Estudos de síntese de dendrons dirigidos de NFOH com potencial antichagásico e modelagem molecular do receptor de manose de macrófagos / Studying the synthesis of NFOH targeted dendrons, potentially active in Chagas disease, and the molecular modeling of manose receptor from macrophages

A doença de Chagas, considerada doença extremamente negligenciada, acomete mais de 6 milhões de pessoas ao redor do mundo e mais de 75 milhões de pessoas vivem sob risco da doença. Considerada endêmica em 21 países da América Latina. No Brasil, grassa, sobretudo, na região Norte, especialmente, na região amazônica. Apesar de se constituir em risco global, a doença de Chagas conta com apenas com dois fármacos, o benznidazol e o nifurtimox, que, além de tóxicos, não apresentam eficácia significativa na fase crônica da parasitose. Assim sendo, torna-se imperativa a busca por quimioterápicos mais eficazes, mormente na fase crônica da doença. A introdução de novos fármacos da terapêutica várias fases, consumindo tempo e recursos. No entanto, há processos que permitem a otimização de fármacos já existentes e de compostos bioativos, com vistas à busca de candidatos a fármacos, que, uma vez bem-sucedidos nos ensaios clínicos, são aprovados para uso terapêutico. Entre esses processos, destaca-se a latenciação, forma de aprimoramento de propriedades farmacêuticas, farmacocinéticas e, indiretamente, farmacodinâmicas, que utiliza, em geral, transportadores para a resolução de problemas dessas naturezas. Os transportadores variam de acordo com o problema a ser resolvido e, entre eles, os dendrons e dendrímeros podem ser ressaltados pela sua natureza química, que permite a ligação de várias moléculas de fármacos/compostos bioativos e, também, de grupos diretores para certos compartimentos ou células. Dessa forma, podem-se obter fármacos dirigidos, que se constituem em formas latentes de alta seletividade. Face ao exposto e, estimulados pela busca de novas alternativas terapêuticas para a doença de Chagas, o objetivo deste trabalho foi a obtenção de dendrons dirigidos, por meio de manose, derivados de hidroximetilnitrofural (NFOH). Esse composto foi mostrou-se altamente ativo contra T. cruzi, também na fase crônica NFOH e menos tóxico que o protótipo e o benznidazol. Efetuaram-se estudos para a síntese desses compostos derivados de dendron triazólico, sintetizado através de click chemistry, tendo a manose como grupo diretor para os macrófagos, onde, também, são encontrados os amastigotas de Trypanosoma cruzi. Obtiveram-se alguns intermediários, que foram caracterizados por RMN 1H e 13C. A rota sintética proposta não pôde ser finalizada. Por outro lado, efetuaram-se estudos de modelagem molecular, utilizando-se dinâmica molecular, com o intuito de conhecer como se dá a interação da manose e de polimanosídeos com seu respectivo receptor e como se realiza a liberação do composto bioativo da ligação com o dendron. Anteriormente, procedeu-se à caracterização da biologia estrutural do receptor de manose e de suas estruturas primárias, secundárias e terciárias, com ênfase para o domínio CRD4 o papel do cálcio principal na interação com o monossacarídeo. A movimentação do domínio foi muito pouco diferente nos meios simulados (neutro, ácido, contendo ligantes e contendo o cálcio auxiliar), evidenciado pelo RMSF e estudo de PCA desses sistemas. Foi possível concluir que este domínio não apresenta nenhuma alteração conformacional responsável pela liberação de ligantes em meio lisossômico, e que o cálcio auxiliar e os ligantes não causam impactos na estabilidade conformacional do CRD4. Há necessidade de mais estudos para o conhecimento dos requisitos estruturais envolvidos na da formação do complexo receptor-composto bioativo

Chagas disease, considered an extremely neglected one, affects more than 6 million people all over de world, with more than 75 million people living under its risk, while endemics in 21 countries in Latin America. In Brazil, it propagates, mainly in North region, especially in Amazon region. Although being a global risk, only two drugs, benznidazole and nifurtimox, are currently available for Chagas disease. These drugs are toxic and not significantly efficient against the chronic phase of the disease. Therefore, the search for more active chemotherapeutic agents, mainly against the chronic phase of the parasitosis, is imperative. The introduction of new drugs in the therapeutics involves many phases, consuming time, and money. Notwithstanding, there are processes that allow either drugs or bioactive compounds to be optimized, towards drug candidates. These derivatives, once well-succeeded in the clinical trials, can be approved for therapeutic uses. Among those processes, prodrug design stands out. It is a way to improve the pharmaceutics, pharmacokinetics and, indirectly, pharmacodynamics, properties of drugs/bioactive compounds, which requires adequate carriers, in general, for these problems´ solution. The carriers vary according to the problem to be solved, and, among them, dendrons and dendrimers can be emphasized due to their chemical nature, which allows the link of many molecules/bioactive compounds and of directing groups to specific compartments or cells. Thus, targeted drugs, which are latent forms of drugs/bioactive compounds with high selectivity. In this connection and stimulated by the search for new therapeutic alternatives for Chagas disease, the objective of this work was obtaining hydroxymethylnitrofurazone (NFOH) targeted dendrons, by means of mannose, as directing groups. NFOH is highly active against T. cruzi, even in chronic phase of the disease, and less toxic than the prototype and benznidazole. Studies have been developed to synthesize these compounds with a triazole dendron, planned to be obtained by click chemistry. Mannose was designed to be the directing groups to macrophages, where the T. cruzi amastigotes can also be found. Some intermediaries have been obtained and structurally characterized by 1H and 13C NMR, but the proposed synthetic route could not be finished. On the other hand, molecular modeling studies have been developed, using molecular dynamics, with the aim to know how the interaction of mannose, and also of polymannoside, occur with the specific receptor, and how NFOH is released from its linkage to the dendron. The structural biology characterization, as well as of primary, secondary and tertiary structures of the mannose receptor was previously performed, with emphasis onCRD4 and main calcium role in the interaction of the mannoside. All systems simulated (neutral medium, acid medium, complexes with ligands and auxiliary calcium) showed little movement differences when analyzed by RMSF and PCA calculations. It was possible to conclude that this domain shows no conformational changes involved in ligand releasing in lysosomal environment and its conformation is not altered when in presence of ligands or the auxiliary calcium. Much more studies are needed to the knowledge of the structural requirements to the complex receptor-drug-compound bioactive to the receptor

Pró-Fármacos dendriméricos potencialmente ativos em Malária e Tuberculose: Síntese e avaliação da atividade biológica / Dendrimeric prodrugs potentially active in malaria and tuberculosis: Synthesis and evaluation of biological activity

HIV/AIDS, tuberculose, malária e as doenças tropicais negligenciadas representam uma grande preocupação em Saúde em muitas regiões do mundo. Os fármacos disponíveis para o tratamento apresentam diversos problemas, tais como toxicidade e resistência ao parasita. Mesmo com esse triste panorama, o investimento em pesquisa nessa área é, ainda, pouco significativo. Assim, dentre os métodos de modificação molecular para melhorar propriedades farmacêuticas, farmacocinéticas e/ou farmacodinâmica de compostos bioativos destaca-se a latenciação. Já os dendrímeros vêm despertando interesse em aplicações biológicas, principalmente como transportadores de fármacos, além de atuarem como transportadores de genes, imagem em diagnóstico e compostos com ação per se. Face ao exposto e tendo em vista o caráter promissor dos dendrímeros como sistemas de drug delivery, o objetivo deste trabalho foi a síntese de pró-fármacos dendriméricos potencialmente ativos em malária e tuberculose. Os dendrímeros de Bis-MPA (gerações 0, 1 e 2) foram sintetizados pelo grupo do Professor Scott Grayson, da Tulane University (EUA). No Brasil, foram feitas as funcionalizações destes compostos, através do acoplamento do ácido succínico (que funciona como espaçante) e as moléculas ativas. Selecionaram-se as seguintes substâncias: (1) primaquina, com ação antimalárica e (2) isoniazida, de ação nos primeiros estágios da tuberculose. Foram sintetizados os pró-fármacos dendriméricos de isoniazida nas gerações 0 e 1 (G0-Iso e G1-Iso), e primaquina nas gerações 0, 1 e 2 (G0-Pq, G1-Pq e G2Pq). Importante mencionar que os resultados de Ressonância Magnética e Nuclear de 1H e de 13C demostraram as obtenções dos respectivos produtos, porém contendo impurezas. Já a análise do resultado proveniente da espectrometria de massas do composto G0-Iso revelou a presença de um subproduto ciclizado da isonizaida succinoilada (CIso-Suc), o qual pode ser um potencial pró-fármaco ou apresentar atividade per se. Como não se conhece este composto, o laboratório coordenado pela Profas Elizabeth Igne Ferreira e Jeanine Giarolla manifestou interesse em pesquisa-lo, principalmente quanto suas propriedades físico- químicas, bem como quanto à atividade biológica. Assim, utilizando metodologia analítica previamente estabelecida para o G0-Iso, os estudos de estabilidade química da CIso-Suc, em diferentes valores de pH, demonstraram a capacidade da forma ciclizada em se converter no protótipo Iso-Suc, majoritariamente em pH 7,4 e 8,5. Como perspectivas, destaca-se a avaliação da estabilidade enzimática deste potencial derivado. Ressalta-se, ainda, a a avaliação da respectiva atividade antimicobacteriana. Em relação aos pró-fármacos, as necessidades de aprimoramentos das sínteses são, também, evidenciadas. Uma vez sintetizados e caracterizados, estes últimos derivados serão avaliados quanto à atividade biológica. Ademais, estudos computacionais, sobretudo simulações de docking molecular, foram desenvolvidos com intuito de se entender o modo de interação de alguns compostos com alvos biológicos pré-determinados

HIV/AIDS, tuberculosis, malaria and neglected diseases are a major health concern in many regions of the world. The drugs available present various problems, such as toxicity and parasite resistance. Even with this sad outlook, research investment in this area is still insignificant. Among the molecular modification methods to improve the pharmaceutical, pharmacokinetic and/or pharmacodynamic properties we stands out prodrug design. On the other hand, dendrimers are arousing interest in biological applications, mainly as drug carriers, besides gene delivery, diagnostic imaging, as well as acting as compounds with activity per se. Considering that, added to the promising dendrimer drug delivery features, the aim of this study was to synthesize potentially active dendrimer prodrugs in malaria and tuberculosis. Bis-MPA dendrimers (generations 0, 1 and 2) were synthesized by the group of Professor Scott Grayson of Tulane University (USA). Herein in Brazil, the compounds were functionalized by coupling succinic acid (spacer group), as well as the active molecules. We selected the following substances: (1) primaquine, with antimalarial action and (2) isoniazid, acting in the early stages of tuberculosis. Isoniazid dendrimer prodrugs were synthesized generations 0 and 1 (G0-Iso and G1-Iso), and primaquine in generations 0, 1 and 2 (G0-Pq, G1-Pq and G2-Pq). It is important to mention that the results related to Nuclear and Magnetic Resonance 113C showed chemical structures features, however with impurities. Analysis of the mass spectrometry regarding G0-Iso has revealed the presence of a cyclized by-product of succinylated isonized (CIso-Suc), which may be a potential prodrug or may presentactivity itself. Using the analytical methodology performed for G0-Iso, ICso-Suc demonstrated its ability to convert the Iso-Suc prototype at different pH values, especially at pH 7.4 and 8.5. As perspectives, we highlight the determinations of the chemical stability of ICsoSuc at pH 1.5 and 6.0, as well as the evaluation of the enzymatic stability. We will also investigate the respective antimicobacterial activities. Regarding prodrugs, the needs for synthesis enhancements are also necessary. Once synthesized and characterized, these latter derivatives will be evaluated for biological activity. Moreover, computational studies, especially molecular docking simulations, were developed in order to understand the mode of interaction of some compounds with predetermined biological targets

Research progress on the biomimetic remineralization of hard tooth tissues based on polyamide-amine dendrimer / 华西口腔医学杂志

Polyamide-amine (PAMAM) dendrimer, a new hyperbranched macromolecular polymer, is considered an "artificial protein" by many scholars on account of its excellent chemical and biological characteristics. PAMAM has internal cavities and a large number of reactive terminal groups. These structures allow the polymer to be used as a bionic macromoleculethat could simulate the biomimetic mineralization of the natural organic matrix on the surface of tooth tissue. Specifically, PAMAM can beused as an organic template to regulate mineral nucleation and crystal growth; thus, the polymerisa more ideal dental restoration material than traditional allogenic materials. This article reviews research progress on thePAMAM-induced biomimetic mineralization of hard tooth tissues.

Modulation of Electroosmotic Flow through Skin: Effect of Poly(Amidoamine) Dendrimers

The objective of this work is to evaluate the effect of polyamidoamine (PAMAM) dendrimers on electroosmotic flow (EOF) through skin. The effect of size and concentration of dendrimer was studied, using generation 1, 4 and 7 dendrimer (G1, G4 and G7, respectively). As a marker molecule for the direction and magnitude of EOF, a neutral molecule, acetoaminophen (AAP) was used. The visualization of dendrimer permeation into the current conducting pore (CCP) of skin was made using G4–fluorescein isothiocyanate (FITC) conjugate and confocal microscopy. Without dendrimer, anodal flux of AAP was much higher than cathodal or passive flux. When G1 dendrimer was added, anodal flux decreased, presumably due to the decrease in EOF by the association of G1 dendrimer with net negative charge in CCP. As the generation increased, larger decrease in anodal flux was observed, and the direction of EOF was reversed. Small amount of methanol used for the preparation of dendrimer solution also contributed to the decrease in anodal flux of AAP. Cross-sectional view perpendicular to the skin surface by confocal laser scanning microscope (CLSM) study showed that G4 dendrimer-FITC conjugate (G4-FITC) can penetrate into the viable epidermis and dermis under anodal current. The permeation route seemed to be localized on hair follicle region. These results suggest that PAMAM dendrimers can permeate into CCP and change the magnitude and direction of EOF. Overall, we obtained a better understanding on the mechanistic insights into the electroosmosis phenomena and its role on flux during iontophoresis.

Estudo de síntese e estabilidades química e enzimática de fármaco dirigido dendrimérico potencialmente ativo em doença de Chagas / Synthesis, chemical and enzymatic stability studies of targeted dendrimer potentially active in Chagas disease

A doença de Chagas representa um problema de saúde pública em muitos países e regiões. O tratamento consiste em fármacos tóxicos, com eficácia discutível, principalmente, na fase crônica da doença. Assim, faz-se necessário o planejamento de novos quimioterápicos, mais seguros e eficazes. Os dendrímeros são novas arquiteturas moleculares formadas por um foco central e ramificações partindo desse foco. Apresentam diversas aplicações biológicas como, por exemplo, atuar como transportadores de fármacos. Face ao exposto, o objetivo deste trabalho foi o estudo de condições para ligar o ácido anacárdico (AA) em derivado dendrimérico com potencial ação na doença de Chagas, o qual tem como foco central o ácido succínico (AS) e ramificações compostas por arginina (Arg) e lisina (Lys). Sabe-se que a cruzaína, uma cisteíno-protease do T. cruzi, catalisa a hidrólise de ligação peptídica entre lisina e arginina. A síntese dos compostos em fase sólida forneceu os derivados brutos: (1) pró-fármaco AA-K-R-NH2 e (2) G.05 AA-K(AS)-R-NH2, que foram purificados e caracterizados por Cromatografia Líquida de Alta Eficiência e espectrometria de massas. Os compostos purificados AA-K-R-NH2 e AA-K(AS)-R-NH2 apresentaram rendimentos de 34% e 47%, com pureza de 88% e 98%, respectivamente. Os resultados dos experimentos enzimáticos utilizando o AA-K-R-NH2 não foram conclusivos. Acredita-se que a baixa solubilidade e/ou baixa concentração podem ter contribuído para tal. Já na estabilidade química em pH 7,4 (que simula pH sanguíneo), pH 1,2 (que simula pH estomacal) e pH 8,5 (que simula pH intestinal), observou-se que o AA-K(AS)-R-NH2 foi estável durante as 24 h de ensaio. Estes últimos resultados são interessantes, pois espera-se que o pró-fármaco dendrimérico alcance o T. cruzi estruturalmente integro, sofrendo hidrólise e liberação do composto ativo no interior do parasita

Chagas disease is a public health problem in many countries and regions. The treatment consists of toxic drugs, with debatable efficacy, mainly, in the chronic phase of the disease. Thus, it is necessary to plan new chemotherapeutics, safer and more effective than those drugs. Dendrimers are new molecular architectures composed by a central focus and branching from that focus. They present several biological applications, such as acting as drug carriers. Thereby, the goal of this work was the study of conditions to bind anacardic acid (AA) in a dendrimeric derivative with potential action in Chagas disease, which was composed by a central focus of succinic acid (AS) and branches of arginine (Arg) and lysine (Lys). Cruzain, a T. cruzi cysteine protease, is known to catalyze the peptide-binding hydrolysis between lysine and arginine. Synthesis of the solid phase compounds provided the crude derivatives: (1) prodrug AA-KR-NH2 and (2) G.05 AA-K(AS)-R-NH2, which were purified and characterized by High Performance Liquid Chromatography (HPLC) and mass spectrometry. The purified AA-K-R-NH2 and AA-K(AS)-R-NH2 compounds showed yields of 34% and 47%, with purity of 88% and 98% respectively. The results of the enzymatic experiments using AA-K-R-NH2 were not conclusive. It is believed that the low solubility and/or low concentration may have contributed for this. On the chemical stability at pH 7.4 (which simulates blood pH), pH 1.2 (which simulates stomach pH) and pH 8.5 (which simulates intestinal pH), it was observed that AA-K(AS)R-NH2 was stable for 24 hours. These latter results are interesting because the dendrimeric prodrug is expected to reach structurally integral T. cruzi, undergoing hydrolysis and release of the active compound within the parasite

Synthesis and anti-intracellular Copper overload evaluation of Nanoconjugated D-penicillamine -Dendrimer in Wilson's model cells

Background and Objective: Wilson's disease [WD] is caused by mutation to the cooer-transporting gene ATP7B. Chelation therapy is the main protochol of treatment for patients with Wilson's disease. D-penicillamine is one of the well-known chelator agants which is used in WD treatment but it can not enter into the intracellular space.This study was done to evaluate the synthesis and anti-intracellular Copper overload evaluation of Nanoconjugated D-penicillamine -Dendrimer in Wilson's model cells

Methods: In this descriptive-analytic study, initially 0.01 mm polyethylene glycol [PEG] and 0.0018 mm citric acid, Dendrimer was synthesized. After purification by dialysis bag and lyophilization, lOmg dendrimer was conjugated to 3.3mg D-penicillamine. Nanoconjugated D-penicillamine-dendrimer was injected on Wilson's model cells. After incubation and centrifugation intracellular measurement of copper concentration and FTIR test were done

Results: Copper accumulation significantly reduced in the HepG2 WD cell by Nanoconjugated D-penicillamine - Dendrimer in compared to D-penicillamine [P<0.05]. Copper accumulation was determined to be 46.61, MTT assay showed no toxicological damage in HepG2 WD cell

Conclusion: Nanoconjugated D-penicillamine -Dendrimer can reduces intracellular concentration of Copper

Antichagásicos e leishmanicidas potenciais: estudo das condições de síntese de pró-fármacos dendriméricos de 3-hidroxiflavona / Potential antichagasic and leishmanicide compounds: study of synthesis conditions of 3-hydroxyflavone dendrimer prodrugs

INTRODUÇÃO: A doença de Chagas e a leishmaniose são doenças tropicais supernegligenciadas, que afetam regiões de extrema pobreza. Os fármacos disponíveis para estas duas doenças são escassos, de eficácia limitada, de alta toxicidade e suscitam casos de resistência. OBJETIVO: Considerando-se a necessidade de desenvolvimento de novos agentes antichagásicos e leishmanicidas, a importância da latenciação no aprimoramento de fármacos/compostos bioativos e a versatilidade de transportadores dendriméricos, o objetivo deste trabalho foi a síntese de pró-fármacos dendriméricos de primeira geração de 3-hidroxiflavona, composto que apresenta potencial atividade tripanomicida e leishmanicida. Desta forma, pretendeu-se obter liberação controlada, melhora da permeabilidade, toxicidade reduzida e aumento da eficácia deste agente bioativo. MATERIAL E MÉTODOS: Para a obtenção desses dendrímeros empregaram-se as abordagens divergente e convergente, compostas por várias etapas de síntese com reações de proteção, desproteção e acoplamentos. RESULTADOS E DISCUSSÃO: A abordagem convergente apresentou problemas sintéticos, devido à instabilidade dos derivados contendo 3-hidroxiflavona nas diferentes condições reacionais e de purificação testadas. No entanto, há indícios da síntese dos pró-fármacos dendriméricos de 3-hidroxiflavona, mas esses compostos apresentam-se impuros. Devido a essa instabilidade e a dificuldade de purificação na abordagem convergente, optou-se pela síntese divergente, no qual o composto bioativo é acoplado na etapa final. Os estudos sintéticos mostraram a obtenção dos intermediários puros formados pelos focos centrais propano- e hexano-diamina acoplados ao ácido málico protegido. CONCLUSÃO: Há indicativos da obtenção de pró-fármacos dendriméricos de 3-hidroxiflavona, ainda que impuros. As maiores dificuldades encontradas foram a purificação e a estabilidade dos compostos obtidos

INTRODUCTION: Chagas' disease and leishmaniasis are super neglected tropical diseases that affect primarily areas of extreme poverty. The drugs available for these diseases are scarce and of limited effectiveness, toxic and rouse resistance. OBJECTIVE: Considering that the development of new antichagasic and leishmanicide agents are urgently needed, the importance of prodrug design to the improvement of drugs and bioactive compounds and the versatility of dendrimers as drug carriers, the objective of this work was the synthesis of dendrimer prodrug of 3-hydroxyflavone, which shows potential antichagasic and leishmanicide activities. Thus, we intended to obtain controlled release, improvement of the permeability, reduction of the toxicity and increase of efficacy of this bioactive agent. MATERIAL AND METHODS: Convergent and divergent approaches have been used to synthesize those compounds. Synthetic steps consist of protection, deprotection and coupling reactions. RESULTS AND DISCUSSION: The convergent approach presented problems due to the instability of the 3-hydroxyflavone derivatives, in different reaction and purification conditions. However, there is evidence of the synthesis of dendrimer prodrugs, though still impure. Due to instability and purification difficulty of intermediate, we performed the divergent synthesis. We obtained the pure intermediates composed by cores propanediamine and hexanediamine coupled to the protected malic acid as spacer group. CONCLUSION: Synthetic studies suggested the synthesis of dendrimer prodrugs, although impure. The greatest difficulties were the purification and the instability of compounds

Non-biological gene carriers designed for overcoming the major extra- and intracellular hurdles in gene delivery, an updated review

Gene therapy as a modern therapeutic approach has not yet advanced to a globally-approved therapeutic approach. Lack of adequate reliable gene delivery system seems to be one of the major reasons from the pharmaceutical biotechnology point of view. Main obstacles delaying successful application of human gene therapy are presented in this review. The unique advantages of non-biological gene carriers as compared to their biological counterparts make them ideal alternatives for overcoming extra- and intracellular barriers in a more safely manner. We, therefore, highlight the significant contributions in non-biological gene delivery and favorable characteristics of different design attitudes with focus on in vivo approaches. Bypassing the rapid extracellular enzymatic degradation of genetic materials is covered in extracellular segment of this review with emphasis on PEGylated and targeted formulations. The successful approaches to pave the rest of the way from cellular uptake to intracellular transfer and gene expression of unpacked DNA are also discussed. From these approaches, we emphasize more on optimization of cationic-based polymers and dendrimers, developing newly designed membrane-effective components, and adjusting the hydrophilic-hydrophobic balance of the synthesized vectors

Preparation and in vitro evaluation of borneol and folic acid co-modified doxorubicin loaded PAMAM drug delivery system / 药学学报

A novel targeting drug carrier (FA-BO-PAMAM) based on the PAMAM G5 dendrimer modified with borneol (BO) and folic acid (FA) molecules on the periphery and doxorubicin (DOX) loaded in the interior was designed and prepared to achieve the purposes of enhancing the blood-brain barrier (BBB) transportation and improving the drug accumulation in the glioma cells. 1H NMR was used to confirm the synthesis of FA-BO-PAMAM; its morphology and mean size were analyzed by dynamic light scattering (DLS) and transmission electron microscope (TEM). Based on the HBMEC and C6 cells, cytotoxicity assay, transport across the BBB, cellular uptake and anti-tumor activity in vitro were investigated to evaluate the properties of nanocarriers in vitro. The results showed that the nanocarrier of FA-BO-PAMAM was successfully synthesized, which was spherical in morphology with the average size of (22.28 ± 0.42) nm, and zeta potential of (7.6 ± 0.89) mV. Cytotoxicity and transport across the BBB assay showed that BO-modified conjugates decreased the cytotoxicity of PAMAM against both HBMEC and C6 cells and exhibited higher BBB transportation ability than BO-unmodified conjugates; moreover, modification with FA increased the total uptake of DOX by C6 cells and enhanced the cytotoxicity of DOX-polymer against C6 cells. Therefore, FA-BO-PAMAM is a promising nanodrug delivery system in employing PAMAM as a drug carrier and treatment for brain glioma.

[ antibacterial effect of polypropylenimine-G2 dendrimer on Escherichia coli, Enterobacter cloacae, Bacillus subtilis, and Staphylococcus aureus]

Dendrimers are a new class of synthetic macromolecules, which have many applications in medical sciences. This study was carried out with the purpose of investigating the antibacterial effect of polypropylenimine-G2 [PPI-G2] dendrimer on some bacterial species. In this study, the antibacterial effects of PPI-G2 dendrimer were studied by disk diffusion and microdilution method. PPI-G2 dendrimer in concentrations of 0.5, 5, 50, and 500microg/ml were inoculated onto blank disks and placed in Mueller-Hinton agar media. Zone of inhibition was investigated by bacterial inoculation according to the McFarland standard 0.5. Minimum inhibitory concentration [MIC] and minimum bactericidal concentration [MBC] of PPI-G2 dendrimer in the concentrations of 0.05, 0.5, 5, 50, and 500microg/ml, were determined using microdilution method in nutrient broth media. In this study, antibacterial activity of dendrimer increased with increasing their concentration in the disk. Zone of inhibition in the concentration of 500microg/ml for E. coli, Enterobacter cloacae, Bacillus subtilis, and Staphylococcus aureus were 19, 20, 25, and 21mm, respectively. The MIC for Enterobacter cloacae, Bacillus subtilis, and Staphylococcus aureus was 5microg/ml and for E. coli was 500microg/ml. In addition, the MBC for Bacillus subtilis and Staphylococcus aurous was 50microg/ml and for E. coli and Enterobacter cloacae was 500microg/ml. The findings of this study showed that PPI-G2 dendrimer has antibacterial effects. However, use of the dendrimer for drinking water disinfection requires further and wider studies

Inhibition of MCF-7/ADR cells by DOX-loaded pluronic-attached PAMAM dendrimer conjugate / 药学学报

Pluronic modified polyamidoamine (PAMAM) conjugate (PF127-PAMAM) was prepared and the inhibiting effect of MDR against MCF-7/ADR was investigated with doxorubicin (DOX) as model drug. 1H NMR and FTIR spectra showed that the conjugate was synthesized successfully. Element analysis accurately measured that 27.63% amino of per PAMAM was modified by pluronic (PAMAM : PF127, 1 : 35.37 mole ratio). PF127-PAMAM showed an increased size and a reduced zeta potential compared to PAMAM. PF127-PAMAM had lower hemolytic toxicity and cytotoxicity due to the reduced zeta potential and the protection of PF127. Each PF127-PAMAM molecular could load 19.58 DOX molecules, and the complex exhibited sustained and pH-sensitive release behavior. PF127-PAMAM/DOX exhibited weaker cytotoxicity than free DOX in MCF-7 cells; while the complex showed much stronger reverse effect of drug resistance in MCF-7/ADR cells, and resistance reversion index (RRI) was as high as 33.15.

Nitric oxide releasing-dendrimers: an overview

Platforms able to storage, release or scavenge NO in a controlled and specific manner is interesting for biological applications. Among the possible matrices for these purposes, dendrimers are excellent candidates for that. These molecules have been used as drug delivery systems and exhibit interesting properties, like the possibility to perform chemical modifications on dendrimers surface, the capacity of storage high concentrations of compounds of interest in the same molecule and the ability to improve the solubility and the biocompatibility of the compounds bonded to it. This review emphasizes the recent progress in the development and in the biological applications of different NO-releasing dendrimers and the nitric oxide release pathways in these compounds.

Plataformas capazes de armazenar, liberar ou capturar NO de forma controlada e específica são de grande interesse tendo-se em vista aplicações biológicas. Dentre as possíveis matrizes que podem ser utilizadas para esse fim, os dendrímeros são excelentes candidatos. Essas moléculas têm sido empregadas em sistemas para o transporte de fármacos e apresentam propriedades interessantes tais como a possibilidade de modificações químicas em sua superfície, a capacidade de estocar altas concentrações de compostos de interesse em uma só molécula e a possibilidade de aumentar a solubilidade e a biocompatibilidade dos compostos a eles ligados. Esta revisão enfatiza os recentes avanços no desenvolvimento e nas aplicações biológicas de diferentes dendrímeros liberadores de NO e a forma em que o óxido nítrico é liberado nesses compostos.

Dendritic surface functionalization of nanomaterials: controlling properties and functions for biomedical applications

A wide variety of nanomaterials have demonstrated promise in medical applications such as drug delivery and imaging. In these applications, the surface chemistry of the materials is critical as it plays an important role in determining the toxicity and biodistribution behavior of the material. We review here the functionalization of nanomaterials with dendrons as an efficient method to alter the surface chemistry of the materials, introducing new properties and functions. Described here is the functionalization of superparamagnetic iron oxide nanoparticles (SPIO) with dendritic guanidines to enhance their transport into cells for magnetic resonance imaging applications. The introduction of dendrons bearing peripheral hydroxyls, amines, guanidines, carbohydrates and Gd(III) chelates to polymer vesicles (polymersomes) is also described. These dendritic moieties allow for modulation of toxicity, cell uptake, protein binding, and contrast agent efficiency, while at the same time allowing the stabilities of the polymersomes to be maintained. Thus, this approach holds promise for the development of a wide range of multifunctional materials for pharmaceutical applications.

Uma grande variedade de nanomateriais tem demonstrado aplicações médicas promissoras, tais como liberação de fármacos e em imagens. Nestas aplicações, a superfície química dos materiais é crítica, uma vez que exerce papel importante na determinação da toxicidade e comportamento de biodistribuição do material. Aqui, nós revisamos a funcionalização de nanomateriais, como dendrons, como método eficiente de alterar a superfície química destes compostos, introduzindo novas propriedades e funções. Descritos aqui estão nanopartículas superparamagnéticas de óxido de ferro (do inglês, SPIO), com guanidinas dendríticas para aumentar seu transporte para o interior das células, úteis em imagens de ressonância magnética. A introdução de dendrons contendo hidroxilas, aminas, guanidinas, carboidratos e quelatos de Gd(III) periféricos em vesículas poliméricas (polymersomes) também está descrita. Esses grupos dendríticos permitem a modulação de toxicidade, captura celular, ligação à proteína e eficiência como agente de contraste, enquanto que, ao mesmo tempo, permitem a manutenção da estabilidade das vesículas poliméricas. Assim, essa abordagem é promissora para o desenvolvimento de grande variedade de materiais multifuncionais para aplicações farmacêuticas.

Biological properties of water-soluble phosphorhydrazone dendrimers

Dendrimers are hyperbranched and perfectly defined macromolecules, constituted of branches emanating from a central core in an iterative fashion. Phosphorhydrazone dendrimers constitute a special family of dendrimers, possessing one phosphorus atom at each branching point. The internal structure of these dendrimers is hydrophobic, but hydrophilic terminal groups can induce the solubility of the whole structure in water. Indeed, the properties of these compounds are mainly driven by the type of terminal groups their bear; this is especially true for the biological properties. For instance, positively charged terminal groups are efficient for transfection experiments, as drug carriers, as anti-prion agents, and as inhibitor of the aggregation of Alzheimer's peptides, whereas negatively charged dendrimers have anti-HIV properties and can influence the human immune system, leading to anti-inflammatory properties usable against rheumatoid arthritis. This review will give the most representative examples of the biological properties of water-soluble phosphorhydrazone dendrimers, organized depending on the type of terminal groups they bear.

Dendrímeros são macromoléculas extremamente ramificadas e perfeitamente definidas constituídas de ramificações que partem de um foco central de uma forma iterativa. Dendrímeros de fosforidrazona constituem uma família especial de dendrímeros, que possuem um átomo de fósforo em cada ponto da ramificação. A estrutura interna destes dendrímeros é hidrofóbica, mas grupos hidrofílicos terminais podem induzir a solubilidade em água de toda estrutura. De fato, as propriedades destes compostos são principalmente orientadas pelos grupos terminais que apresentam, especialmente para as propriedades biológicas. Por exemplo, grupos terminais carregados positivamente são eficientes para experimentos de transfecção, como transportadores de fármacos, agentes antipríons e como inibidores da agregação de peptídeos do Alzheimer, enquanto que dendrímeros carregados negativamente têm propriedades anti-HIV e podem influenciar o sistema imune humano, levando propriedades antiinflamatórias úteis contra artrite reumatoide. Essa revisão dará os exemplos mais representativos das propriedades biológicas de dendrímeros de fosforidrazona solúveis em água, organizados de acordo com os grupos terminais que possuem.

Synthesis and MALDI-ToF characterization of dendronized poly(ethylene glycol)s

Well-defined hybrids of linear poly(ethylene glycol)s (PEGs) and dendritic polyesters were prepared via the dendronization of the alcohol end groups of the mono and difunctional linear PEGs. Though useful for rudimentary product characterization, GPC and NMR could not verify the overall structural purity of these linear-dendritic hybrids. On the other hand, the detailed data provided by MALDI-ToF mass spectrometry enabled confirmation of the high structural purity of the dendronized PEGs at each step of the dendronization procedure. The well-defined number of functionalities on these dendronized PEGs, renders them particularly useful for research in the biomedical sphere where functionality and purity are of the utmost importance. The MALDI-ToF mass spectrometric approach described herein represents a valuable technique for detailed monitoring of these dendronization reactions, as well as a variety of other polymer end group modifications.

Híbridos bem definidos de poli(etilenoglicol) lineares (PEGs) e poliésteres dendriméricos foram preparados via "dendronização" de álcool e grupos de PEGs lineares mono e bifuncionais. Embora úteis para a caracterização rudimentar de produtos, Cromatografia por Permeação em Gel e RMN podem não demonstrar a pureza estrutural global desses híbridos lineares dendríticos. Por outro lado, informações detalhadas provenientes de espectrometria de massas MALDI-ToF permitiram a confirmação de elevada pureza estrutural de PEGs "dendronizados" em cada passo do processo de "dendronização". O número de funcionalidades bem definidas destes PEGs "dendronizados", torna-os particularmente úteis para pesquisa na área biomédica, na qual funcionalidade e pureza são de grande importância. A abordagem de espectrometria de massas MALDI-ToF descrita aqui representa uma técnica valiosa para o monitoramento detalhado destas reações de "dendronização", bem como diversas modificações de outros polímeros e grupos.

Dendrimers as anti-inflammatory agents

Dendrimers constitute an intriguing class of macromolecules which find applications in a variety of areas including biology. These hyperbranched macromolecules with tailored backbone and surface groups have been extensively investigated as nanocarriers for gene and drug delivery, by molecular encapsulation or covalent conjugation. Dendrimers have provided an excellent platform to develop multivalent and multifunctional nanoconjugates incorporating a variety of functional groups including drugs which are known to be anti-inflammatory agents. Recently, dendrimers have been shown to possess anti-inflammatory properties themselves. This unexpected and intriguing discovery has provided an additional impetus in designing novel active pharmaceutical agents. In this review, we highlight some of the recent developments in the field of dendrimers as nanoscale anti-inflammatory agents.

Dendrímeros constituem uma classe intrigante de macromoléculas que apresentam aplicações em diversas áreas incluindo biologia. Essas macromoléculas extremamente ramificadas com esqueleto planejado e grupos de superfície foram extensivamente investigadas como nanotransportadores de genes e de fármacos, por encapsulamento molecular ou conjugação covalente. Dendrímeros têm proporcionado uma plataforma excelente de desenvolvimento nanoconjugados multivalentes e multifuncionais incorporando uma variedade de grupos funcionais, incluindo fármacos que são conhecidos por atuarem agentes antiinflamatórios. Recentemente, os dendrímeros mostraram propriedades antiinflamatórias. Esta inesperada e intrigante descoberta tem proporcionado um impulso adicional no planejamento de novos agente farmacêuticos ativos. Nesta revisão, nós destacamos alguns dos desenvolvimentos recentes no campo dos dendrímeros como agentes antiinflamatórios em nanoescala.

From dendrimers to fractal polymers and beyond

The advent of dendritic chemistry has facilitated materials research by allowing precise control of functional component placement in macromolecular architecture. The iterative synthetic protocols used for dendrimer construction were developed based on the desire to craft highly branched, high molecular weight, molecules with exact mass and tailored functionality. Arborols, inspired by trees and precursors of the utilitarian macromolecules known as dendrimers today, were the first examples to employ predesigned, 1 → 3 C-branched, building blocks; physical characteristics of the arborols, including their globular shapes, excellent solubilities, and demonstrated aggregation, combined to reveal the inherent supramolecular potential (e.g., the unimolecular micelle) of these unique species. The architecture that is a characteristic of dendritic materials also exhibits fractal qualities based on self-similar, repetitive, branched frameworks. Thus, the fractal design and supramolecular aspects of these constructs are suggestive of a larger field of fractal materials that incorporates repeating geometries and are derived by complementary building block recognition and assembly. Use of terpyridine-M2+-terpyridine (where, M = Ru, Zn, Fe, etc) connectivity in concert with mathematical algorithms, such as forms the basis for the Seirpinski gasket, has allowed the beginning exploration of fractal materials construction. The propensity of the fractal molecules to self-assemble into higher order architectures adds another dimension to this new arena of materials and composite construction.

O advento da química dendrítica tem facilitado a pesquisa de materiais por permitir o controle preciso do posicionamento do componente funcional na arquitetura macromolecular. Os protocolos sintéticos iterativos usados para construção dos dendrímeros foram desenvolvidos baseados no desejo de elaborar moléculas extremamente ramificadas, com alta massa molecular, massa exata e funcionalidade planejada. Arborols, inspirados em árvores e precursores de macromoléculas utilitárias, conhecidas hoje como dendrímeros, foram os primeiros exemplos a empregar blocos de construção de ramificação-C 1→3; Características físicas dos Arborols, incluindo a sua forma globular, excelente solubilidade, e agregação, combinam-se para revelar o potencial supramolecular inerente (isto é, a micela unimolecular) destas espécies únicas. A arquitetura que é característica dos materiais dendríticos também exibe qualidades fractais com base em estruturas repetitivas, ramificadas e auto-similares. Assim, o design fractal e os aspectos supramoleculares destas construções são sugestivas de um campo maior de materiais fractais que incorporam geometrias repetidas. O uso de terpiridina-M2+-terpiridina (onde, M = Ru, Zn, Fe, etc) em conjunto com algoritmos matemáticos tais como as formas da base do Triângulo de Seirpinski, tem permitido o início da exploração da construção de materiais fractais. A propensão da auto-criação de moléculas fractais para arquiteturas de ordem superior adiciona outra dimensão para essa nova arena de materiais e construção de compostos.

Glycodendrimers: versatile tools for nanotechnology

Combining nanotechnology with glycobiology has triggered an exponential growth of research activities in the design of novel functional bionanomaterials (glyconanotechnology). More specifically, recent synthetic advances towards the tailored and versatile design of glycosylated nanoparticles namely glyconanoparticles, considered as synthetic mimetics of natural glycoconjugates, paved the way toward diverse biomedical applications. The accessibility of a wide variety of these structured nanosystems, in terms of shapes, sizes, and organized around stable nanoparticles have readily contributed to their development and applications in nanomedicine. In this context, glycosylated gold-nanoparticles (GNPs), glycosylated quantum dots (QDs), fullerenes, single-wall natotubes (SWNTs), and self-assembled glycononanoparticles using amphiphilic glycopolymers or glycodendrimers have received considerable attention to afford powerful imaging, therapeutic, and biodiagnostic devices. This review will provide an overview of the most recent syntheses and applications of glycodendrimers in glycoscience that have permitted to deepen our understanding of multivalent carbohydrate-protein interactions. Together with synthetic breast cancer vaccines, inhibitors of bacterial adhesions to host tissues including sensitive detection devices, these novel bionanomaterials are finding extensive relevance.

A combinação de nanotecnologia com glicobiologia tem desencadeado o crescimento exponencial de atividades de pesquisa em desenvolvimento de novos biomateriais funcionais (gliconanotecnologia). Mais especificamente, recentes avanços sintéticos para o planejamento sob medida e versátil de nanopartículas glicosiladas, ou seja, gliconanopartículas, consideradas como miméticos sintéticos de glicoconjugados naturais, prepararam o caminho para diversas aplicações biomédicas. A acessibilidade da grande variedade destes nanossistemas estruturados, em termos de forma, tamanho e organização, tem prontamente contribuído para seu desenvolvimento e aplicações em nanomedicina. Neste contexto, nanopartículas de ouro glicosiladas (do inglês, GNPs), pontos quânticos glicosilados (do inglês, QDs), fulerenos, nanotubos de parede simples (do inglês, SWNTs) e gliconanopartículas autoconstruídas usando glicopolímeros anfifílicos ou glicodendrímeros têm recebido considerável atenção para originar poderosos instrumentos de imagem, terapêutico e de biodiagnóstico. Esta revisão fornecerá a visão global das mais recentes sínteses e aplicações de glicodendrímeros em glicociência que têm permitindo aprofundar nosso conhecimento das interações multivalentes proteína-carboidrato. Estes novos biomateriais estão sendo considerados de grande relevância, junto com vacinas sintéticas de câncer de mama, inibidores de adesão bacteriana em tecidos hospedeiros incluindo instrumentos de detecção sensível.