[Incidence of intrahospitalary major cardiac events with the use of mechanic thromboaspiration versus only use of IIB/IIIA glucoprotein inhibitors on patients with acute ST elevation myocardial infarction]. / Incidencia de eventos cardiovasculares mayores intrahospitalarios en pacientes sometidos a tromboaspiración mecánica más IIb/IIIa contra solo inhibidores de la glucoproteína IIb/IIIa en infarto agudo al miocardio con elevación del segmento ST.

Objective: To identify the incidence of in-hospital major adverse cardiac events (MACE) with the use of mechanic thromboaspiration plus IIb/IIIa glycoprotein inhibitors versus only use of IIb/IIIa glycoprotein inhibitors on patients with acute ST elevation myocardial infarction. Method: Retrospective, observational, cohort analytic study, on patients with acute ST elevation myocardial infarction that had angiography thrombus TIMI 5 grade, treated between October 2021 and December 2022. Results: A total of 237 patients were included. In 113 patients thromboaspiration were used, 124 patients didn't used. 81.6% were men. In-hospital MACE occurred on 31.9% of patients with thromboaspiration use vs. 30.6% on patients with no use (RR: 1.05; IC95%: 0.61-1.93; p = 0.840). Incidence of malignant arrhythmias were of 8% with thromboaspiration use vs. 1.6% on patients with no use (RR: 5.27; IC95%: 1.11-24.97; p = 0.020). Conclusions: The use of thromboaspiration on concomitant treatment with IIb/IIIa glycoprotein inhibitors was similar with only IIb/IIIa glycoprotein inhibitors in reducing incidence of in-hospital MACE on patients with ST elevation acute myocardial infarction and high thrombus burden. The study has several limitations, so results should be taken with caution.

Objetivo: Identificar la incidencia de eventos cardiovasculares adversos mayores (ECAM) intrahospitalarios con el uso de tromboaspiración mecánica más inhibidores de la glucoproteína IIb/IIIa contra solo inhibidores de la glucoproteína IIb/IIIa en pacientes con infarto agudo al miocardio con elevación del segmento ST (IAMCEST). Método: Estudio retrospectivo, observacional, analítico, de cohorte, en pacientes con IAMCEST con trombo angiográfico de grado TIMI 5, tratados entre octubre de 2021 y diciembre de 2022. Resultados: Cumplieron los criterios de inclusión 237 pacientes. En 113 se usó tromboaspirador más inhibidores IIb/IIIa y en 124 solo inhibidores IIb/IIIa. El 81.6% fueron hombres. La incidencia de ECAM intrahospitalarios fue del 31.9% en los pacientes con tromboaspiración y del 30.6% en los pacientes con solo inhibidores IIb/IIIa (RR: 1.05; IC95%: 0.61-1.93; p = 0.840). La incidencia de arritmias graves fue del 8% en los pacientes con tromboaspiración y del 1.6% en los pacientes con solo inhibidores IIb/IIIa (RR: 5.27; IC95%: 1.11-24.97; p = 0.020). Conclusiones: La frecuencia de ECAM asociados al uso de tromboaspiración mecánica como coadyuvante a los inhibidores de la glucoproteína IIb/IIIa en pacientes con IAMCEST y trombo angiográfico de grado TIMI 5 no es diferente de la de aquellos pacientes en las que solo se utilizan inhibidores de la glucoproteína IIb/IIa. El estudio tiene varias limitaciones, por lo que los resultados deben tomarse con cautela.

A pH-Sensitive Fluorescent Chemosensor Turn-On Based in a Salen Iron (III) Complex: Synthesis, Photophysical Properties, and Live-Cell Imaging Application.

pH regulation is essential to allow normal cell function, and their imbalance is associated with different pathologic situations, including cancer. In this study, we present the synthesis of 2-(((2-aminoethyl)imino)methyl)phenol (HL1) and the iron (III) complex (Fe(L1)2Br, (C1)), confirmed by X-ray diffraction analysis. The absorption and emission properties of complex C1 were assessed in the presence and absence of different physiologically relevant analytes, finding a fluorescent turn-on when OH- was added. So, we determined the limit of detection (LOD = 3.97 × 10-9 M), stoichiometry (1:1), and association constant (Kas = 5.86 × 103 M-1). Using DFT calculations, we proposed a spontaneous decomposition mechanism for C1. After characterization, complex C1 was evaluated as an intracellular pH chemosensor on the human primary gastric adenocarcinoma (AGS) and non-tumoral gastric epithelia (GES-1) cell lines, finding fluorescent signal activation in the latter when compared to AGS cells due to the lower intracellular pH of AGS cells caused by the increased metabolic rate. However, when complex C1 was used on metastatic cancer cell lines (MKN-45 and MKN-74), a fluorescent turn-on was observed in both cell lines because the intracellular lactate amount increased. Our results could provide insights about the application of complex C1 as a metabolic probe to be used in cancer cell imaging.

Synthesis of fluorescent chalcones, photophysical properties, quantitative structure-activity relationship and their biological application.

The development of fluorescent pigments is an area of interest in several research fields due to their high sensitivity. In the current study-eight known and three new N,N-dimethylamino-chalcones (12a-k) were synthesized with good yields using the Claisen-Schmidt reaction. For each molecular system, the photophysical properties, including the maximum absorption wavelength (λAbsorption), molar absorption coefficient (ε), maximum excitation wavelength (λExcitation), maximum emission wavelength (λEmission), Stokes Shift (Δλ), fluorescence quantum yield (Φfl), fluorescence lifetime (τfl), radiative and non-radiative rate constants (kR and kNR, respectively) were evaluated. Variations in each of these properties were analyzed depending on the substituents present on each compound. To relate the chemical structures of the synthesized compounds to their photophysical properties, Hansch analysis (2D-QSPR) was applied. As a result of Hansch analysis, we found different photophysical properties related to molecular orbitals and the energy of their derivatives (Highest Occupied Molecular Orbital-HOMO, Lowest Unoccupied Molecular Orbital-LUMO, Difference between LUMO-HOMO-ΔLH, Chemical potential-µ, Hardness-η, Softness-S, and electrophilic global index-ω) as well as to the atomic charges on atoms C5, Cα, Cß, and CO. The application of this type of analysis has made it possible to understand and subsequently design new molecules with defined photophysical properties. Finally, the compounds were use as fluorescent pigment to get living cell imaging on breast cancer cells, obtaining the compound 12a as promissory alternative.

Resveratrol-Schiff Base Hybrid Compounds with Selective Antibacterial Activity: Synthesis, Biological Activity, and Computational Study.

Nowadays, antimicrobial resistance is a serious concern associated with the reduced efficacy of traditional antibiotics and an increased health burden worldwide. In response to this challenge, the scientific community is developing a new generation of antibacterial molecules. Contributing to this effort, and inspired by the resveratrol structure, five new resveratrol-dimers (9a−9e) and one resveratrol-monomer (10a) were synthetized using 2,5-dibromo-1,4-diaminobenzene (8) as the core compound for Schiff base bridge conformation. These compounds were evaluated in vitro against pathogenic clinical isolates of Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus sp., and Listeria monocytogenes. Antibacterial activity measurements of resveratrol-Schiff base derivatives (9a−9e) and their precursors (4−8) showed high selectivity against Listeria monocytogenes, being 2.5 and 13.7 times more potent than chloramphenicol, while resveratrol showed an EC50 > 320 µg/mL on the same model. Moreover, a prospective mechanism of action for these compounds against L. monocytogenes strains was proposed using molecular docking analysis, finding a plausible inhibition of internalin C (InlC), a surface protein relevant in bacteria−host interaction. These results would allow for the future development of new molecules for listeriosis treatment based on compound 8.

Effects of cholesterol on lipid vesicle fusion mediated by infectious salmon anaemia virus fusion peptides.

Studying the variables that affect the membrane fusion mechanism of enveloped viruses is important for developing new strategies to combat viral infections. We analysed the effects of lipid vesicle cholesterol content on membrane fusion that is facilitated by infectious salmon anaemia virus (ISAV) fusion peptides. Lipid mixing assays were performed to study membrane fusion in large unilamellar vesicles (LUV) composed of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), dipalmitoylphosphatidylcholine (DPPC) and cholesterol. Lipid mixing (%) increased more over time when 0.2 µm LUV contained no cholesterol or when the LUV membranes contained 15 mol% cholesterol. The secondary structure of the ISAV fusion peptides consistently remained a ß-sheet both in water and in the presence of vesicles. Additionally, the dissociation constant (Kd) between the peptides and the lipid vesicles was obtained with different cholesterol contents. In the tests performed with lipid vesicles (0.2 µm or 0.4 µm LUV), cholesterol was found to influence membrane fusion that was facilitated by ISAV fusion peptides; however, the peptides studied did not require cholesterol in their membranes to facilitate membrane fusion in the smallest lipid vesicles (0.2 µm LUV).

QSAR-driven synthesis of antiproliferative chalcones against SH-SY5Y cancer cells: Design, biological evaluation, and redesign.

Neuroblastoma is one of the most frequent types of cancer found in infants, and traditional chemotherapy has limited efficacy against this pathology. Thus, the development of new compounds with higher activity and selectivity than traditional drugs is a current challenge in medicinal chemistry research. In this study, we report the synthesis of 21 chalcones with antiproliferative activity and selectivity against the neuroblastoma cell line SH-SY5Y. Then, we developed three-dimensional quantitative structure-activity relationship models (comparative molecular field analysis and comparative molecular similarity index analysis) with high-quality statistical values (q2 > 0.7; r2 > 0.8; r2 pred > 0.7), using IC50 and selectivity index (SI) data as dependent variables. With the information derived from these theoretical models, we designed and synthesized 16 new molecules to prove their consistency, finding good antiproliferative activity against SH-SY5Y cells on these derivatives, with three of them showing higher SI than the referential drugs 5-fluorouracil and cisplatin, displaying also a proapoptotic effect comparable to these drugs, as proven by measuring their effects on executor caspases 3/7 activity induction, Bcl-2/Bax messenger RNA levels alteration, and DNA fragmentation promotion.

Sensitive fluorescent chemosensor for Hg(II) in aqueous solution using 4'-dimethylaminochalcone.

Mercury (Hg) is an element with high toxicity, especially to the nervous system, and fluorescent pigments are used to visualize dynamic processes in living cells. A little explored fluorescent core is chalcone. Herein, we synthesized chalcone (2E)-3-(4-(dimethylamino)phenyl)-1-phenylprop-2-en-1-one (8) and assessed its photophysical properties. Moreover, the application of this chemosensor in aqueous media shows a selective fluorescence quenching effect with Hg(II). The figures of merit for the chemosensor were calculated to be LOD = 136 nM and LOQ = 454 nM, as well as a stoichiometry of 1:1. Furthermore, the association constant (Ka) and fluorescence quenching constant (KSV) were calculated using the Benesi-Hildebrand and Stern-Volmer equations to be Ka= 9.08 × 104 and KSV= 1.60 × 105, respectively. Finally, by using a computational approach, we explain the interaction between chalcone (8) and Hg(II) and propose a potential quenching mechanism based on the blocking of photoinduced electron transfer.

Coumarin-Resveratrol-Inspired Hybrids as Monoamine Oxidase B Inhibitors: 3-Phenylcoumarin versus trans-6-Styrylcoumarin.

Monoamine oxidases (MAOs) are attractive targets in drug design. The inhibition of one of the isoforms (A or B) is responsible for modulating the levels of different neurotransmitters in the central nervous system, as well as the production of reactive oxygen species. Molecules that act selectively on one of the MAO isoforms have been studied deeply, and coumarin has been described as a promising scaffold. In the current manuscript we describe a comparative study between 3-phenylcoumarin (endo coumarin-resveratrol-inspired hybrid) and trans-6-styrylcoumarin (exo coumarin-resveratrol-inspired hybrid). Crystallographic structures of both compounds were obtained and analyzed. 3D-QSAR models, in particular CoMFA and CoMSIA, docking simulations and molecular dynamics simulations have been performed to support and better understand the interaction of these molecules with both MAO isoforms. Both molecules proved to inhibit MAO-B, with trans-6-styrylcoumarin being 107 times more active than 3-phenylcoumarin, and 267 times more active than trans-resveratrol.

Carfilzomib as a potential inhibitor of NADH-dependent enoyl-acyl carrier protein reductases of Klebsiella pneumoniae and Mycobacterium tuberculosis as a drug target enzyme: insights from molecular docking and molecular dynamics.

Multiple antibiotic-resistant strains of Klebsiella pneumoniae can cause life-threatening infections. Bacterial enoyl-acyl carrier protein (ACP) reductases (ENRs) are considered critical targets for developing antibiotics. Our current study aims to identify inhibitors of K. pneumoniae ENRs (FabI and FabV). Due to the unavailability of experimental structures, protein models of FabI and FabV were predicted and validated in this study. Virtual screening of the 1930 FDA-approved drug database was conducted against the active site of the FabI protein with the help of the LEA3D server, and carfilzomib was chosen among the screened drugs for further docking studies. Carfilzomib, a proteasome inhibitor used in the treatment of multiple myeloma, was among the best-suited compounds obtained from the virtual screening and was found to be bactericidal in the in vitro experiment. Carfilzomib was docked against the active sites of the FabI and FabV proteins, and the ENR of Mycobacterium tuberculosis, InhA. Carfilzomib showed a high binding affinity with all three proteins. Molecular dynamics (MD) simulations were conducted following the docking studies. MD simulations revealed that carfilzomib binds strongly to the active sites of the above mentioned ENRs. Our study found that carfilzomib is a potential inhibitor of the ENRs of K. pneumoniae and M. tuberculosis. This is a possible mechanism of its bactericidal property against M. tuberculosis observed in vitro in addition to its predicted actions on zinc-dependent metalloprotease-1 and peptide deformylase, two other drug target enzymes of M. tuberculosis. Our study suggests that this drug could be used as a lead compound to develop antibiotics that can selectively act against ENRs of bacteria, without interfering with the activities of human proteasome. Communicated by Ramaswamy H. Sarma.

3-aryl-indolinones derivatives as antiplasmodial agents: synthesis, biological activity and computational analysis.

Malaria is an infectious illness, affecting vulnerable populations in Third World countries. Inspired by natural products, indole alkaloids have been used as a nucleus to design new antimalarial drugs. So, eighteen oxindole derivatives, aza analogues were obtained with moderate to excellent yields. Also, the saturated derivatives of oxindole and aza derivatives via H2/Pd/C reduction were obtained in good yields, leading to racemic mixtures of each compound. Next, the inhibitory activity against P. falciparum of 18 compounds were tested, founding six compounds with IC50 < 20 µM. The most active of these compounds was 8c; however, their unsaturated derivative 7c was inactive. Then, a structure-activity relationship analysis was done, founding that focused LUMO lobe on the specific molecular zone is related to inhibitory activity against P. falciparum. Finally, we found a potential inhibition of lactate dehydrogenase by oxindole derivatives, using molecular docking virtual screening.

Inhibition of Caco-2 and MCF-7 cancer cells using chalcones: synthesis, biological evaluation and computational study.

Cancer is the second death cause worldwide, with breast and colon cancer among the most prevalent types. Traditional treatment strategies have several side effects that inspire the development of novel anticancer agents derived from natural sources, like chalcone derivatives. For this investigation, twenty-three chalcones (4a-w) were synthesized and evaluated as antiproliferative agents against MCF-7 and Caco-2 cells, finding three and two compounds with similar or higher antiproliferative activity than daunorubicin, while only two chalcones showed better selectivity indexes than daunorubicin on MCF-7. From these results, we developed good-performance QSAR models (r > 0.850, q2>0.650), finding several structural features that could modify chalcone activity and selectivity. According to these models, chalcones 4w and 4t have high potency and selectivity against Caco-2 and MCF-7, respectively, which make them attractive candidates for hit-to-lead development of ROS-independent pro apoptotic agents.

Combined 3D-QSAR and docking analysis for the design and synthesis of chalcones as potent and selective monoamine oxidase B inhibitors.

Monoamine oxidases (MAOs) are important targets in medicinal chemistry, as their inhibition may change the levels of different neurotransmitters in the brain, and also the production of oxidative stress species. New chemical entities able to interact selectively with one of the MAO isoforms are being extensively studied, and chalcones proved to be promising molecules. In the current work, we focused our attention on the understanding of theoretical models that may predict the MAO-B activity and selectivity of new chalcones. 3D-QSAR models, in particular CoMFA and CoMSIA, and docking simulations analysis have been carried out, and their successful implementation was corroborated by studying twenty-three synthetized chalcones (151-173) based on the generated information. All the synthetized molecules proved to inhibit MAO-B, being ten out of them MAO-B potent and selective inhibitors, with IC50 against this isoform in the nanomolar range, being (E)-3-(4-hydroxyphenyl)-1-(2,2-dimethylchroman-6-yl)prop-2-en-1-one (152) the best MAO-B inhibitor (IC50 of 170 nM). Docking simulations on both MAO-A and MAO-B binding pockets, using compound 152, were carried out. Calculated affinity energy for the MAO-A was +2.3 Kcal/mol, and for the MAO-B was -10.3 Kcal/mol, justifying the MAO-B high selectivity of these compounds. Both theoretical and experimental structure-activity relationship studies were performed, and substitution patterns were established to increase MAO-B selectivity and inhibitory efficacy. Therefore, we proved that both 3D-QSAR models and molecular docking approaches enhance the probability of finding new potent and selective MAO-B inhibitors, avoiding time-consuming and costly synthesis and biological evaluations.

Toxic effects of the anticancer drug epirubicin in vitro assayed in human erythrocytes.

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.

An in vitro study on the interaction of the anti-Alzheimer drug rivastigmine with human erythrocytes.

The inhibition of the enzyme acetylcholinesterase (AChE) is a frequently used therapeutic option to treat Alzheimer's disease (AD). By decreasing the levels of acetylcholine degradation in the synaptic space, some cognitive functions of patients suffering from this disease are significantly improved. Rivastigmine is one of the most widely used AChE inhibitors. The objective of this work was to determine the effects of this drug on human erythrocytes, which have a type of AChE in the cell membrane. To that end, human erythrocytes and molecular models of its membrane constituted by dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylethanolamine (DMPE) were used. They correspond to classes of phospholipids present in the outer and inner monolayers of the human erythrocyte membrane, respectively. The experimental results obtained by X-ray diffraction and differential scanning calorimetry (DSC) indicated that rivastigmine molecules were able to interact with both phospholipids. Fluorescence spectroscopy results showed that rivastigmine produce a slight change in the acyl chain packing order and a weak displacement of the water molecules of the hydrophobic-hydrophilic membrane interface. On the other hand, observations by scanning electron microscopy (SEM) showed that the drug changed the normal biconcave shape of erythrocytes in stomatocytes (cup-shaped cells) and echinocytes (speculated shaped).

In vitro antioxidant and antiproliferative effect of the extracts of Ephedra chilensis K Presl aerial parts.

BACKGROUND: Ephedra chilensis K Presl, known locally as pingo-pingo, is a Chilean endemic plant used in traditional medicine as an anti-inflammatory and used in other treatments. However, unlike for the other Ephedra species, there have been no reports on the antioxidant and cytotoxic effects of this plant. The present study aims to explore the potential applications of E. chilensis extract as a cytotoxic agent against in vitro cancer cell lines and to explore the relationship between this extract and antioxidant activity. METHODS: Total anthraquinone, flavonoid, and phenolic contents, as well as antioxidant activity (DPPH, FRAP, and TRAP assays) and cytotoxic effect on several cancer cell lines (MCF-7, PC-3, DU-145, and HT-29) were measured for the hexane, dichloromethane and ethanol extracts of E. chilensis. In addition, several correlations among the phytochemical content, antioxidant activity, and cytotoxic effect were evaluated. Finally, GC-MS analyses of the most active extracts were carried out to identify their major components and to relate these components to the cytotoxic effect. RESULTS: Antioxidant activity was found in the EtOH extracts of Ephedra, and the results were correlated with the phenolic content. For the cytotoxic activity, the non-polar extracts of E. chilensis had the highest antiproliferative effect for the MCF-7 and PC-3 cancer lines; the extract was shown to be up to three times more selective than doxorubicin. However, the cytotoxic effect was not correlated with the antioxidant activity. Lastly, the GC-MS analysis showed a high concentration of saturated fatty acids (mainly n-hexadecanoic acid) and terpenoids (mainly 4-(hydroxy-ethyl)-γ-butanolactone). CONCLUSION: The cytotoxic activity and selectivity of the non-polar extracts of E. chilensis for the MCF-7 and PC-3 cell lines could be related to the terpenic compounds and fatty acids of the extracts or to the synergistic effect of all of the compounds in the extracts. These non-polar extracts can be used for the development of new drugs against breast and prostate cancer.

The acetylcholinesterase (AChE) inhibitor and anti-Alzheimer drug donepezil interacts with human erythrocytes.

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.

In vitro effects of the antitumor drug miltefosine on human erythrocytes and molecular models of its membrane.

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.

An in vitro study of the protective effect of caffeic acid on human erythrocytes.

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.

Protective effect of epigallocatechin gallate on human erythrocytes.

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.