Pyrrole Carboxamide Research Articles

Mechanisms of cytotoxic activity of pyrrole-carboxamides against multidrug-resistant tumor cell sublines

Introduction. Mitotic poisoning agents (MPAs) affecting the dynamic state of the microtubules, are the well-known and effective chemotherapeutic agents. Mitotic poisoning agents are binding to the microtubules, and thereby interfere with tubulin polymerization or depolymerization dynamic state, resulting in the cell cycle arrest in M-phase (mitotic catastrophe) and subsequent apoptotic cell death. We reported previously about potent cytotoxic activities against the pyrrole-carboxamides (PCs) (PC-61 and PC-84) against broad spectrum of cancer cell lines, including triple negative breast cancer, lung and prostate cancer.Aim. To examine the cytotoxic activities of PC-61 and PC-84 against multidrug-resistant cancer cell lines indicated above.Materials and methods. Studу was performed on the triple-negative paclitaxel-resistant breast cancer cell line HCC1806 Tx-R and doxorubicin-resistant osteosarcoma SaOS-2 Dox-R cell line.Results. The cytotoxic activity of PCs was due to the inhibition of tubulin polymerization. Immunofluorescence staining data revealed PC’s ability to interfere with tubulin’s assembly in multidrug-resistant cancer cell lines. As an outcome of inhibition of tubulin polymerization, PCs induced cell cycle arrest in M-phase, and further led to apoptotic cell death of cancer cells.Conclusion. Collectively, we demonstrated potent cytotoxic activity of PCs against cancer cell lines with multidrug-resistant phenotype, which arising the possibilities to develop novel and effective anti-tumor agents that belongs to mitotic poisoning agents

Divergent synthesis of pyrrole carboxamides from pyrrole carboxaldehyde and formamides/amines via oxidative amidation involving pyrrole acyl radicals.

A non-traditional approach for the synthesis of pyrrole carboxamides from pyrrole carboxaldehyde and formamides or amines with catalytic amounts of nBu4NI and TBHP as oxidants is reported herein. The method is operationally simple providing straightforward access to primary, secondary, and tertiary pyrrole carboxamides in good to excellent yields utilizing inexpensive reagents under mild conditions. Unlike traditional amidations that involve ionic reactions, a mechanistic study of our current method unveils the involvement of 2- or 3-pyrrole acyl radicals that are otherwise rarely postulated. The applicability of the current method is further demonstrated in the synthesis of a drug-like compound, i.e., an optically pure carboetomidate amide.

Parallel Optimization of Potency and Pharmacokinetics Leading to the Discovery of a Pyrrole Carboxamide ERK5 Kinase Domain Inhibitor.

The nonclassical extracellular signal-related kinase 5 (ERK5) mitogen-activated protein kinase pathway has been implicated in increased cellular proliferation, migration, survival, and angiogenesis; hence, ERK5 inhibition may be an attractive approach for cancer treatment. However, the development of selective ERK5 inhibitors has been challenging. Previously, we described the development of a pyrrole carboxamide high-throughput screening hit into a selective, submicromolar inhibitor of ERK5 kinase activity. Improvement in the ERK5 potency was necessary for the identification of a tool ERK5 inhibitor for target validation studies. Herein, we describe the optimization of this series to identify nanomolar pyrrole carboxamide inhibitors of ERK5 incorporating a basic center, which suffered from poor oral bioavailability. Parallel optimization of potency and in vitro pharmacokinetic parameters led to the identification of a nonbasic pyrazole analogue with an optimal balance of ERK5 inhibition and oral exposure.

Structure- and Ligand-Based in silico Studies towards the Repurposing of Marine Bioactive Compounds to Target SARS-CoV-2

This work was a structured virtual screening for marine bioactive compounds with reported antiviral activities which were subjected to structure-based studies against SARS-CoV-2 co-crystallized proteins. The molecular docking of marine bioactive compounds against the main protease (Mpro, PDB ID: 6lu7 and 6y2f), the spike glycoprotein (PDB ID: 6vsb), and the RNA polymerase (PDB ID: 6m71) of SARS-CoV-2 was performed. Ligand-based approach with the inclusion of rapid overlay chemical structures (ROCS) was also addressed in order to examine the probability of these marine compounds sharing relevance and druggability with the reported drugs. Among the examined marine library, the highest scores in different virtual screening aspects were displayed by compounds with flavonoids core, acyl indole, and pyrrole carboxamide alkaloids. Moreover, a complete overlay with the co-crystallized ligands of Mpro was revealed by sceptrin and debromo-sceptrin. Thalassoilin (A-B) which was found in the Red Sea exhibited the highest binding and similarity outcomes among all target proteins. These data highlight the importance of marine natural metabolites in regard to further studies for discovering new drugs to combat the COVID-19 pandemic.

Pyrrole carboxamide introduction in the total synthesis of pyrrole–imidazole alkaloids

In this review various strategies for the incorporation of the signature pyrrole carboxamide moiety in the total syntheses of pyrrole-imidazole alkaloids (PIA) are discussed. These so-called oroidin alkaloids have a broad range of biological activities and display interesting skeletal diversity and complexity. These alkaloids are sponge-derived secondary metabolites and thus far more than 200 members of the PIA family have been isolated over the past few decades. Methods range from classical amide bond forming processes to non-traditional bond formation including the de novo synthesis of the pyrrole itself.

Synthesis and biological evaluation of new indole and pyrrole carboxamides based on amino acids

Synthesis and biological evaluation of new indole and pyrrole carboxamides based on amino acids

Benzofuran and pyrrole derivatives as cannabinoid receptor modulators with in vivo efficacy against ulcerative colitis.

Aim: Highlighting the need for effective therapies for the treatment of ulcerative colitis, novel series of potential CB2 modulators (benzofuran and pyrrole carboxamides) were developed and tested for their functional activities on CB1/CB2 receptors. Results: In the benzofuran series, the cannabinoid (CB) receptor selectivity and the functional profile were dependent on the nature of the amide substituent and the position of the methoxy group, meanwhile the pyrrole derivatives, displayed an exclusive selectivity to the CB2 receptor and a functionality that is controlled by the nature of the pyrrole nitrogen substituent. Conclusion: Remarkably, we succeeded to develop potent and selective pyrrole-based CB2 receptor agonists, represented by compound 25a, which also demonstrated an exquisite anti-inflammatory effect in a dextran sodium sulfate-induced colitis model in mice.

Xanthine oxidase inhibitory activity of new pyrrole carboxamide derivatives: In vitro and in silico studies.

Pyrrole carboxamide rings are rarely used as active scaffold in designing inhibitors for enzymes. Herein, we described the structure-activity relationship for novel xanthine oxidase inhibitors based on the pyrrole carboxamide scaffold. A series of novel-substituted pyrrole carboxamide derivatives were synthesized and characterized; their in vitro and in silico inhibitory activities were determined against xanthine oxidase. Among these compounds, those which contain no substituent and one methyl group at the para-position of the phenyl moiety in the main structure, respectively, were found out as most active according to the xanthine oxidase inhibition activity study. In silico techniques reveal why these compounds display more activities than others, based on their binding interactions with xanthine oxidase and the surface scanning results of the enzyme. Furthermore, the binding energy calculations displayed good agreement with the experimental activity values.

Directing Group‐Assisted Copper(II)‐Catalyzed ortho‐Carbonylation to Benzamide using 2,2′‐Azobisisobutyronitrile (AIBN)

AbstractAn efficient copper‐catalyzed regioselective C—H bond carbonylation of benzamides has been developed using 2,2′‐azobisisobutyronitrile (AIBN) as traceless cyanating agent. The non‐toxic and readily available AIBN was used for the carbonylative cyclization of benzamides via copper catalysis. The method is also applicable for the regioselective cyanation of furan, benzofuran, thiophene, benzothiophene, and pyrrole carboxamide derivatives.magnified image

Novel pyrrole carboxamide inhibitors of JAK2 as potential treatment of myeloproliferative disorders

Compound 1, a hit from the screening of our chemical collection displaying activity against JAK2, was deconstructed for SAR analysis into three regions, which were explored. A series of compounds was synthesized leading to the identification of the potent and orally bioavailable JAK2 inhibitor 16 (NMS-P830), which showed an encouraging tumour growth inhibition in SET-2 xenograft tumour model, with evidence for JAK2 pathway suppression demonstrated by in vivo pharmacodynamic effects.

Selective synthesis of N-substituted pyrrolo[1,2-a]pyrazin-1(2H)-one derivatives via alkyne cyclization

A novel and efficient synthesis of N-substituted pyrrolo-pyrazinone derivatives has been developed. A trichloroacetyl group connected to the pyrrole ring was converted into the desired carboxamide derivatives. Promoted by NaH, the pyrrole carboxamide derivatives underwent a tandem reaction with propargyl bromide to afford pyrrolo-pyrazinones with high efficiency under very mild conditions. The mechanism for the formation of the products is discussed and supported by DFT calculations.

Binol Based Chirality Conversion Reagents for Underivatized Amino Acids

Four binol based pyrrole carboxamide chiral receptors has been synthesized and effectively used as a Chirality Conversion Reagent (CCR) for underivatized amino acids. Three points of interactions take place for the conversion process. They are the reversible imine formation, the internal resonance assisted Hydrogen Bonding (RAHB) and the additional hydrogen bonds between the amino acids and the heterocylic moiety of the pendant groups. The conversion efficiency of all the receptors was found to be comparable with those of the receptors reported earlier.

New Carboxylic Acid Amides of the Pyrrole Series: Synthetic Routes and Biological Aspects

Abstract Complex II inhibitors play an important role in agrochemical fungicide research and have been known for more than 40 years. With the introduction of ortho-substituted heterocyclic amides, a breakthrough in activity level and spectrum within this class was achieved. In the meantime all major agrochemical companies have entered this field. In this paper, a special complex II subclass, the pyrrole carboxamides, will be introduced in more detail and the synthesis of selected compounds as well as a short biological SAR analysis of the pyrrole subclass will be discussed.

Structurally Unique Inhibitors of Human Mitogen-Activated Protein Kinase Phosphatase-1 Identified in a Pyrrole Carboxamide Library

Mitogen-activated protein kinase phosphatase 1 (MKP-1) is a tyrosine phosphatase superfamily member that dephosphorylates and inactivates cardinal mitogen-activated protein kinase (MAPK) substrates, such as p38, c-Jun NH(2)-terminal kinase, and extracellular signal-regulated kinase. Although these MAPK substrates regulate many essential cellular processes associated with human diseases, few pharmacological inhibitors have been described. The lack of readily available selective MKP-1 inhibitors has severely limited interrogation of its biological role and was one rationale for using a recently described tricyclic pyrrole-2-carboxamide library in our screening efforts. In this report we demonstrate the pharmacological richness of the pyrrole carboxamide library by the finding that 10 of 172 members inhibited human MKP-1. Two of the pyrrole carboxamides, PSI2106 and MDF2085, were especially notable in vitro inhibitors of recombinant human MKP-1 enzyme activity with IC(50) values of 8.0 +/- 0.9 and 8.3 +/- 0.8 microM, respectively. Both showed some selectivity for MKP-1 over the closely related phosphatases MKP-3, Cdc25B, VHR, and PTP1B. Computational examination of the surface properties near the catalytic site revealed that the phosphatases studied differ significantly in their electrostatic potential at the substrate binding site. The compounds inhibited MKP-1 reversibly but displayed mixed kinetics. Phosphatase inhibition was retained in the presence of physiologically relevant concentrations of glutathione. Molecular docking studies suggested that PSI2106 may interact with His(229) and Phe(299) on MKP-1. These results reveal the power of using a small focused library for identifying pharmacological probes.

Programmable Oligomers for Minor Groove DNA Recognition

The four Watson-Crick base pairs of DNA can be distinguished in the minor groove by pairing side-by-side three five-membered aromatic carboxamides, imidazole (Im), pyrrole (Py), and hydroxypyrrole (Hp), four different ways. On the basis of the paradigm of unsymmetrical paired edges of aromatic rings for minor groove recognition, a second generation set of heterocycle pairs, imidazopyridine/pyrrole (Ip/Py) and hydroxybenzimidazole/pyrrole (Hz/Py), revealed that recognition elements not based on analogues of distamycin could be realized. A new set of end-cap heterocycle dimers, oxazole-hydroxybenzimidazole (No-Hz) and chlorothiophene-hydroxybenzimidazole (Ct-Hz), paired with Py-Py are shown to bind contiguous base pairs of DNA in the minor groove, specifically 5'-GT-3' and 5'-TT-3', with high affinity and selectivity. Utilizing this technology, we have developed a new class of oligomers for sequence-specific DNA minor groove recognition no longer based on the N-methyl pyrrole carboxamides of distamycin.

DNA Binding Properties of Novel Dansylated Distamycin Analogues in Which the Fluorophore is Directly Conjugated to the N-methyl-pyrrole Carboxamide Backbone

Polyamides that are structural analogues of the naturally occurring DNA minor groove binding antibiotic distamycin (Dst) are promising candidates as gene modulators. Developing strategies for the large scale screening and monitoring of the cellular distribution of such ligands would aid the faster discovery of molecules, which would have eventual utility in molecular biology and medicine. Attachment of fluorescent tags would be a useful step towards this end. A fundamental question in this connection is whether the tag modifies the DNA binding affinity of the parent compounds. Towards answering this question, we have developed two oligopeptides that bear the dansyl (N, N-dimethylaminonaphthalene sulfonamido fluorophore) coupled directly to the N-terminus of the conjugated N-methylpyrrole carboxamide network, and possess three or four N-methyl pyrrole carboxamide units (abbreviated as Dn3 and Dn4 respectively). DNA binding abilities of these molecules were assessed from fluorescence titration experiments, duplex-DNA Tm analysis (employing both UV and fluorescence spectroscopy), induced circular dichroism measurements (ICD), salt dependence of ICD and apparent binding constant measurements (Kapp) employing ethidium bromide (EtBr) displacement assay. Both these molecules ‘reported’ DNA binding in the form of an enhanced fluorescence emission. As judged from the ICD measurements, salt dependence of ICD, Tm analysis and Kapp measurements, the binding affinities of the molecules that possessed dansyl group at their N-termini were lower than the ones with equivalent number of amide units, but possessed N-methylpyrrole carboxamide unit at their N-ter- mini. These results would have implications in the future design of fluorescent polyamides.

Synthesis of pyrrole carboxamide nucleotide triphosphates—putative labelled nucleotide analogues

The syntheses of pyrrole carboxamide nucleotide triphosphates and the initial results of their incorporation by Klenow fragment are reported.

Synthesis and Incorporation of Pyrrole Carboxamide Nucleoside Triphosphates by DNA Polymerases

We have synthesised and examined the enzymatic incorporation properties of the 5′-triphosphates of 2′-deoxyribosyl pyrrole 3-monocarboxamide (dMTP) and 2′-deoxyribosyl pyrrole 3,4-dicarboxamide (dDTP). These analogues we had hoped would behave as ambivalent base analogues in that they can present two alternative hydrogen-bonding faces either by rotation about the carboxamide group or about the glycosidic bond. The two pyrrole derivatives, dMTP and dDTP, exhibit a preference for incorporation with Klenow polymerase. They are preferentially incorporated as either A or C.

Facile synthesis of oligopeptide distamycin analogs devoid of hydrogen bond donors or acceptors at the N-terminus: sequence-specific duplex DNA binding as a function of peptide chain length

The first examples of distamycin analogs, which lack hydrogen bond interactor groups at the N-terminus, have been synthesized. The bispyrrole peptide did not exhibit any detectable binding with double-stranded (ds) DNA. However, all other homologues did bind to ds-DNA strongly, with the binding affinities increasing as a function of the number of repeating pyrrole carboxamide units, implying that a hydrogen bond donor or acceptor atom per se at the N-terminus is not essential for their DNA binding. Studies with poly d(GC) showed that the N-terminal formamide is not a prerequisite for GC binding, contrary to earlier postulations.

DNA Binding Properties of Novel Distamycin Analogs That Lack the Leading Amide Unit at the N-Terminus

First examples of distamycin (Dst) analogs which lack hydrogen bond donor or acceptor groups at the N-terminus have been synthesized. The first molecule of this series, which is a bispyrrole peptide, did not exhibit any detectable binding with double-stranded (ds) DNA. However, all other analogs did bind strongly to AT-rich sequences of ds-DNA, with the binding affinities increasing as a function of the number of repeating pyrrole carboxamide units. These results imply that a hydrogen bond donor or acceptor atom per se at the N-terminus is not a prerequisite for DNA binding in the case of pyrrole carboxamide-based Dst analogs. However, in the absence of H-bond donor or acceptor at the N-terminus, a minimum of three pyrrole carboxamide units is necessary for the onset of DNA binding. Beyond this minimum number, the binding affinity increases as a function of the number of pyrrole units, as a result of the greater availability of hydrogen bonding and van der Waals surface. Experiments with poly[d(G-C)] have shown that the presence of the N-terminus formamide group is not inevitable for GC binding of this class of molecules. The observation that the N-terminus formamide unit can be dispensed with suggests that these molecules, which are much easier to synthesize and functionalize, can be used in place of the conventional analogs of distamycin for the development of novel minor groove binders with extended sequence recognition properties.