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.