RESUMO
Aß(1-42) peptide is a neurotoxic agent strongly associated with the etiology of Alzheimer's disease (AD). Current treatments are still of very low effectiveness, and deaths from AD are increasing worldwide. Huprine-derived molecules have a high affinity towards the enzyme acetylcholinesterase (AChE), act as potent Aß(1-42) peptide aggregation inhibitors, and improve the behavior of experimental animals. AVCRI104P4 is a multitarget donepezil-huprine hybrid that improves short-term memory in a mouse model of AD and exerts protective effects in transgenic Caenorhabditis elegans that express Aß(1-42) peptide. At present, there is no information about the effects of this compound on human erythrocytes. Thus, we considered it important to study its effects on the cell membrane and erythrocyte models, and to examine its protective effect against the toxic insult induced by Aß(1-42) peptide in this cell and models. This research was developed using X-ray diffraction and differential scanning calorimetry (DSC) on molecular models of the human erythrocyte membrane constituted by lipid bilayers built of dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylethanolamine (DMPE). They correspond to phospholipids representative of those present in the external and internal monolayers, respectively, of most plasma and neuronal membranes. The effect of AVCRI104P4 on human erythrocyte morphology was studied by scanning electron microscopy (SEM). The experimental results showed a protective effect of AVCRI104P4 against the toxicity induced by Aß(1-42) peptide in human erythrocytes and molecular models.
Assuntos
Peptídeos beta-Amiloides , Membrana Eritrocítica , Compostos Heterocíclicos de 4 ou mais Anéis , Modelos Moleculares , Fragmentos de Peptídeos , Doença de Alzheimer/tratamento farmacológico , Doença de Alzheimer/metabolismo , Doença de Alzheimer/patologia , Peptídeos beta-Amiloides/química , Peptídeos beta-Amiloides/toxicidade , Membrana Eritrocítica/química , Membrana Eritrocítica/metabolismo , Membrana Eritrocítica/ultraestrutura , Compostos Heterocíclicos de 4 ou mais Anéis/química , Compostos Heterocíclicos de 4 ou mais Anéis/farmacologia , Humanos , Fragmentos de Peptídeos/química , Fragmentos de Peptídeos/toxicidadeRESUMO
In addition to their own antioxidants, human cells feed on external antioxidants, such as the phenolic compounds of fruits and vegetables, which work together to keep oxidative stress in check. Sechium edule, an edible species of chayote, has phenolic compounds with antioxidant activity and antineoplastic activity. A Sechium hybrid shows one thousand times greater antineoplastic activity than edible species, but its antioxidant and anti-inflammatory activities and the content of phenolic compounds are unknown. The aim of this study was to determine the antioxidant and anti-inflammatory capacity of the extract of fruits of the Sechium hybrid in vitro and in vivo. Phytochemical analysis using HPLC showed that the extract of the Sechium hybrid has at least 16 phenolic compounds; galangin, naringenin, phloretin and chlorogenic acid are the most abundant. In an in vitro assay, this extract inhibited 2,2-diphenyl-L-picrylhydrazyl (DPPH) activity and protected the dimyristoylphosphatidylethanolamine (DMPE) phospholipid model cell membrane from oxidation mediated by hypochlorous acid (HClO). In vivo, it was identified that the most abundant metabolites in the extract enter the bloodstream of the treated mice. On the other hand, the extract reduces the levels of tumor necrosis factor alpha (TNFα), interferon gamma (IFNγ), and interleukin-6 (IL-6) but increases interleukin-10 (IL-10) and glutathione peroxidase levels. Our findings indicate that intake of the fruits of the Sechium hybrid leads to antioxidant and anti-inflammatory effects in a mouse model. Therefore, these results support the possibility of exploring the clinical effect of this hybrid in humans.
Assuntos
Antioxidantes/química , Frutas/química , Interleucina-10/química , Fator de Necrose Tumoral alfa/química , Animais , Compostos de Bifenilo/química , Glutationa Peroxidase/química , Humanos , Interferon gama/metabolismo , Interleucina-6/metabolismo , Camundongos , Fosfatidiletanolaminas/química , Picratos/química , Extratos Vegetais/químicaRESUMO
Epirubicin is a cytotoxic drug used in the treatment of different types of cancer and increasing evidence suggests that its target is cell membranes. In order to gain insight on its toxic effects, intact red blood cells (RBC), human erythrocyte membranes and molecular models were used. The latter consisted in bilayers of dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylethanolamine (DMPE), phospholipid classes found mainly in the outer and inner monolayers of the human erythrocyte membrane, respectively. The results obtained by X-ray diffraction displayed that epirubicin induced structural perturbations in multilayers of DMPC. Differential scanning calorimetry (DSC) showed that epirubicin disturbed the thermotropic behavior of both DMPC and DMPE vesicles, whereas fluorescence spectroscopy demonstrated alterations in the fluidity of DMPC vesicles and the erythrocyte membrane. Scanning electron microscopy (SEM) revealed that epirubicin changed the normal discoid form of RBC to echinocytes and stomatocytes. Electron paramagnetic resonance (EPR) disclosed that this drug induced conformational changes in the erythrocyte membrane proteins. These findings demonstrate that epirubicin interacts with lipids and proteins of the human erythrocyte membrane, effects that might compromise the integrity and function of cell membranes. This is the first time that its toxic effects on the human erythrocyte membrane have been described.
Assuntos
Antibióticos Antineoplásicos/toxicidade , Epirubicina/toxicidade , Eritrócitos/efeitos dos fármacos , Varredura Diferencial de Calorimetria , Células Cultivadas , Dimiristoilfosfatidilcolina , Eritrócitos/patologia , Eritrócitos/ultraestrutura , Humanos , Lipossomos , Microscopia Eletrônica de Varredura , Fosfatidiletanolaminas , Difração de Raios XRESUMO
Donepezil is used to treat symptomatically the Alzheimer's disease (AD). This drug is a specific inhibitor of the enzyme acetylcholinesterase (AChE), whose main physiological function is to hydrolyze the neurotransmitter acetylcholine. The main objective of this work was to study the effect of donepezil on human erythrocytes as AChE is present in its membrane. For this purpose, human erythrocytes and molecular model of its membrane built-up of dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylethanolamine (DMPE) were used. The latter correspond to classes of phospholipids present in the outer and inner monolayers of the human erythrocyte membrane, respectively. Our experimental evidences obtained from X-ray diffraction and differential scanning calorimetry (DSC) analysis indicated that donepezil was capable of interacting with both phospholipids. Fluorescence spectroscopy results showed a moderate increase in the fluidity of the hydrophobic tails of DMPC and isolated unsealed human erythrocyte membranes (IUM). On the other hand, results by scanning electron microscopy (SEM) and optical defocusing microscopy (DM) showed that the drug changed the normal biconcave shape of the erythrocytes inducing the formation of stomatocytes (cup-shaped cells). This effect was explained by the incorporation of donepezil molecules into the erythrocyte membrane and interactions with AChE.
Assuntos
Acetilcolinesterase/efeitos dos fármacos , Doença de Alzheimer/tratamento farmacológico , Inibidores da Colinesterase/farmacologia , Donepezila/farmacologia , Eritrócitos/efeitos dos fármacos , Nootrópicos/farmacologia , Inibidores da Colinesterase/uso terapêutico , Dimiristoilfosfatidilcolina/metabolismo , Donepezila/uso terapêutico , Membrana Eritrocítica/efeitos dos fármacos , Membrana Eritrocítica/metabolismo , Humanos , Nootrópicos/uso terapêutico , Fosfatidiletanolaminas/metabolismoRESUMO
The human red blood cell (RBC) membrane has significant elastic capabilities which can be described measuring typical membrane edge fluctuations and mechanical properties by optical techniques. The RBC elastic properties can be affected by changes in the surrounding media. In an attempt to elucidate the molecular mechanisms of the interaction of resveratrol with the red cell membrane and of its antioxidant capacity the changes in mechanical properties of the RBC membrane were analyzed. These studies were carried out through measurements of RBC membrane fluctuations in the presence of the oxidant agent HClO using thermal fluctuation spectroscopy (TFS). The observed results showed that the elastic capabilities of RBC changed with low concentration of hypochlorous acid but without morphological changes. However, in the presence of resveratrol the deformation and decrease of elastic capabilities induced by HClO on RBC decreased. These in vitro results demonstrated the protective effect of RV against the detrimental effects triggered by HClO upon human erythrocytes.
Assuntos
Antioxidantes/metabolismo , Eritrócitos/metabolismo , Resveratrol/sangue , Análise Espectral/métodos , Membrana Eritrocítica/metabolismo , Humanos , Ácido Hipocloroso/metabolismo , Análise de Célula ÚnicaRESUMO
The interaction and protective effect of caffeic acid (CA) on human erythrocytes (RBC) and molecular models of its membrane were studied. The latter consisted of bilayers built up of dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylethanolamine (DMPE), representative of phospholipid classes located in the outer and inner monolayers of the human erythrocyte membrane, respectively. X-ray diffraction and differential scanning calorimetry results indicated that CA induced structural and thermotropic perturbations in multilayers and vesicles of DMPC. Fluorescence spectroscopy analysis showed that CA increased the fluidity of DMPC vesicles and of human erythrocyte ghosts. Scanning electron microscopy observations displayed that CA induced morphological alterations to RBC from their normal discoid form to echinocytes. The assessment of its protective capacity showed that CA inhibits RBC morphological alterations and lysis induced by HClO. These findings imply that CA molecules were located in the outer monolayer of the erythrocyte membrane, and that this preferential location might effectively protect the red cells from damage caused by oxidizing species.
Assuntos
Ácidos Cafeicos/farmacologia , Eritrócitos/efeitos dos fármacos , Varredura Diferencial de Calorimetria , Dimiristoilfosfatidilcolina/metabolismo , Eritrócitos/metabolismo , Glicerofosfolipídeos/metabolismo , Hemólise/efeitos dos fármacos , Humanos , Técnicas In Vitro , Microscopia Eletrônica de Varredura , Espectrometria de Fluorescência , Difração de Raios XRESUMO
The interactions and the protective effect of epigallocatechin gallate (EGCG) on human erythrocytes (RBC) and molecular models of its membrane were investigated. The latter consisted of bilayers built- up of dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylethanolamine (DMPE), representative of phospholipid classes located in the outer and inner monolayers of the human erythrocyte membrane, respectively. X-ray diffraction and differential scanning calorimetry experiments showed that EGCG induced significant structural and thermotropic perturbations in multilayers and vesicles of DMPC; however, these effects were not observed in DMPE. Fluorescence spectroscopy results revealed that EGCG produced alterations of the molecular dynamics at the level of the hydrophobic-hydrophilic interface in DMPC vesicles, and in isolated unsealed human erythrocyte membranes (IUM). EGCG also induced morphological alterations in RBC from their normal discoid form to echinocytes. These outcomes indicate that EGCG molecules were located in the outer monolayer of the erythrocyte membrane. The assessment of EGCG protective effect demonstrated that it inhibits the morphological alterations and lysis induced by HClO to human erythrocytes. The results obtained from this study suggest that the insertion of EGCG into the outer monolayer of the erythrocyte membrane might prevent the access and deleterious effects of oxidant molecules such as HClO and free radicals into the red cells, protecting them from oxidative damage.
Assuntos
Antioxidantes/farmacologia , Catequina/análogos & derivados , Membrana Eritrocítica/efeitos dos fármacos , Ácido Hipocloroso/antagonistas & inibidores , Oxidantes/antagonistas & inibidores , Antioxidantes/química , Catequina/química , Catequina/farmacologia , Dimiristoilfosfatidilcolina/química , Membrana Eritrocítica/química , Hemólise/efeitos dos fármacos , Humanos , Interações Hidrofóbicas e Hidrofílicas , Ácido Hipocloroso/farmacologia , Cinética , Bicamadas Lipídicas/química , Oxidantes/farmacologia , Fosfatidiletanolaminas/química , Espectrometria de Fluorescência , TermodinâmicaRESUMO
This study was aimed at elucidating the molecular mechanisms of the interaction of the antitumor alkylphospholipid drug miltefosine with human erythrocytes (RBC) and molecular models of its membrane. The latter consisted of bilayers of dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylethanolamine (DMPE), representative of phospholipid classes located in the outer and inner monolayers of the human erythrocyte membrane, respectively. X-ray results showed that the drug interacted with DMPC multilayers; however, no effects on DMPE were detected. The experimental findings obtained by differential scanning calorimetry (DSC) indicated that miltefosine altered the thermotropic behavior of both DMPC and DMPE vesicles. Fluorescence spectroscopy evidenced an increase in the fluidity of DMPC vesicles and human erythrocyte membranes. Scanning electron microscopy (SEM) observations on human erythrocytes showed that miltefosine induced morphological alterations to RBC from its normal biconcave to an echinocyte type of shape. These results confirm that miltefosine interacts with the outer moiety of the human erythrocyte membrane affecting the cell morphology.
Assuntos
Antineoplásicos/farmacologia , Membrana Eritrocítica/efeitos dos fármacos , Eritrócitos/efeitos dos fármacos , Bicamadas Lipídicas/química , Fosfolipídeos/química , Fosforilcolina/análogos & derivados , Varredura Diferencial de Calorimetria , Dimiristoilfosfatidilcolina/química , Eritrócitos/citologia , Hemólise , Humanos , Microscopia Eletrônica de Varredura , Modelos Moleculares , Fosfatidiletanolaminas/química , Fosforilcolina/farmacologia , Espectrometria de Fluorescência , Termodinâmica , Difração de Raios XRESUMO
Labetalol is one of the most used drugs for the treatment of hypertension. This molecule is able to bind to both alpha-1 (α1) and beta (ß) adrenergic receptors present in vascular smooth muscle among other tissues. It has been determined that human erythrocytes possess both alpha receptors and beta-adrenergic receptors expressed on their surface. The objective of this work was to study the effect of labetalol on the morphology of human erythrocytes. To accomplish this goal, human erythrocytes and model membranes built of dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylethanolamine (DMPE) were used. These lipid species are present in the outer and inner monolayers of the red blood cell membrane, respectively. Our findings obtained by X-ray diffraction and differential scanning calorimetry (DSC) indicate that labetalol interacted with both lipids in a process dependent on concentration. In fact, at low concentrations labetalol preferentially interacted with DMPE. On the other hand, results obtained by scanning electron microscopy (SEM) showed that labetalol alters the normal biconcave form of erythrocytes to stomatocytes and knizocytes (cells with one or more cavities, respectively). According to the bilayers couple hypothesis, this result implied that the drug inserted in the inner monolayer of the human erythrocyte membrane.
Assuntos
Antagonistas de Receptores Adrenérgicos alfa 1/farmacologia , Antagonistas Adrenérgicos beta/farmacologia , Eritrócitos/efeitos dos fármacos , Labetalol/farmacologia , Antagonistas de Receptores Adrenérgicos alfa 1/química , Antagonistas Adrenérgicos beta/química , Varredura Diferencial de Calorimetria , Dimiristoilfosfatidilcolina/química , Membrana Eritrocítica/efeitos dos fármacos , Membrana Eritrocítica/metabolismo , Membrana Eritrocítica/ultraestrutura , Eritrócitos/metabolismo , Eritrócitos/ultraestrutura , Humanos , Técnicas In Vitro , Labetalol/química , Lipossomos/química , Membranas Artificiais , Microscopia Eletrônica de Varredura , Fosfatidiletanolaminas/química , Difração de Raios XRESUMO
The antioxidant and antihemolytic properties contained in the leaves of Buddleja globosa (B. globosa), also known as "Matico," were determined. Aqueous extracts of leaves were assayed in human erythrocytes and molecular models of its membrane. The latter were bilayers built-up of lipids located in the outer and inner leaflets of the erythrocyte membrane. Observations by scanning electron microscopy showed that the extract altered the morphology of erythrocytes inducing the formation of crenated echinocytes. This result implied that the extract components were inserted into the outer leaflet of the cell membrane. This conclusion was confirmed by experiments carried out by fluorescence spectroscopy of red cell membranes and vesicles (LUV) of dimyristoylphosphatidylcholine (DMPC) and by X-ray diffraction of DMPC and dimyristoylphosphatidylethanolamine bilayers. Human erythrocytes were in vitro exposed to HClO, which is a natural powerful oxidant. Results demonstrated that low concentrations of B. globosa aqueous extract neutralized the harmful capacity of HClO. Hemolysis experiments also showed that the extract in very low concentrations reduced hemolysis induced by HClO.