Philesia magellanica (P. magellanica) is a plant collected in the Chilean Patagonia. Its antioxidant properties were assessed in human erythrocytes exposed in vitro to oxidative stress induced by HClO. Scanning electron microscopy (SEM) observations showed that HClO induced a morphological alteration in the red blood cells from a normal discoid to a spherocytic form, and cells of unequal size. However, a concentration as low as 1 μM gallic acid equivalents (GAE) of P. magellanica aqueous extract neutralized the change effects of 50 μΜ HClO. On the other hand, 20 μΜ (GAE) of the extract considerably reduced the deleterious capacity of 0.25 mM HClO to induce hemolysis in red blood cells. In addition, X-ray diffraction experiments were performed in molecular models of the human erythrocyte membrane. These consisted in multilayers of dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylethanolamine (DMPE), classes of lipids preferentially located in the outer and inner monolayers, respectively of the human erythrocyte membrane. It was observed that P. magellanica only interacted with DMPC affecting its multilayer structure. It was also observed that 0.1 μM (GAE) of P. magellanica neutralized the structural perturbation induced by 0.05 and 0.5 mM HClO. These experiments confirmed the antioxidant properties of P. magellanica aqueous extracts.

Auranofin is a gold compound that is widely used for the treatment of rheumatoid arthritis. It is a monomeric linear complex with triethylphosphine and thiolate moieties bounded to an Au(I) center. Gold compounds are well known for their neurological and nephrotoxic implications. However, haematological toxicity is one of the most serious toxic and less studied effects. The lack of information on these aspects of auranofin prompted us to study the structural effects induced on cell membranes, particularly that of human erythrocytes. Auranofin was incubated with intact erythrocytes and molecular models of the erythrocyte membrane. The latter consisted of multibilayers of dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylethanolamine (DMPE), phospholipids classes located in the outer and inner monolayers of the human erythrocyte membrane, respectively. This report presents evidence in order that auranofin interacts with red cell membranes as follows: a) in scanning electron microscopy studies on human erythrocytes it was observed that auranofin induced shape changes; b) X-ray diffraction studies showed that auranofin induced increasing structural perturbation to DMPC and to a lower extent to DMPE bilayers. Additional experiments were performed in human neuroblastoma cells SH-SY5Y. A statistically significant decrease of cell viability was observed.

O ácido mefenâmico é um anti-inflamatório não esteroidal (NSAID), também prescrito no tratamento da dor. No presente trabalho, os efeitos estruturais na membrana de eritrócitos humanos e de modelos moleculares foram investigados. Esta última foi composta em bicamadas construídas de dimiristoilfosfatidilcolina (DMPC) e dimiristoilfosfatidiletanolamina (DMPE), classes de lipídios encontrados nas porções interna e externa do eritrócito e da maioria das membranas celulares, respectivamente. Este artigo apresenta evidências de que o ácido mefenâmico interage com as membranas das células vermelhas, como segue: (i) em estudos de microscopia eletrônica de varredura (SEM) em eritrócitos humanos, foi observado que a droga induziu mudanças na forma, produzindo estomatócitos; (ii) estudos de difração de raios X mostraram que a droga interagiu com bicamadas de DMPC e efeitos de perturbação um pouco menores, em DMPE, foram detectados; (iii) medições de FT-IR mostraram que NSAID induziu a fluidização das cadeias acílicas de ambos, DMPC e DMPE; (iv) a espectroscopia de transferência de energia por ressonância Förster (FRET) indicou uma rápida intercalação do ácido mefenâmico nas cadeias hidrofóbicas do lipossoma DMPC.

Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID), also prescribed to treat pain. In the present work, the structural effects on the human erythrocyte membrane and molecular models have been investigated. The latter consisted in bilayers built-up of dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylethanolamine (DMPE), classes of lipids found in the outer and inner moieties of the erythrocyte and most cell membranes, respectively. This report presents evidence that mefenamic acid interacts with red cell membranes as follows: (i) in scanning electron microscopy (SEM) studies on human erythrocytes it has been observed that the drug induced shape changes, forming stomatocytes; (ii) X-ray diffraction showed that the drug interacted with DMPC bilayers; somewhat lower perturbing effects on DMPE were detected; (iii) FT-IR measurements showed that NSAID induced fluidization of both DMPC and DMPE acyl chains; (iv) Förster resonance energy transfer spectroscopy (FRET) indicated a rapid intercalation of the mefenamic acid into DMPC liposome hydrophobic chains.

The content and relative composition of tocopherols, plastochromanol, plastoquinone and pigments in fifteen Antarctic species (five mosses and ten lichens) were analyzed by HPLC. Total tocopherols in mosses ranged from 90 mg/g (Warnstrofia sarmentosa) to 220 mg/g (Syntrichia magellanica), while in lichens it ranged from 0.89 mg/g in Caloplaca sp. to 45 mg/g in Placopsis contortuplicata. With the exception of Ochrolechia frigida, in all other mosses and lichens species, a-tocopherol accounted for more than 90% of total tocopherols. Plastochromanol was detected in four mosses and two lichen species; the highest level was found in Polytrichastrum alpinum (19.1 mg/g). The highest content of plastoquinone-9 (PQ-9) in mosses was found in Bryum pseudotriquetrum (42.6 mg/g), whereas in lichens it was 24.5 mg/g in Stereocaulon alpinum, and 23.17 mg/g in Umbilicaria antarctica. Pigment composition in mosses was typical for higher plants. Some lichen species lacked chlorophyll b, violaxanthin and β-carotene. Based on these results it is suggested that tocochromanols and carotenoid pigments are involved in the protection of mosses and lichens against the oxidative stress caused by the extreme Antarctic conditions.

Verapamil is one of the frequently prescribed calcium channel blockers used in the treatment of hypertension and angina pectoris. Results of evaluations of the therapy have led to reports of toxic effects. This study presents several evidences that verapamil affects human cells. Scanning electrón microscopy observations of intact human erythrocytes indicated that they underwent morphological alterations as increasing verapamil concentrations starting from 5 µM changed their discoid normal shape, and finally to hemolysis. Fluorescence spectroscopy on isolated unsealed human erythrocyte membranes confirmed these outcomes. In fact, the assays showed that verapamil induced a significant increase of the anisotropy parameters and a modérate one of the generalized polarization, indicative of enhanced order at the acyl chain and polar head regions of the erythrocyte membrane lipid bilayer. X-ray diffraction experiments on dimyristoylphosphatidylcholine and dimyristoylphosphatidylethanolamine bilayers, classes of the major phospholipids present in both outer and inner sides of the erythrocyte membrane, respectively showed that verapamil perturbed the polar head and acyl chain regions of both lipid bilayers. These interactions were found to be stronger with DMPC bilayers. On the other hand, human SH-SY5Y neuroblastoma cells incubated with verapamil suffered a sharp decrease of cell viability.

Actual evidences affirm that free radicals and the oxygen reactive species involved play a central role in our homeostatic balance. The chemical reactions of free radicals take place constantly in the cells and they are necessary for human health, but the process must be controlled with an adequate antioxidant protection. Among the antioxidants that are ingested in the diet, vitamins and phenolic compounds are prominent because they neutralize the radical species through several mechanisms. These species that can be found in the plasma may stabilize reactive oxygen species, preventing reactions that can generate more deleterious molecules. Ingestion of antioxidants through the diet is of special importance, as well as to avoid risk factors that induce oxidative reactions in our bodies

En la última década se han acumulado evidencias que permiten afirmar que los radicales libres y el conjunto de especies reactivas que se les asocian juegan un papel central en nuestro equilibrio homeostático. Las reacciones químicas de los radicales libres se dan constantemente en las células de nuestro cuerpo y son necesarias para la salud, pero el proceso debe ser controlado con una adecuada protección antioxidante. Entre los antioxidantes que se ingieren por la dieta destacan las vitaminas y los compuestos fenólicos que por diversos mecanismos neutralizan especies radicalarias. Estas especies pueden encontrarse en el plasma sanguíneo, el que puede estabilizar especies reactivas del oxígeno, previniendo reacciones que pueden generar especies aún más nocivas. Es de especial importancia su consumo moderado a través de la dieta y evitar los factores de riesgo que inducen reacciones oxidativas en nuestro organismo

Biological membranes are the initial targets of pollutants from the surrounding environment. Understanding the mechanisms controlling their interactions at the molecular level is of primary importance to interpret the results of bio-accumulation and toxic effects. Mercury is a major environmental contaminant, which has been shown to cause increased morbidity and mortality in humans. In order to understand the molecular mechanism of mercury toxicity with cell membranes HgCl2 and CH3HgCl were made to interact with multilayers built up of dimyristoylphosphatidylcholine (DMPC) and dimyristoylhosphatidylethanolamine (DMPE), which represent classes of phospholipids located in the outer and inner monolayers of the human erythrocyte membrane, respectively. Results presented in this paper indicated that both mercuric compounds interacted with and perturbed the molecular structures of DMPC and DMPE. These studies were performed by X-ray diffraction methods

Las membranas biológicas constituyen el blanco inicial de la interacción de los contaminantes químicos con los seres vivos. Por tal razón es de una importancia fundamental entender los mecanismos moleculares que controlan sus interacciones, los que permiten interpretar los efectos de su bioacumulación y toxicidad. El mercurio es un contaminante químico ambiental de la mayor importancia ya que se ha demostrado que causa morbilidad y mortalidad en los seres humanos. Con el propósito de explicar los mecanismos moleculares de la toxicidad del mercurio sobre las membranas celulares, HgCl2 y CH3HgCl se hicieron interaccionar con multicapas de los fosfolípidos dimiristoilfosfatidilcolina (DMPC) y dimiristoilfosfatidiletanolamina (DMPE), que representan lípidos presentes respectivamente en la monocapa externa e interna de las membranas de los glóbulos rojos humanos. Los resultados obtenidos indican que ambos compuestos interaccionan y perturban las estructuras moleculares de la DMPC y DMPE. Estos estudios se efectuaron por métodos de difracción de rayos X