Evaluation of the Physico-Chemical Properties of Liposomes Assembled from Bioconjugates of Anisic Acid with Phosphatidylcholine

Understanding the Transepithelial Transport and Transbilayer Diffusion of the Antihypertensive Peptide Asn-Cys-Trp: Insights from Caco-2 Cell Monolayers and the DPPC Model Membrane

Understanding the transport mechanism of the peptide Asn-Cys-Trp (NCW) is crucial to improving its intestinal absorption and bioavailability. This study investigated the absorption of NCW through Caco-2 cell monolayers and its interaction with the DPPC bilayers. Results revealed that after a 3 h incubation, the Papp (AP-BL) and Papp (BL-AP) values of NCW at a concentration of 5 mmol/L were (22.24 ± 4.52) × 10-7 and (6.63 ± 2.31) × 10-7 cm/s, respectively, with the transport rates of 1.59 ± 0.32 and 0.62 ± 0.20%, indicating its moderate absorption. NCW was found to be transported via PepT1 and paracellular transport pathways, as evidenced by the significant impact of Gly-Pro and cytochalasin D on the Papp values. Moreover, NCW upregulated ZO-1 mRNA expression. Further investigation of the ZO-1-mediated interaction between NCW and tight junction proteins will contribute to a better understanding of the paracellular transport mechanism of NCW. The interaction between NCW and the DPPC bilayers was predominantly driven by entropy. NCW permeated the bilayers through electrostatic, hydrogen bonding, and hydrophobic interactions, resulting in increased fluidity, flexibility, and disorder as well as phase transition and phase separation of the bilayers.

The effect of trans-resveratrol on the physicochemical properties of lipid membranes with different cholesterol content

Resveratrol is one of the most popular phytoalexins, which naturally occurs in grapes and red wine. This compound not only has beneficial effects on the human body, especially on the cardiovascular system, but also has antiviral, antibacterial and antifungal properties. In addition, resveratrol may have therapeutic effects against various types of cancer. The mechanism of action of resveratrol is not fully understood, but it is suspected that one of the most important steps is its interaction with the cell membrane and changing its molecular organization. Therefore, in the present study, we investigated the effects of resveratrol at different concentrations (0-75 μM) on model membranes composed of POPC, SM and cholesterol, in systems with different cholesterol contents and a constant POPC/SM molar ratio (1:1). Our tests included systems containing 5, 15 and 33.3 mol% cholesterol. Tests were carried out for monolayers using the Langmuir monolayer technique supported by Brewster angle microscopy and penetration experiments. Bilayer (liposome) experiments included calcein release, steady-state DPH fluorescence anisotropy and partition coefficients. The results showed that resveratrol interacts with model cell membranes (lipid monolayers and lipid bilayers), and its incorporation into membranes is accompanied by changes in their physicochemical parameters, such as lipid packing, fluidity and permeability. Furthermore, we showed that the cholesterol content of the membrane significantly affects the degree of incorporation of resveratrol into the model membrane, which may indicate that the molecular mechanism of action of this compound is closely related to its interactions with lipid rafts, domains responsible for regulating various cellular functions.

Anti-CD4 antibody and dendrimeric peptide based targeted nano-liposomal dual drug formulation for the treatment of HIV infection

AIMS

Development and characterization of LAM and DTG loaded liposomes conjugated anti-CD4 antibody and peptide dendrimer (PD2) to improve the therapeutic efficacy and to achieve targeted treatment for HIV infection.

MAIN METHODS

A 2-level full factorial design was used to optimize the preparation of dual drug loaded liposomes. Optimized dual drug loaded ligand conjugated liposomes were assessed for their cytotoxicity and cell internalization on TZM-bl cells. Anti-HIV efficiency of the dual drug loaded liposomes were screened for their inhibitory potential in TZM-bl cells and the activities were confirmed using Peripheral Blood Mononuclear Cells (PBMCs).

KEY FINDINGS

The particle size of the optimized dual drug-loaded liposomes was 133.7 ± 4.04 nm, and the spherical morphology of the liposomes was confirmed by TEM analysis. The entrapment efficiency was 34 ± 4.9 % and 54 ± 1.8 % for LAM and DTG, respectively, and a slower in vitro release of LAM and DTG was observed when entrapped into liposomes. The cytotoxicity of the dual drug loaded liposomes was similar to the cytotoxicity of free drug solutions. Conjugation of anti-CD4 antibody and PD2 did not significantly influence the cytotoxicity but it enhanced the uptake of liposomes into the cells. Conjugated dual drug loaded liposomes exhibited better HIV inhibition with lower IC50 values (0.0003 ± 0.0002 μg/mL) compared to their free drug solutions (0.002 ± 0.001 μg/mL). The liposomal formulations have shown similar activities in both screening and confirmatory cell-based assays.

SIGNIFICANCE

The results demonstrated the cell targeting ability of dual drug loaded liposomes conjugated with anti-CD4 antibody and peptide dendrimer. Conjugated liposomes also improved anti-HIV efficiency of LAM and DTG.

Effects of Hydrophobic Gold Nanoparticles on Structure and Fluidity of SOPC Lipid Membranes

Gold nanoparticles (AuNPs) are promising candidates in various biomedical applications such as sensors, imaging, and cancer therapy. Understanding the influence of AuNPs on lipid membranes is important to assure their safety in the biological environment and to improve their scope in nanomedicine. In this regard, the present study aimed to analyze the effects of different concentrations (0.5, 1, and 2 wt.%) of dodecanethiol functionalized hydrophobic AuNPs on the structure and fluidity of zwitterionic 1-stearoyl-2-oleoyl-sn-glycerol-3-phosphocholine (SOPC) lipid bilayer membranes using Fourier-transform infrared (FTIR) spectroscopy and fluorescent spectroscopy. The size of AuNPs was found to be 2.2 ± 1.1 nm using transmission electron microscopy. FTIR results have shown that the AuNPs induced a slight shift in methylene stretching bands, while the band positions of carbonyl and phosphate group stretching were unaffected. Temperature-dependent fluorescent anisotropy measurements showed that the incorporation of AuNPs up to 2 wt.% did not affect the lipid order in membranes. Overall, these results indicate that the hydrophobic AuNPs in the studied concentration did not cause any significant alterations in the structure and membrane fluidity, which suggests the suitability of these particles to form liposome-AuNP hybrids for diverse biomedical applications including drug delivery and therapy.

Effect of Distigmasterol-Modified Acylglycerols on the Fluidity and Phase Transition of Lipid Model Membranes

Plant sterols are known for their health-promoting effects, lowering blood cholesterol levels and alleviating cardiovascular disease. In this work, we continue our research on the asymmetric acylglycerols in which fatty acid residues are replaced by two stigmasterol residues in sn-1 and sn-2 or sn-2 and sn-3 positions as new thermostable carriers of phytosterols for their potential application in foods or as components of new liposomes in the pharmaceutical industry. The aim of this manuscript was to compare and analyze the effects of four distigmasterol-modified acylglycerols (dStigMAs) on the fluidity and the main phase transition temperature of the model phospholipid membrane. Their properties were determined using differential scanning calorimetry (DSC), steady-state fluorimetry and attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR). The determination of the effect of the tested compounds on the mentioned physicochemical parameters of the model membranes will allow for the determination of their properties and stability, which is essential for their practical application. The results indicated that all compounds effect on the physicochemical properties of the model membrane. The degree of these changes depends on the structure of the compound, especially the type of linker by which stigmasterol is attached to the glycerol backbone, as well as on the type of hydrocarbon chain.

Acylglycerols of Myristic Acid as New Candidates for Effective Stigmasterol Delivery-Design, Synthesis, and the Influence on Physicochemical Properties of Liposomes

New carriers of phytosterols; acylglycerols containing natural myristic acid at sn-1 and sn-3 positions and stigmasterol residue linked to sn-2 position by carbonate and succinate linker have been designed and synthesized in three-step synthesis from dihydroxyacetone (DHA). The synthetic pathway involved Steglich esterification of DHA with myristic acid; reduction of carbonyl group of 1,3-dimyristoylpropanone and esterification of 1,3-dimyristoylglicerol with stigmasterol chloroformate or stigmasterol hemisuccinate. The structure of the obtained hybrids was established by the spectroscopic methods (NMR; IR; HRMS). Obtained hybrid molecules were used to form new liposomes in the mixture with model phospholipid and their effect on their physicochemical properties was determined, including the polarity, fluidity, and main phase transition of liposomes using differential scanning calorimetry and fluorimetric methods. The results confirm the significant effect of both stigmasterol-containing acylglycerols on the hydrophilic and hydrophobic region of liposome membranes. They significantly increase the order in the polar heads of the lipid bilayer and increase the rigidity in the hydrophobic region. Moreover, the presence of both acylglycerols in the membranes shifts the temperature of the main phase transition towards higher temperatures. Our results indicate stabilization of the bilayer over a wide temperature range (above and below the phase transition temperature), which in addition to the beneficial effects of phytosterols on human health makes them more attractive components of novel lipid nanocarriers compared to cholesterol.