Phosphatidylcholine Solution Research Articles

Evaluation of the ionization efficiency in phosphatidylcholine positional isomers with docosahexaenoic acid bound to the sn-1 or sn-2 position

Phosphatidylcholine (PC), a key phospholipid, contains 2 fatty acids that can be bound at the sn-1 and sn-2 positions, resulting in positional isomers when different fatty acids are attached. Currently, there is no established method for identifying phospholipid molecular species and quantifying individual isomers using authentic standards of each PC isomer. In this study, we prepare authentic analytical standards for PC positional isomers through chemical synthesis and preparative purification. These isomers contain docosahexaenoic acid (DHA, 22:6) and palmitic acid (16:0) attached at the sn-1 and sn-2 positions and are denoted as PC(22:6/16:0) and PC(16:0/22:6), respectively. Standard solutions of PC(22:6/16:0) and PC(16:0/22:6) were analyzed using liquid chromatography-tandem mass spectrometry, and calibration curves of the PC positional isomers were generated to compare their ionization efficiencies. The ionization efficiency of PC(22:6/16:0) was 2.32 times higher than that of PC(16:0/22:6), indicating that the ionization efficiency depends on the binding position of the fatty acid. Elucidating and correcting the differences in the ionization efficiencies of the PC positional isomers will enable the accurate quantitative analysis of lipidomes in the future.

The study of the interaction of quantum dots with phosphatidylcholine to create hybrid functional materials

Quantum dots (QDs) are widely used as biomarkers that has both fundamental and applied importance. Since cell membranes are mainly composed of lipids such as phosphatidylcholine (PC) and its derivatives, it is important to investigate the interaction of QDs with PC in monolayers to understand the penetration mechanism. This work is devoted to the study of the interaction of QDs with PC by determining their surface-active properties at various interfaces by dynamic surface tension. The isotherms of the surface tension of 5 μg/L QDs solution or 0.17 mM (0.86 mM) PC solutions, as well as the solutions of the mixtures of QDs and PC: 0.17 mM (0.86 mM) PC and 5 μg/L QDs or 0.17 mM (0.86 mM) PC and 15 μg/L QDs were obtained. The mixed QDs/PC monolayers (at low content of QDs equal to 1:100) were characterized by the formation of a stable domain structures. An adsorption of PC at QDs allows to vary the degree of surface modification by changing the amount of the lipid. Such nanoparticles have dimensions not very different from the sizes of the initial QDs, due to the small size of lipids and are well suited for incorporation into biomembrane models.

Effect of surface modification on starch/phospholipid wettability

Abstract The objective of this work was to determine surface properties of biopolymer film as a function of temperature and/or after plasma treatment with the aim of further wettability tests and biocompatibility. The examined biopolymers were native starch and starch modified by solution of PC (phosphatidylcholine). Contact angles for polar water (and formamide) and nonpolar diiodomethane on the glass plates covered with starch film before and after gelatinization (25 °C, 37 °C and 60 °C) were measured for the base and plasma modified film. The surface free energy of solid (gel) was determined from the advancing and receding contact angles of these probe liquids, using the contact angle hysteresis model (CAH). The plasma treatment was immediately followed by a sharp decrease of contact angle and in the course of ageing the contact angle also decreased due to the reorientation of polar groups into the polymer surface layer. To depict better changes in hydrophilic/hydrophobic character of the starch surface before and after modification the work of water spreading, W S was calculated. A sharp decrease in negative values of W S takes place which indicates more hydrophilic character of starch surface after modification. Surface morphology and roughness were studied by optical profilometer and FTIR measurements which confirm the contact angle results. It was also proved that a combination of input treatment parameters led to improvement of biopolymer wettability and provided possibilities of starch application where uniform thin films are required.

Purification of Soybean Phosphatidylcholine Using D113‐III Ion Exchange Macroporous Resin Packed Column Chromatography

AbstractTen ion‐exchange resins were compared for their abilities to separate soybean phosphatidylcholine (PC). D113‐III resin was selected for PC purification among ten resins tested. The optimum PC adsorption conditions were: concentration of PC solution, 3 mg/mL; pH of PC solution, 7.5; and adsorption flow rate, 1 mL/min. The optimum PC desorption conditions were: eluent, 95% ethanol aqueous solution; and elution flow rate, 1 mL/min. Under these conditions, the PC content in the product and the amount of product were 94 and 80% (wt.%), respectively, and the D113‐III resin was able to be used at least six times for purifying PC. The adsorption and desorption characteristics were also studied.

Physicochemical stability of phospholipid-dispersed suspensions of crystalline itraconazole

The physicochemical stability of an aqueous, phospholipid-based dispersion of itraconazole microcrystals was studied as a model water-insoluble drug suspension. The particle size, phospholipid concentrations, free fatty acid (FFA) content, pH, and zeta potential of two test suspensions were followed over 63 days at 5 and 40 °C storage conditions. Hydrolysis of a control suspension containing Lipoid E80 led to rapid FFA formation, pH drop, and subsequent particle aggregation. In the second suspension, sodium oleate used in conjunction with Lipoid E80 significantly enhanced the suspension physicochemical stability. Oleate anions effectively (1) increased the anionic charge of the phospholipid surface layer, (2) buffered the suspension near pH 7, and (3) reduced the specific production of oleic acid as a phosphatidylcholine (PC) degradant. The observed hydrolysis rate constants k obs ∼ 2 × 10 −7 (Lipoid only) and k obs ∼ 5 × 10 −8 (Lipoid and oleate) were consistent with the pH dependent behavior reported for saturated soybean PC solutions. Mechanistically, FFA formed initially in the control suspension partitioned to the aqueous phase with limited influence on the phospholipid microenvironment at the itraconazole particle surface. Phospholipid stabilization of water-insoluble drugs was demonstrated with clear benefits from fatty acid anions as co-additives to influence the surface microenvironment, reduce hydrolysis kinetics, and enhance suspension physicochemical stability.

Sensitive assay for hormone-sensitive lipase using NBD-labeled monoacylglycerol to detect low activities in rat adipocytes

The recent finding that p-nitrobenzofurazan (NBD)-FA is incorporated into and released from the acylglycerols of isolated rat adipocytes in an insulin-sensitive manner [G. Muller, H. Jordan, C. Jung, H. Kleine, and S. Petry. 2003. Biochimie. 85: 1245-1246] suggests that NBD-FA-labeled acylglycerols are cleaved by rat adipocyte hormone-sensitive lipase (HSL) in vivo. In the present study, we developed a continuous, sensitive in vitro lipase assay using a monoacylglycerol (MAG) containing NBD (NBD-MAG). NBD-MAG was found to provide an efficient substrate for rat adipocyte and human recombinant HSL. Ultrasonic treatment applied in the presence of phospholipids leads to the incorporation of NBD-MAG into the phospholipid liposomes and to a concomitant change of its spectrophotometric properties. The enzymatic release of NBD-FA and its dissociation from the carrier liposomes is accompanied by the recovery of the original spectrophotometric characteristics. The rate of lipolysis was monitored by measuring the increase in optical density at 481 nm, which was found to be linear with time and linearly proportional to the amount of lipase added. To assess the specific activity of recombinant HSL, we determined the molar extinction coefficient of NBD-FA under the assay conditions. This convenient assay procedure based on NBD-MAG should facilitate the search for small molecule HSL inhibitors.

Phospholipids hydrolysis in organic solvents catalysed by immobilised phospholipase C

Phospholipase C from Bacillus cereus has been immobilised on XAD7, Sepabeads FP-DA, Eupergit C, Celite 547, Silica gel 60 by covalent attachment or by adsorption. Preparates obtained with the two different immobilisation techniques show good hydrolytic activity in water-saturated organic solvents with phosphatidylcholine (PC) as a substrate. The chiral 1,2-diacyl glycerol can easily be obtained from the organic phase. The catalysts obtained by covalent attachment have been prepared with a higher specific activity and are suitable for repeated uses, while the ones prepared by adsorption with lower specific activity can only be used once. The initial rates of hydrolysis of PC solutions in different organic solvents and water content are compared.

Effect of phosphatidylcholine on the process of peritoneal adhesion following implantation of a polypropylene mesh prosthesis

The postimplantation peritoneal adhesions formed with some biomaterials continue to represent a serious problem when these biomaterials are placed in contact with the organs of the abdominal cavity. The objective was to test the effects of phosphatidylcholine (PC) in the attempt to modulate the adhesive process, thus improving the biomaterial/visceral peritoneum interface. We have carried out an experimental study using the New Zealand white rabbit, implanting a 7 × 5 cm2 polypropylene prosthesis into the anterior abdominal wall in such a way that it replaced all the tissue layers and was in contact with the intestinal loops. Three study groups were established: group I (control), in which only implantation of the biomaterial was performed; group II, in which the prosthesis was pretreated with a solution of PC; and group III, in which the implants were treated as in group II and the animals underwent intraperitoneal administration of 10ml of the same solution. The animals were killed on postimplantation day 14. The total surface of the prosthesis occupied by adhesions was measured and light and scanning electron microscopy were performed to analyse the healing process. In comparison with the controls, groups II and III did not present significant differences with respect to the resistance or extension of the adhesions. The microscopic results showed a rapid formation of disorderly and well-vascularised scar tissue enveloping the entire prosthesis. Thus, PC was unable to modulate the process of adhesion formation between the prosthesis and the organs of the abdominal cavity; nor did it induce changes in the cells of sufficient importance to alter the results of the healing process in the presence of this biomaterial.

Intercalation and Bilayer Formation of Phospholipids in γ-Type Layered Transition Metal Phosphates

Abstract Intercalation of natural phospholipids, phosphatidylethanolamine (PEA) and phosphatidylcholine (PC), into inorganic layered compounds was examined in ethanol and chloroform solutions. γ-Type titanium(IV) phosphate and zirconium(IV) phosphate were selected as host layered compounds. They are strong solid acids and also known as inorganic ion exchangers. The intercalation of PEA was propagated in chloroform solution in the presence of n-alkylamine forming a bilayers of PEA–alkylamine mixture. The direct reaction of PEA with γ-phosphates was not successful. On the other hand PC reacted directly with the layered compounds either in the chloroform or in the ethanol solution of PC and successfully formed bilayers.

Solubility of phosphatidylcholine in chloroform. Formation of hydrogen bonding between phosphatidylcholine and chloroform

The solubility of phosphatidylcholine (PC) was studied by the spectroscopic analysis and the measurement of the solubility. The qualitative analysis of infrared absorptionspectra confirmed the existence of two types of hydrogen bondings between chloroform and PC, one between chloroform and the CO group of PC and the other between chloroform and the phosphorylcholine group of PC. The quantitative analysiss of the C‖ stretching vibration bands of the chloroform-d solution of PC showed that the latter hydrogen bonding mainly contributes to the solubility and that PC dissolves in chloroform to form a complex consisting of a few or more molecules of chloroform and one molecule of PC. We discussed in this report about the molecular organization of PC in chloroform solution.