Binding of -[Ru(phen)(3,4Apy)] to Model Lipid Membranes: Implications for New Tools in the Development of Antiamyloid Drugs.

This study explores the interactions of the -[Ru(phen)(Apy)] complex (RuApy, phen = 1,10-phenanthroline, Apy = 3,4-aminopyridine) with model lipid membranes to explain the role this complex plays in mitigating Aβ toxicity in PC12 neuronal cells. Fluorescence quenching, surface pressure isotherms in Langmuir monolayers, and infrared reflection-absorption analyses revealed that the positively charged RuApy interacts with the phosphate headgroups of monolayers, indirectly affecting ester carbonyl groups through hydrogen bonding with the amino group of the pyridine ligand of RuApy. These results offer a scenario for the protective effect of RuApy against Aβ toxicity in neuronal cells in which these interactions shield the electrostatic interactions of Aβ with lipid membranes, preserving membrane integrity and mitigating the deleterious influence of Aβ.

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.

In situ interaction between the hormone 17α-ethynylestradiol and the liquid-ordered phase composed of the lipid rafts sphingomyelin and cholesterol.

Hormone treatments are frequently associated with cardiovascular diseases and cancers in women. Additionally, the detrimental effects of their presence as contaminants in water remain a concern. The transport of hormones through cell membranes is essential for their biological action, but investigating cell permeability is challenging owing to the experimental difficulty in dealing with whole cells.

pH-Dependence Cytotoxicity Evaluation of Artepillin C against Tumor Cells.

Brazilian green propolis is a well-known product that is consumed globally. Its major component, Artepillin C, showed potential as an antitumor product. This study explored the impact of Artepillin C on fibroblast and glioblastoma cell lines, used as healthy and very aggressive tumor cell lines, respectively.

Biological responses to imazapic and methyl parathion pesticides in bioinspired lipid membranes and Tilapia fish.

Pesticide misuse has well-documented detrimental effects on ecosystems, with Nile tilapia (Oreochromis niloticus) being particularly vulnerable. The current study focuses on the impact of widely used sugarcane crop pesticides, Imazapic (IMZ) and Methyl Parathion (MP), on tilapia gill tissues and their lipid membranes. This investigation was motivated by the specific role of the lipid membrane in transport regulation.

Immunoassay platform with surface-enhanced resonance Raman scattering for detecting trace levels of SARS-CoV-2 spike protein.

The early diagnosis of Coronavirus disease (COVID-19) requires either an accurate detection of genetic material or a sensitive detection of viral proteins. In this work, we designed an immunoassay platform for detecting trace levels of SARS-CoV-2 spike (S) protein. It is based on surface-enhanced resonance Raman scattering (SERRS) of methylene blue (MB) adsorbed onto spherical gold nanoparticles (AuNPs) and coated with a 6 nm silica shell.

The efficiency of photothermal action of gold shell-isolated nanoparticles against tumor cells depends on membrane interactions.

Photoinduced hyperthermia with nanomaterials has been proven effective in photothermal therapy (PTT) of tumor tissues, but a precise control in PTT requires determination of the molecular-level mechanisms. In this paper, we determined the mechanisms responsible for the action of photoexcited gold shell-isolated nanoparticles (AuSHINs) in reducing the viability of MCF7 (glandular breast cancer) and especially A549 (lung adenocarcinoma) cells in vitro experiments, while the photoinduced damage to healthy cells was much smaller. The photoinduced effects were more significant than using other nanomaterials, and could be explained by the different effects from incorporating AuSHINs on Langmuir monolayers from lipid extracts of tumoral (MCF7 and A549) and healthy cells.

Luminescent imaging of insulin amyloid aggregation using a sensitive ruthenium-based probe in the red region.

A sensitive and selective strategy to identify insulin fibrils remains a challenge for researchers in amyloid protein research. Thus, it is critical to detect, in vitro, the species generated during amyloid aggregation, particularly the fibrillar species. Here we demonstrate that the luminescent complex cis-[Ru(phen)(3,4Apy)] (RuApy; phen = 1,10-phenanthroline; 3,4Apy = 3,4-diaminopyridine) is a rapid, low-cost alternative to in vitro detection of fibrillar insulin, using conventional optical techniques.

Chemical and morphological effects of the contraceptive hormone 17 α-ethynylestradiol on fluid lipid membranes.

The lack of studies involving the effects in human health associated with the chronic ingestion of pollutants lead to the path of investigating the action of these compounds in cell membrane models. We demonstrated the interaction (causes and consequences) of the hormone 17 α-ethinylestradiol (EE2) with lipid monolayers (prepared as Langmuir films) and bilayers prepared as small unilamellar vesicles (SUVs) and giant unilamellar vesicles (GUVs). Both fluidity and majority chemical composition of real plasma cell membrane were guaranteed using the phospholipid 1-palmitoil-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC).

Langmuir-Schaefer Perylene Derivative Films: Influence of the Molecular Chemical Structure on the Supramolecular Arrangement.

Since the optical and electrical properties of organic thin films devices depend on their supramolecular arrangement and the molecular chemical structure, the understanding of such characteristics is essential for the optimization of these devices. In this study, we determine the supramolecular arrangement of thin films produced using the Langmuir-Schaefer (LS) technique and explain how its supramolecular arrangement is affected by the molecular chemical structure using two perylene derivatives: bis-butylimide (BuPTCD) and bis-phenethylimide (PhPTCD). The optical absorption measurements reveal that both films grow homogeneously and indicate that the presence of H aggregates (forbidden emission) is higher for BuPTCD LS film than for PhPTCD LS film.

Correlating Artepillin C cytotoxic activity on HEp-2 cells with bioinspired systems of plasma membranes.

Artepillin C is the main compound present in propolis from Baccharis dracunculifolia, whose antitumor activity has been the focus of many studies. Herein, we shall investigate the Artepillin C mechanisms of action against cells derived from the oropharyngeal carcinoma (HEp-2). Cytotoxicity tests revealed that the concentrations of Artepillin C required to reduce cell viability by 50% (CC) are dependent on the incubation time, decreasing from 40.

Vibrational Spectroscopic Characterization and Coherent Anti-Stokes Raman Spectroscopy (CARS) Imaging of Artepillin C.

In the following work, the vibrational spectroscopic characteristics of artepillin C are reported by means of Fourier transform infrared (FT-IR) and Raman spectroscopies, surface-enhanced Raman scattering (SERS), and coherent anti-Stokes Raman scattering (CARS) microscopy. Artepillin C is an interesting compound due to its pharmacological properties, including antitumor activity. It is found as the major component of Brazilian green propolis, a resinous mixture produced by bees to protect their hives against intruders.

Luminescent nanohybrids based on silica and silylated Ru(II)-Yb(III) heterobinuclear complex: new tools for biological media analysis.

Lanthanide (Ln) complexes emitting in the near-infrared (NIR) region have fostered great interest as upcoming optical tags owing to their high spatial and temporal resolution emission as well deeper light penetration in biological tissues for non-invasive monitoring. For use in live-cell imaging, lanthanide complexes with long-wavelength absorption and good brightness are especially critical. Light-harvesting ligands of Ln complexes are typically excited in the ultraviolet region, which in turn trigger simultaneously autofluorescence and long-exposition damage of living systems.

Near-infrared/visible-emitting nanosilica modified with silylated Ru(II) and Ln(III) complexes.

Three luminescent silica-based nanohybrids were fabricated by grafting of silylated Ru(II) and Nd/Yb(III) complexes onto mesoporous silica nanoparticles obtained by microemulsion method. The prepared nanohybrids were characterized by Fourier transform-Raman spectroscopy, solid state-nuclear magnetic resonance, high resolution-transmission electron microscopy and scanning and transmission electron microscopy techniques. The chemical integrity and the grafting of all complexes inside MSNs nanopores as well as a good distribution of metal complexes onto MSNs surface were achieved for all nanohybrids.

Bioactivity and action mechanism of green propolis against Pythium aphanidermatum.

We have established how natural compounds from green propolis collected by the species Apis mellifera act against the growth of Pythium aphanidermatum. On the basis of mass spectrometry (Q-ToF MS), we determined that Artepillin C, the major constituent of green propolis, underlies the effect and displays activity against P. aphanidermatum at a minimal inhibitory concentration of 750 µg.

pH and Charge Effects Behind the Interaction of Artepillin C, the Major Component of Green Propolis, With Amphiphilic Aggregates: Optical Absorption and Fluorescence Spectroscopy Studies.

Brazilian green propolis is one of the bee products most consumed in the world to prevent diseases, owing antioxidant, antimicrobial, anti-inflammatory and antitumor activities. The major component of Brazilian green propolis is Artepillin C (ArtC), a cinnamic acid derivative with two prenylated groups that improve the affinity of the compound for lipophilic environment. Here, we have employed optical absorption and fluorescence techniques to draw conclusions on how ArtC interacts with amphiphilic aggregates commonly used as model membranes having different charges in the polar head group.

Photoluminescent properties in perylene PVD films: Influence of molecular aggregates and supramolecular arrangement.

Organic thin films are at the forefront of basic studies and applications in the field of physics, chemistry, biochemistry and materials science. For example, the intrinsic supramolecular arrangement, or simply the formation of aggregates may alter the optical and electrical properties, which would impact the potential applications of the material. Here, an attempt is made to correlate the molecular structures of two perylene derivatives, bis butylimido perylene (BuPTCD) and bis phenethylimido perylene (PhPTCD), with their film formation, in particular, the supramolecular arrangement and the photoluminescent properties.

Interaction of Artepillin C with model membranes: Effects of pH and ionic strength.

Artepillin C is the major constituent of green propolis, one of the most consumed products in popular medicine owing to its therapeutic effects, including antitumor activity. Artepillin C differs from other cinnamic acid derivatives due to the presence of two prenylated groups in its structure, believed to enhance access to the cell membrane and resulting in pharmacological activity. The membrane outer leaflet of tumor cells is exposed to an acidic extracellular environment, which could modulate the protonation state of antitumor drugs and hence their interaction with the cell membrane.

Optical absorption and fluorescence spectroscopy studies of Artepillin C, the major component of green propolis.

The bioactivity of propolis against several pathogens is well established, leading to the extensive consumption of that bee product to prevent diseases. Brazilian green propolis, collected by the species Apis mellifera, is one of the most consumed in the world. The chemical composition of green propolis is complex and it has been shown that it displays antioxidant, antimicrobial, anti-inflammatory and antitumor activities, especially due to the high content of Artepillin C.

Biophysical studies suggest a new structural arrangement of crotoxin and provide insights into its toxic mechanism.

Crotoxin (CTX) is the main neurotoxin found in Crotalus durissus rattlesnake venoms being composed by a nontoxic and non-enzymatic component (CA) and a toxic phospholipase A (CB). Previous crystallographic structures of CTX and CB provided relevant insights: (i) CTX structure showed a 1:1 molecular ratio between CA and CB, presenting three tryptophan residues in the CA/CB interface and one exposed to solvent; (ii) CB structure displayed a tetrameric conformation. This study aims to provide further information on the CTX mechanism of action by several biophysical methods.

Acridine orange interaction with DNA: Effect of ionic strength.

Background: The study of acridine orange (AO) spectral characteristics and the quenching of its singlet and triplet excited states by TEMPO radical at its binding to DNA in the function of the DNA concentration and in the absence and presence of NaCl is reported.

Methods: The study was performed using steady-state and time resolved optical absorption and florescence, fluorescence correlation spectroscopy and resonant light scattering techniques.

Results: The presence of different species in equilibrium: AO monomers and aggregates bound to DNA, has been demonstrated, their relative content depending on the DNA and the AO concentrations.

Interaction of Artepillin C with model membranes.

Green propolis, a mixture of beeswax and resinous compounds processed by Apis mellifera, displays several pharmacological properties. Artepillin C, the major compound in green propolis, consists of two prenylated groups bound to a phenyl group. Several studies have focused on the therapeutic effects of Artepillin C, but there is no evidence that it interacts with amphiphilic aggregates to mimic cell membranes.

Luminescent Ru(II) Phenanthroline Complexes as a Probe for Real-Time Imaging of Aβ Self-Aggregation and Therapeutic Applications in Alzheimer's Disease.

The complexes cis-[Ru(phen)(Apy)], Apy = 4-aminopyridine and 3,4-aminopyridine, are stable in aqueous solution with strong visible absorption. They present emission in the visible region with long lifetime that accumulates in the cytoplasm of Neuro2A cell line without appreciable cytotoxicity. The complexes also serve as mixed-type reversible inhibitors of human AChE and BuChE with high active site contact.

Miltefosine-loaded lipid nanoparticles: Improving miltefosine stability and reducing its hemolytic potential toward erythtocytes and its cytotoxic effect on macrophages.

The toxic effects of miltefosine on the epithelial cells of the gastrointestinal tract and its hemolytic action on erythrocytes have limited its use as an antileishmanial agent. As part of our search for new strategies to overcome the side effects of miltefosine during the treatment of leishmaniasis, we have developed stable miltefosine-loaded lipid nanoparticles in an attempt to reduce the toxic effects of the drug. We have evaluated lipid nanoparticles containing varying amounts of miltefosine and cholesterol, prepared by sonication, in terms of their physicochemical properties, preliminary stability, hemolytic potential toward erythrocytes, and cytotoxicity to macrophages and to promastigote and amastigote forms of Leishmania (L.

Insights on the structure of native CNF, an endogenous phospholipase A2 inhibitor from Crotalus durissus terrificus, the South American rattlesnake.

Several snake species possess endogenous phospholipase A2 inhibitors (sbPLIs) in their blood plasma, the primary role of which is protection against an eventual presence of toxic phospholipase A2 (PLA2) from their venom glands in the circulation. These inhibitors have an oligomeric structure of, at least, three subunits and have been categorized into three classes (α, β and γ) based on their structural features. SbγPLIs have been further subdivided into two subclasses according to their hetero or homomeric nature, respectively.