RESUMO
Alzheimer's disease (AD) is a slowly progressive neurodegenerative disease conceptualized as a continuous process, ranging from mild cognitive impairment (MCI), to the mild, moderate, and severe clinical stages of AD dementia. AD is considered a complex multifactorial disease. Currently, the use of cholinesterase inhibitors (ChEI), such as tacrine, donepezil, rivastigmine, and galantamine, has been the main treatment for AD patients. Interestingly, there is evidence that ChEI also promotes neuroprotective effects, bringing some benefits to AD patients. The mechanisms by which the ChEI act have been investigated in AD. ChEI can modulate the PI3K/AKT pathway, which is an important signaling cascade that is capable of causing a significant functional impact on neurons by activating cell survival pathways to promote neuroprotective effects. However, there is still a huge challenge in the field of neuroprotection, but in the context of unravelling the details of the PI3K/AKT pathway, a new scenario has emerged for the development of more efficient drugs that act on multiple protein targets. Thus, the mechanisms by which ChEI can promote neuroprotective effects and prospects for the development of new drug candidates for the treatment of AD are discussed in this review.
RESUMO
The synthesis of MUC1 glycopeptides bearing modified tumor-associated carbohydrate antigens (TACAs) represents an effective strategy to develop potential antitumor vaccines that trigger strong immune response. In this context, we present herein the multistep synthesis of the triazole glycosyl amino acid Neu5Ac-α/ß2-triazole-6-ßGalNAc-ThrOH 1 as STn antigen analog, along with its assembly on the corresponding MUC1 peptide to give NAcProAsp [Neu5Acα/ß2-triazole-6-ßGalNAc]ThrArgProGlyOH 2. Despite interacting differently with SM3 monoclonal antibody, as shown by molecular dynamic simulations, this unnatural triazole glycopeptide may represent a promising candidate for cancer immunotherapy.
Assuntos
Antígenos Glicosídicos Associados a Tumores/química , Glicopeptídeos/química , Glicopeptídeos/síntese química , Mucina-1/química , Triazóis/química , Técnicas de Química SintéticaRESUMO
Dystroglycanopathies are diseases characterized by progressive muscular degeneration and impairment of patient's quality of life. They are associated with altered glycosylation of the dystrophin-glycoprotein (DGC) complex components, such as α-dystroglycan (α-DG), fundamental in the structural and functional stability of the muscle fiber. The diagnosis of dystroglycanopathies is currently based on the observation of clinical manifestations, muscle biopsies and enzymatic measures, and the available monoclonal antibodies are not specific for the dystrophic hypoglycosylated muscle condition. Thus, modified α-DG mucins have been considered potential targets for the development of new diagnostic strategies toward these diseases. In this context, this work describes the synthesis of the hypoglycosylated α-DG mimetic glycopeptide NHAc-Gly-Pro-Thr-Val-Thr[αMan]-Ile-Arg-Gly-BSA (1) as a potential tool for the development of novel antibodies applicable to dystroglycanopathies diagnosis. Glycopeptide 1 was used for the development of polyclonal antibodies and recombinant monoclonal antibodies by Phage Display technology. Accordingly, polyclonal antibodies were reactive to glycopeptide 1, which enables the application of anti-glycopeptide 1 antibodies in immune reactive assays targeting hypoglycosylated α-DG. Regarding monoclonal antibodies, for the first time variable heavy (VH) and variable light (VL) immunoglobulin domains were selected by Phage Display, identified by NGS and described by in silico analysis. The best-characterized VH and VL domains were cloned, expressed in E. coli Shuffle T7 cells, and used to construct a single chain fragment variable that recognized the Glycopeptide 1 (GpαDG1 scFv). Molecular modelling of glycopeptide 1 and GpαDG1 scFv suggested that their interaction occurs through hydrogen bonds and hydrophobic contacts involving amino acids from scFv (I51, Y33, S229, Y235, and P233) and R8 and α-mannose from Glycopeptide 1.
Assuntos
Anticorpos Monoclonais/imunologia , Distroglicanas/imunologia , Glicoproteínas/imunologia , Mucinas/imunologia , Síndrome de Walker-Warburg/diagnóstico , Distroglicanas/química , Glicoproteínas/síntese química , Humanos , Mucinas/químicaRESUMO
α-Dystroglycan (α-DG) mucins are essential for maintenance of the structural and functional stability of the muscle fiber and, when hypoglycosylated, they are directly involved in pathological processes such as dystroglycanopathies. Thus, this work reports the synthesis of the novel 1,2,3-triazole-derived glycosyl amino acids αGlcNAc-1-O-triazol-2Manα-ThrOH (1) and Gal-ß1,4-αGlcNAc-1-O-triazol-2Manα-ThrOH (2), followed by solid-phase assembly to get the corresponding glycopeptides NHAcThrVal[αGlcNAc-1-triazol-2Manα]ThrIleArgGlyOH (3) and NHAcThrVal[Gal-ß1,4-αGlcNAc-1-triazol-2Manα]ThrIleArgGlyOH (4) as analogs of α-DG mucins. The glycosyl amino acids 1 (72%) and 2 (35%) were synthesized by Cu(I)-assisted 1,3-dipolar azide-alkyne cycloaddition reactions (CuAAC) between the azide-glycosyl amino acid αManN3-FmocThrOBn (5) and the corresponding alkyne-functionalyzed sugars 2'-propynyl-αGlcNAc (6) and 2'-propynyl-Gal-ß1,4-αGlcNAc (7), followed by hydrogenation reactions. Subsequently, glycopeptides 3 (23%) and 4 (12%) were obtained by solid phase synthesis, involving sequential couplings of Fmoc-protected amino acids or the glycosyl amino acids 1 and 2, followed by cleavage from resin, N-acetylation and O-deacetylation (NaOMe) reactions. Lastly, enzymatic galactosylation of glycopeptide 3 with bovine ß-1,4-GalT showed that it was not a substrate for this enzyme, which could be better elucidated by docking simulations with ß-1,4-GalT.
Assuntos
Distroglicanas/química , Glicopeptídeos/síntese química , Mucinas/química , Triazóis/química , Animais , Bovinos , Glicopeptídeos/química , Simulação de Acoplamento Molecular , Estrutura Molecular , N-Acetil-Lactosamina Sintase/metabolismo , Técnicas de Síntese em Fase SólidaRESUMO
Chagas disease is still a worldwide threat, with estimated 6 to 7 million infected people, mainly in Latin America. Current treatments still rely only on benznidazol and nifurtimox, drugs with poor efficacy in chronic infection phase and recognized toxicity. Thus, there is an urgent need for new therapeutic agents against this disease. In this review we present an updated selection over the last decade of synthetic glycoconjugates as anti-trypanosomal agents, properly addressed as monosaccharideand disaccharide-based agents, and multivalent-based derivatives, disclosing relevant methods for their synthesis, along with their activities on T. cruzi and its trans-sialidase (TcTS). In addition, synthetic glycoconjugates as potential vaccines and diagnostic antigens against T. cruzi are also reported.
Assuntos
Glicoconjugados/farmacologia , Tripanossomicidas/farmacologia , Trypanosoma cruzi/efeitos dos fármacos , Animais , Glicoconjugados/síntese química , Glicoconjugados/química , Humanos , Modelos Moleculares , Estrutura Molecular , Testes de Sensibilidade Parasitária , Tripanossomicidas/síntese química , Tripanossomicidas/químicaRESUMO
The synthesis of the O-3 triazole-linked galactosyl arylsulfonamides 1-7 as potential inhibitors of Trypanosoma cruzi cell invasion is described. These target compounds were synthesized by Cu(I)-catalysed azide-alkyne cycloaddition reaction ('click chemistry') between different azide arylsulfonamides and the alkyne-based sugar 3-O-propynyl-ßGalOMe. Inhibition assays of T. cruzi cell invasion with compounds 1-7 showed reduced values of infection index (â¼20) for compounds 3 and 5, bearing the corresponding 5-methylisoxazole and 2,4-dimethoxypyrimidine groups, which also presented higher binding affinities to galectin-3 (EC50 17-18⯵M) in Corning Epic label-free assays. In agreement with experimental results, the assessment of the theoretical binding of compounds 1-7 to galectin-3 by MM/PBSA method displayed higher affinities for compounds 3 (-9.7â¯kcal/mol) and 5 (-11.1â¯kcal/mol). Overall, these achievements highlight compounds 3 and 5 as potential T. cruzi cell invasion blockers by means of a galectin-3 binding-related mechanism, revealing galectin-3 as an important host target for design of novel anti-trypanosomal agents.
Assuntos
Inibidores Enzimáticos/farmacologia , Fibroblastos/efeitos dos fármacos , Galectina 3/metabolismo , Tripanossomicidas/farmacologia , Trypanosoma cruzi/efeitos dos fármacos , Animais , Sítios de Ligação/efeitos dos fármacos , Proteínas Sanguíneas , Relação Dose-Resposta a Droga , Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/química , Fibroblastos/parasitologia , Galactose/química , Galactose/farmacologia , Galectinas , Glicoproteínas/antagonistas & inibidores , Glicoproteínas/metabolismo , Haplorrinos , Humanos , Estrutura Molecular , Neuraminidase/antagonistas & inibidores , Neuraminidase/metabolismo , Relação Estrutura-Atividade , Sulfonamidas/química , Sulfonamidas/farmacologia , Triazóis/química , Triazóis/farmacologia , Tripanossomicidas/síntese química , Tripanossomicidas/química , Trypanosoma cruzi/enzimologiaRESUMO
This study presents the synthesis of the novel protected O-glycosylated amino acid derivatives 1 and 2, containing ßGalNAc-SerOBn and ßGalNAc-ThrOBn units, respectively, as mimetics of the natural Tn antigen (αGalNAc-Ser/Thr), along with the solid-phase assembly of the glycopeptides NHAcSer-Ala-Pro-Asp-Thr[αGalNAc]-Arg-Pro-Ala-Pro-Gly-BSA (3-BSA) and NHAcSer-Ala-Pro-Asp-Thr[ßGalNAc]-Arg-Pro-Ala-Pro-Gly-BSA (4-BSA), bearing αGalNAc-Thr or ßGalNAc-Thr units, respectively, as mimetics of MUC1 tumor mucin glycoproteins. According to ELISA tests, immunizations of mice with ßGalNAc-glycopeptide 4-BSA induced higher sera titers (1:320 000) than immunizations with αGalNAc-glycopeptide 3-BSA (1:40 000). Likewise, flow cytometry assays showed higher capacity of the obtained anti-glycopeptide 4-BSA antibodies to recognize MCF-7 tumor cells. Cross-recognition between immunopurified anti-ßGalNAc antibodies and αGalNAc-glycopeptide and vice versa was also verified. Lastly, molecular dynamics simulations and surface plasmon resonance (SPR) showed that ßGalNAc-glycopeptide 4 can interact with a model antitumor monoclonal antibody (SM3). Taken together, these data highlight the improved immunogenicity of the unnatural glycopeptide 4-BSA, bearing ßGalNAc-Thr as Tn antigen isomer.
Assuntos
Anticorpos Monoclonais/metabolismo , Formação de Anticorpos/efeitos dos fármacos , Antígenos Glicosídicos Associados a Tumores/química , Mucina-1/metabolismo , Mucina-1/farmacologia , Animais , Antineoplásicos/síntese química , Antineoplásicos/metabolismo , Antineoplásicos/farmacologia , Bioensaio/normas , Sequência de Carboidratos , Humanos , Isomerismo , Células MCF-7 , Camundongos , Modelos Biológicos , Simulação de Dinâmica Molecular , Mucina-1/química , Técnicas de Síntese em Fase Sólida , Ressonância de Plasmônio de SuperfícieRESUMO
Galectin-3 is associated with the development and malignancy of several types of tumor, mediating important tumor-related functions, such as tumorigenesis, neoplastic transformation, tumor cell survival, angiogenesis, tumor metastasis and regulation of apoptosis. Therefore, synthetic galectin-3 inhibitors are of utmost importance for development of new antitumor therapeutic strategies. In this review we present an updated selection of synthetic glycoconjugates inhibitors of tumor-related galectin-3, properly addressed as monosaccharide- and disaccharide-based inhibitors, and multivalent-based inhibitors, disclosuring relevant methods for their synthesis along with their inhibitory activities towards galectin-3. In general, Cu(I)-assisted 1,3-dipolar azide-alkyne cycloaddition (CuAAC) reactions were predominantly applied for the synthesis of the described inhibitors, which had their inhibitory activities against galectin-3 evaluated by fluorescence polarization, surface plasmon resonance (SPR), hemagglutination, ELISA and cell imaging assays. Overall, the presented synthetic glycoconjugates represent frontline galectin-3 inhibitors, finding important biomedical applications in cancer.
Assuntos
Galectina 3/antagonistas & inibidores , Glicoconjugados , Proteínas de Neoplasias/antagonistas & inibidores , Neoplasias/tratamento farmacológico , Animais , Proteínas Sanguíneas , Galectina 3/metabolismo , Galectinas , Glicoconjugados/síntese química , Glicoconjugados/química , Glicoconjugados/uso terapêutico , Humanos , Proteínas de Neoplasias/metabolismo , Neoplasias/metabolismoRESUMO
This work describes the synthesis of the 1,2,3-triazole amino acid-derived-3-O-galactosides 1-6 and the 1,2,3-triazole di-lactose-derived glycoconjugate 7 as potential galectin-3 inhibitors. The target compounds were synthesized by Cu(I)-catalyzed azide-alkyne cycloaddition reaction ('click chemistry') between the azido-derived amino acids N3-ThrOBn, N3-PheOBn, N3-N-Boc-TrpOBn, N3-N-Boc-LysOBn, N3-O-tBu-AspOBn and N3-l-TyrOH, and the corresponding alkyne-based sugar 3-O-propynyl-GalOMe, as well as by click chemistry reaction between the azido-lactose and 2-propynyl lactose. Surface plasmon resonance (SPR) assays showed that all synthetic glycoconjugates 1-7 bound to galectin-3 with high affinity, but the highest binders were the amino acids-derived glycoconjugates 2 (KD 7.96µM) and 4 (KD 4.56µM), and the divalent lactoside 7 (KD1 0.15µM/KD2 19µM). Molecular modeling results were in agreement with SPR assays, since more stable interactions with galectin-3 were identified for glycoconjugates 2, 4 and 7. Regarding compounds 2 and 4, they established specific cation-π (Arg144) and ionic (Asp148) interactions, whereas glycoconjugate 7 was capable to bridge two independent galectin-3 CRDs, creating a non-covalent cross-link between two monomers and, thus, reaching a submicromolar affinity towards galectin-3.
Assuntos
Aminoácidos/química , Galactosídeos/química , Galectina 3/química , Glicoconjugados/química , Triazóis/química , Alcinos/química , Azidas/química , Proteínas Sanguíneas , Química Click , Reação de Cicloadição , Galectinas , Glicoconjugados/síntese química , Humanos , Lactose/química , Ligantes , Simulação de Acoplamento Molecular , Simulação de Dinâmica Molecular , Ligação ProteicaRESUMO
Aim: Mechanical characteristics of the preparation along with luting agent are significant elements on the maintenance of fixed prostheses. This study aimed at assessing the retention of metal complete crowns luted with two different luting agents under different preparation height. Methods: Forty human third molars were selected and prepared to receive total crowns, and were randomly divided in 4 groups: (1) 5-mm preparation height (PH) and RelyX U100 self-adhesive resin cement (SA); (2) 5-mm PH and zinc phosphate (ZP); (3) 3-mm PH and SA; and (4) 3-mm PH and ZP. Crowns were cast in nickel-chromium alloy. The tensile strength was tested in a universal testing machine. Results: Mean tensile strength values to crown displacement (kgf) and standard deviation were 39.6 (13.0) for group 1; 16.9 (8.1) for group 2; 32.2 (7.9) for group 3; and 10.6(3.2) for group 4. Overall, the crowns cemented with SA presented significantly higher mean tensile strength values than ZP, and the 5-mm PH presented significantly higher mean tensile strength values than 3-mm PH. Conclusions: The self-adhesive resin cement and higher preparation height improved crown retention.
Assuntos
Humanos , Coroas , Cimentação/métodos , Cimentos de Resina , Retenção em Prótese Dentária/métodos , Resistência à Tração , Análise de VariânciaRESUMO
A disostose cleidocraniana é uma síndrome relativamente rara, congênita, que se caracteriza por apresentar anomalias esqueléticas específicas e manifestações na cavidade bucal. É descrita como uma doença genética de herança autossômica dominantes relacionada com a perda de um dos alelos do gene CBFA1. Os sinais clínicos mais característicos são a hipoplasia ou aplasia das clavículas e o envolvimento da cavidade bucal e dos dois terços superiores da face. Este estudo relata dois casos clínicos familiares da disostose cleidocraniana, bem como revisa a literatura enfocando os aspectos clínicos e readiográficos dessa síndrome