Immobilization Of Phospholipids Research Articles

Interactions of Polyphenols with Immobilized Artificial Membrane and Human Serum Albumin Determined by High Performance Liquid Chromatography

Within recent years, a promising new field of chromatography has opened up with immobilization of phospholipids and human serum albumin in columns and their use in prediction of drug candidates' pharmacokinetics. It is important to investigate early in the drug discovery both the oral absorption of new drug and the extent to which it binds to plasma proteins. In the last few decades plant polyphenols became very popular phytochemicals due to their presumed role in the prevention of various degenerative diseases, such as various types of cancer and cardiovascular diseases [1]. Until recently, relatively little information was available on their absorption and subsequent distribution and excretion in humans. The aim of our work was to investigate interactions of 30 polyphenols with immobilized artificial membrane (IAM) and human serum albumin (HSA) by high performance liquid chromatography in order to predict their oral absorption and plasma protein binding. The interaction of polyphenols with IAM was evaluated by using IAM.PC.DD 2 column. The solvent system (methanol-buffer) was used as a mobile phase with a varying content of organic modifier. The interaction of polyphenols with phospholipids was expressed as the logarithm of capacity factor, which was in the range from 1.345 to 3.581. The HSA binding values were derived from the gradient retention times using Chiral HSA column with buffer and 2-propanol as a mobile phase. The binding of polyphenols to HSA was in the range from 81.8% to 99.8%. Furthermore, the correlation between experimental and pharmacokinetic parameters predicted by different computer programs was considered in order to establish relationship between chromatographic behavior and predicted parameters. According to our research, chromatographic parameters proved to be useful for evaluation of lipophilicity, oral absorption and plasma protein binding properties of investigated polyphenols.

Hydrolysis by phospholipase D of phospholipids in solution state or adsorbed on a silica matrix

Phospholipases D (PLD) catalyse hydrolysis and transphosphatidylation reactions in phospholipids. In the present study, the hydrolytic activity for cabbage PLD was investigated with five different substrates (dipalmitoylphosphatidylethanolamine (DPPE), dipalmitoylphosphatidylcholine (DPPC), didecanoylphosphatidylcholine (DDPC), 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine and lyso-phosphatidylcholine (lyso-PC)) in solution or adsorbed on a silica matrix. In the specific buffer solutions, where the substrates were proved to form large multilamellar polydisperse aggregates, PLD showed preference for DPPC > DPPE > DDPC > 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine > lyso-PC. When the substrates were adsorbed on the silica matrix, PLD hydrolysed 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine and lyso-PC, DDPC, but not DPPC or DPPE. Theoretical studies of the simplest possible adducts between the phospholipids and the silica matrix were performed. Examination of local geometries of DPPC showed a significant blocking of the P–O–X bond-prone to hydrolysis, which could possibly block the access of PLD. Immobilization of phospholipids could be applied for improving the yield of reactions catalysed by PLD as well as for performing a targeted production of short-chain length phosphatidic acid analogs.

Emulsion polymerization of styrene using phospholipid as emulsifier. Immobilization of phospholipids on the latex surface

AbstractEmulsion polymerization of styrene using polymerizable and non‐polymerizable phospholipids with double alkyl chains (1a, 1b), and their single‐chain analogues (2a, 2b) as emulsifier gave polymer latices with narrow size distribution. The resulting latices, which were subjected to acid and enzymatic hydrolysis, and reprecipitation with methanol, were characterized by phosphorus analysis and X‐ray photoelectron spectroscopy (XPS). The phospholipids remained mainly on the surface of the latices. The non‐polymerizable emulsifiers were physically adsorbed on the latices, but the polymerizable emulsifiers were chemically bound to the latices. Phospholipid 1b on the latex prepared with a lipophilic radical initiator was hydrolyzed by phospholipase C.

Immobilization of phospholipids on silicon, platinum, indium/tin oxide and gold surfaces with characterization by x-ray photoelectron spectroscopy and time-of-flight secondary-ion mass spectrometry

Simple procedures are described for the covalent binding of phospholipids to silicon, platinum, indium/tin oxide and gold surfaces. The protocol for the first three surfaces consists of silanization with γ-amino propyltriethoxysilane, followed by reaction of the amino function with a derivative of a long-chain aliphatic dicarboxylic acid used as a cross-linker and treatment with a lyso-lipid. The seposition of a lipid on gold emplys the reactivity of a sulphur substituent at the terminus on one of the acyl chains of the lipid. Surface coverages ranging from 60 to 75% are obtained as deduced from elemtnal determinations and N(1 s)-to-P(2 p binding energy peak ratios obtained in x-ray photoelectron spectroscopic study of the immobilized species. Functional group determinations were done through a high-resolutions of the C(1 s peaks together with comparison of spectra from intermediate surface structures. Depth profiling of the lipid-bound silicon surface through argon ion etching indicated a model involving the orientation of the sn-2 chain perpendicular to the surface plane. The molecular structure of the immobilized lipid on silicon is established by positive and negative time-of-flight secondary-ion mass spectrometry.