Egg Phosphatidylcholine Research Articles

CRGD peptide-conjugated polyethylenimine-based lipid nanoparticle for intracellular delivery of siRNA in hepatocarcinoma therapy

The effective delivery system plays an important role in the application of siRNA in the antitumor study. However, until now, researches on the delivery systems targeting hepatocarcinoma cells are still being explored. Here we designed and prepared a novel siRNA delivery system, cRGD-PSH-NP, which was based on a modified polyethyleneimine (PSH) and DSPE-PEG2000-cRGD. cRGD-PSH-NP loaded with survivin siRNA (cRGD-PSH-NP/S) was composed of egg phosphatidylcholine, cationic PSH, PEGylated lipids, survivin siRNA, and cRGD peptide as a targeting ligand. The formulations of cRGD-PSH-NP/S were optimized and characterized. In vitro investigations showed excellent gene silencing and antitumor activity compared with the unmodified nanoparticles in HepG2 cells. In vivo antitumor efficacy of cRGD-PSH-NP/S exhibited potent tumor inhibition (74.71%) in HepG2-bearing nude mice without inducing toxicity. These data suggested further research of cRGD-PSH-NP/S in hepatocarcinoma therapy.

Elastic moduli of lipid membranes: Reproducibility of AFM measures

Membrane elastic properties play a major role in membrane remodeling events, such as vesicle fusion and fission. They are also crucial in drug delivery by liposomes. Different experimental techniques are available to measure elastic properties. Among them, atomic force microscopy (AFM) presents the unique advantage of being directly applicable to nano-sized liposomes. Unfortunately, different AFM measures reported in the literature show little agreement among each other and are difficult to compare with measures of bending modulus obtained by other experimental techniques or by molecular simulations. In this work we determine the bending rigidity of Egg PC liposomes in terms of Young modulus via AFM measurements, using two different tip shapes and different cantilever force constants. We interpret the measures using the Hertz and Shell models, and observe a clear dependency of the Young modulus values on the tip properties and on the interpretative theory. The effect of the AFM tip shape is less important than the effect of the cantilever force constant, and the mathematical model has a major effect on the interpretation of the data. The Shell theory provides the closest agreement between AFM data and other experimental data for the membrane bending modulus. Finally, we compare the results to calculations of bending modulus from molecular dynamics simulations of membrane buckles. Simulations provide values of bending modulus consistent with literature data, but the agreement with AFM experiments is reasonable only for some specific experimental conditions.

P.725 ACC neurometabolites in Bipolar Disorder are influenced by mood state and medication: a systematic review and meta-analysis of 1H-MRS studies

Local anesthetics promote analgesia by interacting with excitable membranes. Articaine (ATC) has a unique composition among local anesthetics as it possesses a thiophene instead of the typical phenyl ring. Aiming to characterize the interaction of neutral articaine (nATC) with phospholipid membranes, we have employed a synergistic approach of experimental and computational techniques. Fluorescence measurements supported nATC partitioning into the membranes, since its intrinsic fluorescence anisotropy increased from 0.03 in water to 0.29 in the presence of egg phosphatidylcholine (EPC) liposomes, and the fluorescence of AHBA, a probe that monitors the water-membrane interface, was quenched by nATC. 1H NMR experiments revealed changes in the chemical shifts of articaine and EPC hydrogens after partitioning, and shorter T1 values of nATC hydrogens when inserted into the EPC vesicles. Contacts of nATC and the phospholipid polar head group were inferred from 2D-NOE. Taken together, these results indicate a superficial insertion of the nATC molecules inside EPC bilayers. This conclusion was confirmed by molecular dynamics simulations, which allowed the identification of the key interactions underlying the preferential location of nATC in the bilayer. Contrary to what is often stated (that articaine is a high lipophilic local anesthetic agent) our results place ATC among the hydrophilic ones, such as lidocaine, prilocaine, and mepivacaine, for which the water/membrane interface is the preferred location.

A Phospholipase-A Activity in Soluble Leishmania Antigens Causes Instability of Liposomes.

This study aimed to investigate the existence of phospholipase-A (PLA) activity in Soluble L. major Antigens (SLA) because of no reports for it so far. Liposomes were used as sensors to evaluate PLA activity. Liposomal SLA consisting of Egg Phosphatidylcholine (EPC) or Sphingomyelin (SM) were prepared by two different methods in different pH or temperatures and characterized by Dynamic Light Scattering (DLS) and Thin Layer Chromatography (TLC). Lipid hydrolysis led to the disruption of EPC liposomal SLA in both methods but the Film Method (FM) produced more stable liposomes than the Detergent Removal Method (DRM). The preparation of EPC liposomal SLA at pH 6 via FM protected liposomes from hydrolysis to some extent for a short time. EPC liposomes but not SM liposomes were disrupted in the presence of SLA. Therefore, a phospholipid without ester bond such as SM should be utilized in liposome formulations containing PLA as an encapsulating protein.

Physical Characterization and Biodistribution of Cisplatin Loaded in Surfactant Modified-Hybrid Nanoparticles Using Polyethylene Oxide-b-Polymethacrylic Acid.

Purpose: Conjugating cisplatin into hybrid nanoparticles is intended to enhance tumor accumulation in cancer therapy due to drug interaction with polymer and prevent premature drug release because of the presence of a lipid layer. Methods: Hybrid nanoparticles composed of polyethylene oxide-b-polymethacrylic acid, egg phosphatidylcholine, and surfactant, i.e. sodium cholate/sodium deoxycholate/Tween 80, were prepared by the injection method. Cisplatin was subsequently loaded by incubating the polymer-drug mixtures at the molar ratio of carboxylate ions of 2:1. Results: The results showed that the addition of surfactants produced particle sizes between 33 and 52 nm. The addition of cisplatin increased the ζ-potential to slightly positive charges with encapsulation efficiencies of 5%-18%. An in vivo biodistribution study of mice identified a cisplatin plasma concentration of sodium cholate-modified hybrid nanoparticles 10 times higher than cisplatin solution, thus producing high tumor accumulation. Conclusion: Conjugating cisplatin into sodium cholate-modified hybrid nanoparticles improves its accumulation in tumors.

Choline Intake as Supplement or as a Component of Eggs Increases Plasma Choline and Reduces Interleukin-6 without Modifying Plasma Cholesterol in Participants with Metabolic Syndrome.

Metabolic syndrome (MetS) is characterized by low-grade inflammation and insulin resistance, which increase the risk of heart disease. Eggs have numerous nutrients including choline, carotenoids, and fat-soluble vitamins that may protect against these conditions. Egg phosphatidylcholine (PC) is a major contributor of dietary choline in the American diet. However, uncertainty remains regarding eggs due to their high concentration of cholesterol. In this study, we evaluated the effect of two sources of choline, whole eggs (a source of PC) and a choline supplement (choline bitartrate, CB), on plasma lipids, glucose, insulin resistance, and inflammatory biomarkers. We recruited 23 subjects with MetS to participate in this randomized cross-over intervention. After a 2-week washout, with no choline intake, participants were randomly allocated to consume three eggs/day or CB (~400 mg choline/d for both) for 4 weeks. After a 3-week washout period, they were allocated to the alternate treatment. Dietary records indicated higher concentrations of vitamin E and selenium during the egg period (p < 0.01). Interestingly, there were no changes in plasma total, low density lipoprotein (LDL)- or high density lipoprotein (HDL)-cholesterol, triglycerides, or glucose, compared either to baseline or between treatments. In contrast, interleukin-6 was reduced, with both sources of choline compared to baseline, while eggs also had an effect on lowering C-reactive protein, insulin, and insulin resistance compared to baseline. This study demonstrates that in a MetS population, intake of three eggs per day does not increase plasma LDL cholesterol, and has additional benefits on biomarkers of disease compared to a choline supplement, possibly due to the presence of other antioxidants in eggs.

Stability of Alkyl Chain-Mediated Lipid Anchoring in Liposomal Membranes.

Lipid exchange among biological membranes, lipoprotein particles, micelles, and liposomes is an important yet underrated phenomenon with repercussions throughout the life sciences. The premature loss of lipid molecules from liposomal formulations severely impacts therapeutic applications of the latter and thus limits the type of lipids and lipid conjugates available for fine-tuning liposomal properties. While cholesterol derivatives, with their irregular lipophilic surface shape, are known to readily undergo lipid exchange and interconvert, e.g., with serum, the situation is unclear for lipids with regular, linear-shaped alkyl chains. This study compares the propensity of fluorescence-labeled lipid conjugates of systematically varied lengths to migrate from liposomal particles consisting mainly of egg phosphatidyl choline 3 (EPC3) and cholesterol into biomembranes. We show that dialkyl glyceryl lipids with chains of 18–20 methylene units are inherently stable in liposomal membranes. In contrast, C16 lipids show some lipid exchange, albeit significantly less than comparable cholesterol conjugates. Remarkably, the C18 chain length, which confers noticeable anchor stability, corresponds to the typical chain length in biological membranes.

Recombination Monophosphoryl Lipid A-Derived Vacosome for the Development of Preventive Cancer Vaccines.

Recently, there has been an increasing interest for utilizing the host immune system to fight against cancer. Moreover, cancer vaccines, which can stimulate the host immune system to respond to cancer in the long term, are being investigated as a promising approach to induce tumor-specific immunity. In this work, we prepared an effective cancer vaccine (denoted as “vacosome”) by reconstructing the cancer cell membrane, monophosphoryl lipid A as a toll-like receptor 4 agonist, and egg phosphatidylcholine. The vacosome triggered and enhanced bone marrow dendritic cell maturation as well as stimulated the antitumor response against breast cancer 4T1 cells in vitro. Furthermore, an immune memory was established in BALB/c mice after three-time preimmunization with the vacosome. After that, the immunized mice showed inhibited tumor growth and prolonged survival period (longer than 50 days). Overall, our results demonstrate that the vacosome can be a potential candidate for clinical translation as a cancer vaccine.

Development of a Liposomal Dosage Form Based on Hydrophobic Derivative of Indolocarbazole

Introduction . An original N-glycoside derivative of indolocarbazole LHS-1269 with a carbohydrate xylose residue was synthesized at the N.N. Blokhin Russian Cancer Research Center Ministry of Health of Russia. It is characterized by high antitumor activity against a number of transferable ascitic and solid tumors in vivo experiments. Due to the hydrophobic properties of the substance LHS-1269, a method of solubilization by encapsulation in phospholipid vesicles - liposomes is proposed for creating an injectable dosage form. Aim . Development of the composition of a model of a liposomal dosage form for injection of an indolocarbazole derivative LHS-1269. Materials and methods . Substance LHS-1269 (N.N. Blokhin Russian Cancer Research Center Ministry of Health of Russia), egg phosphatidylcholine (PC, E PC S, Lipoid, Germany), cholesterol >99 % (Sigma-Aldrich, Japan), polyethylene glycol-2000-distearoylphosphatidylethanolamine (PEG-PE, Lipoid, Germany). To prepare phospholipid vesicles, the method of lipid film hydration with subsequent filtration and extrusion was used. The obtained liposomes were analyzed using the method of spectrophotometry, laser scattering spectroscopy, the method of determining the electrophoretic mobility of particles, and viscometry. Results and discussion . On the basis of lipid components and active substance in various molar ratios, compositions were made and experimental models of liposomal dispersion were obtained. The compositions were evaluated based on the effectiveness of LHS-1269 incorporation into liposomes and physical and chemical parameters - dispersion viscosity, vesicle size distribution, and zeta-potential. As a result of the analysis of 7 studied compositions, the optimal molar ratios of the drug form components - LHS-1269/PC 1:160 and PC/cholesterol/PEG-PE 1:0.33:0.003 were determined. The use of this composition allows us to obtain relatively stable (zeta-potential -33 mV) homogeneous liposomes with a diameter of 190 nm with a maximum level of encapsulation of the active substance of 98 %. Conclusions . As a result of technological and chemical-pharmaceutical research, the composition of a model of a liposomal dosage form for injection of the indolocarbazole derivative LHS-1269 has been developed.

Development of eugenol-loaded submicron emulsion and its antiepileptic effect through regulating the oxidative stress.

The purpose of this study was to develop an injectable submicron emulsion of eugenol (Eug-SE) and to investigate its antagonism on epilepsy. The formulation was optimized using a complete randomized design, comprising 5% (w/v) eugenol, 5% (w/v) soybean oil, 1.2% (w/v) egg phosphatidylcholine, 0.3% (w/v) poloxamer 188, and 0.03% (w/v) sodium oleate. The prepared Eug-SE was comprehensively evaluated in terms of its pharmaceutical characteristics, physicochemical stability, injection safety, antioxidant activity in vitro, and anti-epileptic effect in vivo. The mean particle size of Eug-SE was 176.1±10.3nm, the ζ-potential was -40.2±1.8mV, and the drug content was (95.3±0.4) %. Moreover, the Eug-SE displayed excellent stability and improved safety compared to the eugenol solution. The Eug-SE (20μg/mL) produced a significant neuroprotective effect against H2O2-induced oxidative damage in PC12 cells, which was attributed to the decrease of cellular reactive oxygen species level and mitochondrial damage. Besides, the in vivo test indicated that Eug-SE exerted an anti-epileptic effect in the PTZ treated mice. These results suggested that Eug-SE was a suitable dosage form of eugenol for injection, and displayed great therapeutic potential for neurological disease in the future.

Articaine interaction with phospholipid bilayers

Local anesthetics promote analgesia by interacting with excitable membranes. Articaine (ATC) has a unique composition among local anesthetics as it possesses a thiophene instead of the typical phenyl ring. Aiming to characterize the interaction of neutral articaine (nATC) with phospholipid membranes, we have employed a synergistic approach of experimental and computational techniques. Fluorescence measurements supported nATC partitioning into the membranes, since its intrinsic fluorescence anisotropy increased from 0.03 in water to 0.29 in the presence of egg phosphatidylcholine (EPC) liposomes, and the fluorescence of AHBA, a probe that monitors the water-membrane interface, was quenched by nATC. 1H NMR experiments revealed changes in the chemical shifts of articaine and EPC hydrogens after partitioning, and shorter T1 values of nATC hydrogens when inserted into the EPC vesicles. Contacts of nATC and the phospholipid polar head group were inferred from 2D-NOE. Taken together, these results indicate a superficial insertion of the nATC molecules inside EPC bilayers. This conclusion was confirmed by molecular dynamics simulations, which allowed the identification of the key interactions underlying the preferential location of nATC in the bilayer. Contrary to what is often stated (that articaine is a high lipophilic local anesthetic agent) our results place ATC among the hydrophilic ones, such as lidocaine, prilocaine, and mepivacaine, for which the water/membrane interface is the preferred location.

Liposomal Formulation of a Melphalan Lipophilic Prodrug: Studies of Acute Toxicity, Tolerability, and Antitumor Efficacy.

Recently we developed a scalable scheme of synthesis of melphalan ester conjugate with 1,2-dioleoyl-sn-glycerol (MlphDG) and a protocol for the fabrication of its lyophilized liposomal formulation. Herein we compared this new convenient in use formulation of MlphDG with parent drug Alkeran® in rats concerning several toxicological parameters and evaluated its antitumor efficacy in the model of breast cancer in mice. Liposomes of approximately 100 nm in diameter, consisting of egg phosphatidylcholine, soybean phosphatidylinositol, and MlphDG, or placebo liposomes without the drug were produced by extrusion and lyophilized. Alkeran® or liposomes recovered by the addition of water were injected into the tail vein of animals. Clinical examination of rats consisted of detailed inspection of the behavior, general status, and hematological parameters. Mice with transplanted breast cancer WNT-1 were subjected to multiple treatments with the drugs; tumor growth inhibition was assessed, together with cellular immunity parameters. Liposomes showed approximately two times lower acute toxicity and better tolerability than Alkeran® in terms of behavioral criteria. The toxic effects of liposomes on hemopoiesis were manifested at higher doses than in the case of Alkeran®, proportionally to the difference in LD50 values. The formulation inhibited tumor growth significantly more effectively than Alkeran®, delaying the start of the exponential growth phase and exhibiting no additional toxic effects toward bone marrow. Lower toxicity of the liposomal formulation of MlphDG promises improved quality of life for cancer patients in need of treatment with melphalan. Presumably, the list of indications for melphalan therapy could be extended.

Preclinical study of Doxorubicine-loaded liposomal drug delivery for the treatment of head and neck cancer: Optimization by Box-Behnken statistical design.

The present investigation aimed at developing Doxorubicin (DOX)-loaded liposome-mediated drug delivery system for head and neck cancer. The liposomes were prepared by film hydration technique using egg phosphatidylcholine and cholesterol using Box-Behnken statistical design. The prepared liposomes were evaluated for the percentage encapsulation efficiency, particle size and in vitro release. The average particle size of the DOX-encapsulating liposomes formulated by thin-film hydration technique was between 150.5 nm and 200 nm with an average particle size of 165.80 nm. The PDI (Polydispersity index) was found to be 0.315 which indicated that particles were monodispersed and narrow-dispersed. In vitro drug release of DOX-loaded liposomes and DOX-loaded peptide-conjugated liposomes was performed in phosphate buffered saline (pH 7.4) and both formulations showed sustained release behavior over the period of 40 hours. The optimized liposomal formulation was conjugated to a peptide and subsequently radiolabeled with 186Re-perrhenate solution and BMEDA-glucoheptonate-stannous chloride solution. Comparative cytotoxicity assay of DOX, DOX-liposomes and DOX-liposomes-peptide on SCC9 cells was performed and it was found that liposomal formulation was not cytotoxic. The antitumor efficacy of 186Re-liposomes, unlabelled liposomes, 186Re-perrhenate solution and 186Re-BMEDA solution was determined in SCC cell lines injected into BALB/c-nu/nu athymic nude rats. The efficacy of antitumor activity was found to be in the following order: peptide-conjugated DOX-loaded liposomes>unlabelled liposomes>186Re-perrhenate solution>186Re-BMEDA solution. The present investigation showed that peptide-conjugated DOX-loaded liposomes significantly suppress the tumor growth in the nude rat model. These results suggest the significant potential of liposomes as carriers for clinical applications in head and neck cancer.

Effect of gangliosides on structure and integrity of polyethylene glycol (PEG)-stabilized liposomes

The in vivo efficacy and tolerance of polyethylene glycol (PEG)-decorated drug nanocarriers, such as liposomes, is compromised bytheir tendency to induce the generation of PEG-specific immunoglobulin M (IgM) antibodies. Recently, a number of independent studies have reported on an attenuated anti-PEG immune response upon incorporation of gangliosides in the membrane of PEGylated liposomes.In the present study we investigate the effect of gangliosides on the self-assembled structures found in lipid dispersions based on hydrogenated egg phosphatidylcholine (HEPC), cholesterol and 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethyleneglycol)-2000] (DSPE-PEG(2000)). Results from cryo-transmission electron microscopy (cryo-TEM) and dynamic light scattering (DLS) investigations show that gangliosides promote structural transitions from liposomes to bilayer disks. In case of samples comprising 5 mol% PEG-conjugated lipids (PEG-lipid), inclusion of 2.5 mol% ganglioside (porcine ganglioside extract) results in the presence of a small but significant amount of disks. With increasing ganglioside content the population of disks grows at the expense of the liposomes. Comparative investigations using isolated ganglioside components reveal that disialoganglioside GD1a is more potent than monosialoganglioside GM1 in promoting disk formation. Experiments involving liposome encapsulated carboxyfluorescein confirm that the ganglioside-induced structural transformations have a detrimental effect on the total entrapped aqueous volume of the samples. The reported coexistence of liposomes and bilayer disks may if overlooked have important implications for the therapeutic efficacy and immunogenicity of ganglioside-supplemented liposomal formulations.

Comparison of β-carotene loaded marine and egg phospholipids nanoliposomes

Encapsulation using nanoliposomes is widely recognized as an effective technique to protect sensitive bioactive compounds from adverse processing or gastrointestinal conditions. In this study, marine phospholipids (MPL) nanoliposomes containing β-carotene were prepared as novel carriers by thin-film evaporation method and their characteristics were compared with traditional egg phosphatidylcholine (EPC) nanoliposomes. Initially, the average size of nanoliposomes was in the range of 162.86–365.81 nm and MPL nanoliposomes showed lower sizes compared to EPC nanoliposomes. A good size distribution and homogeneous dispersion for MPL nanoliposomes was also observed. The highest encapsulation efficiency (EE) recorded for MPL nanoliposomes was 99.06% compared to 96.53% for EPC nanoliposomes. Both types of nanoliposomes were able to inhibit lipid peroxidation but the highest inhibition was recorded for MPL nanoliposomes (42.9%) and the lowest (10.26%) for their EPC counterparts. Overall, MPL nanoliposomes showed higher stability at 4 °C for 70 days. Therefore, MPL can be explored for production of nanoliposomal systems as carriers for delivery of sensitive bioactive compounds in the food industry.

Investigating interactions of phthalate environmental toxicants with lipid structures

Di(2-ethylhexyl) phthalate (DEHP) is one of the most abundant plasticizers in common household products. It leaches from materials, resulting in exposure associated with detrimental health effects. The main objective of this study was to investigate how DEHP and its metabolite, mono(2-ethylhexyl) phthalate (MEHP), interact with and permeate lipid structures, namely vesicles and planar bilayers. Using dynamic light scattering, we observed significant changes in the size and polydispersity of L-α-phosphatidylcholine (egg PC) vesicles when incubated with DEHP but not MEHP at the same concentrations (100 and 200 μM). We demonstrated that these effects are mitigated by pre-treatment with chitosan nanoparticles which adsorb the phthalates. Using quartz crystal microbalance with dissipation monitoring (QCM-D), we observed a concentration dependence on the interaction of DEHP with egg PC supported lipid bilayers (SLBs). QCM-D results suggested lipid removal for 5 and 100 μM DEHP, and adsorption and potential embedment in the bilayer at 50 and 200 μM DEHP. SLB mass decrease was observed for all concentrations of MEHP (5, 50, 100, and 200 μM), suggesting lipid removal. We also investigated the permeability of DEHP and MEHP as well as several small molecules across a 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) suspended lipid bilayer. We found that DEHP and MEHP both had low permeabilities, but only DEHP remained associated with the bilayer. Exposure to DEHP and MEHP influenced how several common small molecules interacted with DOPC bilayers. Ultimately, this work provides insight into mechanisms of phthalate interactions with lipid structures, having implications for human health.

Anaesthetic benefits of a ternary drug delivery system (Ropivacaine-in-Cyclodextrin-in-Liposomes): in-vitro and in-vivo evaluation.

To evaluate whether a ternary system composed of hydroxypropyl-β-cyclodextrin (HP-βCD) further encapsulated into egg phosphatidylcholine liposomes (LUV) could prolong the action and reduce the toxicity of ropivacaine (RVC). Dynamic light scattering and NMR were used to characterize the inclusion complex (RVC:HP-βCD), liposomal (RVC:LUV) and ternary (LUV:RVC:HP-βCD) systems containing 0.25% RVC. Their encapsulation efficiency, release kinetics, in-vitro cytotoxicity and in-vivo anaesthetic effect (paw-withdraw tests in mice) were also evaluated. 1:1 RVC:HP-βCD inclusion complex was encapsulated in liposomes (220.2±20.3nm size, polydispersity <0.25, zeta potentials=-31.7±1.4mV). NMR (diffusion-ordered spectroscopy (DOSY)) revealed stronger anaesthetic binding to LUV:RVC:HP-βCD (Ka =342m-1 ) than to RVC:HP-βCD (Ka =128m-1 ) or liposomal formulation (Ka =22m-1 ). The formulations promoted in-vitro sustained drug release and partially reverted the cytotoxicity of RVC against 3T3 fibroblasts in the profile: LUV:RVC:HP-βCD≥RVC:HP-βCD>RVC:LUV. Accordingly, in-vivo sensory block of free RVC (180min) was prolonged ca. 1.7 times with the ternary system and RVC:HP-βCD (300min) and 1.3 times with RVC:LUV (240min). These results confirm the suitability of this double-carrier system in clinical practice, to decrease the toxicity and prolong the anaesthesia time evoked by RVC.

Chemo-enzymatic synthesis, characterization, in vitro antioxidant capacity and oxidative stability studies of novel phosphatidylcholines with ω-3/ω-6 PUFAs and phenolic acids

Novel phosphatidylcholines containing PUFAs and phenolic acids were synthesized from egg phosphatidylcholine (PC), PUFAs (docosahexaenoic, arachidonic and linoleic acids) and phenolic acids (caffeic, ferulic and p-coumaric acids) as substrates. The structures of modified PCs were confirmed by spectral analysis and were evaluated for antioxidant activities. The modified PCs containing caffeic and ferulic acids exhibited excellent antioxidant activities compared with butylated hydroxytoluene (BHT) and α-tocopherol. The synthesized compounds were also evaluated for the oxidative stabilities in liposome and organic solvent. The modified PCs showed more oxidative stable compared with standard PUFA-PCs and PUFA-PCs + BHT. Results showed that the oxidative stability decreased with increasing degree of unsaturation in organic solvent whereas in liposomes, increased with increasing degree of unsaturation due to tight packed configuration. In this study, phenolic acids were found to render protections for PUFAs in modified PCs from oxidation. Modified PCs may have great potential for applications in food, cosmetic and pharmaceutical industries.

Toxicological evaluation of DSPC (1,2-distearoyl-sn-glycero-3-phosphocholine)

In the inhalation field, lipids such as egg phosphatidylcholine (PC), 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) and dipalmitoylphosphatidylcholine (DPPC), are considered to be generally recognized as safe (GRAS), comprising materials that are endogenous to the lungs and locally present in large quantities. Indeed, PC, DSPC and DPPC may be used to form liposomes which are known to promote an increase in drug retention time and reduce the toxicity of drugs after administration. Unfortunately, published literature guidance about the safety evaluation of these lipids as pharmaceutical excipients for use in inhaled products and about application for marketing authorization, is very limited. The purpose of this article is to review the potential toxicity of DSPC for pulmonary administration. Given the use of air and vehicle controls in a range of inhalation toxicology studies as well as negative genotoxicity and also reproductive toxicity results, it is thought that the use of DSPC is shown to be safe for pulmonary administration.

Lipophilic Prodrug of Methotrexate in the Membrane of Liposomes Promotes Their Uptake by Human Blood Phagocytes.

Previously, we showed that incorporation of methotrexate (MTX) in the form of a lipophilic prodrug (MTXDG) in 100-nm lipid bilayer liposomes of egg phosphatidylcholine can allow one to reduce toxicity and improve the antitumor efficiency of MTX in a mouse model of T-cell leukemic lymphoma. However, in our hemocompatibility tests in vitro, MTX liposomes caused complement (C) activation, obviously due to binding on the liposome surface and fragmentation of the C3 complement factor. In this work, we studied the interactions of MTX liposomes carrying stabilizing molecules phosphatidylinositol (PI), ganglioside GM1, or a lipid conjugate of N-carboxymethylated oligoglycine (CMG) in the bilayer with subpopulations of human blood leukocytes. Liposomes labeled with BODIPY-phosphatidylcholine were incubated with whole blood (30 min and 1 h, 37°C), blood cells were lysed with a hypotonic buffer, and the fluorescence of the liposomes bound but not internalized by the leukocytes was quenched by crystal violet. Cell suspensions were analyzed by flow cytometry. Incorporation of MTXDG dramatically enhanced the phagocytosis of liposomes of any composition by monocytes. Neutrophils consumed much less of the liposomes. Lymphocytes did not accumulate liposomes. The introduction of PI into MTX liposomes practically did not affect the specific consumption of liposomes by monocytes, while CMG was likely to increase the consumption rate regardless of the presence of MTXDG. The GM1 ganglioside presumably shielded MTX liposomes from phagocytosis by one of the monocyte populations and increased the efficiency of monocyte uptake by another population, probably one expressing C3b-binding receptors (C3b was detected on liposomes after incubation with blood plasma). MTX liposomes were shown to have different effects on TNF-α production by activated leukocytes, depending on the structure of the stabilizing molecule.