RESUMO
Maleic acid was studied by Raman spectroscopy and powder synchrotron X-ray diffraction (XRD) under high pressure conditions by using a diamond anvil cell. The Raman spectroscopy measurements were performed from ambient pressure up to 9.2 GPa in the 100-3200 cm-1 spectral range. While the XRD measurements were performed up to 10.1 GPa. Here we present the pressure-dependence behavior from both the Raman modes and cell parameters. Maleic acid lattice parameters decrease anisotropically as a function of pressure and a reduction of 27% in the volume of the unit cell was observed. Modifications in the material's compressibility were observed at around 2 and 6 GPa.
RESUMO
Propionic acid (PA) predominantly accumulates in tissues and biological fluids of patients affected by propionic acidemia that may manifest chronic renal failure along development. High urinary excretion of maleic acid (MA) has also been described. Considering that the underlying mechanisms of renal dysfunction in this disorder are poorly known, the present work investigated the effects of PA and MA (1-5 mM) on mitochondrial functions and cellular viability in rat kidney and cultured human embryonic kidney (HEK-293) cells. Mitochondrial membrane potential (∆ψm), NAD(P)H content, swelling and ATP production were measured in rat kidney mitochondrial preparations supported by glutamate or glutamate plus malate, in the presence or absence of Ca2+. MTT reduction and propidium iodide (PI) incorporation were also determined in intact renal cells pre-incubated with MA or PA for 24 h. MA decreased Δψm and NAD(P)H content and induced swelling in Ca2+-loaded mitochondria either respiring with glutamate or glutamate plus malate. Noteworthy, these alterations were fully prevented by cyclosporin A plus ADP, suggesting the involvement of mitochondrial permeability transition (mPT). MA also markedly inhibited ATP synthesis in kidney mitochondria using the same substrates, implying a strong bioenergetics impairment. In contrast, PA only caused milder changes in these parameters. Finally, MA decreased MTT reduction and increased PI incorporation in intact HEK-293 cells, indicating a possible association between mitochondrial dysfunction and cell death in an intact cell system. It is therefore presumed that the MA-induced disruption of mitochondrial functions involving mPT pore opening may be involved in the chronic renal failure occurring in propionic acidemia.
Assuntos
Falência Renal Crônica , Acidemia Propiônica , Difosfato de Adenosina/metabolismo , Trifosfato de Adenosina/metabolismo , Animais , Cálcio/metabolismo , Ciclosporina/metabolismo , Ciclosporina/farmacologia , Ácido Glutâmico/farmacologia , Células HEK293 , Humanos , Rim , Falência Renal Crônica/metabolismo , Malatos/metabolismo , Malatos/farmacologia , Maleatos , Potencial da Membrana Mitocondrial , Mitocôndrias/metabolismo , Proteínas de Transporte da Membrana Mitocondrial/metabolismo , Poro de Transição de Permeabilidade Mitocondrial , NAD/metabolismo , Permeabilidade , Propídio/metabolismo , Propídio/farmacologia , Acidemia Propiônica/metabolismo , Ratos , Ratos WistarRESUMO
This study was focused on synthesizing, characterizing, and evaluating the antimicrobial effect of polymer nanoparticles (NPs) loaded with ampicillin. For this, the NPs were produced through polymeric self-assembly in aqueous media assisted by high-intensity sonication, using anionic polymers corresponding to the sodium salts of poly(maleic acid-co-vinylpyrrolidone) and poly(maleic acid-co-vinylpyrrolidone) modified with decyl-amine, here named as PMA-VP and PMA-VP-N10, respectively. The polymeric NPs were analyzed and characterized through the formation of polymeric pseudo-phases utilizing pyrene as fluorescent probe, as well as by measurements of particle size, zeta potential, polydispersity index, and encapsulation efficiency. The antimicrobial effect was evaluated by means of the broth microdilution method employing ampicillin sensitive and resistant Staphylococcus aureus strains. The results showed that PMA-VP and PMA-VP-N10 polymers can self-assemble, forming several types of hydrophobic pseudo-phases with respect to the medium pH and polymer concentration. Likewise, the results described that zeta potential, particle size, polydispersity index, and encapsulation efficiency are extremely dependent on the medium pH, whereas the antimicrobial activity displayed an interesting recovery of antibiotic activity when ampicillin is loaded in the polymeric NPs.
Assuntos
Anti-Infecciosos , Staphylococcus aureus Resistente à Meticilina , Nanopartículas , Ampicilina/farmacologia , Antibacterianos/química , Antibacterianos/farmacologia , Anti-Infecciosos/farmacologia , Maleatos , Nanopartículas/química , Tamanho da Partícula , Polímeros/química , Staphylococcus aureusRESUMO
Antimicrobial treatment alternatives for methicillin-resistant Staphylococcus aureus (MRSA) are increasingly limited. MRSA strains are resistant to methicillin due to the formation of ß-lactamase enzymes, as well as the acquisition of the mecA gene, which encodes the penicillin-binding protein (PBP2a) that reduces the affinity for ß-lactam drugs. Previous studies have shown that the use of ampicillin-loaded nanoparticles can improve antimicrobial activity on resistant S. aureus strains. However, the biological mechanism of this effect has not yet been properly elucidated. Therefore, this short communication focused on characterizing the in silico interactions of the PBP2a membrane receptor protein from S. aureus against the monomeric units of two polymeric materials previously used in the development of different nanoparticles loaded with ampicillin. Such polymers correspond to Eudragit E-100 chloride (EuCl) and the sodium salt of poly(maleic acid-alt-octadecene) (PAM-18Na). For this, molecular coupling studies were carried out in the active site of the PBP2a protein with the monomeric units of both polymers in neutral and ionized form, as well as with ampicillin antibiotic (model ß-lactam drug). The results showed that ampicillin, as well as the monomeric units of EuCl and PAM18Na, described a slight binding free energy to the PBPa2 protein. In addition, it was found that the amino acids of the active site of the PBPa2 protein have interactions of different types and intensities, suggesting, in turn, different forms of protein-substrate coupling.
RESUMO
Alternating amphiphilic copolymers are macromolecular systems with a polarity duality in their structure, since they are generally formed by alternating segments corresponding to a potential electrolyte group and an alkyl (aliphatic or aromatic) group. These systems, depending on the ionization degree, as well as the time, may form different types of intra and interpolymeric aggregates in aqueous media. Therefore, this study, which in fact is the continuation of a previously reported work, is focused on establishing how the ionization degree of the sodium and potassium salts of the poly(maleic acid-alt-octadecene) affect zeta potential, pH, electrical conductivity, particle size, polydispersity index, and surface tension over time. The results showed that polymeric salts with a high ionization degree in aqueous media formed homogeneous systems with bimodal sizes and high zeta potential values, which tended to quickly become less negative, lowering the pH and slightly increasing the electrical conductivity; while systems with low ionization degree lead to the opposite, forming heterodispersed systems with several populations of particle sizes, high polydispersity, low zeta potential values, neutral and invariable pH values, and high electrical conductivity values. Consequently, these results suggest that the values of particle size, polydispersity index, zeta potential, pH, and electrical conductivity change regarding the polymeric ionization degree, as well as the time. Therefore, such variables should be considered and controlled when working with this kind of polymeric materials.
RESUMO
The kidney proximal tubule function relies on oxidative phosphorylation (OXPHOS), thus mitochondrial dysfunction is characteristic of acute kidney injury (AKI). Maleic acid (MA) can induce an experimental model of Fanconi syndrome that is associated to oxidative stress and decreased oxygen consumption. Sulforaphane (SF) is an antioxidant known to protect against MA-induced AKI. The molecular basis by which SF maintains the bioenergetics in MA-induced AKI is not fully understood. To achieve it, rats were submitted to a protective scheme: SF (1 mg/kg/day i.p.) for four days and, at the fourth day, they received a single dose of MA (400 mg/kg i.p.), getting four main experimental groups: (1) control (CT), (2) MA-nephropathy (MA), (3) SF-protected and (4) SF-control (SF). Additionally, a similar protective schema was tested in cultured NRK-52E cells with different concentrations of SF and MA. In the animal model, SF prevented the MA-induced alterations: decrease in fatty acid-related oxygen consumption rate, OXPHOS capacity, mitochondrial membrane potential (Ψmt), and the activity of complex I (CI) as its monomeric and supercomplexes forms; the antioxidant also increased the activity of cytochrome c oxidase as well as mitochondrial biogenesis markers. Thus, SF prevented the MA-induced increase in fission, mitophagy and autophagy markers. In NRK-52E cells, we found that SF prevented the MA-induced cell death, increased mitochondrial mass and ameliorated the loss of Ψmt. We concluded that SF-induced biogenesis protects against mitochondrial dysfunction maintaining Ψmt, activities of mitochondrial complexes and supercomplexes, and prevents the extensive fission and mitophagy.
Assuntos
Síndrome de Fanconi , Mitofagia , Animais , Síndrome de Fanconi/induzido quimicamente , Síndrome de Fanconi/tratamento farmacológico , Síndrome de Fanconi/genética , Ácidos Graxos , Isotiocianatos , Biogênese de Organelas , Ratos , SulfóxidosRESUMO
AIMS: Biodegradable polymeric microneedles containing atorvastatin calcium were developed in order to improve the percutaneous absorption of the drug, useful for the treatment of hypercholesterolemia. BACKGROUND: The use of physical enhancers like microneedles have shown good results to increase the delivery of drugs through the skin, the use of microneedles has very important advantages for transdermal drug delivery, for example, they are painless, easy to use and safe, they increase time interval of drug activity, dose, and reductions in adverse reactions, they also offer, the facility to remove the system instantly of the skin. OBJECTIVE: Develop polymer microneedles loaded with a calcium atorvastatin and evaluate them by Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM), bioadhesion, postwetting- bioadhesion, breaking strength, drug release test and in vitro percutaneous absorption studies to demonstrate the use of microneedles atorvastatin is able to cross the skin. METHODS: The microneedles were made with poly (methyl vinyl ether-alt-maleic acid) as biodegradable polymer using the technique of casting in solution in a mold. After solidification these microneedles were characterized by Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM), bioadhesion, post-wetting-bioadhesion, breaking strength, drug release test and in vitro percutaneous absorption studies. RESULTS: In general, the performances were satisfactory for optimal formulation in terms of DSC with no interactions between drug and excipients, SEM shows microneedles with a conical shape, bioadhesion of 1570 g.f, post wetting-bioadhesion of 1503.4 g.f, breaking strength of 1566.7g.f that is sufficient to disrupt Stratum corneum, good drug release and a flux of 33.4 µg/cm2*h with a tLag of 15.14 h for the in vitro percutaneous absorption. CONCLUSION: The results indicate that it is possible to generate microneedles to increase the percutaneous absorption of calcium atorvastatin transdermally, with the potential to be used as an alternative to the oral route for the treatment of dyslipidemias.
Assuntos
Anticolesterolemiantes/administração & dosagem , Atorvastatina/administração & dosagem , Plásticos Biodegradáveis/química , Portadores de Fármacos/química , Maleatos/química , Polietilenos/química , Administração Cutânea , Animais , Anticolesterolemiantes/farmacocinética , Atorvastatina/farmacocinética , Sistemas de Liberação de Medicamentos/métodos , Liberação Controlada de Fármacos , Humanos , Técnicas In Vitro , Agulhas , Pele/metabolismo , Absorção CutâneaRESUMO
A promising strategy to improve the effectivity of anticancer treatment and decrease its side effects is to modulate drug release by using nanoparticulates (NPs) as carriers. In this study, methotrexate-loaded chitosan-polyanion nanoparticles were produced by polyelectrolyte complexation assisted by high-intensity sonication, using several anionic polymers, such as the sodium and potassium salts of poly(maleic acid-alt-ethylene) and poly(maleic acid-alt-octadecene), here named PAM-2 and PAM-18, respectively. Such NPs were analyzed and characterized according to particle size, polydispersity index, zeta potential and encapsulation efficiency. Likewise, their physical stability was tested at 4 °C and 40 °C in order to evaluate any change in the previously mentioned particle parameters. The in vitro methotrexate release was assessed at a pH of 7.4, which simulated physiological conditions, and the data were fitted to the heuristic models of order one, Higuchi, Peppas-Sahlin and Korsmeyer-Peppas. The results revealed that most of the MTX-chitosan-polyanion NPs have positive zeta potential values, sizes <280 nm and monodisperse populations, except for the NPs formed with PAM-18 polyanions. Further, the NPs showed adequate physical stability, preventing NP-NP aggregation. Likewise, these carriers modified the MTX release by an anomalous mechanism, where the NPs formed with PAM-2 polymer led to a release mechanism controlled by diffusion and relaxation, whereas the NPs formed with PAM-18 led to a mainly diffusion-controlled release mechanism.
RESUMO
Propionic acidemia is caused by lack of propionyl-CoA carboxylase activity. It is biochemically characterized by accumulation of propionic (PA) and 3-hydroxypropionic (3OHPA) acids and clinically by severe encephalopathy and cardiomyopathy. High urinary excretion of maleic acid (MA) and 2-methylcitric acid (2MCA) is also found in the affected patients. Considering that the underlying mechanisms of cardiac disease in propionic acidemia are practically unknown, we investigated the effects of PA, 3OHPA, MA and 2MCA (0.05-5 mM) on important mitochondrial functions in isolated rat heart mitochondria, as well as in crude heart homogenates and cultured cardiomyocytes. MA markedly inhibited state 3 (ADP-stimulated), state 4 (non-phosphorylating) and uncoupled (CCCP-stimulated) respiration in mitochondria supported by pyruvate plus malate or α-ketoglutarate associated with reduced ATP production, whereas PA and 3OHPA provoked less intense inhibitory effects and 2MCA no alterations at all. MA-induced impaired respiration was attenuated by coenzyme A supplementation. In addition, MA significantly inhibited α-ketoglutarate dehydrogenase activity. Similar data were obtained in heart crude homogenates and permeabilized cardiomyocytes. MA, and PA to a lesser degree, also decreased mitochondrial membrane potential (ΔΨm), NAD(P)H content and Ca2+ retention capacity, and caused swelling in Ca2+-loaded mitochondria. Noteworthy, ΔΨm collapse and mitochondrial swelling were fully prevented or attenuated by cyclosporin A and ADP, indicating the involvement of mitochondrial permeability transition. It is therefore proposed that disturbance of mitochondrial energy and calcium homeostasis caused by MA, as well as by PA and 3OHPA to a lesser extent, may be involved in the cardiomyopathy commonly affecting propionic acidemic patients.
Assuntos
Maleatos/metabolismo , Mitocôndrias Cardíacas/patologia , Mioblastos Cardíacos/patologia , Propionatos/metabolismo , Animais , Cálcio/metabolismo , Cardiomiopatias/etiologia , Cardiomiopatias/metabolismo , Cardiomiopatias/patologia , Fracionamento Celular , Linhagem Celular , Metabolismo Energético , Humanos , Masculino , Mitocôndrias Cardíacas/metabolismo , Dilatação Mitocondrial , Mioblastos Cardíacos/citologia , Mioblastos Cardíacos/metabolismo , Oxigênio/análise , Oxigênio/metabolismo , Acidemia Propiônica/complicações , Acidemia Propiônica/metabolismo , Acidemia Propiônica/patologia , RatosRESUMO
Maleic acid (MA), which has been reported to be highly excreted in propionic acidemia (PAcidemia), was demonstrated to cause nephropathy by bioenergetics impairment and oxidative stress, but the effects on kidney mitochondrial respiration has not yet been properly investigated. Therefore, the present study investigated the effects of MA (0.05-5 mM), as well as of propionic (PA) and 3-hydroxypropionic (3OHPA) acids (5 mM) that accumulate in PAcidemia, on mitochondrial respiration supported by glutamate, glutamate plus malate or succinate in mitochondrial fractions and homogenates from rat kidney, as well as in permeabilized kidney cells. MA markedly decreased oxygen consumption in state 3 (ADP-stimulated) and uncoupled (CCCP-stimulated) respiration in glutamate and glutamate plus malate-respiring mitochondria, with less prominent effects when using succinate. We also found that PA significantly decreased state 3 and uncoupled respiration in glutamate- and glutamate plus malate-supported mitochondria, whereas 3OHPA provoked milder or no changes. Furthermore, glutamate dehydrogenase and α-ketoglutarate dehydrogenase activities necessary for glutamate oxidation were significantly inhibited by MA in a dose-dependent and competitive fashion. The MA-induced decrease of state 3 and uncoupled respiration found in mitochondrial fractions were also observed in homogenates and permeabilized renal cells that better mimic the in vivo cellular milieu. Taken together, our data indicate that MA, and PA to a lesser extent, disturb mitochondrial-oxidative metabolism in the kidney with the involvement of critical enzymes for glutamate oxidation. It is postulated that our present findings may be possibly involved in the chronic renal failure observed in patients with PAcidemia.
Assuntos
Glutamato Desidrogenase/metabolismo , Ácido Glutâmico/metabolismo , Complexo Cetoglutarato Desidrogenase/metabolismo , Rim/metabolismo , Maleatos/metabolismo , Mitocôndrias/metabolismo , Animais , Masculino , Oxirredução , Ratos , Ratos WistarRESUMO
Maleic acid (MA)-induced nephropathy that is characterized by proteinuria, glycosuria, phosphaturia and a deficient urinary acidification and concentration. Sulforaphane (SF) is an indirect antioxidant that shows nephroprotective effects. The aim of the present work was to test the pre-treatment with SF against the MA-induced nephropathy. Wistar rats (230-260 g) were separated in the following groups: control, MA (which received 400 mg/kg of MA), SF + MA (which received MA and 1 mg/kg of SF each day for four days) and SF (which only received SF). MA induced proteinuria, an increase in urinary excretion of N-acetyl-ß-d-glucosaminidase, and a decrease in plasma glutathione peroxidase activity, renal blood flow, and oxygenation and perfusion of renal cortex. All these impairments correlated with higher levels of oxidative damage markers and exacerbated superoxide anion production on renal cortex. Moreover, MA impaired mitochondrial bioenergetics associated to complex I, mitochondrial membrane potential and respiratory control index and increased the mitochondrial production of hydrogen peroxide. Further it disrupted mitochondrial morphology. SF prevented all the above-described alterations. In conclusion, the protective effect of SF against MA-induced nephropathy is associated with preservation of mitochondrial bioenergetics, amelioration of oxidative stress and improvement of renal hemodynamics and renal cortex oxygenation.
Assuntos
Isotiocianatos/administração & dosagem , Nefropatias/prevenção & controle , Maleatos/efeitos adversos , Mitocôndrias/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Extratos Vegetais/administração & dosagem , Animais , Metabolismo Energético/efeitos dos fármacos , Hemodinâmica , Humanos , Rim/efeitos dos fármacos , Rim/metabolismo , Nefropatias/induzido quimicamente , Nefropatias/metabolismo , Masculino , Mitocôndrias/metabolismo , Ratos Wistar , Espécies Reativas de Oxigênio/metabolismo , SulfóxidosRESUMO
This study evaluated the association of N-hexyl-2-methyl-4-nitroimidazol, a model drug, to aggregates formed by anionic polyelectrolytes on aqueous solution. The alternating copolymers of maleic anhydride and N-vinyl-2-pyrrolidone were synthesized and then modified by reaction of the anhydride groups with aliphatic amines and alcohols of varying length of the alkyl chain. The partition of the model drug between water and the hydrophobic microdomains provided by the copolymers was studied using the pseudo-phase model to determinate the distribution coefficient K S, and the standard free energy of transfer ∆µ°t. The results indicate that all copolymers assessed are potential pharmaceutical reservoirs of the model drug. Nevertheless, the solubility of N-hexyl-2-methyl-4-nitroimidazol on the polymeric solutions is independent from the length of the alkyl chain of the copolymer.
Realizou-se estudo sobre a associação da N-hexil-2-metil-4-nitroimidazol, fármaco modelo, aos agregados formados por polieletrólitos aniônicos em solução aquosa. Os copolímeros alternados de anidrido maléico e N-vinil-2-pirrolidona foram sintetizados e, em seguida, modificados pela reação dos grupos de anidrido com aminas e álcoois alifáticos de duração variável da cadeia alquílica. A partição do fármaco modelo entre a água e os microdomínios hidrofóbicos fornecido pelos copolímeros foi estudada usando o modelo de pseudo-fase, a fim de determinar a distribuição do coeficiente K S e a energia livre padrão de transferência ∆µ°t. Os resultados indicam que todos os copolímeros avaliados são potenciais reservatórios farmacêuticos do fármaco. No entanto, a solubilidade do N-hexil-2-metil-4-nitroimidazol sobre as soluções poliméricas é independente do comprimento da cadeia alquílica do copolímero.