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1.
Int J Mol Sci ; 22(19)2021 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-34638964

RESUMO

G-quadruplex existence was proved in cells by using both antibodies and small molecule fluorescent probes. However, the G-quadruplex probes designed thus far are structure- but not conformation-specific. Recently, a core-extended naphthalene diimide (cex-NDI) was designed and found to provide fluorescent signals of markedly different intensities when bound to G-quadruplexes of different conformations or duplexes. Aiming at evaluating how the fluorescence behaviour of this compound is associated with specific binding modes to the different DNA targets, cex-NDI was here studied in its interaction with hybrid G-quadruplex, parallel G-quadruplex, and B-DNA duplex models by biophysical techniques, molecular docking, and biological assays. cex-NDI showed different binding modes associated with different amounts of stacking interactions with the three DNA targets. The preferential binding sites were the groove, outer quartet, or intercalative site of the hybrid G-quadruplex, parallel G-quadruplex, and B-DNA duplex, respectively. Interestingly, our data show that the fluorescence intensity of DNA-bound cex-NDI correlates with the amount of stacking interactions formed by the ligand with each DNA target, thus providing the rationale behind the conformation-sensitive properties of cex-NDI and supporting its use as a fluorescent probe of G-quadruplex structures. Notably, biological assays proved that cex-NDI mainly localizes in the G-quadruplex-rich nuclei of cancer cells.

2.
Cancers (Basel) ; 13(20)2021 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-34680314

RESUMO

Selectivity and efficacy towards target cancer cells, as well as biocompatibility, are current challenges of advanced chemotherapy powering the discovery of unconventional metal-based drugs and the search for novel therapeutic approaches. Among second-generation metal-based chemotherapeutics, ruthenium complexes have demonstrated promising anticancer activity coupled to minimal toxicity profiles and peculiar biochemical features. In this context, our research group has recently focused on a bioactive Ru(III) complex-named AziRu-incorporated into a suite of ad hoc designed nucleolipid nanosystems to ensure its chemical stability and delivery. Indeed, we proved that the structure and properties of decorated nucleolipids can have a major impact on the anticancer activity of the ruthenium core. Moving in this direction, here we describe a preclinical study performed by a mouse xenograft model of human breast cancer to establish safety and efficacy in vivo of a cationic Ru(III)-based nucleolipid formulation, named HoThyRu/DOTAP, endowed with superior antiproliferative activity. The results show a remarkable reduction in tumour with no evidence of animal suffering. Blood diagnostics, as well as biochemical analysis in both acute and chronic treated animal groups, demonstrate a good tolerability profile at the therapeutic regimen, with 100% of mice survival and no indication of toxicity. In addition, ruthenium plasma concentration analysis and tissue bioaccumulation were determined via appropriate sampling and ICP-MS analysis. Overall, this study supports both the efficacy of our Ru-containing nanosystem versus a human breast cancer model and its safety in vivo through well-tolerated animal biological responses, envisaging a possible forthcoming use in clinical trials.

3.
Pharmaceutics ; 13(10)2021 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-34683905

RESUMO

In the quest for selective G-quadruplex (G4)-targeting chemotypes, natural compounds have been thus far poorly explored, though representing appealing candidates due to the high structural diversity of their scaffolds. In this regard, a unique high diversity in-house library composed of ca. one thousand individual natural products was investigated. The combination of molecular docking-based virtual screening and the G4-CPG experimental screening assay proved to be useful to quickly and effectively identify-out of many natural compounds-five hit binders of telomeric and oncogenic G4s, i.e., Bulbocapnine, Chelidonine, Ibogaine, Rotenone and Vomicine. Biophysical studies unambiguously demonstrated the selective interaction of these compounds with G4s compared to duplex DNA. The rationale behind the G4 selective recognition was suggested by molecular dynamics simulations. Indeed, the selected ligands proved to specifically interact with G4 structures due to peculiar interaction patterns, while they were unable to firmly bind to a DNA duplex. From biological assays, Chelidonine and Rotenone emerged as the most active compounds of the series against cancer cells, also showing good selectivity over normal cells. Notably, the anticancer activity correlated well with the ability of the two compounds to target telomeric G4s.

4.
Int J Mol Sci ; 22(17)2021 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-34502432

RESUMO

In the search for optimized thrombin binding aptamers (TBAs), we herein describe the synthesis of a library of TBA analogues obtained by end-functionalization with the electron-rich 1,5-dialkoxy naphthalene (DAN) and the electron-deficient 1,8,4,5-naphthalenetetra-carboxylic diimide (NDI) moieties. Indeed, when these G-rich oligonucleotides were folded into the peculiar TBA G-quadruplex (G4) structure, effective donor-acceptor charge transfer interactions between the DAN and NDI residues attached to the extremities of the sequence were induced, providing pseudo-cyclic structures. Alternatively, insertion of NDI groups at both extremities produced TBA analogues stabilized by π-π stacking interactions. All the doubly-modified TBAs were characterized by different biophysical techniques and compared with the analogues carrying only the DAN or NDI residue and unmodified TBA. These modified TBAs exhibited higher nuclease resistance, and their G4 structures were markedly stabilized, as evidenced by increased Tm values compared to TBA. These favorable properties were also associated with improved anticoagulant activity for one DAN/NDI-modified TBA, and for one NDI/NDI-modified TBA. Our results indicated that TBA pseudo-cyclic structuring by ad hoc designed end-functionalization represents an efficient approach to improve the aptamer features, while pre-organizing and stabilizing the G4 structure but allowing sufficient flexibility to the aptamer folding, which is necessary for optimal thrombin recognition.

5.
Biomolecules ; 11(7)2021 07 16.
Artigo em Inglês | MEDLINE | ID: mdl-34356672

RESUMO

In the search for new therapeutic strategies to contrast SARS-CoV-2, we here studied the interaction of polydatin (PD) and resveratrol (RESV)-two natural stilbene polyphenols with manifold, well known biological activities-with Spike, the viral protein essential for virus entry into host cells, and ACE2, the angiotensin-converting enzyme present on the surface of multiple cell types (including respiratory epithelial cells) which is the main host receptor for Spike binding. Molecular Docking simulations evidenced that both compounds can bind Spike, ACE2 and the ACE2:Spike complex with good affinity, although the interaction of PD appears stronger than that of RESV on all the investigated targets. Preliminary biochemical assays revealed a significant inhibitory activity of the ACE2:Spike recognition with a dose-response effect only in the case of PD.


Assuntos
Enzima de Conversão de Angiotensina 2/metabolismo , COVID-19/tratamento farmacológico , Glucosídeos/farmacologia , Resveratrol/farmacologia , SARS-CoV-2/efeitos dos fármacos , Glicoproteína da Espícula de Coronavírus/metabolismo , Estilbenos/farmacologia , COVID-19/metabolismo , Descoberta de Drogas , Medicamentos de Ervas Chinesas/farmacologia , Inibidores Enzimáticos/farmacologia , Interações Hospedeiro-Patógeno/efeitos dos fármacos , Humanos , Simulação de Acoplamento Molecular , Ligação Proteica/efeitos dos fármacos , SARS-CoV-2/metabolismo
6.
Sci Rep ; 11(1): 9380, 2021 04 30.
Artigo em Inglês | MEDLINE | ID: mdl-33931690

RESUMO

In several biomedical applications, the detection of biomarkers demands high sensitivity, selectivity and easy-to-use devices. Organic electrochemical transistors (OECTs) represent a promising class of devices combining a minimal invasiveness and good signal transduction. However, OECTs lack of intrinsic selectivity that should be implemented by specific approaches to make them well suitable for biomedical applications. Here, we report on a biosensor in which selectivity and a high sensitivity are achieved by interfacing, in an OECT architecture, a novel gate electrode based on aptamers, Au nanoparticles and graphene hierarchically organized to optimize the final response. The fabricated biosensor performs state of the art limit of detection monitoring biomolecules, such as thrombin-with a limit of detection in the picomolar range (≤ 5 pM) and a very good selectivity even in presence of supraphysiological concentrations of Bovine Serum Albumin (BSA-1mM). These accomplishments are the final result of the gate hierarchic structure that reduces sterich indrance that could contrast the recognition events and minimizes false positive, because of the low affinity of graphene towards the physiological environment. Since our approach can be easily applied to a large variety of different biomarkers, we envisage a relevant potential for a large series of different biomedical applications.

7.
Chemistry ; 27(34): 8832-8845, 2021 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-33890349

RESUMO

Stilbenoids are natural compounds endowed with several biological activities, including cardioprotection and cancer prevention. Among them, (±)-trans-δ-viniferin, deriving from trans-resveratrol dimerization, was investigated in its ability to target DNA duplex and G-quadruplex structures by exploiting NMR spectroscopy, circular dichroism, fluorescence spectroscopy and molecular docking. (±)-trans-δ-Viniferin proved to bind both the minor and major grooves of duplexes, whereas it bound the 3'- and 5'-ends of a G-quadruplex by stacking on the outer quartets, accompanied by rearrangement of flanking residues. Specifically, (±)-trans-δ-viniferin demonstrated higher affinity for the investigated DNA targets than its monomeric counterpart. Additionally, the methoxylated derivatives of (±)-trans-δ-viniferin and trans-resveratrol, i. e. (±)-pterostilbene-trans-dihydrodimer and trans-pterostilbene, respectively, were evaluated, revealing similar binding modes, affinities and stoichiometries with the DNA targets as their parent analogues. All tested compounds were cytotoxic at µM concentration on several cancer cell lines, showing DNA damaging activity consistent with their ability to tightly interact with duplex and G-quadruplex structures.


Assuntos
Quadruplex G , Estilbenos , Dicroísmo Circular , DNA , Simulação de Acoplamento Molecular , Resveratrol
8.
J Med Chem ; 64(7): 3578-3603, 2021 04 08.
Artigo em Inglês | MEDLINE | ID: mdl-33751881

RESUMO

In the context of developing efficient anticancer therapies aimed at eradicating any sort of tumors, G-quadruplexes represent excellent targets. Small molecules able to interact with G-quadruplexes can interfere with cell pathways specific of tumors and common to all cancers. Naphthalene diimides (NDIs) are among the most promising, putative anticancer G-quadruplex-targeting drugs, due to their ability to simultaneously target multiple G-quadruplexes and their strong, selective in vitro and in vivo anticancer activity. Here, all the available biophysical, biological, and structural data concerning NDIs targeting G-quadruplexes were systematically analyzed. Structure-activity correlations were obtained by analyzing biophysical data of their interactions with G-quadruplex targets and control duplex structures, in parallel to biological data concerning the antiproliferative activity of NDIs on cancer and normal cells. In addition, NDI binding modes to G-quadruplexes were discussed in consideration of the structures and properties of NDIs by in-depth analysis of the available structural models of G-quadruplex/NDI complexes.


Assuntos
Antineoplásicos/farmacologia , DNA/metabolismo , Quadruplex G , Naftalimidas/farmacologia , Animais , Antineoplásicos/química , Antineoplásicos/metabolismo , Linhagem Celular Tumoral , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Simulação de Dinâmica Molecular , Estrutura Molecular , Naftalimidas/química , Naftalimidas/metabolismo , Relação Estrutura-Atividade
9.
Pharmacol Ther ; 217: 107649, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-32777331

RESUMO

First studies on thrombin-inhibiting DNA aptamers were reported in 1992, and since then a large number of anticoagulant aptamers has been discovered. TBA - also named HD1, a 15-mer G-quadruplex (G4)-forming oligonucleotide - is the best characterized thrombin binding aptamer, able to specifically recognize the protein exosite I, thus inhibiting the conversion of soluble fibrinogen into insoluble fibrin strands. Unmodified nucleic acid-based aptamers, in general, and TBA in particular, exhibit limited pharmacokinetic properties and are rapidly degraded in vivo by nucleases. In order to improve the biological performance of aptamers, a widely investigated strategy is the introduction of chemical modifications in their backbone at the level of the nucleobases, sugar moieties or phosphodiester linkages. Besides TBA, also other thrombin binding aptamers, able to adopt a well-defined G4 structure, e.g. mixed duplex/quadruplex sequences, as well as homo- and hetero-bivalent constructs, have been identified and optimized. Considering the growing need of new efficient anticoagulant agents associated with the strong therapeutic potential of these thrombin inhibitors, the research on thrombin binding aptamers is still a very hot and intriguing field. Herein, we comprehensively described the state-of-the-art knowledge on the DNA-based aptamers targeting thrombin, especially focusing on the optimized analogues obtained by chemically modifying the oligonucleotide backbone, and their biological performances in therapeutic applications.

10.
Int J Biol Macromol ; 166: 1320-1334, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-33166559

RESUMO

To selectively target telomeric G-quadruplex (G4) DNA, monomeric and dimeric naphthalene diimides (NDIs) were investigated as binders of multimeric G4 structures able to discriminate duplex DNA. These NDIs were analysed by the affinity chromatography-based screening G4-CPG (G-quadruplex on Controlled Pore Glass), using the sequence d[AGGG(TTAGGG)7] (tel46), folding into two consecutive G4s, as model of the human telomeric G4 multimer. In parallel, a telomeric G4 monomer (tel26) and a duplex structure (ds27) were used as controls. According to G4-CPG screening, NDI-5 proved to be the best ligand in terms of dimeric G4 vs. duplex DNA selectivity and was analysed by circular dichroism (CD), gel electrophoresis, isothermal titration calorimetry (ITC) and fluorescence spectroscopy in its interactions with tel46. NDI-5 strongly binds and stabilizes tel46 G4, favouring a hybrid folding in K+-containing buffer. Under these conditions, the binding process comprises a first event involving three molecules of NDI-5 and a second one in which other six molecules bind to the DNA. In a metal cation-free system, NDI-5 induces tel46 G4 folding, as indicated by CD and PAGE, favouring an antiparallel structuring. Docking simulations showed that NDI-5 can effectively bind to the pocket between two G4 units, representing a promising ligand for multimeric G4s.


Assuntos
Quadruplex G , Imidas/química , Substâncias Intercalantes/química , Naftalenos/química , Humanos , Simulação de Acoplamento Molecular , Telômero/química
11.
Med Res Rev ; 41(1): 464-506, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33038031

RESUMO

The vascular endothelial growth factor (VEGF) family and its receptors play fundamental roles not only in physiological but also in pathological angiogenesis, characteristic of cancer progression. Aiming at finding putative treatments for several malignancies, various small molecules, antibodies, or protein-based drugs have been evaluated in vitro and in vivo as VEGF inhibitors, providing efficient agents approved for clinical use. Due to the high clinical importance of VEGF, also a great number of anti-VEGF nucleic acid-based aptamers-that is, oligonucleotides able to bind with high affinity and specificity a selected biological target-have been developed as promising agents in anticancer strategies. Notable research efforts have been made in optimization processes of the identified aptamers, searching for increased target affinity and/or bioactivity by exploring structural analogues of the lead compounds. This review is focused on recent studies devoted to the development of DNA-based aptamers designed to target VEGF. Their therapeutic potential as well as their significance in the construction of highly selective biosensors is here discussed.

12.
Nucleic Acids Res ; 48(21): 12380-12393, 2020 12 02.
Artigo em Inglês | MEDLINE | ID: mdl-33170272

RESUMO

Naphthalene diimides showed significant anticancer activity in animal models, with therapeutic potential related to their ability to strongly interact with G-quadruplexes. Recently, a trifunctionalized naphthalene diimide, named NDI-5, was identified as the best analogue of a mini-library of novel naphthalene diimides for its high G-quadruplex binding affinity along with marked, selective anticancer activity, emerging as promising candidate drug for in vivo studies. Here we used NMR, dynamic light scattering, circular dichroism and fluorescence analyses to investigate the interactions of NDI-5 with G-quadruplexes featuring either parallel or hybrid topology. Interplay of different binding modes of NDI-5 to G-quadruplexes was observed for both parallel and hybrid topologies, with end-stacking always operative as the predominant binding event. While NDI-5 primarily targets the 5'-end quartet of the hybrid G-quadruplex model (m-tel24), the binding to a parallel G-quadruplex model (M2) occurs seemingly simultaneously at the 5'- and 3'-end quartets. With parallel G-quadruplex M2, NDI-5 formed stable complexes with 1:3 DNA:ligand binding stoichiometry. Conversely, when interacting with hybrid G-quadruplex m-tel24, NDI-5 showed multiple binding poses on a single G-quadruplex unit and/or formed different complexes comprising two or more G-quadruplex units. NDI-5 produced stabilizing effects on both G-quadruplexes, forming complexes with dissociation constants in the nM range.


Assuntos
Antineoplásicos/metabolismo , DNA de Neoplasias/metabolismo , Quadruplex G , Guanina/metabolismo , Imidas/metabolismo , Naftalenos/metabolismo , Antineoplásicos/síntese química , Sequência de Bases , Sítios de Ligação , DNA de Neoplasias/química , Guanina/química , Humanos , Imidas/síntese química , Ligantes , Naftalenos/síntese química , Soluções , Termodinâmica
13.
Molecules ; 25(22)2020 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-33182593

RESUMO

Multivalent interactions frequently occur in biological systems and typically provide higher binding affinity and selectivity in target recognition than when only monovalent interactions are operative. Thus, taking inspiration by nature, bivalent or multivalent nucleic acid aptamers recognizing a specific biological target have been extensively studied in the last decades. Indeed, oligonucleotide-based aptamers are suitable building blocks for the development of highly efficient multivalent systems since they can be easily modified and assembled exploiting proper connecting linkers of different nature. Thus, substantial research efforts have been put in the construction of dimeric/multimeric versions of effective aptamers with various degrees of success in target binding affinity or therapeutic activity enhancement. The present review summarizes recent advances in the design and development of dimeric and multimeric DNA-based aptamers, including those forming G-quadruplex (G4) structures, recognizing different key proteins in relevant pathological processes. Most of the designed constructs have shown improved performance in terms of binding affinity or therapeutic activity as anti-inflammatory, antiviral, anticoagulant, and anticancer agents and their number is certainly bound to grow in the next future.


Assuntos
Aptâmeros de Nucleotídeos/química , Quadruplex G , Fosfoproteínas/química , Proteínas de Ligação a RNA/química , Anti-Inflamatórios/química , Anticoagulantes/química , Antineoplásicos/química , Antivirais/química , Complexo CD3/química , Moléculas de Adesão Celular/química , DNA/química , Dimerização , Humanos , Imunoglobulina M/química , Estrutura Secundária de Proteína , Proteínas Proto-Oncogênicas c-met/química , Pirrolidinas/química , Receptores Proteína Tirosina Quinases/química , Receptores de Antígenos de Linfócitos T/química , Fator A de Crescimento do Endotélio Vascular/metabolismo , Vitronectina/química
14.
Pharmaceuticals (Basel) ; 13(10)2020 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-33007911

RESUMO

We here report our studies on the reaction with the platinum(II) ion of a nucleoamino acid constituted by the l-2,3-diaminopropanoic acid linked to the thymine nucleobase through a methylenecarbonyl linker. The obtained new platinum complexes, characterized by spectroscopic and mass spectrometric techniques, were envisaged to exploit synergistic effects due to the presence of both the platinum center and the nucleoamino acid moiety. The latter can be potentially useful to protect the complexes from early deactivation, as well as to facilitate their cell internalization. The biological activity of the complexes in terms of antiproliferative effects was evaluated in vitro on different cancer cell lines and healthy cells, showing the best results on human cervical adenocarcinoma (HeLa) cells along with good selectivity for cancer over normal cells. In contrast, the metal-free nucleoamino acid did not show any cytotoxicity on both normal and cancer cell lines. Finally, the ability of the novel Pt(II) complexes to bind various DNA model systems was investigated by circular dichroism (CD) spectroscopy and polyacrylamide gel electrophoresis analyses proving that the newly obtained compounds can potentially target DNA, similarly to other well-known anticancer Pt complexes, with a peculiar G-quadruplex vs. duplex selectivity.

15.
Int J Mol Sci ; 21(11)2020 May 29.
Artigo em Inglês | MEDLINE | ID: mdl-32485818

RESUMO

NU172-a 26-mer oligonucleotide able to bind exosite I of human thrombin and inhibit its activity-was the first aptamer to reach Phase II clinical studies as an anticoagulant in heart disease treatments. With the aim of favoring its functional duplex-quadruplex conformation and thus improving its enzymatic stability, as well as its thrombin inhibitory activity, herein a focused set of cyclic NU172 analogues-obtained by connecting its 5'- and 3'-extremities with flexible linkers-was synthesized. Two different chemical approaches were exploited in the cyclization procedure, one based on the oxime ligation method and the other on Cu(I)-assisted azide-alkyne cycloaddition (CuAAC), affording NU172 analogues including circularizing linkers with different length and chemical nature. The resulting cyclic NU172 derivatives were characterized using several biophysical techniques (ultraviolet (UV) and circular dichroism (CD) spectroscopies, gel electrophoresis) and then investigated for their serum resistance and anticoagulant activity in vitro. All the cyclic NU172 analogues showed higher thermal stability and nuclease resistance compared to unmodified NU172. These favorable properties were, however, associated with reduced-even though still significant-anticoagulant activity, suggesting that the conformational constraints introduced upon cyclization were somehow detrimental for protein recognition. These results provide useful information for the design of improved analogues of NU172 and related duplex-quadruplex structures.


Assuntos
Anticoagulantes/síntese química , Aptâmeros de Nucleotídeos/síntese química , Dicroísmo Circular , Reação de Cicloadição/métodos , Fibrinogênio/química , Quadruplex G , Oximas/química , Raios Ultravioleta
16.
Cells ; 9(6)2020 06 05.
Artigo em Inglês | MEDLINE | ID: mdl-32517101

RESUMO

In this review we have showcased the preclinical development of original amphiphilic nanomaterials designed for ruthenium-based anticancer treatments, to be placed within the current metallodrugs approach leading over the past decade to advanced multitarget agents endowed with limited toxicity and resistance. This strategy could allow for new options for breast cancer (BC) interventions, including the triple-negative subtype (TNBC) with poor therapeutic alternatives. BC is currently the second most widespread cancer and the primary cause of cancer death in women. Hence, the availability of novel chemotherapeutic weapons is a basic requirement to fight BC subtypes. Anticancer drugs based on ruthenium are among the most explored and advanced next-generation metallotherapeutics, with NAMI-A and KP1019 as two iconic ruthenium complexes having undergone clinical trials. In addition, many nanomaterial Ru complexes have been recently conceived and developed into anticancer drugs demonstrating attractive properties. In this field, we focused on the evaluation of a Ru(III) complex-named AziRu-incorporated into a suite of both zwitterionic and cationic nucleolipid nanosystems, which proved to be very effective for the in vivo targeting of breast cancer cells (BBC). Mechanisms of action have been widely explored in the context of preclinical evaluations in vitro, highlighting a multitarget action on cell death pathways which are typically deregulated in neoplasms onset and progression. Moreover, being AziRu inspired by the well-known NAMI-A complex, information on non-nanostructured Ru-based anticancer agents have been included in a precise manner.


Assuntos
Antineoplásicos/uso terapêutico , Neoplasias da Mama/tratamento farmacológico , Complexos de Coordenação/uso terapêutico , Lipídeos/química , Nanopartículas/química , Rutênio/uso terapêutico , Animais , Feminino , Humanos
17.
Int J Mol Sci ; 21(6)2020 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-32183038

RESUMO

A focused library of newly designed monomeric and dimeric naphthalene diimides (NDIs) was analyzed in its ability to recognize specific G-quadruplex (G4) structures discriminating duplex DNA. The best G4 ligands-according to an affinity chromatography-based screening method named G4-CPG-were tested on human cancer and healthy cells, inducing DNA damage at telomeres, and in parallel, showing selective antiproliferative activity on HeLa cancer cells with IC50 values in the low nanomolar range. CD and fluorescence spectroscopy studies allowed detailed investigation of the interaction in solution with different G4 and duplex DNA models of the most promising NDI of the series, as determined by combining the biophysical and biological assays' data.


Assuntos
Antineoplásicos/química , Quadruplex G/efeitos dos fármacos , Iminas/química , Naftalenos/química , Antineoplásicos/farmacologia , Proliferação de Células/efeitos dos fármacos , Dano ao DNA , Células HeLa , Humanos , Iminas/farmacologia , Ligantes , Naftalenos/farmacologia , Telômero/efeitos dos fármacos
18.
Int J Mol Sci ; 21(6)2020 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-32183039

RESUMO

In the optimization process of nucleic acid aptamers, increased affinity and/or activity are generally searched by exploring structural analogues of the lead compound. In many cases, promising results have been obtained by dimerization of the starting aptamer. Here we studied a focused set of covalent dimers of the G-quadruplex (G4) forming anti-Vascular Endothelial Growth Factor (VEGF) V7t1 aptamer with the aim of identifying derivatives with improved properties. In the design of these covalent dimers, connecting linkers of different chemical nature, maintaining the same polarity along the strand or inverting it, have been introduced. These dimeric aptamers have been investigated using several biophysical techniques to disclose the conformational behavior, molecularity and thermal stability of the structures formed in different buffers. This in-depth biophysical characterization revealed the formation of stable G4 structures, however in some cases accompanied by alternative tridimensional arrangements. When tested for their VEGF165 binding and antiproliferative activity in comparison with V7t1, these covalent dimers showed slightly lower binding ability to the target protein but similar if not slightly higher antiproliferative activity on human breast adenocarcinoma MCF-7 cells. These results provide useful information for the design of improved dimeric aptamers based on further optimization of the linker joining the two consecutive V7t1 sequences.


Assuntos
Aptâmeros de Nucleotídeos/química , Quadruplex G , Fator A de Crescimento do Endotélio Vascular/metabolismo , Aptâmeros de Nucleotídeos/farmacologia , Proliferação de Células/efeitos dos fármacos , Humanos , Células MCF-7 , Ligação Proteica
19.
J Inorg Biochem ; 203: 110868, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31837618

RESUMO

An artificial alanine-based amino acid {(S)-2-amino-3-[4-propyl-3-(thiophen-2-yl)-5-thioxo-4,5-dihydro-1H-1,2,4-triazol-1-yl]propanoic acid, here named TioxAla}, bearing a substituted triazolyl-thione group on the side chain and able to bind RNA biomedical targets, was here chosen as a valuable scaffold for the synthesis of new platinum complexes with potential dual action owing to the concomitant presence of the metal centre and the amino acid moiety. Three new platinum complexes, obtained from the reaction of TioxAla with K2PtCl4, were characterized by mass spectrometry, nuclear magnetic resonance and UV-vis spectroscopy: one compound (Pt1, bis-{(S)-2-amino-3-[4-propyl-3-(thiophen-2-yl)-5-thioxo-4,5-dihydro-1H-1,2,4-triazol-1-yl]propanoate-O,S} platinum(II)) consisted of two amino acid units coordinating the Pt(II) ion; the other two, Pt2 [potassium dichloro-{(S)-2-amino-3-[4-propyl-3-(thiophen-2-yl)-5-thioxo-4,5-dihydro-1H-1,2,4-triazol-1-yl]propanoate (O,S)} platinum(II)] and Pt3 [potassium dichloro-{(S)-2-amino-3-[4-propyl-3-(thiophen-2-yl)-5-thioxo-4,5-dihydro-1H-1,2,4-triazol-1-yl]propanoate (O,N)} platinum(II)], were isomers bearing one TioxAla unit, and two chlorides as Pt-ligands. Pt coordination involved preferentially the amino, carboxylic and thione functions of TioxAla. By preliminary antiproliferative assays, a moderate cytotoxic activity on cancer cells was observed only for Pt2 and Pt3, while no anticancer activity was found for both the chloride-free complex (Pt1) and TioxAla. This cytotoxicity, however lower than that of cisplatin, well correlated with the marked ability, here found only for Pt2 and Pt3 complexes, to bind DNA sequences either in random coil or in structured forms (duplex and G-quadruplex), as verified by spectroscopic and spectrometric analysis.


Assuntos
Alanina/farmacologia , Antineoplásicos/farmacologia , Complexos de Coordenação/farmacologia , DNA/metabolismo , Alanina/análogos & derivados , Alanina/metabolismo , Antineoplásicos/síntese química , Antineoplásicos/metabolismo , Linhagem Celular Tumoral , Complexos de Coordenação/síntese química , Complexos de Coordenação/metabolismo , DNA/genética , Ensaios de Seleção de Medicamentos Antitumorais , Quadruplex G , Humanos , Ligantes , Platina/química
20.
Bioorg Chem ; 94: 103379, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31699393

RESUMO

A small library of cyclic TBA analogues (named cycTBA I-IV), obtained by covalently connecting its 5'- and 3'-ends with flexible linkers, has been synthesized with the aim of improving its chemical and enzymatic stability, as well as its anticoagulant properties. Two chemical procedures have been exploited to achieve the desired cyclization, based on the oxime ligation method (providing cycTBA I and II) or on Cu(I)-assisted azide-alkyne cycloaddition (CuAAC) protocols (for cycTBA III and IV), leading to analogues containing circularizing linkers with different chemical nature and length, overall spanning from 22 to 48 atoms. The resulting cyclic TBAs have been characterized using a variety of biophysical methods (UV, CD, gel electrophoresis, SE-HPLC analyses) and then tested for their serum resistance and anticoagulant activity under in vitro experiments. A fine-tuning of the length and flexibility of the linker allowed identifying a cyclic analogue, cycTBA II, with improved anticoagulant activity, associated with a dramatically stabilized G-quadruplex structure (ΔTm = +17 °C) and a 6.6-fold higher enzymatic resistance in serum compared to unmodified TBA.


Assuntos
Anticoagulantes/farmacologia , Aptâmeros de Nucleotídeos/farmacologia , Coagulação Sanguínea/efeitos dos fármacos , Anticoagulantes/síntese química , Anticoagulantes/química , Aptâmeros de Nucleotídeos/síntese química , Aptâmeros de Nucleotídeos/química , Ciclização , Relação Dose-Resposta a Droga , Estrutura Molecular , Relação Estrutura-Atividade
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