RESUMEN
The aim of the present work is the characterization of smart auto-degradable microspheres composed of calcium alginate/high methoxylated pectin containing an alginate lyase (AL) from Sphingobacterium multivorum and levofloxacin. Microspheres were prepared by ionotropic gelation containing AL in its inactive form at pH 4.0. Incubation of microspheres in Tris-HCl and PBS buffers at pH 7.40 allowed to establish the effect of ion-chelating phosphate on matrix erodability and suggested an intrinsically activation of AL by turning the pH close to neutrality. Scanning electron and optical microscopies revealed the presence of holes and surface changes in AL containing microspheres. Furthermore, texturometric parameters, DSC profiles and swelling properties were showing strong changes in microspheres properties. Encapsulation of levofloxacin into microspheres containing AL showed 70% efficiency and 35% enhancement of antimicrobial activity against Pseudomonas aeruginosa biofilm. Levofloxacin release from microspheres was not changed at acidic pH, but was modified at neutral pH in presence of AL. Advantageously, only gel matrix debris were detectable after overnight incubation, indicating an autodegradative gel process activated by the pH. Absence of matrix cytotoxicity and a reduction of the levofloxacin toxicity after encapsulation were observed in mammalian CHO-K1 cell cultures. These properties make the system a potent and versatile tool for antibiotic oral delivery targeted to intestine, enhancing the drug bioavailability to eradicate bacterial biofilm and avoiding possible intestinal obstructions.
Asunto(s)
Alginatos/química , Antibacterianos/administración & dosificación , Biopelículas/efectos de los fármacos , Sistemas de Liberación de Medicamentos , Hidrogel de Polietilenoglicol-Dimetacrilato/química , Levofloxacino/administración & dosificación , Ácido Glucurónico/química , Ácidos Hexurónicos/química , Concentración de Iones de Hidrógeno , Levofloxacino/química , Levofloxacino/farmacología , Microesferas , SolubilidadRESUMEN
Resveratrol oligomers are biologically active polyphenols found in wine. No information about the bioavailability of these polyphenols is available. In order to discover if the resveratrol oligomers can pass the intestinal barrier, transport of the dimer ε-viniferin and the tetramer hopeaphenol was studied in the Caco-2 transwell system. A flux through the cell monolayer could neither be observed for ε-viniferin nor for hopeaphenol (apparent permeability coefficient (Papp)<1×10(-6)cms(-1)). In contrast, resveratrol showed a Papp of 11.9×10(-6)cms(-1). Nevertheless, about 16-30% of the oligomers were found in the lysed cellular fraction. This leads to the conclusion that the intestinal absorption rate of the two resveratrol oligomers, ε-viniferin and hopeaphenol, is low and negligible when compared to resveratrol. Therefore, it is unlikely that the oligomers could elicit a systemic biological effect after dietary intake. However, the compounds may act locally on the intestinal epithelium.
Asunto(s)
Células CACO-2/química , Absorción Intestinal/fisiología , Estilbenos/química , Transporte Biológico , Humanos , Polifenoles , Resveratrol , Vino/análisisRESUMEN
Benznidazole (Bz) and Nifurtimox (Nfx) have been used to treat Chagas disease. As recent studies have de-monstrated cardiotoxic effects of Nfx, we attempted to determine whether Bz behaves similarly. Bz reached the heart tissue of male rats after intragastric administration. No cytosolic Bz nitroreductases were detected, although microsomal NADPH-dependent Bz nitroreductase activity was observed, and appeared to be mediated by P450 reductase. No ultrastructurally observable deleterious effects of Bz were detected, in contrast to the overt cardiac effects previously reported for Nfx. In conclusion, when these drugs are used in chagasic patients, Bz may pose a lesser risk to heart function than Nfx when any cardiopathy is present.
Asunto(s)
Corazón/efectos de los fármacos , Miocardio/metabolismo , Nifurtimox/farmacocinética , Nitroimidazoles/farmacocinética , Tripanocidas/farmacocinética , Animales , Biotransformación , Evaluación Preclínica de Medicamentos , Masculino , Microscopía Electrónica de Transmisión , Microsomas/enzimología , Nifurtimox/efectos adversos , Nitroimidazoles/efectos adversos , Nitrorreductasas/análisis , Ratas , Ratas Sprague-Dawley , Factores de Tiempo , Tripanocidas/efectos adversosRESUMEN
Benznidazole (Bz) and Nifurtimox (Nfx) have been used to treat Chagas disease. As recent studies have de-monstrated cardiotoxic effects of Nfx, we attempted to determine whether Bz behaves similarly. Bz reached the heart tissue of male rats after intragastric administration. No cytosolic Bz nitroreductases were detected, although microsomal NADPH-dependent Bz nitroreductase activity was observed, and appeared to be mediated by P450 reductase. No ultrastructurally observable deleterious effects of Bz were detected, in contrast to the overt cardiac effects previously reported for Nfx. In conclusion, when these drugs are used in chagasic patients, Bz may pose a lesser risk to heart function than Nfx when any cardiopathy is present.
Asunto(s)
Animales , Masculino , Ratas , Corazón/efectos de los fármacos , Miocardio/metabolismo , Nifurtimox/farmacocinética , Nitroimidazoles/farmacocinética , Tripanocidas/farmacocinética , Biotransformación , Evaluación Preclínica de Medicamentos , Microscopía Electrónica de Transmisión , Microsomas/enzimología , Nifurtimox/efectos adversos , Nitroimidazoles/efectos adversos , Nitrorreductasas/análisis , Ratas Sprague-Dawley , Factores de Tiempo , Tripanocidas/efectos adversosRESUMEN
Nifurtimox (Nfx) is a nitroheterocyclic drug used in the treatment of Chagas' disease. It has serious side effects which frequently force to interrupt the treatment. Nfx toxicity has been linked to its nitroreduction to a nitroanion radical with a subsequent redox cycling which generate reactive oxygen species. We analyzed the ability of Sprague Dawley male rat pancreas to nitroreduce Nfx and whether this drug may cause deleterious effects in this organ. The microsomal fraction exhibited Nfx nitroreductase activity in the presence of NADPH under anaerobic atmosphere, which was fully inhibited under air but not altered when N2 was replaced by pure CO. The cytosol nitroreduced Nfx in the presence of hypoxanthine under N2; it was inhibited by allopurinol and negligible in aerobiosis. Nfx reached pancreatic tissue at 1, 3 or 6 h after intragastric administration (100 mg/kg). Six hours after drug administration, a significant increase in t-buthylhydroperoxide promoted chemiluminiscence was detected. Pancreatic protein sulfhydryl content significantly decreased at either 1, 3 or 6 h after Nfx administration. No changes in either protein carbonyl or in lipid hydroperoxides were observable. Ultrastructural alterations were observed in the endoplasmic reticulum and nuclei from acinar cells and in the insulin-containing granules from the pancreas. However, the seric amylase levels were not changed, but the blood glucose levels were slightly but significantly increased 24 h after Nfx administration. These studies might suggest that Nfx treatment could impose an increased risk to patients exposed to other insults provoking oxidative stress or having preexisting pathologies in the pancreas.
Asunto(s)
Nitrorreductasas/metabolismo , Páncreas/citología , Páncreas/enzimología , Animales , Citosol/efectos de los fármacos , Citosol/enzimología , Células Secretoras de Insulina/efectos de los fármacos , Células Secretoras de Insulina/metabolismo , Luminiscencia , Masculino , Microscopía Electrónica de Transmisión , Microsomas/efectos de los fármacos , Microsomas/enzimología , Nifurtimox/metabolismo , Páncreas/ultraestructura , Ratas , Ratas Sprague-Dawley , Fracciones Subcelulares/efectos de los fármacos , Fracciones Subcelulares/enzimología , Compuestos de Sulfhidrilo/metabolismo , Superóxidos/metabolismo , terc-Butilhidroperóxido/metabolismoRESUMEN
Chagas' disease (American trypanosomiasis) is an endemic parasitic disease in some areas of Latin America. About 16-18 million persons are infected with the aetiological agent of the disease, Trypanosoma cruzi, and more than 100 million are living at risk of infection. There are different modes of infection: (1) via blood sucking vector insects infected with T. cruzi, accounting for 80-90% of transmission of the disease; (2) via blood transfusion or congenital transmission, accounting for 0.5-8% of transmission; (3) other less common forms of infection, eg, from infected food or drinks or via infected organs used in transplants. The acute phase of the disease can last from weeks to months and typically is asymptomatic or associated with fever and other mild nonspecific manifestations. However, life-threatening myocarditis or meningoencephalitis can occur during the acute phase. The death rate for persons in this phase is about 10%. Approximately 10-50% of the survivors develop chronic Chagas' disease, which is characterized by potentially lethal cardiopathy and megacolon or megaoesophagus. There are two drugs available for the aetiological treatment of Chagas' disease: nifurtimox (Nfx) and benznidazole (Bz). Nfx is a nitrofurane and Bz is a nitroimidazole compound. The use of these drugs to treat the acute phase of the disease is widely accepted. However, their use in the treatment of the chronic phase is controversial. The undesirable side effects of both drugs are a major drawback in their use, frequently forcing the physician to stop treatment. The most frequent adverse effects observed in the use of Nfx are: anorexia, loss of weight, psychic alterations, excitability, sleepiness, digestive manifestations such as nausea or vomiting, and occasionally intestinal colic and diarrhoea. In the case of Bz, skin manifestations are the most notorious (e.g., hypersensitivity, dermatitis with cutaneous eruptions, generalized oedema, fever, lymphoadenopathy, articular and muscular pain), with depression of bone marrow, thrombocytopenic purpura and agranulocytosis being the more severe manifestations. Experimental toxicity studies with Nfx evidenced neurotoxicity, testicular damage, ovarian toxicity, and deleterious effects in adrenal, colon, oesophageal and mammary tissue. In the case of Bz, deleterious effects were observed in adrenals, colon and oesophagus. Bz also inhibits the metabolism of several xenobiotics biotransformed by the cytochrome P450 system and its reactive metabolites react with fetal components in vivo. Both drugs exhibited significant mutagenic effects and were shown to be tumorigenic or carcinogenic in some studies. The toxic side effects of both nitroheterocyclic derivatives require enzymatic reduction of their nitro group. Those processes are fundamentally mediated by cytochrome P450 reductase and cytochrome P450. Other enzymes such as xanthine oxidoreductase or aldehyde oxidase may also be involved.