Interaction between vitamin D2 and magnesium in liposomes: Differential scanning calorimetry and FTIR spectroscopy studies

Liposomal Forms of Fluoroquinolones and Antifibrotics Decorated with Mannosylated Chitosan for Inhalation Drug Delivery

The severe course of COVID-19 leads to the long-terming pulmonary diseases, such as bacterial pneumonia and post-COVID-19 pulmonary fibrosis. Thus, the essential task of biomedicine is a design of new effective drug formulations, including those for inhalation administration. In this work, we propose an approach to the creation of lipid–polymer delivery systems for fluoroquinolones and pirfenidone based on liposomes of various compositions decorated with mucoadhesive mannosylated chitosan. A generalizing study on the physicochemical patterns of the interactions of drugs with bilayers of various compositions was carried out, and the main binding sites were identified. The role of the polymer shell in the stabilization of vesicles and the delayed release of the contents has been demonstrated. For the liquid–polymer formulation of moxifloxacin, a prolonged accumulation of the drug in lung tissues was found after a single endotracheal administration to mice, significantly exceeding the control intravenous and endotracheal administration of the drug.

Interaction mechanism of three egg protein derived ACE inhibitory tri-peptides and DPPC membrane using FS, FTIR, and DSC studies

Understanding the interaction of food derived angiotensin converting enzyme (ACE) inhibitory peptides and intestinal epithelial cell membrane may help to improve their absorption. This research aimed to study the molecular interaction of ACE inhibitory tri-peptides ADF, FGR, and MIR with DPPC membrane during absorption process. The DPPC liposome was prepared and characterized, then used as a model membrane. The permeability of tri-peptides across the membrane was investigated using Fluorescence spectroscopy. The effect of tri-peptides on the structure and dynamics of DPPC bilayers was determined using Fourier transform infrared spectroscopy. The effect of tri-peptides on the phase transition temperature in the DPPC membrane was also analyzed using Differential scanning calorimetry. The results showed that ACE inhibitory tri-peptides ADF, FGR, and MIR can penetrate into both the membrane-water interface and hydrophobic region of DPPC bilayer, and the tri-peptide FGR have higher permeability across the membrane.

Drug–Membrane Interaction as Revealed by Spectroscopic Methods: The Role of Drug Structure in the Example of Rifampicin, Levofloxacin and Rapamycin

We have investigated the nature of the interaction of small organic drug molecules with lipid membranes of various compositions. Using infrared spectroscopy and differential scanning calorimetry methods, we studied the role of the structure of the active molecule in interaction with the membrane using the example of dipalmitoylphosphatidylcholine (DPPC) and dipalmitoylphosphatidylcholine:cardiolipin (DPPC:CL) liposomes. We discovered the key role of the heterocycle in interaction with the polar part of the bilayer and the network of unsaturated bonds in interaction with the hydrophobic part. For rifampicin and levofloxacin, the main binding sites were phosphate and carbonyl groups of lipids, and in the case of anionic liposomes we found a slight penetration of rifampicin into the hydrophobic part of the bilayer. For rapamycin, experimental confirmation of the localization of the molecule in the region of fatty acid chains was obtained, and perturbation in the region of phosphate groups was demonstrated for the first time. The process of phase transition of liposomal forms of rifampicin and levofloxacin was studied. DPPC liposomes accelerate the phase transition when loaded with a drug. DPPC:CL liposomes are less susceptible to changes in the phase transition rate.

Stress impact of liposomes loaded with ciprofloxacin on the expression level of MepA and NorB efflux pumps of methicillin-resistant Staphylococcus aureus

One mechanism of ciprofloxacin resistance is attributed to chromosomal DNA-encoded efflux pumps such as the MepA and NorB proteins. The goal of this research is to find a way to bypass Staphylococcus aureus' efflux pumps. Because of its high membrane permeability and low association with NorB and MepA efflux proteins, a liposome-encapsulating antibiotic is one of the promising, cost-effective drug carriers and coating mechanisms for overcoming active transport of methicillin-resistant S. aureus (MRSA) multidrug-resistant efflux protein . The calculated "Log Perm RRCK" membrane permeability values of 1,2-distearoyl-sn-glycerol-3-phosphocholine (DSPC) ciprofloxacin liposome-encapsulated (CFL) showed a lower negative value of - 4,652 cm/s and greater membrane permeability than ciprofloxacin free (CPF). The results of RT-qPCR showed that cationic liposomes containing ciprofloxacin in liposome-encapsulated form (CFL) improved CPF antibacterial activity and affinity for negatively charged bacterial cell surface membrane in comparison to free drug and liposome, as it overcame several resistance mechanisms and reduced the expression of efflux pumps. Ciprofloxacin liposome-encapsulated (CFL) is therefore more effective than ciprofloxacin alone. Liposomes can be combined with a variety of drugs that interact with bacterial cell efflux pumps to maintain high sustained levels of antibiotics in bacterial cells.

Effect of cholecalciferol on unsaturated model membranes

Vitamin D plays an important role in many physiological processes, particularly calcium and phosphorous homeostasis. The biochemistry of vitamin D is also complex, encompassing a range of active molecules that may be either endogenous or dietary in origin. The role of lipids and fats in the production, processing and use of vitamin D is an interesting one, with a relative paucity of model studies into the interactions of vitamin D with lipidic systems such as micelles and vesicles. Here, we have studied the effect of vitamin D3 in simple unsaturated phospholipid systems. We used NMR and FTIR spectroscopy to investigate the effect of increasing vitamin D concentration on the structure and dynamics of the lipid chains and interfacial region. In order to link these model studies with more complex biomimetic environments, we compare results in the presence of buffer and vitamin D binding protein. We have also used DLS to determine that vitamin D3-DOPC vesicles can retain their size distribution for varying amounts of time in different conditions. We find that the acyl chain region of vitamin D3-DOPC membranes are generally disordered, and that the addition of buffer and/or protein alters the properties of the interfacial region.

Determination of the dose-dependent toxic effects of mad honey on mouse liver using ATR-FTIR spectroscopy

Mad honey (MH) is obtained from Rhododendron plants, which are extensively grown in some regions of the world such as Europe, North America, Tropical Asia and Turkey. Although it has been known that MH induces adverse effects in the body due to grayanotoxin (GTX) in it, it is widely used for some medical purposes by the public. In this study, the effects of MH (25, 50 and 75 mg/kg) and GTX-III (0.01 mg/kg), which is the pure form of the most toxic type of the GTXs in MH, were investigated on the mouse liver at molecular level via Attenuated Total Reflection-Fourier Transform Infrared (ATR-FTIR) spectroscopy. The results showed that 25 and 50 mg/kg of MH didn't cause any significant alterations in the liver tissue except a decrease in the glycogen amount. However, significant differences were observed between 75 mg/kg MH and GTX-III treated groups and control group. For example, the amounts of saturated lipids, nucleic acids and proteins increased in the 75 mg/kg MH and GTX-III treated groups. A decrease in the ratios of unsaturated/saturated lipid, CH₂/lipid and carbonyl/lipid and an increase in the ratio of CH₃/lipid were observed after the administration of 75 mg/kg MH and GTX-III, all of which may be a consequence of lipid peroxidation. Moreover, 75 mg/kg MH and GTX-III caused a decrease in the membrane order, an increase in the membrane fluidity and some important changes on the secondary structure of proteins indicating protein denaturation. In addition, Hierarchical Cluster Analysis (HCA) and Principal Component Analysis (PCA) confirmed these findings. These results revealed that MH induces significant dose-dependent toxic effects in the structure and function of the liver tissue. This study also showed that ATR-FTIR spectroscopy provides a rapid and sensitive monitoring of the changes induced by a toxic compound on biological tissues at molecular level.

Moxifloxacin interacts with lipid bilayer, causing dramatic changes in its structure and phase transitions

Most drugs besides their intended activity, express undesired side effects, including those with the engagement of cell membrane. Previously, such undesired nonspecific effects on the membrane have been shown for a number of widely used nonsteroidal anti-inflammatory drugs. In this paper, we study the mechanism of interaction between moxifloxacin (Mox), antibacterial drug of broad specificity, with lipid bilayer of the liposomes of various compositions as a model of cell membrane using a combination of spectroscopy methods, including ATR-FTIR spectroscopy, circular dichroism, UV and fluorescence spectroscopy. The fine structure of the moxifloxacin-liposome complex, localization of the drug in bilayer and the main sites of Mox interaction with lipid membrane were determined. Lipid composition of the liposome plays a key role in the interaction with moxifloxacin, drastically affecting the loading efficiency, strength and character of drug binding, lipid phase segregation and phase transition parameters. In case of anionic liposomes composed of dipalmitoylphosphatidylcholine (DPPC) and cardiolipin (CL^2-) the electrostatic interaction of negatively charged nitrogen in heterocycle moiety of moxifloxacin with cardiolipin phosphate groups is a crucial factor for stable complex formation. The study of moxifloxacin-liposome complex behavior at phase transition in bilayer by DSC method revealed that in DPPC/CL^2- liposomes system two microphases with different content of CL^2- coexist and Mox interacts with both of these microphases resulting in the formation of two types of complexes with different structure and phase transition temperature. This binding stabilized the gel-state of the lipid bilayer with increasing the phase transition temperature Tm up to 3-5 °C. A different situation is observed for neutral DPPC liposomes: drug interaction with bilayer results in defects formation and a fluidization effect in lipid bilayer, resulted to decrease the Tm value by 2-4 °C. Moxifloxacin is not firmly binding in the membrane of DPPC and drug releases rapidly.

Atomic force microscopy measurements of anionic liposomes reveal the effect of liposomal rigidity on antigen-specific regulatory T cell responses

Regulatory T cells (Tregs) are vital for maintaining a balanced immune response and their dysfunction is often associated with auto-immune disorders. We have previously shown that antigen-loaded anionic liposomes composed of phosphatidylcholine (PC) and phosphatidylglycerol (PG) and cholesterol can induce strong antigen-specific Treg responses. We hypothesized that altering the rigidity of these liposomes while maintaining their size and surface charge would affect their capability of inducing Treg responses. The rigidity of liposomes is affected in part by the length and saturation of carbon chains of the phospholipids in the bilayer, and in part by the presence of cholesterol. We used atomic force microscopy (AFM) to measure the rigidity of anionic OVA₃₂₃-containing liposomes composed of different types of PC and PG, with or without cholesterol, in a molar ratio of 4:1(:2) distearoyl (DS)PC:DSPG (Young's modulus (YM) 3611 ± 1271 kPa), DSPC:DSPG:CHOL (1498 ± 531 kPa), DSPC:dipalmitoyl (DP)PG:CHOL (1208 ± 538), DPPC:DPPG:CHOL (1195 ± 348 kPa), DSPC:dioleoyl (DO)PG:CHOL (825 ± 307 kPa), DOPC:DOPG:CHOL (911 ± 447 kPa), and DOPC:DOPG (494 ± 365 kPa). Next, we assessed if rigidity affects the association of liposomes to bone marrow-derived dendritic cells (BMDCs) in vitro. Aside from DOPC:DOPG liposomes, we observed a positive correlation between liposomal rigidity and cellular association. Finally, we show that rigidity positively correlates with Treg responses in vitro in murine DCs and in vivo in mice. Our findings underline the suitability of AFM to measure liposome rigidity and the importance of this parameter when designing liposomes as a vaccine delivery system.

Designing food delivery systems: challenges related to the in vitro methods employed to determine the fate of bioactives in the gut

This review discussesin vitroavailable approaches to study delivery and uptake of bioactive compounds and the associated challenges.

A nanovesicle topical formulation of Bhut Jolokia (hottest capsicum): a potential anti-arthritic medicine

OBJECTIVES

Bhut Jolokia is a capsicum variety indigenous to Northeast India and is recognized as the hottest capsicum variety of the world. The ethnobotanical survey revealed that it has potential anti-arthritic activity but its topical adverse events restrict its usability. In the present study, the semipurified capsaicinoids extract of Bhut Jolokia was formulated as a topical formulation via ethosomal nanovesicle approach, which enhanced the acceptability.

METHODS

Prepared formulation was optimized by surface response methodology and characterized for morphology, zeta potential, differential scanning calorimetry study and permeation and penetration studies. The experimental formulations were characterized on Freunds complete adjuvant-induced chronic arthritis model.

RESULTS

Ethosomal nanovesicles prepared with the semipurified capsaicinoids extract demonstrated good anti-arthritic activity in rat model, superior to Thermagel (a marketed formulation of capsaicin) in the reduction of joint swelling and pain throughout the observation period. Nanovesicle formulation showed better tolerability and acceptance on both animal and human models. Results obtained from the study strengthen the potential application of Bhut Jolokia semipurified extract in an ethosomal nanovesicle carrier as a topical analgesic as well as an anti-arthritic.

CONCLUSION

The significant positive results, with reduced irritant effect of the semipurified capsaicinoids extract of Bhut Jolokia-loaded ethosomal nanovesicle carrier, suggest that it could be one of the choices for formulation development in anti-arthritic medicine.

Vitamin D therapy and related metabolomics: is the calciferol dose and form the only requirements for successful clinical therapeutics?

A nutraceutical that has exploded onto the prescription pad in recent years is the fat soluble vitamin, vitamin D. This is due to an increasing medical interest in the utility of the vitamin in the treatment and prevention of an array of diseases and ailments. Despite the continued debate over the correct dose, form and serum levels, many clinicians fail to achieve intended therapeutic responses with their patients and deficiencies still exist. This may be due to medical professionals being less aware of the multitude of factors that can influence treatment when dosing a product. In this paper we explore the magnitude of interactions that exist between the host physiology and the vitamin and cite such points as a reason for confounding treatment end points. Aspects that are proposed to influence treatment success more critically than dose and molecular form prescribed are: organ pathology, intracellular states, the endocrine system, concomitant products, genetics, lifestyle, quality of product, and modern delivery systems.