Membrane Phospholipids Research Articles

Antibacterial and anti-biofilm activities of antibiotic-free phosphatidylglycerol/docosahexaenoic acid lamellar and non-lamellar liquid crystalline nanoparticles

Infectious diseases, particularly those associated with biofilms, are challenging to treat due to an increased tolerance to commonly used antibiotics. This underscores the urgent need for innovative antimicrobial strategies. Here, we present an alternative simple-by-design approach focusing on the development of biocompatible and antibiotic-free nanocarriers from docosahexaenoic acid (DHA) that has the potential to combat microbial infections and phosphatidylglycerol (DOPG), which is attractive for use as a biocompatible prominent amphiphilic component of Gram-positive bacterial cell membranes. We assessed the anti-bacterial and anti-biofilm activities of these nanoformulations (hexosomes and vesicles) against S. aureus and S. epidermidis, which are the most common causes of infections on catheters and medical devices by different methods (including resazurin assay, time-kill assay, and confocal laser scanning microscopy on an in vitro catheter biofilm model). In a DHA-concentration-dependent manner, these nano-self-assemblies demonstrated strong anti-bacterial and anti-biofilm activities, particularly against S. aureus. A five-fold reduction of the planktonic and a four-fold reduction of biofilm populations of S. aureus were observed after treatment with hexosomes. The nanoparticles had a bacteriostatic effect against S. epidermidis planktonic cells but no anti-biofilm activity was detected. We discuss the findings in terms of nanoparticle-bacterial cell interactions, plausible alterations in the phospholipid membrane composition, and potential penetration of DHA into these membranes, leading to changes in their structural and biophysical properties. The implications for the future development of biocompatible nanocarriers for the delivery of DHA alone or in combination with other anti-bacterial agents are discussed, as novel treatment strategies of Gram-positive infections, including biofilm-associated infections.

Membrane phospholipids activate the inflammatory response in macrophages by various mechanisms.

Exosomes, which are small membrane-encapsulated particles derived from all cell types, are emerging as important mechanisms for intercellular communication. In addition, exosomes are currently envisioned as potential carriers for the delivery of drugs to target tissues. The natural population of exosomes is very variable due to the limited amount of cargo components present in these small vesicles. Consequently, common components of exosomes may play a role in their function. We have proposed that membrane phospholipids could be a common denominator in the effect of exosomes on cellular functions. In this regard, we have previously shown that liposomes made of phosphatidylcholine (PC) or phosphatidylserine (PS) induced a robust alteration of macrophage (Mϕ) gene expression. We herewith report that these two phospholipids modulate gene expression in Mϕs by different mechanisms. PS alters cellular responses by the interaction with surface receptors, particularly CD36. In contrast, PC is captured by a receptor-independent process and likely triggers an activity within endocytic vesicles. Despite this difference in the capture mechanisms, both lipids mounted similar gene expression responses. This investigation suggests that multiple mechanisms mediated by membrane phospholipids could be participating in the alteration of cellular functions by exosomes.

Nitrogen Forms Regulate the Response of Microcystis aeruginosa to Nanoplastics at Environmentally Relevant Nitrogen Concentrations.

As essential primary producers, cyanobacteria play a major role in global carbon and nitrogen cycles. Though the influence of nanoplastics on the carbon metabolism of cyanobacteria is well-studied, little is known about how nanoplastics affect their nitrogen metabolism, especially under environmentally relevant nitrogen concentrations. Here, we show that nitrogen forms regulated growth inhibition, nitrogen consumption, and the synthesis and release of microcystin (MC) in Microcystis aeruginosa exposed to 10 μg/mL amino-modified polystyrene nanoplastics (PS-NH2) with a particle size of 50 nm under environmentally relevant nitrogen concentrations of nitrate, ammonium, and urea. We demonstrate that PS-NH2 inhibit M. aeruginosa differently in nitrate, urea, and ammonium, with inhibition rates of 51.87, 39.70, and 36.69%, respectively. It is caused through the differences in impairing cell membrane integrity, disrupting redox homeostasis, and varying nitrogen transport pathways under different nitrogen forms. M. aeruginosa respond to exposure of PS-NH2 by utilizing additional nitrogen to boost the production of amino acids, thereby enhancing the synthesis of MC, extracellular polymeric substances, and membrane phospholipids. Our results found that the threat of nanoplastics on primary producers can be regulated by the nitrogen forms in freshwater ecosystems, contributing to a better understanding of nanoplastic risks under environmentally relevant conditions.

Photoresponsive Azobenzene Nanocluster-Modified Liposomes: Mechanism Analysis Combining Experiments and Simulations.

Stimuli-responsive behaviors and controlled release in liposomes are pivotal in nanomedicine. To this end, we present an approach using a photoresponsive azobenzene nanocluster (AzDmpNC), prepared from azobenzene compounds through melting and aggregation. When integrated with liposomes, they form photoresponsive vesicles. The morphology and association with liposomes were investigated by using transmission electron microscopy. Liposomes loaded with calcein exhibited a 9.58% increased release after UV exposure. To gain insights into the underlying processes and elucidate the mechanisms involved. The molecular dynamic simulations based on the reactive force field and all-atom force field were employed to analyze the aggregation of isomers into nanoclusters and their impacts on phospholipid membranes, respectively. The results indicate that the nanoclusters primarily aggregate through π-π and T-stacking forces. The force density inside the cis-isomer of AzDmpNC formed after photoisomerization is lower, leading to its easier dispersion, rapid diffusion, and penetration into the membrane, disrupting the densification.

Mechanism of antimalarial action and mitigation of infection-mediated mitochondrial dysfunction by phyto-constituents of Andrographis paniculata ((Burm f.) Wall. ex Nees) in Plasmodium berghei-infected mice

Ethnopharmacological relevanceAndrographis paniculata (AP) ((Burm f.) Wall. ex Nees) is a medicinal plant, documented for its folkloric use in the treatment of malaria. AimThis study was designed to determine the potency of extract and fractions of A. paniculata (AP) as a curative, both for susceptible and resistant malaria and to also determine the plant's mechanism of action. This study was also designed to determine whether AP extract and its most potent fraction will mitigate infection-mediated mitochondrial dysfunction, and to assess the phytochemical constituents of the most potent fraction. Materials and methodsn-Hexane, dichloromethane, ethylacetate and methanol were used to partition the methanol extract of A. paniculata. Graded doses of these extract and fractions were used to treat mice infected with chloroquine-sensitive strain of P. berghei in a curative model. The most potent fraction was used to treat mice infected with resistant (ANKA strain) P. berghei. Inhibition of hemozoin formation, reversal of mitochondrial dysfunction and antiinflammatory potentials were determined. A combination of ultraperformance liquid chromatography-quadrupole time of flight-mass spectrometry and nuclear magnetic resonance spectroscopy were used for chemical analysis. ResultsMicroscopy revealed that the dichloromethane fraction decreased the parasite burden the most, and inhibition of the hemozoin formation is one of its mechanisms of action. The dichloromethane fraction reversed parasite-induced mitochondrial pore opening in the host, enzyme-dependent ATP hydrolysis and peroxidation of host mitochondrial membrane phospholipids as well as its antiinflammatory potentials. The UPLC-qTOF-MS report and NMR fingerprints of the dichloromethane fraction of A. paniculata yielded fourteen compounds of which sibiricinone C was identified from the plant for the first time. ConclusionFractions of A. paniculata possess antiplasmodial effects with the dichloromethane fraction having the highest potency. The potent effect of this fraction may be attributed to the phytochemicals present because it contains terpenes implicated with antimalarial and antiinflammatory activities.

Relationships between erythrocyte membrane mono- and poly- unsaturated fatty acid composition and clinical/cognitive indices in antipsychotic-free schizophrenia patients.

Membrane phospholipid abnormalities are considered a pathophysiological background for schizophrenia. The aim of the study was to explore in detail the fatty acid (FA) composition in patients with antipsychotic-free schizophrenia and its association with clinical symptoms and cognitive function. Erythrocyte membrane FAs were measured in 29 antipsychotic-free patients with schizophrenia (male/female = 11/18; mean [standard deviation] age=26.7 [7.9] years) and age and sex-matched 32 healthy volunteers. Clinical symptoms and cognitive function were assessed using the Positive and Negative Syndrome Scale (PANSS), Brief Assessment of Cognition in Schizophrenia (BACS), and the Schizophrenia Cognition Rating Scale (SCoRS). Eicosapentaenoic acid levels were lower in the schizophrenia group than in the healthy control group. In contrast, arachidonic acid and nervonic acid levels were higher in the schizophrenia group than in the control group. Nervonic acid levels were significantly associated with depression scores as measured by the PANSS. No FA levels were correlated with BACS score; however, oleic acid levels were significantly related to cognitive dysfunction, as measured by the SCoRS. These findings suggest that depressive symptoms along with cognitive dysfunction in daily living in schizophrenia may be linked to the FA composition abnormalities. Further studies will be needed to examine potential longitudinal FA changes during the course of schizophrenia as well as disease specificity.

Phospholipid analyses of rabbit ocular surface tissues

The tissues of the integument covering the ocular surface comprise a mucus membrane functioning as a protective physical barrier and has the ability to mount a defensive inflammatory response. Since lipid metabolism has a role in both of these functions, we studied normal membrane phospholipids (PL) of the cornea and bulbar conjunctiva to (1) determine baseline PL profiles of these tissues, (2) compare and contrast these individual PL metabolite profiles as well as groups of metabolites, and (3) describe pathway-specific metabolic interrelations among these tissues. Corneal and conjunctival tissue samples were isolated from rabbit eyes (n = 30) and extracted with chloroform-methanol using a modified Folch procedure. 31P nuclear magnetic resonance spectroscopy was used to qualitatively and quantitatively measure tissue PL profiles. The cornea and conjunctiva, respectively, have the following PL composition (mole % of total detected phospholipid): phosphatidylglycerol (PG) –, 0.4; lysophosphatidylethanolamine 1.2, –; phosphatidic acid –, 0.4; diPG (cardiolipin) 2.1, 3.5; unknown PL at the chemical shift of 0.13 δ 1.5, 0.9; ethanolamine plasmalogen 11.2, 13.0; phosphatidylethanolamine 11.5, 12.8; phosphatidylserine 8.9, 10.1; sphingomyelin 10.2, 10.7; lysophosphatidylcholine 0.9, 1.4; phosphatidylinositol 5.3, 5.3; phosphatidylcholine (PC) plasmalogen or alkylacylPC 2.2, 1.9; PC 45.1, 40.0. In addition, 28 PL metabolic indices were calculated from these data, which permitted pathway-specific lipid analyses. This study (1) establishes PL profiles of the two ocular tissues of the integument that cover the surface of the eye, (2) compares and contrasts indices comprised of ratios and combinations of PL, and (3) describes pathway-specific metabolic interrelations among these tissues to serve as baselines for studies involving the distribution of tissue phospholipids.

Hydrophobic Sorption Properties of an Extended Series of Anionic Per- and Polyfluoroalkyl Substances Characterized by C18 Chromatographic Retention Measurement.

Partitioning from water to nonaqueous phases is an important process that controls the behavior of contaminants in the environment and biota. However, for ionic chemicals including many perfluoroalkyl and polyfluoroalkyl substances (PFAS), environmentally relevant partition coefficients cannot be predicted using the octanol/water partition coefficient, which is commonly used as a hydrophobicity indicator for neutral compounds. As an alternative, this study measured C18 liquid chromatography retention times of 39 anionic PFAS and 20 nonfluorinated surfactants using isocratic methanol/water eluent systems. By measuring a series of PFAS with different perfluoroalkyl chain lengths, retention factors at 100% water (k0) were successfully extrapolated even for long-chain PFAS. Molecular size was the most important factor determining the k0 of PFAS and non-PFAS, suggesting that the cavity formation process is the key driver for retention. Log k0 showed a high correlation with the log of partition coefficients from water to the phospholipid membrane, air/water interface, and soil organic carbon. The results indicate the potential of C18 retention factors as predictive descriptors for anionic PFAS partition coefficients and the possibility of developing a more comprehensive multiparameter model for the partitioning of anionic substances in general.

Interaction of functionalized graphene with cellular membranes: an in silico investigation of graphene-based nanovehicle toward biomedical applications

Nanomaterials, especially graphene derivatives, have become major tools in the biomedical area. Understanding the way that graphene interacts with component elements of biological systems, like biological membranes, is critical for the development of successful biomedical applications. The interaction mechanism of graphene sheets with a model cell membrane was investigated in this study using molecular dynamics (MD) simulations under three different conditions: pristine graphene (PG), carboxyl group-functionalized graphene (G-COOH), and amine group-functionalized graphene (G-NH2). The MD simulations demonstrated that functional groups on graphene surfaces improve their interaction with the head groups of the membrane. In 200 nanoseconds, PG reached equilibrium outside and near the phospholipid membrane. G-NH2 was positioned away from the model membrane’s surface, while G-COOH and G-NH2 also achieved equilibrium outside the membrane. It was shown by molecular dynamics simulations that after 200 ns, all three systems had attained their stable states. Crucially, it is discovered that the kind of functional groups greatly affected how the nanoparticles and membrane interacted. Each and every nanocarrier has a strong propensity to break through the membrane. The van der Waals interaction energies for the PG, G-NH2, and G-COOH systems were further shown by the obtained data to be roughly −400.66, −397.52, and −876.36 kJ/mol, respectively. These results support the notion that G-COOH interacts with the model cell bilayer more strongly than PG and G-NH2. This work highlights the influence of functional groups on the interaction of graphene sheets with biological membranes, offering important insights into the equilibrium behavior and entry mechanism of graphene sheets in a model cell membrane.

The Association between the Plasma Phospholipid Profile and Insulin Resistance: A Population-Based Cross-Section Study from the China Adult Chronic Disease and Nutrition Surveillance.

The dysfunction of phospholipid metabolism enzymes and the change in membrane phospholipid composition are associated with insulin resistance, indicating that phospholipids play an important role in the regulation of insulin sensitivity. The reflection of phospholipid changes in blood might provide clues for both mechanism understanding and intervention. Using a targeted phospholipidomic approach, 199 phospholipid molecular species were identified and quantified in the plasma of 1053 middle-aged participants from a national investigation. The associations of the phospholipid matrix, clusters, and molecular species with insulin resistance were investigated. A significant association was confirmed between the phospholipid matrix and the homeostatic-model assessment of insulin resistance (HOMA-IR) by a distance-based linear model. Furthermore, three clustered phospholipid modules and 32 phospholipid molecular species were associated with HOMA-IR with the strict control of demographic and lifestyle parameters, family history of diabetes, BMI, WC, and blood lipid parameters. The overall decline in lysophosphatidylcholines (LPCs), the decrease in saturated lysophosphatidylethanolamines (LPEs), the decrease in polyunsaturated/plasmenyl phosphatidylcholines (PCs), and the increase in polyunsaturated phatidylethanolamines (PEs) were the prominent characters of plasma phospholipid perturbation associated with insulin resistance. This suggested that PC- and PE-related metabolic pathways were widely involved in the process of insulin resistance, especially the disorder of LPC acylation to diacyl-PC.

Separation of milk fat using silicon carbide support ceramic membranes with different pore sizes

The effect of pore size and type of material on the separation of fat from raw milk using hydrophilic silicon carbide (SiC) support ceramic membranes has not previously been reported in literature. The separation performance of the fat globules (MFGs) showed 98% for SiC 0.5 μm, 92% for SiC 1.4 μm, 90% fat for ZrO2-SiC 0.06 μm, while the permeate had a fat % ranging from 0.1 to 0.6% (w/w). The MFGs were kept highly intact with well distributed proteins and phospholipids in the MFG membrane. The total filtration time at 50 °C to reach maximum VCR was 134 min for ZrO2 (VCR 3), 148 min for SiC 0.5 μm and 16 min for SiC 1.4 μm (VCR4). Further, all membranes showed a fully recoverable water permeability indicating no irreversible fouling. Industrial relevanceMicrofiltration may be an alternative process to fat separation from raw milk. In this study, for the first time was demonstrated that effective milk fat separation, and retentate and permeate streams with variable characteristics, in terms of composition and integrity of the milk fat globules can be obtained by using silicon carbide support membranes with different sizes and materials. The results obtained, provide new insights for industrial use of membrane technology to separate milk.

Experimental and molecular dynamics simulation study on antifouling performance of antimicrobial peptide‐modified aluminum alloy surfaces

Marine biofouling poses a major challenge to ship navigation and hinders the development of the shipping industry. Urgent action is required to tackle this problem through the implementation of innovative strategies. Antimicrobial peptides have garnered considerable attention due to their outstanding effectiveness, wide range of activity, and eco‐friendly characteristics. This study involved grafting the antibacterial peptide andricin 01 (AIGHCLGATL) onto the surface of an aluminum alloy, thereby creating a modified surface with antibacterial properties. In summary, amino groups were introduced onto the surface of aluminum alloys through the silanization process using (3‐aminopropyl) triethoxysilane (APTES), and then the peptides were covalently immobilized on the treated surface using glutaraldehyde as a cross‐linking agent. The successful modification of the peptide was confirmed by Fourier transform‐infrared spectroscopy (FT‐IR) and X‐ray photoelectron spectroscopy (XPS) analysis. The antimicrobial peptide‐modified aluminum alloy surfaces exhibited significant bactericidal activity, killing 75.3% of Bacillus sp. and 85.5% of Escherichia coli, while achieving antifouling efficiencies of 88.6% and 90.7% against Bacillus sp. and E. coli, respectively. Furthermore, molecular dynamics simulations showed that the inserted of the peptides into the phospholipid membrane caused a change in the local membrane curvature, which eventually led to membrane rupture. These results provide valuable information for the application of antimicrobial peptides in the field of antifouling and the elucidation of antifouling mechanisms.

Impact of Lipid Composition on Vesicle Protein Adsorption: A BSA Case Study.

Investigating the interaction between liposomes and proteins is of paramount importance in the development of liposomal formulations with real potential for bench-to-bedside transfer. Upon entering the body, proteins are immediately adsorbed on the liposomal surface, changing the nanovehicles' biological identity, which has a significant impact on their biodistribution and pharmacokinetics and ultimately on their therapeutic effect. Albumin is the most abundant plasma protein and thus usually adsorbs immediately on the liposomal surface. We herein report a comprehensive investigation on the adsorption of model protein bovine serum albumin (BSA) onto liposomal vesicles containing the zwitterionic lipid 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), in combination with either cholesterol (CHOL) or the cationic lipid 1,2-dioleoyl-3-trimethylammoniumpropane (DOTAP). While many studies regarding protein adsorption on the surface of liposomes with different compositions have been performed, to the best of our knowledge, the differential responses of CHOL and DOTAP upon albumin adsorption on vesicles have not yet been investigated. UV-vis spectroscopy and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) revealed a strong influence of the phospholipid membrane composition on protein adsorption. Hence, it was found that DOTAP-containing vesicles adsorb proteins more robustly but also aggregate in the presence of BSA, as confirmed by DLS and TEM. Separation of liposome-protein complexes from unadsorbed proteins performed by means of centrifugation and size exclusion chromatography (SEC) was also investigated. Our results show that neither method can be regarded as a golden experimental setup to study the protein corona of liposomes. Yet, SEC proved to be more successful in the separation of unbound proteins, although the amount of lipid loss upon liposome elution was higher than expected. In addition, coarse-grained molecular dynamics simulations were employed to ascertain key membrane parameters, such as the membrane thickness and area per lipid. Overall, this study highlights the importance of surface charge and membrane fluidity in influencing the extent of protein adsorption. We hope that our investigation will be a valuable contribution to better understanding protein-vesicle interactions for improved nanocarrier design.

Pros and cons of alternative therapy omega-3 fatty acids during pregnancy and lactation for mental problems

IntroductionFatty acids omega-3 are irreplaceable. They stabilize cell membranes, nerve impulses, homeostasis, immune reactions, the birth process, the psycho-emotional state of the fetus-mother dyad. Correlations between adequate dietary intake of omega-3 and cognitive health have been described in detail. According to the literature, docosahexaenoic acid is associated with the synthesis of serotonin, dopamine, acetylcholine, glutamate, neuroprotective and anti-apoptotic action, has antidepressant effect. Omega-3 makes up 60% of neuronal membrane phospholipids. Under clinical aspect,according to publications, fish oil reduces the risk of preterm birth by 44%.Objectives The aim is to study the risks and benefits of using omega-3 during pregnancy and lactation in patients with mental disorders.Methods Comparative analysis of evidence-based scientific publications for the use of omega-3 fatty acids in pregnancy and lactation.Results The body level of omega-3 depends on the quantitative intake from food, as well as gene polymorphism and age. For pregnant and lactating women are recommended 200-300 mg per day or about 300 g per week from food. Deficiency of omega-3 (protectins) affects the processes of myelination, neurogenesis, synaptogenesis, the metabolism of neurotransmitters, cell differentiation, neuronal migration and inflammatory responses.Conclusions There are many probably mechanisms of action of omega-3, namely: Enhances peroxisomal oxidation, reduces the synthesis of triglycerides in the liver; inhibits plasma acyltransfrerase. Omega-3 acts on phospholipids of the cell membranes of the nervous system and retina, their adequate functioning, improve psychomotor development of newborns. It was found the effect of decreasing the levels of cytokines and depressive symptoms, as well the risk of food allergies and depression. In conclusion, in adequate doses, omega-3 fatty acids seems to be useful in deficiencies and for prophylactic purposes in pregnancy and lactation.Keywordsomega- 3 fatty acids, pregnancy, lactation, mental disorders.Disclosure of InterestNone Declared

Deletion of the TMEM30A gene enables leukemic cell evasion of NK cell cytotoxicity

Natural killer (NK) cell immunotherapy has gained attention as a promising strategy for treatment of various malignancies. In this study, we used a genome-wide CRISPR screen to identify genes that provide protection or susceptibility to NK cell cytotoxicity. The screen confirmed the role of several genes in NK cell regulation, such as genes involved in interferon-γ signaling and antigen presentation, as well as genes encoding the NK cell receptor ligands B7-H6 and CD58. Notably, the gene TMEM30A, encoding CDC50A-beta-subunit of the flippase shuttling phospholipids in the plasma membrane, emerged as crucial for NK cell killing. Accordingly, a broad range of TMEM30A knock-out (KO) leukemia and lymphoma cells displayed increased surface levels of phosphatidylserine (PtdSer). TMEM30A KO cells triggered less NK cell degranulation, cytokine production and displayed lower susceptibility to NK cell cytotoxicity. Blockade of PtdSer or the inhibitory receptor TIM-3, restored the NK cell ability to eliminate TMEM30A-mutated cells. The key role of the TIM-3 - PtdSer interaction for NK cell regulation was further substantiated by disruption of the receptor gene in primary NK cells, which significantly reduced the impact of elevated PtdSer in TMEM30A KO leukemic cells. Our study underscores the potential significance of agents targeting the interaction between PtdSer and TIM-3 in the realm of cancer immunotherapy.

Effect of food environment on the ability of microorganisms to form biofilms

AbstractThe aim of this study is to understand the effect of the food product's, even in trace amounts, in the biofilm formation potential of Escherichia coli and Staphylococcus aureus. Bacterial adhesion was tested using three different food media, in which bacterial cells were adapted before determining how this would affect their adhesion score and biofilm formation potential: sterilized milk, mineral water, and pasteurized commercial orange juice. After characterization of the bacteria and the adhesion support by the contact angle, the adhesion score obtained by the theoretical mathematical model XDLVO developed by van Oss was compared to that obtained by the experimental approach, in order to examine the role of non‐specific (thermodynamic) and specific (biological) interactions in adhesion. Changes in the membrane composition of bacteria, as a function of acclimation conditions, were evaluated by infrared spectroscopy. Results reveal variability in the spectral region between 900 and 1200 cm−1 specific to capsular polysaccharides (CPS) or lipopolysaccharides (LPS), and also in the range between 2800 and 3000 cm−1 characteristic of membrane lipids and phospholipids. Biofilm formation by S. aureus and E. coli was affected by commercial UHT milk. This led to increased hydrophobicity and total adhesion energy within the environment of these strains. However, no correlation was observed between the adhesion scores obtained through experimental and theoretical approaches. This underscores the necessity of considering the specific characteristics of individual food products in understanding the phenomenon of biofilm formation. Understanding, the mechanism, the variations in bacterial surface characteristics, and the conditions that favor or disadvantage the formation of biofilms, may have important implications, in the development of preventive and curative strategies, to control of food‐borne infections.

Efek Ekstrak Ampas Seduhan Bubuk Kopi Dalam Menghambat Produksi Malondialdehid Pada Isolat Monosit Perifer Manusia yang Distimuli Dengan Eksotoksin Streptococcus mutans

Monocytes as non-specific immune cells provide an early response to pathogens and foreign objects that enter the body. When exposed to pathogens or foreign objects, monocytes experience an increase in the number of free radicals. Free radicals activate phospholipase enzymes that break down membrane phospholipids into phosphate, glycerol and fatty acids. Unsaturated fatty acids (PUFAs) react with free radicals to undergo peroxidation to produce malondialdehyde (MDA). It takes antioxidant compounds that can reduce excess free radicals in the body. Coffee grounds as solid waste from the consumption of processed coffee products are not used and disposed of, it is suspected that they can be used as antioxidants. This study aims to determine the effect of coffee grounds steeping antioxidants on the profile of MDA levels in monocytes stimulated by the S. mutans exotoxin (In Vitro). Research was done in experimental post test only control group design. The object of this study was human peripheral blood monocytes, which were isolated by the Gradient Density method. Following in vitro exposure to the exotoxin S. mutans, the monocyte isolates were subjected to treatment with brewed coffee grounds extract at three different concentrations (0.25 mg/ml, 0.50 mg/ml, and 0.75 mg/ml). The MDA levels were subsequently determined by employing the TBArs method on a UV-Vis spectrophotometer. The results of MDA levels were analyzed using One Way Anova and LSD. The MDA level data showed significance (p<0.05) with the average MDA level in the Negative Control group1.49 g/ml; Positive Control 10.62 g/ml; T1 8.15 g/ml; T2 6.59 g/ml; and T3 4.69 g/ml. It can be concluded that the extract of brewed coffee grounds can reducing MDA levels in monocytes exposed to the exotoxin of S. mutans.

Assessing the negative impact of chlorantraniliprole, isoxaflutole, and simazine pesticides on phospholipid membrane models and tilapia gill tissues

The indiscriminate and, very often, incorrect use of pesticides in Brazil, as well as in other countries, results in severe levels of environmental pollution and intoxication of human life. Herein, we studied plasma membrane models (monolayer and bilayer) of the phospholipid Dioleoyl-sn-glycerol-3-phosphocholine (DOPC) using Langmuir films, and large (LUVs) and giant (GUVs) unilamellar vesicles, to determine the effect of the pesticides chlorantraniliprole (CLTP), isoxaflutole (ISF), and simazine (SMZ), used in sugarcane. CLTP affects the lipid organization of the bioinspired models of DOPC π-A isotherms, while ISF and SMZ pesticides significantly affect the LUVs and GUVs. Furthermore, the in vivo study of the gill tissue in fish in the presence of pesticides (2.0 × 10−10 mol/L for CLTP, 8.3 × 10−9 mol/L for ISF, and SMZ at 9.9 × 10−9 mol/L) was performed using optical and fluorescence images. This investigation was motivated by the gill lipid membranes, which are vital for regulating transporter activity through transmembrane proteins, crucial for maintaining ionic balance in fish gills. In this way, the presence of phospholipids in gills offers a model for understanding their effects on fish health. Histological results show that exposure to CLTP, ISF, and SMZ may interfere with vital gill functions, leading to respiratory disorders and osmoregulation dysfunction. The results indicate that exposure to pesticides caused severe morphological alterations in fish, which could be correlated with their impact on the bioinspired membrane models. Moreover, the effect does not depend on the exposure period (24h and 96h), showing that animals exposed to pesticides for a short period suffer irreparable damage to gill tissue. In summary, we can conclude that the harm caused by pesticides, both in membrane models and in fish gills, occurs due to contamination of the aquatic system with pesticides. Therefore, water quality is vital for the preservation of ecosystems.

Measurement of the rotational relaxation time of intracellular water in dried yeast and Jurkat cells by near infrared spectroscopy

Molecular mobility of intracellular water is a crucial parameter in the study of the mechanism of desiccation tolerance. As one of the parameters that reflecting molecular mobility, the viscosity of intracellular water has been found intimately related with the protection of the phospholipid membrane because it quantifies the diffusion ability of water and mass in the intracellular environment. In this work we measured the intracellular water relaxation time, which can be translated into water viscosity, by using a previously established NIR-dielectric method to monitor the drying process of baker's yeast and Jurkat cells with different desiccation tolerance. We found that intracellular saccharide can significantly decrease the intracellular water viscosity. Also, the intracellular water diffusion coefficient obtained from this method were found in good agreement with other reports.

Modulation of Phospholipase A2 Membrane Activity by Anti-inflammatory Drugs.

The phospholipase A2 (PLA2) superfamily consists of lipolytic enzymes that hydrolyze specific cell membrane phospholipids and have long been considered a central hub of biosynthetic pathways, where their lipid metabolites exert a variety of physiological roles. A misregulated PLA2 activity is associated with mainly inflammatory-derived pathologies and thus has shown relevant therapeutic potential. Many natural and synthetic anti-inflammatory drugs (AIDs) have been proposed as direct modulators of PLA2 activity. However, despite the specific chemical properties that these drugs share in common, little is known about the indirect modulation able to finely tune membrane structural changes at the precise lipid-binding site. Here, we use a novel experimental strategy based on differential scanning calorimetry to systematically study the structural properties of lipid membrane systems during PLA2 cleavage and under the influence of several AIDs. For a better understanding of the AIDs-membrane interaction, we present a comprehensive and comparative set of molecular dynamics (MD) simulations. Our thermodynamic results clearly demonstrate that PLA2 cleavage is hindered by those AIDs that significantly reduce the lipid membrane cooperativity, while the rest of the AIDs oppositely tend to catalyze PLA2 activity to different extents. On the other hand, our MD simulations support experimental results by providing atomistic details on the binding, insertion, and dynamics of each AID on a pure lipid system; the drug efficacy to impact membrane cooperativity is related to the lipid order perturbation. This work suggests a membrane-based mechanism of action for diverse AIDs against PLA2 activity and provides relevant clues that must be considered in its modulation.