Quercetin Induces Lipid Domain-Dependent Permeability

In this work, we present our results on quercetin interaction with distinct model membranes exploring the importance of lipid phases, ld, ld/lo and ld+lo+so, to the action of this flavonoid in bilayers and possibly contributing to clarifying some controversial aspects related to quercetin multiple activities. We found out that quercetin is able to increase membrane permeability in a manner dependent on the presence and characteristics of lipid domains. In the presence of sphingomyelin, we found the greatest increase in mean membrane permeability (at least 10 times higher than the other lipid compositions). We also observed the presence of micrometric domains whose shape and size were disturbed by the action of quercetin. The presence of cholesterol increased membrane rigidity. This effect was enhanced with the presence of quercetin, but for chol-sphingomyelin combination, the bilayers became more flaccid at low quercetin/lipid proportions (< 1/5) and moderately rigid at proportions of the 1/1 order. The affinity parameters were higher for the most homogeneous systems and with larger areas and extensions of disordered liquid phase than for those systems of higher heterogeneity.

Quercetin Induces Lipid Domain-Dependent Permeability

In this work, we present our results on quercetin interaction with distinct model membranes exploring the importance of lipid phases, ld, ld/lo and ld+lo+so, to the action of this flavonoid in bilayers and possibly contributing to clarifying some controversial aspects related to quercetin multiple activities. We found out that quercetin is able to increase membrane permeability in a manner dependent on the presence and characteristics of lipid domains. In the presence of sphingomyelin, we found the greatest increase in mean membrane permeability (at least 10 times higher than the other lipid compositions). We also observed the presence of micrometric domains whose shape and size were disturbed by the action of quercetin. The presence of cholesterol increased membrane rigidity. This effect was enhanced with the presence of quercetin, but for chol-sphingomyelin combination, the bilayers became more flaccid at low quercetin/lipid proportions (< 1/5) and moderately rigid at proportions of the 1/1 order. The affinity parameters were higher for the most homogeneous systems and with larger areas and extensions of disordered liquid phase than for those systems of higher heterogeneity.

Quercetin Induces Lipid Domain-Dependent Permeability

In this work, we present our results on quercetin interaction with distinct model membranes exploring the importance of lipid phases, ld, ld/lo and ld+lo+so, to the action of this flavonoid in bilayers and possibly contributing to clarifying some controversial aspects related to quercetin multiple activities. We found out that quercetin is able to increase membrane permeability in a manner dependent on the presence and characteristics of lipid domains. In the presence of sphingomyelin, we found the greatest increase in mean membrane permeability (at least 10 times higher than the other lipid compositions). We also observed the presence of micrometric domains whose shape and size were disturbed by the action of quercetin. The presence of cholesterol increased membrane rigidity. This effect was enhanced with the presence of quercetin, but for chol-sphingomyelin combination, the bilayers became more flaccid at low quercetin/lipid proportions (< 1/5) and moderately rigid at proportions of the 1/1 order. The affinity parameters were higher for the most homogeneous systems and with larger areas and extensions of disordered liquid phase than for those systems of higher heterogeneity.

An Overview of the Potential Therapeutic Applications of Essential Oils

The emergence of antimicrobial resistance (AMR) has urged researchers to explore therapeutic alternatives, one of which includes the use of natural plant products such as essential oils (EO). In fact, EO obtained from clove, oregano, thymus, cinnamon bark, rosemary, eucalyptus, and lavender have been shown to present significant inhibitory effects on bacteria, fungi, and viruses; many studies have been done to measure EO efficacy against microorganisms. The strategy of combinatory effects via conventional and non-conventional methods revealed that the combined effects of EO–EO or EO–antibiotic exhibit enhanced efficacy. This paper aims to review the antimicrobial effects of EO, modes of EO action (membrane disruption, efflux inhibition, increase membrane permeability, and decrease in intracellular ATP), and their compounds’ potential as effective agents against bacteria, fungi, and viruses. It is hoped that the integration of EO applications in this work can be used to consider EO for future clinical applications.

Methyl to trifluoromethyl substitution as a strategy to increase membrane permeability of short peptides

Here, we investigated the effect of CH3 to CF3 substitution on membrane permeability of peptides. We synthesized a series of peptides with CF3 groups and corresponding nonfluorinated peptides and measured...

Protect to Detect: A Golgi Apparatus Targeted Probe to Image Mobile Zinc Through the Use of a Lipophilic Cell-Labile Protecting Group Strategy

The Golgi apparatus requires zinc for its normal function, but the role it plays in these processes at the sub-cellular level is not well-understood due to the lack of appropriate tools to image it. Herein, a small molecule Golgi apparatus targeted probe was developed to image mobile Zn2+. A trityl group was used to protect a Golgi apparatus targeting cysteine residue to increase membrane permeability, which was then removed in cellulo within 24 hours, revealing the free cysteine targeting motif to anchor the probe to the Golgi apparatus. The probe shows good photophysical properties, good selectivity and Zn2+ response over a wide range of pH as well as low cellular toxicity. The probe was shown to be capable of targeting the Golgi apparatus and responding to Zn2+ in a number of different cell lines and was also applied to monitor the change of concentration of mobile Zn2+ in the Golgi apparatus in response to oxidative stress.

Protect to Detect: A Golgi Apparatus Targeted Probe to Image Mobile Zinc Through the Use of a Lipophilic Cell-Labile Protecting Group Strategy

The Golgi apparatus requires zinc for its normal function, but the role it plays in these processes at the sub-cellular level is not well-understood due to the lack of appropriate tools to image it. Herein, a small molecule Golgi apparatus targeted probe was developed to image mobile Zn2+. A trityl group was used to protect a Golgi apparatus targeting cysteine residue to increase membrane permeability, which was then removed in cellulo within 24 hours, revealing the free cysteine targeting motif to anchor the probe to the Golgi apparatus. The probe shows good photophysical properties, good selectivity and Zn2+ response over a wide range of pH as well as low cellular toxicity. The probe was shown to be capable of targeting the Golgi apparatus and responding to Zn2+ in a number of different cell lines and was also applied to monitor the change of concentration of mobile Zn2+ in the Golgi apparatus in response to oxidative stress.

Viroporins in the Influenza Virus

Influenza is a highly contagious virus that causes seasonal epidemics and unpredictable pandemics. Four influenza virus types have been identified to date: A, B, C, and D, where only A–C are known to infect humans. Influenza A (IAV) and B (IBV) viruses are responsible for seasonal influenza epidemics in humans and are responsible for up to a billion flu infections annually. The M2 protein is present in all influenza types and belongs to the class of viroporins (i.e., small proteins that form ion channels that increase membrane permeability in virus-infected cells). In influenza A and B, AM2 and BM2 are predominantly proton channels, although they also show some permeability to monovalent cations. In contrast, M2 proteins in influenza C (ICV) and D (IDV), CM2 and DM2, appear to be especially selective for chloride ions, with possibly some permeability to protons. These differences point to different biological roles for M2 in types A and B versus C and D, which is also reflected in their sequences. AM2 is by far the best characterized viroporin, and mechanistic details and rationale of its acid activation, proton selectivity, unidirectionality and relative low conductance are just beginning to be understood. The present review summarizes the biochemical and structural aspects of influenza viroporins and discusses the most relevant aspects of function, inhibition and interaction with the host.

Cell electrotransfection and viability dependence on electrotransfection and viability dependence on electoporation medium

Electroporation is a physical method that uses electric fields to increase membrane permeability. The method is widely used for intracellular drug and gene delivery. In this study we aimed to investigate the importance of the medium for efficiency of cell electrotransfection and viability following the application of electric field pulses. The experiments were performed using 2 different cell lines: Chinese hamster ovary (CHO) and Chinese hamster lung fibroblast (DC-3F) and 2 different electroporation media: SMEM (medium conductivity equal to 1.3 S/m) and laboratory-made low-conductivity (0.1 S/m) electroporation (EP) medium. Cells suspended in these media were supplemented with plasmid (10 µg/ml) encoding luciferase and then were treated with 1, 5, or 10 high-voltage (1200 V/cm, 100 µs, at 1 Hz) pulses. Transfection efficiency was determined by luciferase activity 24 h after cell treatment, while cell viability was determined by clonogenic assay. Results showed significant differences between cell lines and used electroporation media. CHO transfection was higher when electroporation was performed in low conductivity EP medium. Low transfection efficiency in SMEM medium resulted from low viability. In contrast, transfection efficiency of DC-3F cells was higher in SMEM. Possible mechanisms governing these differences are discussed.