerevisiae strain. In the initial screening of twenty-nine piperazinyl-pyrrolo[1,2-a]quinoxaline derivatives, twenty-three compounds behaved as dual inhibitors of CaCdr1p and CaMdr1p. Only four compounds showed exclusive inhibition of CaCdr1p or CaMdr1p. Further biological investigations were developed and for example, their antifungal potential was evaluated by measuring the growth of control yeast cells (AD1-8u-) and efflux pump-overexpressing cells (AD-CDR1 and AD-MDR1) after exposition to variable concentrations of the tested compounds. The MIC80 values of nineteen compounds ranging from 100 to 901 µM for AD-CDR1 demonstrated that relative resistance index (RI) values were between 8 and 274. In comparison, only seven compounds had RI values superior to 4 in cells overexpressing Mdr1p. These results indicated substrate behavior for nineteen compounds for CaCdr1p and seven compounds for CaMdr1p, as these compounds were transported via MDR transporter overexpressing cells and not by the AD1-8u- cells. Finally, in a combination assay with fluconazole, two compounds (1d and 1f) have shown a synergistic effect (fractional inhibitory concentration index (FICI) values ≤ 0.5) at micromolar concentrations in the AD-MDR1 yeast strain overexpressing CaMdr1p-protein, indicating an excellent potency toward chemosensitization.

Synthesis and Antimalarial Activity of New Enantiopure Aminoalcoholpyrrolo[ 1,2-a]quinoxalines.

BACKGROUND: We prepared a novel series of enantiopure mefloquine analogues with pyrrolo[ 1,2-a]quinoxaline core in order to fight Plasmodium falciparum resistant strain. OBJECTIVES: To observe the influence of pyrrolo[1,2-a]quinoxaline core versus quinoline core on the antimalarial activity. METHOD: Four enantiopure aminoalcoholpyrrolo[1,2-a]quinoxalines 2 were synthetized via Sharpless asymmetric dihydroxylation reaction in eight steps. Their antimalarial activity was evaluated on two Plasmodium falciparum strains 3D7 and W2 with a SYBR Green I fluorescence-based method and their cytotoxicity was measured on four cell lines HepG2, THP-1, CHO and HFF. RESULTS: IC50 values of the four compounds 2 were close to the micromolar against the two P. falciparum strains. They were more active against P. falciparum strain W2 vs. P. falciparum strain 3D7. (R)- enantiomers were always more active than their (S)-counterpart whatever the strain. Selectivity indexes of compounds 2 were lower than 100. CONCLUSION: A novel series of enantiopure aminoalcohols with pyrrolo[1,2-a]quinoxaline core were synthesized in eight steps. They displayed IC50 values close to the micromolar against two P. falciparum strains 3D7 and W2. Although, In this series, 2,8-bistrifluoromethylquinoline was a best core than pyrrolo[1,2-a]quinoxaline for an optimal antimalarial activity, the pyrroloquinoxaline 2b showed an interesting antimalarial activity.

Design, synthesis, and antiprotozoal evaluation of new 2,9-bis[(substituted-aminomethyl)phenyl]-1,10-phenanthroline derivatives.

A series of new 2,9-bis[(substituted-aminomethyl)phenyl]-1,10-phenanthroline derivatives was synthesized, and the compounds were screened in vitro against three protozoan parasites (Plasmodium falciparum, Leishmania donovani, and Trypanosoma brucei brucei). Biological results showed antiparasitic activity with IC50 values in the µm range. The in vitro cytotoxicity of these molecules was assessed by incubation with human HepG2 cells; for some derivatives, cytotoxicity was observed at significantly higher concentrations than antiparasitic activity. The 2,9-bis[(substituted-aminomethyl)phenyl]-1,10-phenanthroline 1h was identified as the most potent antimalarial candidate with ratios of cytotoxic-to-antiparasitic activities of 107 and 39 against a chloroquine-sensitive and a chloroquine-resistant strain of P. falciparum, respectively. As the telomeres of the parasite P. falciparum are the likely target of this compound, we investigated stabilization of the Plasmodium telomeric G-quadruplexes by our phenanthroline derivatives through a FRET melting assay. The ligands 1f and 1m were noticed to be more specific for FPf8T with higher stabilization for FPf8T than for the human F21T sequence.

Synthesis and Antiproliferative Effect of Ethyl 4-[4-(4-Substituted Piperidin-1-yl)]benzylpyrrolo[1,2-a]quinoxalinecarboxylate Derivatives on Human Leukemia Cells.

Acute leukemia is a hematological malignancy with high incidence and recurrence rates and is characterized by an accumulation of blasts in bone marrow due to proliferation of immature lymphoid or myeloid cells associated with a blockade of differentiation. The heterogeneity of leukemia led us to look for new specific molecules for leukemia subtypes or for therapy-resistant cases. Among heterocyclic derivatives that attracted attention due to their wide range of biological activities, we focused our interest on the pyrrolo[1,2-a]quinoxaline heterocyclic framework that has been previously identified as an interesting scaffold for antiproliferative activities against various human cancer cell lines. In this work, new ethyl 4-[4-(4-substituted piperidin-1-yl)]benzylpyrrolo[1,2-a]quinoxalinecarboxylate derivatives (1 a-o) were designed, synthesized, and evaluated against five different leukemia cell lines, including Jurkat and U266 (lymphoid cell lines) and K562, U937, and HL60 (myeloid cell lines), as well as on normal human peripheral blood mononuclear cells (PBMCs). This new pyrrolo[1,2-a]quinoxaline series showed interesting cytotoxic potential against all tested leukemia cell lines. In particular, pyrroloquinoxalines 1 a and 1 m,n seem to be interesting due to their high activity against leukemia and their low activity against normal hematopoietic cells, leading to a high index of selectivity.

Design, synthesis and antimalarial activity of novel bis{N-[(pyrrolo[1,2-a]quinoxalin-4-yl)benzyl]-3-aminopropyl}amine derivatives.

Novel series of bis- and tris-pyrrolo[1,2-a]quinoxaline derivatives 1 were synthesized and tested for in vitro activity upon the intraerythrocytic stage of W2 and 3D7 Plasmodium falciparum strains. Biological results showed good antimalarial activity with IC50 in the µM range. In attempting to investigate the large broad-spectrum antiprotozoal activities of these new derivatives, their properties toward Leishmania donovani were also investigated and revealed their selective antiplasmodial profile. In parallel, the in vitro cytotoxicity of these molecules was assessed on the human HepG2 cell line. Structure-activity relationships of these new synthetic compounds are discussed here. The bis-pyrrolo[1,2-a]quinoxalines 1n and 1p were identified as the most potent antimalarial candidates with selectivity index (SI) of 40.6 on W2 strain, and 39.25 on 3D7 strain, respectively. As the telomeres of the parasite could constitute an attractive target, we investigated the possibility of targeting Plasmodium telomeres by stabilizing the Plasmodium telomeric G-quadruplexes through a FRET melting assay by our new compounds.

Design, Synthesis, and Evaluation of 2,9-Bis[(substituted-aminomethyl)phenyl]-1,10-phenanthroline Derivatives as G-Quadruplex Ligands.

Genomic sequences able to form guanine quadruplexes (G4) are found in oncogene promoters, in telomeres, and in 5'- and 3'-untranslated regions as well as introns of messenger RNAs. These regions are potential targets for drugs designed to treat cancer. Herein, we present the design and syntheses of ten new phenanthroline derivatives and characterization of their interactions with G4-forming oligonucleotides. We evaluated ligand-induced stabilization and specificity and selectivity of ligands for various G4 conformations using FRET-melting experiments. We investigated the interaction of compound 1 a (2,9-bis{4-[(3-dimethylaminopropyl)aminomethyl]phenyl}-1,10-phenanthroline), which combined the greatest stabilizing effect and specificity for G4, with human telomeric sequences using FRET, circular dichroism, and ESI-MS. In addition, we showed that compound 1 a interferes with the G4 helicase activity of Saccharomyces cerevisiae Pif1. Interestingly, compound 1 a was significantly more cytotoxic toward two human leukemic cell lines than to normal human blood mononuclear cells. These novel phenanthroline derivatives will be a starting point for further development and optimization of potent G4 ligands that have potential as anticancer agents.

Synthesis and evaluation of the cytotoxic activity of novel ethyl 4-[4-(4-substitutedpiperidin-1-yl)]benzyl-phenylpyrrolo[1,2-a]quinoxaline-carboxylate derivatives in myeloid and lymphoid leukemia cell lines.

Leukemia is the most common blood cancer, and its development starts at diverse points, leading to distinct subtypes that respond differently to therapy. This heterogeneity is rarely taken into account in therapies, so it is still essential to look for new specific drugs for leukemia subtypes or even for therapy-resistant cases. Among heterocyclic compounds that attracted a lot of attention because of its wide spread biological activities, the pyrrolo[1,2-a]quinoxaline heterocyclic framework has been identified as interesting scaffolds for antiproliferative activity against various human cancer cell lines. In the present study, novel ethyl 4-[4-(4-substitutedpiperidin-1-yl)]benzyl-phenylpyrrolo[1,2-a]quinoxaline-carboxylate derivatives 1a-l have been designed and synthesized. Their cytotoxicities were evaluated against five different leukemia cell lines, including Jurkat and U266 (lymphoid cell lines), and K562, U937, HL60 (myeloid cell lines), as well as normal human peripheral blood mononuclear cells (PBMNCs). Then, apoptosis study was performed with the more interesting compounds. The new pyrrolo[1,2-a]quinoxaline series showed promising cytotoxic potential against all leukemia cell lines tested, and some compounds showed better results than the reference compound A6730. Some compounds, such as 1a, 1e, 1g and 1h are promising because of their high activity against leukemia and their low activity against normal hematopoietic cells. Structure-activity relationships of these new synthetic compounds 1a-l are here also discussed.

Design, synthesis and biological evaluation of novel 4-alkapolyenylpyrrolo[1,2-a]quinoxalines as antileishmanial agents--part III.

A series of new 4-alkapolyenylpyrrolo[1,2-a]quinoxaline derivatives, original and structural analogues of alkaloid chimanine B and of previously described 4-alkenylpyrrolo[1,2-a]quinoxalines, was synthesized in good yields using efficient palladium-catalyzed Suzuki-Miyaura cross-coupling reactions. These new compounds were tested for in vitro antiparasitic activity upon three Leishmania spp. strains. Biological results showed activity against the promastigote forms of L. major, L. mexicana and L. donovani with IC50 ranging from 1.2 to 14.7 µM. In attempting to investigate if our pyrrolo[1,2-a]quinoxaline derivatives are broad-spectrum antiprotozoal compounds activities toward one Trypanosoma brucei brucei strain and the W2 and 3D7 Plasmodium falciparum strains were also investigated. In parallel, the in vitro cytotoxicity of these molecules was assessed on the murine J774 and human HepG2 cell lines. Structure-activity relationships of these new synthetic compounds are here discussed.

Synthesis and biological evaluation of novel substituted pyrrolo[1,2-a]quinoxaline derivatives as inhibitors of the human protein kinase CK2.

Herein we describe the synthesis and properties of substituted phenylaminopyrrolo[1,2-a]quinoxaline-carboxylic acid derivatives as a novel class of potent inhibitors of the human protein kinase CK2. A set of 15 compounds was designed and synthesized using convenient and straightforward synthesis protocols. The compounds were tested for inhibition of human protein kinase CK2, which is a potential drug target for many diseases including inflammatory disorders and cancer. New inhibitors with IC50 in the micro- and sub-micromolar range were identified. The most promising compound, the 4-[(3-chlorophenyl)amino]pyrrolo[1,2-a]quinoxaline-3-carboxylic acid 1c inhibited human CK2 with an IC50 of 49 nM. Our findings indicate that pyrrolo[1,2-a]quinoxalines are a promising starting scaffold for further development and optimization of human protein kinase CK2 inhibitors.