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Nocentini A, Di Porzio A, Bonardi A, Bazzicalupi C, Petreni A, Biver T, Bua S, Marzano S, Amato J, Pagano B, Iaccarino N, De Tito S, Amente S, Supuran CT, Randazzo A, Gratteri P. Development of a multi-targeted chemotherapeutic approach based on G-quadruplex stabilisation and carbonic anhydrase inhibition. J Enzyme Inhib Med Chem 2024; 39:2366236. [PMID: 38905127 PMCID: PMC11195807 DOI: 10.1080/14756366.2024.2366236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2024] [Accepted: 06/02/2024] [Indexed: 06/23/2024] Open
Abstract
A novel class of compounds designed to hit two anti-tumour targets, G-quadruplex structures and human carbonic anhydrases (hCAs) IX and XII is proposed. The induction/stabilisation of G-quadruplex structures by small molecules has emerged as an anticancer strategy, disrupting telomere maintenance and reducing oncogene expression. hCAs IX and XII are well-established anti-tumour targets, upregulated in many hypoxic tumours and contributing to metastasis. The ligands reported feature a berberine G-quadruplex stabiliser scaffold connected to a moiety inhibiting hCAs IX and XII. In vitro experiments showed that our compounds selectively stabilise G-quadruplex structures and inhibit hCAs IX and XII. The crystal structure of a telomeric G-quadruplex in complex with one of these ligands was obtained, shedding light on the ligand/target interaction mode. The most promising ligands showed significant cytotoxicity against CA IX-positive HeLa cancer cells in hypoxia, and the ability to stabilise G-quadruplexes within tumour cells.
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Affiliation(s)
- Alessio Nocentini
- NEUROFARBA Department, Pharmaceutical and Nutraceutical Section and Laboratory of Molecular Modeling Cheminformatics & QSAR, University of Florence, Sesto Fiorentino, Florence, Italy
| | - Anna Di Porzio
- Department of Pharmacy, University of Naples Federico II, Naples, Italy
| | - Alessandro Bonardi
- NEUROFARBA Department, Pharmaceutical and Nutraceutical Section and Laboratory of Molecular Modeling Cheminformatics & QSAR, University of Florence, Sesto Fiorentino, Florence, Italy
| | - Carla Bazzicalupi
- Department of Chemistry “Ugo Schiff”, University of Florence, Sesto Fiorentino, Florence, Italy
| | - Andrea Petreni
- NEUROFARBA Department, Pharmaceutical and Nutraceutical Section and Laboratory of Molecular Modeling Cheminformatics & QSAR, University of Florence, Sesto Fiorentino, Florence, Italy
| | - Tarita Biver
- Department of Chemistry and Industrial Chemistry, University of Pisa, Pisa, Italy
| | - Silvia Bua
- Research Institute of the University of Bucharest (ICUB), Bucharest, Romania
| | - Simona Marzano
- Department of Pharmacy, University of Naples Federico II, Naples, Italy
| | - Jussara Amato
- Department of Pharmacy, University of Naples Federico II, Naples, Italy
| | - Bruno Pagano
- Department of Pharmacy, University of Naples Federico II, Naples, Italy
| | - Nunzia Iaccarino
- Department of Pharmacy, University of Naples Federico II, Naples, Italy
| | - Stefano De Tito
- Molecular Cell Biology of Autophagy, The Francis Crick Institute, London, UK
| | - Stefano Amente
- Department of Molecular Medicine and Medical Biotechnologies, University of Naples Federico II, Naples, Italy
| | - Claudiu T. Supuran
- NEUROFARBA Department, Pharmaceutical and Nutraceutical Section and Laboratory of Molecular Modeling Cheminformatics & QSAR, University of Florence, Sesto Fiorentino, Florence, Italy
| | - Antonio Randazzo
- Department of Pharmacy, University of Naples Federico II, Naples, Italy
| | - Paola Gratteri
- NEUROFARBA Department, Pharmaceutical and Nutraceutical Section and Laboratory of Molecular Modeling Cheminformatics & QSAR, University of Florence, Sesto Fiorentino, Florence, Italy
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2
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Schlosser J, Ihmels H. Ligands for Abasic Site-containing DNA and their Use as Fluorescent Probes. Curr Org Synth 2023; 20:96-113. [PMID: 35170411 DOI: 10.2174/1570179419666220216091422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2021] [Revised: 12/16/2021] [Accepted: 12/16/2021] [Indexed: 12/16/2022]
Abstract
Apurinic and apyrimidinic sites, also referred to as abasic or AP sites, are residues of duplex DNA in which one DNA base is removed from a Watson-Crick base pair. They are formed during the enzymatic repair of DNA and offer binding sites for a variety of guest molecules. Specifically, the AP site may bind an appropriate ligand as a substitute for the missing nucleic base, thus stabilizing the abasic site-containing DNA (AP-DNA). Notably, ligands that bind selectively to abasic sites may be employed for analytical and therapeutical purposes. As a result, there is a search for structural features that establish a strong and selective association of a given ligand with the abasic position in DNA. Against this background, this review provides an overview of the different classes of ligands for abasic site-containing DNA (AP-DNA). This review covers covalently binding substrates, namely amine and oxyamine derivatives, as well as ligands that bind to AP-DNA by noncovalent association, as represented by small heterocyclic aromatic compounds, metal-organic complexes, macrocyclic cyclophanes, and intercalator-nucleobase conjugates. As the systematic development of fluorescent probes for AP-DNA has been somewhat neglected so far, this review article contains a survey of the available reports on the fluorimetric response of the ligand upon binding to the AP-DNA. Based on these data, this compilation shall present a perspective for future developments of fluorescent probes for AP-DNA.
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Affiliation(s)
- Julika Schlosser
- Department of Chemistry and Biology, University of Siegen, Center of Micro- and Nanochemistry and (Bio)Technology (Cμ), Adolf-Reichwein-Str. 2, 57068 Siegen, Germany
| | - Heiko Ihmels
- Department of Chemistry and Biology, University of Siegen, Center of Micro- and Nanochemistry and (Bio)Technology (Cμ), Adolf-Reichwein-Str. 2, 57068 Siegen, Germany
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3
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Zonjić I, Radić Stojković M, Crnolatac I, Tomašić Paić A, Pšeničnik S, Vasilev A, Kandinska M, Mondeshki M, Baluschev S, Landfester K, Glavaš-Obrovac L, Jukić M, Kralj J, Brozovic A, Horvat L, Tumir LM. Styryl dyes with N-Methylpiperazine and N-Phenylpiperazine Functionality: AT-DNA and G-quadruplex binding ligands and theranostic agents. Bioorg Chem 2022; 127:105999. [DOI: 10.1016/j.bioorg.2022.105999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 06/24/2022] [Accepted: 06/28/2022] [Indexed: 11/28/2022]
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Research Progress on G-Quadruplexes in Human Telomeres and Human Telomerase Reverse Transcriptase (hTERT) Promoter. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2022; 2022:2905663. [PMID: 35707279 PMCID: PMC9192192 DOI: 10.1155/2022/2905663] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 05/19/2022] [Indexed: 12/21/2022]
Abstract
The upregulation telomerase activity is observed in over 85-90% of human cancers and provides an attractive target for cancer therapies. The high guanine content in the telomere DNA sequences and the hTERT promoter can form G-quadruplexes (G4s). Small molecules targeting G4s in telomeres and hTERT promoter could stabilize the G4s and inhibit hTERT expression and telomere extension. Several G4 ligands have shown inhibitory effects in cancer cells and xenograft mouse models, indicating these ligands have a potential for cancer therapies. The current review article describes the concept of the telomere, telomerase, and G4s. Moreover, the regulation of telomerase and G4s in telomeres and hTERT promoter is discussed as well. The summary of the small molecules targeting G4s in telomeric DNA sequences and the hTERT promoter will also be shown.
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5
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Mendes E, Aljnadi IM, Bahls B, Victor BL, Paulo A. Major Achievements in the Design of Quadruplex-Interactive Small Molecules. Pharmaceuticals (Basel) 2022; 15:ph15030300. [PMID: 35337098 PMCID: PMC8953082 DOI: 10.3390/ph15030300] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 02/22/2022] [Accepted: 02/24/2022] [Indexed: 12/17/2022] Open
Abstract
Organic small molecules that can recognize and bind to G-quadruplex and i-Motif nucleic acids have great potential as selective drugs or as tools in drug target discovery programs, or even in the development of nanodevices for medical diagnosis. Hundreds of quadruplex-interactive small molecules have been reported, and the challenges in their design vary with the intended application. Herein, we survey the major achievements on the therapeutic potential of such quadruplex ligands, their mode of binding, effects upon interaction with quadruplexes, and consider the opportunities and challenges for their exploitation in drug discovery.
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Affiliation(s)
- Eduarda Mendes
- Faculty of Pharmacy, Research Institute for Medicines (iMed.Ulisboa), Universidade de Lisboa, 1649-003 Lisbon, Portugal; (E.M.); (I.M.A.); (B.B.)
| | - Israa M. Aljnadi
- Faculty of Pharmacy, Research Institute for Medicines (iMed.Ulisboa), Universidade de Lisboa, 1649-003 Lisbon, Portugal; (E.M.); (I.M.A.); (B.B.)
- Faculty of Sciences, BioISI, Biosystems and Integrative Sciences Institute, Universidade de Lisboa, 1749-016 Lisbon, Portugal;
| | - Bárbara Bahls
- Faculty of Pharmacy, Research Institute for Medicines (iMed.Ulisboa), Universidade de Lisboa, 1649-003 Lisbon, Portugal; (E.M.); (I.M.A.); (B.B.)
- Faculty of Sciences, BioISI, Biosystems and Integrative Sciences Institute, Universidade de Lisboa, 1749-016 Lisbon, Portugal;
| | - Bruno L. Victor
- Faculty of Sciences, BioISI, Biosystems and Integrative Sciences Institute, Universidade de Lisboa, 1749-016 Lisbon, Portugal;
| | - Alexandra Paulo
- Faculty of Pharmacy, Research Institute for Medicines (iMed.Ulisboa), Universidade de Lisboa, 1649-003 Lisbon, Portugal; (E.M.); (I.M.A.); (B.B.)
- Correspondence:
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Dickerhoff J, Brundridge N, McLuckey SA, Yang D. Berberine Molecular Recognition of the Parallel MYC G-Quadruplex in Solution. J Med Chem 2021; 64:16205-16212. [PMID: 34677968 PMCID: PMC8614230 DOI: 10.1021/acs.jmedchem.1c01508] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The medicinal natural product berberine is one of the most actively studied and pursued G-quadruplex (G4)-ligands. The major G-quadruplex formed in the promoter region of the MYC oncogene (MycG4) is an attractive drug target and a prominent example and model structure for parallel G-quadruplexes. G4-targeted berberine derivatives have been actively developed; however, the analogue design was based on a previous crystal structure in which berberine binds as a dimer to a parallel G-quadruplex. Herein, we show that in solution, the binding mode and stoichiometry of berberine are substantially different from the crystal structure: berberine binds as a monomer to MycG4 using a base-recruitment mechanism with a reversed orientation in that the positively charged convex side is actually positioned above the tetrad center. Our structure provides a physiologically relevant basis for the future structure-based rational design of G4-targeted berberine derivatives, and this study demonstrates that it is crucial to validate the ligand-DNA interactions.
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Affiliation(s)
- Jonathan Dickerhoff
- Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, 575 W Stadium Avenue, West Lafayette, Indiana 47904, United States
| | - Nicole Brundridge
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
| | - Scott A McLuckey
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
| | - Danzhou Yang
- Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, 575 W Stadium Avenue, West Lafayette, Indiana 47904, United States
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
- Purdue Center for Cancer Research, and Purdue Institute for Drug Discovery, West Lafayette, Indiana 47907, United States
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7
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Wickhorst PJ, Druzhinin SI, Ihmels H, Müller M, Sutera Sardo M, Schönherr H, Viola G. A Dimethylaminophenyl‐Substituted Naphtho[1,2‐
b
]quinolizinium as a Multicolor NIR Probe for the Fluorimetric Detection of Intracellular Nucleic Acids and Proteins. CHEMPHOTOCHEM 2021. [DOI: 10.1002/cptc.202100148] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Peter Jonas Wickhorst
- Department of Chemistry – Biology University of Siegen, and Center of Micro- and Nanochemistry and (Bio)Technology (Cμ) Adolf-Reichwein-Str. 2 57068 Siegen Germany
| | - Sergey I. Druzhinin
- Department of Chemistry – Biology University of Siegen, and Center of Micro- and Nanochemistry and (Bio)Technology (Cμ) Adolf-Reichwein-Str. 2 57068 Siegen Germany
| | - Heiko Ihmels
- Department of Chemistry – Biology University of Siegen, and Center of Micro- and Nanochemistry and (Bio)Technology (Cμ) Adolf-Reichwein-Str. 2 57068 Siegen Germany
| | - Mareike Müller
- Department of Chemistry – Biology University of Siegen, and Center of Micro- and Nanochemistry and (Bio)Technology (Cμ) Adolf-Reichwein-Str. 2 57068 Siegen Germany
| | | | - Holger Schönherr
- Department of Chemistry – Biology University of Siegen, and Center of Micro- and Nanochemistry and (Bio)Technology (Cμ) Adolf-Reichwein-Str. 2 57068 Siegen Germany
| | - Giampietro Viola
- Department of Women's and Child's health Oncohematology laboratory University of Padova Via Giustiniani 2 I-35128 Padova Italy
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Santos T, Salgado GF, Cabrita EJ, Cruz C. G-Quadruplexes and Their Ligands: Biophysical Methods to Unravel G-Quadruplex/Ligand Interactions. Pharmaceuticals (Basel) 2021; 14:769. [PMID: 34451866 PMCID: PMC8401999 DOI: 10.3390/ph14080769] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2021] [Revised: 07/31/2021] [Accepted: 08/03/2021] [Indexed: 12/12/2022] Open
Abstract
Progress in the design of G-quadruplex (G4) binding ligands relies on the availability of approaches that assess the binding mode and nature of the interactions between G4 forming sequences and their putative ligands. The experimental approaches used to characterize G4/ligand interactions can be categorized into structure-based methods (circular dichroism (CD), nuclear magnetic resonance (NMR) spectroscopy and X-ray crystallography), affinity and apparent affinity-based methods (surface plasmon resonance (SPR), isothermal titration calorimetry (ITC) and mass spectrometry (MS)), and high-throughput methods (fluorescence resonance energy transfer (FRET)-melting, G4-fluorescent intercalator displacement assay (G4-FID), affinity chromatography and microarrays. Each method has unique advantages and drawbacks, which makes it essential to select the ideal strategies for the biological question being addressed. The structural- and affinity and apparent affinity-based methods are in several cases complex and/or time-consuming and can be combined with fast and cheap high-throughput approaches to improve the design and development of new potential G4 ligands. In recent years, the joint use of these techniques permitted the discovery of a huge number of G4 ligands investigated for diagnostic and therapeutic purposes. Overall, this review article highlights in detail the most commonly used approaches to characterize the G4/ligand interactions, as well as the applications and types of information that can be obtained from the use of each technique.
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Affiliation(s)
- Tiago Santos
- CICS-UBI—Centro de Investigação em Ciências da Saúde, Universidade da Beira Interior, Av. Infante D. Henrique, 6200-506 Covilhã, Portugal;
| | - Gilmar F. Salgado
- ARNA Laboratory, Université de Bordeaux, Inserm U1212, CNRS UMR 5320, IECB, 33607 Pessac, France;
| | - Eurico J. Cabrita
- UCIBIO, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal;
- Associate Laboratory i4HB—Institute for Health and Bioeconomy, NOVA School of Science and Technology, NOVA University Lisbon, 2819-516 Caparica, Portugal
| | - Carla Cruz
- CICS-UBI—Centro de Investigação em Ciências da Saúde, Universidade da Beira Interior, Av. Infante D. Henrique, 6200-506 Covilhã, Portugal;
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Wickhorst PJ, Ihmels H. Selective, pH-Dependent Colorimetric and Fluorimetric Detection of Quadruplex DNA with 4-Dimethylamino(phenyl)-Substituted Berberine Derivatives. Chemistry 2021; 27:8580-8589. [PMID: 33855748 PMCID: PMC8252107 DOI: 10.1002/chem.202100297] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Indexed: 12/20/2022]
Abstract
The 9- and 12-dimethylaminophenyl-substituted berberine derivatives 3 a and 3 b were readily synthesized by Suzuki-Miyaura reactions and shown to be useful fluorescent probes for the optical detection of quadruplex DNA (G4-DNA). Their association with the nucleic acids was investigated by spectrometric titrations, CD and LD spectroscopy, and with DNA-melting analysis. Both ligands bind to duplex DNA by intercalation and to G4-DNA by terminal π stacking. At neutral conditions, they bind with higher affinity (Kb =105 -106 M-1 ) to representative quadruplex forming oligonucleotides 22AG, c-myc, c-kit, and a2, than to duplex calf thymus (ct) DNA (Kb =5-7×104 M-1 ). At pH 5, however, the affinity of 3 a towards G4-DNA 22AG is higher (Kb =1.2×106 M-1 ), whereas the binding constant towards ct DNA is lower (Kb =3.9×103 M-1 ) than under neutral conditions. Notably, the association of the ligand with DNA results in characteristic changes of the absorption and emission properties under specific conditions, which may be used for optical DNA detection. Other than the parent berberine, the ligands do not show a noticeable increase of their very low intrinsic emission intensity upon association with DNA at neutral conditions. In contrast, a fluorescence light-up effect was observed upon association to duplex (Φfl =0.01) and quadruplex DNA (Φfl =0.04) at pH 5. This fluorimetric response to G4-DNA association in combination with the distinct, red-shifted absorption under these conditions provides a simple and conclusive optical detection of G4-DNA at lower pH.
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Affiliation(s)
- Peter Jonas Wickhorst
- Department of Chemistry – BiologyUniversity of Siegen, andCenter of Micro- and Nanochemistry and Engineering (Cμ)Adolf-Reichwein-Str. 257068SiegenGermany
| | - Heiko Ihmels
- Department of Chemistry – BiologyUniversity of Siegen, andCenter of Micro- and Nanochemistry and Engineering (Cμ)Adolf-Reichwein-Str. 257068SiegenGermany
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10
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Wickhorst PJ, Blachnik M, Lagumdzija D, Ihmels H. Synthesis of 10- O-aryl-substituted berberine derivatives by Chan-Evans-Lam coupling and investigation of their DNA-binding properties. Beilstein J Org Chem 2021; 17:991-1000. [PMID: 34025807 PMCID: PMC8111429 DOI: 10.3762/bjoc.17.81] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 04/22/2021] [Indexed: 12/16/2022] Open
Abstract
Eleven novel 10-O-aryl-substituted berberrubine and berberine derivatives were synthesized by the Cu2+-catalyzed Chan–Evans–Lam coupling of berberrubine with arylboronic acids and subsequent 9-O-methylation. The reaction is likely introduced by the Cu2+-induced demethylation of berberrubine and subsequent arylation of the resulting 10-oxyanion functionality. Thus, this synthetic route represents the first successful Cu-mediated coupling reaction of berberine substrates. The DNA-binding properties of the 10-O-arylberberine derivatives with duplex and quadruplex DNA were studied by thermal DNA denaturation experiments, spectrometric titrations as well as CD and LD spectroscopy. Fluorimetric DNA melting analysis with different types of quadruplex DNA revealed a moderate stabilization of the telomeric quadruplex-forming oligonucleotide sequence G3(TTAG3)3. The derivatives showed a moderate affinity towards quadruplex DNA (Kb = 5–9 × 105 M−1) and ct DNA (Kb = 3–5 × 104 M−1) and exhibited a fluorescence light-up effect upon complexation to both DNA forms, with slightly higher intensity in the presence of the quadruplex DNA. Furthermore, the CD- and LD-spectroscopic studies revealed that the title compounds intercalate into ct DNA and bind to G4-DNA by terminal stacking.
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Affiliation(s)
- Peter Jonas Wickhorst
- Department of Chemistry - Biology, University of Siegen, and Center of Micro- and Nanochemistry and Engineering (Cµ), Adolf-Reichwein-Str. 2, 57068 Siegen, Germany
| | - Mathilda Blachnik
- Department of Chemistry - Biology, University of Siegen, and Center of Micro- and Nanochemistry and Engineering (Cµ), Adolf-Reichwein-Str. 2, 57068 Siegen, Germany
| | - Denisa Lagumdzija
- Department of Chemistry - Biology, University of Siegen, and Center of Micro- and Nanochemistry and Engineering (Cµ), Adolf-Reichwein-Str. 2, 57068 Siegen, Germany
| | - Heiko Ihmels
- Department of Chemistry - Biology, University of Siegen, and Center of Micro- and Nanochemistry and Engineering (Cµ), Adolf-Reichwein-Str. 2, 57068 Siegen, Germany
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Wickhorst PJ, Ihmels H. Berberrubine Phosphate: A Selective Fluorescent Probe for Quadruplex DNA. Molecules 2021; 26:2566. [PMID: 33924894 PMCID: PMC8124163 DOI: 10.3390/molecules26092566] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 04/20/2021] [Accepted: 04/22/2021] [Indexed: 12/31/2022] Open
Abstract
A phosphate-substituted, zwitterionic berberine derivative was synthesized and its binding properties with duplex DNA and G4-DNA were studied using photometric, fluorimetric and polarimetric titrations and thermal DNA denaturation experiments. The ligand binds with high affinity toward both DNA forms (Kb = 2-7 × 105 M-1) and induces a slight stabilization of G4-DNA toward thermally induced unfolding, mostly pronounced for the telomeric quadruplex 22AG. The ligand likely binds by aggregation and intercalation with ct DNA and by terminal stacking with G4-DNA. Thus, this compound represents one of the rare examples of phosphate-substituted DNA binders. In an aqueous solution, the title compound has a very weak fluorescence intensity (Φfl < 0.01) that increases significantly upon binding to G4-DNA (Φfl = 0.01). In contrast, the association with duplex DNA was not accompanied by such a strong fluorescence light-up effect (Φfl < 0.01). These different fluorimetric responses upon binding to particular DNA forms are proposed to be caused by the different binding modes and may be used for the selective fluorimetric detection of G4-DNA.
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Affiliation(s)
| | - Heiko Ihmels
- Department of Chemistry-Biology, University of Siegen, Center of Micro- and Nanochemistry and Engineering (Cµ), Adolf-Reichwein-Str. 2, 57068 Siegen, Germany;
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