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1.
Ayat A Allam Md Ehsan Sadat Sarah J Potter David B Mast Dina F Mohamed Fawzia S Habib Giovanni M Pauletti 《Nanoscale research letters》2013,8(1):426
Magnetic nanoparticles that are currently explored for various biomedical applications exhibit a high propensity to minimize total surface energy through aggregation. This study introduces a unique, thermoresponsive nanocomposite design demonstrating substantial colloidal stability of superparamagnetic Fe3O4 nanoparticles (SPIONs) due to a surface-immobilized lipid layer. Lipid coating was accomplished in different buffer systems, pH 7.4, using an equimolar mixture of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and l-α-dipalmitoylphosphatidyl glycerol (DPPG). Particle size and zeta potential were measured by dynamic laser light scattering. Heating behavior within an alternating magnetic field was compared between the commercial MFG-1000 magnetic field generator at 7 mT (1 MHz) and an experimental, laboratory-made magnetic hyperthermia system at 16.6 mT (13.7 MHz). The results revealed that product quality of lipid-coated SPIONs was significantly dependent on the colloidal stability of uncoated SPIONs during the coating process. Greatest stability was achieved at 0.02 mg/mL in citrate buffer (mean diameter = 80.0 ± 1.7 nm; zeta potential = -47.1 ± 2.6 mV). Surface immobilization of an equimolar DPPC/DPPG layer effectively reduced the impact of buffer components on particle aggregation. Most stable suspensions of lipid-coated nanoparticles were obtained at 0.02 mg/mL in citrate buffer (mean diameter = 179.3 ± 13.9 nm; zeta potential = -19.1 ± 2.3 mV). The configuration of the magnetic field generator significantly affected the heating properties of fabricated SPIONs. Heating rates of uncoated nanoparticles were substantially dependent on buffer composition but less influenced by particle concentration. In contrast, thermal behavior of lipid-coated nanoparticles within an alternating magnetic field was less influenced by suspension vehicle but dramatically more sensitive to particle concentration. These results underline the advantages of lipid-coated SPIONs on colloidal stability without compromising magnetically induced hyperthermia properties. Since phospholipids are biocompatible, these unique lipid-coated Fe3O4 nanoparticles offer exciting opportunities as thermoresponsive drug delivery carriers for targeted, stimulus-induced therapeutic interventions.
PACS
7550Mw; 7575Cd; 8185Qr 相似文献2.
Karli Lipinski Matthew J. McKay Fahmida Afrose Dr. Ashley N. Martfeld Prof. Roger E. Koeppe II Dr. Denise V. Greathouse 《Chembiochem : a European journal of chemical biology》2019,20(21):2784-2792
Membrane proteins are essential for many cell processes yet are more difficult to investigate than soluble proteins. Charged residues often contribute significantly to membrane protein function. Model peptides such as GWALP23 (acetyl-GGALW5LAL8LALALAL16ALW19LAGA-amide) can be used to characterize the influence of specific residues on transmembrane protein domains. We have substituted R8 and R16 in GWALP23 in place of L8 and L16, equidistant from the peptide center, and incorporated specific 2H-labeled alanine residues within the central sequence for detection by solid-state 2H NMR spectroscopy. The resulting pattern of [2H]Ala quadrupolar splitting (Δνq) magnitudes indicates the core helix for R8,16GWALP23 is significantly tilted to give a similar transmembrane orientation in thinner bilayers with either saturated C12:0 or C14:0 acyl chains (1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC) or 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC)) or unsaturated C16:1 Δ9 cis acyl chains. In bilayers of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC; C18:1 Δ9 cis) multiple orientations are indicated, whereas in longer, unsaturated 1,2-dieicosenoyl-sn-glycero-3-phosphocholine (DEiPC; C20:1 Δ11 cis) bilayers, the R8,16GWALP23 helix adopts primarily a surface orientation. The inclusion of 10–20 mol % cholesterol in DOPC bilayers drives more of the R8,16GWALP23 helix population to the membrane surface, thereby allowing both charged arginines access to the interfacial lipid head groups. The results suggest that hydrophobic thickness and cholesterol content are more important than lipid saturation for the arginine peptide dynamics and helix orientation in lipid membranes. 相似文献
3.
Filomena Battista Rosario Oliva Pompea Del Vecchio Roland Winter Luigi Petraccone 《International journal of molecular sciences》2021,22(6)
Lasioglossin III (LL-III) is a cationic antimicrobial peptide derived from the venom of the eusocial bee Lasioglossum laticeps. LL-III is extremely toxic to both Gram-positive and Gram-negative bacteria, and it exhibits antifungal as well as antitumor activity. Moreover, it shows low hemolytic activity, and it has almost no toxic effects on eukaryotic cells. However, the molecular basis of the LL-III mechanism of action is still unclear. In this study, we characterized by means of calorimetric (DSC) and spectroscopic (CD, fluorescence) techniques its interaction with liposomes composed of a mixture of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and 1-palmitoyl-2-oleoyl-sn-glycero-3-rac-phosphoglycerol (POPG) lipids as a model of the negatively charged membrane of pathogens. For comparison, the interaction of LL-III with the uncharged POPC liposomes was also studied. Our data showed that LL-III preferentially interacted with anionic lipids in the POPC/POPG liposomes and induces the formation of lipid domains. Furthermore, the leakage experiments showed that the peptide could permeabilize the membrane. Interestingly, our DSC results showed that the peptide-membrane interaction occurs in a non-disruptive manner, indicating an intracellular targeting mode of action for this peptide. Consistent with this hypothesis, our gel-retardation assay experiments showed that LL-III could interact with plasmid DNA, suggesting a possible intracellular target. 相似文献
4.
Resolution of individual molecular species of human platelet 1,2-diradyl-sn-glycero-3-phosphocholines and 1,2-diradyl-sn-glycero-3-phosphoethanolamines by reverse phase high pressure liquid chromatography (HPLC) allowed a thorough analysis of
those phospholipids labeled with [3H]arachidonic acid. Approximately 54% and 16% of the total incorporated radiolabel was found in choline glycerophospholipids
and ethanolamine glycerophospholipids, respectively, with ca. 90% of this being found in the 1,2-diacyl molecular species.
Eighty percent of [3H]-arachidonic acid incorporated into 1-acyl-2-arachidonoyl-sn-glycero-3-phosphocholine in resting platelets was equally distributed between 1-palmitoyl-2-arachidonoyl and 2-stearoyl-2-arachidonoyl-sn-glycero-3-phosphocholine, while 70% of the radiolabel in 1-acyl-2-arachidonoyl-sn-glycero-3-phosphoethanolamine was found in 1-stearoyl-2-arachidonoyl-sn-glycero-3-phosphoethanolamine. Thrombin stimulation (5 U/ml for 5 min) resulted in deacylation of all 1-acyl-2-[3H]arachidonoyl molecular species of 1-acyl-2-arachidonoyl-sn-glycero-3-phosphocholine and 1-acyl-2-arachidonoyl-sn-glycero-3-ethanolamine. There was also a slight increase in 1-O-alkyl-2-[3H]arachidonoyl-sn-glycero-3-phosphocholine and a significant increase in 1-O-alk-1′-enyl-2-[3H]arachidonoyl-sn-glycero-3-phosphoethanolamine molecular species of over 300%. Thus, HPLC methodology indicates that arachidonoyl-containing
molecular species of phosphatidylcholine and phosphatidylethanolamine are the major source of arachidonic acid in thrombin-stimulated
human platelets, while certain ether phospholipid molecular species become enriched in arachidonate. 相似文献
5.
1-O-Octadecyl-2-O-methyl-rac-glycero-3-phosphocholine (ET-18-OCH3) is an ether-linked lipid that exhibits selective cytotoxicity toward several types of tumor cells and is relatively inactive toward normal cells under the same conditions of treatment. The mechanism of this selective cytotoxicity is unknown. We conducted studies to determine whether this compound is metabolized by phospholipases C and D and, if so, whether sensitive and resistant cells differ in their ability to degrade ET-18-OCH3 by these enzymes. We have examined the metabolism of the L-isomer of ET-18-OCH3, 1-O-octadecyl-2-O-methyl-sn-glycero-3-phosphocholine (L-ET-18-OCH3), by lysophospholipase D of rat liver microsomes and by a phospholipase D from the marine bacteriumVibrio damsela. The metabolism of L-ET-18-OCH3 was also examined in cell culture using Madin-Darby canine kidney cells, human promyelocytic leukemia cells and human myelocytic leukemia cells. In these studies, L-ET-18-OCH3 and related 1-O-alkyl-linked phosphocholine analogs radiolabeled with3H in the 1-O-alkyl chain were used. L-ET-18-OCH3 was not hydrolyzed by lysophospholipase D from rat liver microsomes under conditions where cleavage of 1-O-alkyl-2-lyso-sn-glycero-3-phosphocholine was observed. However, phospholipase D from the marine bacteriumV. damsela readily hydrolyzed L-ET-18-OCH3 to 1-O-[3H]octadecyl-2-O-methyl-sn-glycero-3-phosphate, demonstrating that L-ET-18-OCH3 can be degraded by a phospholipase D. Platelet-activating factor (PAF) and lyso-PAF were also substrates for the bacterial phospholipase D. When intact cells were incubated with radiolabeled L-ET-18-OCH3 a product was formed that was identified as 1-O-[3H]octadecyl-2-O-methyl-sn-glycerol. There are two mechanisms that could account for the appearance of this product. The first involves cleavage of the compound by a phospholipase C, resulting in direct release of the diglyceride. The second possible mechanism involves cleavage by a phospholipase D to form the phosphatidic acid analog with subsequent hydrolysis to the diglyceride by a phosphohydrolase. Preliminary data support the phospholipase C-type mechanism. Regardless of which mechanism operates in intact cells, the metabolic degradation of L-ET-18-OCH3 does not appear to be a significant factor in the selective cytotoxicity of this antitumor agent. 相似文献
6.
In vivo intestinal perfusion was used to follow the absorption of three different choline glycerophospholipids (CGP) in guinea
pig. These included 1-[3H]palmitoyl-2-acyl-sn-glycero-3-phosphocholine (diacyl-GPC), 1-[3H]-O-hexadecyl-2-acyl-sn-glycero-3-phosphocholine (alkylacyl-GPC) and 1,2-di-O-hexadecyl-sn-glycero-3-phospho-[3H]-choline (dialkyl-GPC). About 80% of diacyl-GPC was absorbed within 4 hr, compared to 60% of alkylacyl-GPC and 30% of dialkyl-GPC.
The radioactivity disappearing from the perfusion fluid was recovered in intestinal lipids, mostly triacylglycerol, free fatty
acid and CGP from diacyl-GPC, CGP from alkylacyl-GPC and dialkyl-GPC. These results indicated that the nonhydrolyzable substrate
dialkyl-GPC was much less absorbed, whereas diacyl-GPC, which released over 80% of [3H]palmitic acid in the perfusion fluid, displayed the highest absorption rate. The intermediate picture observed for alkylacyl-GPC
suggested the possible involvement of a phospholipase A2, which was detected in the entire intestinal tract. This enzyme was further found to concentrate in villus cells, where it
is localized in the brush border membrane, as shown using two different subcellular fractionation procedures. These data suggest
a possible role of this new enzyme in the digestion of alimentary phospholipids. 相似文献
7.
The acylation of lysophospholipids by rat liver acyltransferases was studied. A comparison between ester and ether lysophospholipids as substrates revealed large differences in substrate properties. For instance, oleic acid from oleoyl-CoA and arachidonic acid from arachidonoyl-CoA were not incorporated into 1-O-octadecyl-sn-glycero-3-phosphocholine under experimental conditions that allowed an optimal transfer of oleic acid and arachidonic acid to 1-O-palmitoyl-sn-glycero-3-phosphocholine. However, we observed an acyl-CoA-independent transfer of arachidonic acid from 1-O-stearoyl-2-O-arachidonoyl-sn-glycero-3-phosphoinositol to 1-O-octadecyl-sn-glycero-3-phosphocholine. 相似文献
8.
A simple method for synthesizing diastereomerically pure phosphatidylglycerols (PtdGro), namely, 1,2-diacyl-sn-glycero-3-phospho-3′-sn-glycerol (R,R configuration) and 1,2-diacyl-sn-glycero-3-phospho-1′-sn-glycerol (R,S configuration) was established. For this purpose, diastereomeric 1,2-O-isopropylidene PtdGro were prepared from 1,2-diacyl-sn-glycero-3-phosphocholine (PtdCho) and enantiomeric 1,2-O-isopropylideneglycerols by transphosphatidylation with phospholipase D (PLD) from Actinomadura sp. This species was selected because of its higher transphosphatidylation activity and lower phosphatidic acid (PtdOH) formation
than PLD from some Streptomyces species tested. The reaction proceeded well, giving almost no hydrolysis of PtdCho to PtdOH in a biphasic system consisting
of diethyl ether and acetate buffer at 30°C. The isopropylidene protective group was removed by heating the diastereomeric
isopropylidene PtdGro at 100°C in trimethyl borate in the presence of boric acid to obtain the desired PtdGro diastereomers.
The purities of the products, which were determined by chiral-phase HPLC, were exclusively dependent on the optical purities
of the original isopropylideneglycerols used. The present method is simple and can be utilized for the synthesis of pure PtdGro
diastereomers having saturated and unsaturated acyl chains. 相似文献
9.
M. P. Murari R. Murari S. Parthasarathy C. A. Guy V. V. Kumar B. Malewicz Wolfgang J. Baumann 《Lipids》1990,25(10):606-612
Described is a reaction sequence for the total synthesis of lyso platelet activating factor (lysoPAF; 1-O-alkyl-sn-glycero-3-phosphocholine) and its enantiomer. The procedure is versatile and yields optically pure isomers of defined chain
length. The synthesis is equally suited for the preparation of lysoPAF analogues and its enantiomers with unsaturation in
the long aliphatic chain. First,rac-1(3)-O-alkylglycerol is prepared by alkylation ofrac-isopropylideneglycerol with alkyl methanesulfonate followed by acid-catalyzed removal of the ketal group. The primary hydroxy
group of alkylglycerol is then protected by tritylation, the secondary hydroxy group is acylated, and the protective trityl
group is removed under mild acidic conditions with boric acid on silicic acid, essentially without acyl migration. Condensation
of the diradylglycerol with bromoethyl dichlorophosphate in diethyl ether, hydrolysis of the resulting chloride, and nucleophilic
displacement of the bromine with trimethylamine givesrac-1-O-alkyl-2-acylglycero-3-phosphocholine in good overall yield. The racemic alkylacylglycerophosphocholine is finally treated
with snake venom phospholipase A2 (Ophiophagus hannah) which affords 1-O-alkyl-sn-glycero-3-phosphocholine (lysoPAF) of natural configuration in optically pure form. The “unnatural” 3-O-alkyl-2-O-acyl-sn-glycerol-1-phosphocholine enantiomer, which is not susceptible to phospholipase A2 cleavage, gives 3-O-alkyl-sn-glycero-1-phosphocholine upon deacylation with methanolic sodium hydroxide. Homogeneity and structure of the intermediates
and final products were ascertained by carbon-13 nuclear magnetic resonance spectroscopy on monomeric solutions. 相似文献
10.
Ether lipid content and fatty acid distribution in rabbit polymorphonuclear neutrophil phospholipids
This study was undertaken to determine if rabbit neutrophils contain sufficient ether-linked precursor for the synthesis of
1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine (platelet activatin factor) by a deacylation-reacylation pathway. The phospholipids from rabbit
peritoneal polymorphonuclear neutrophils were purified and quantitated, and the choline-containing and ethanolamine-containing
phosphoglycerides were analyzed for ether lipid content. Choline-containing phosphoglycerides (37%), ethanolamine-containing
phosphoglycerides (30%), and sphingomyelin (28%) were the predominant phospholipid classes, with smaller amounts of phosphatidylserine
(5%) and phosphatidylinositol (<1%). The choline-linked fraction contained high amounts of 1-O-alkyl-2-acyl-(46%) and 1,2-diacyl-sn-glycero-3-phosphocholine (54%), with a trace of the 1-O-alk-1′-enyl-2-acyl species. The ethanolamine-linked fraction contained high amounts of 1-O-alk-1′-enyl-2-acyl-(63%) and 1,2-diacyl-sn-glycero-3-phosphoethanolamine (34%), and a low quantity of the 1-O-alkyl-2-acyl species (3%). The predominant 1-O-alkyl ether chains found in thesn-1 position of the choline-linked fraction were 16∶0 (35%), 18∶0 (14%), 18∶1 (26%), 20∶0 (16%), and 22∶0 (9%). The major 1-O-alk-1′-enyl ether chains found in thesn-1 position of the ethanolamine-linked fraction were 14∶0 (13%), 16∶0 (44%), 18∶0 (27%), 18∶1 (12%) and 18∶2 (3%). The major
acyl groups in thesn-1 position of 1,2-diacyl-sn-glycero-3-phosphocholine and 1,2-diacyl-sn-glycero-3-phosphoethanolamine were 16∶0, 18∶0 and 18∶1. The most abundant acyl group in thesn-2 position of all classes of choline- and ethanolamine-linked phosphoglycerides was 18⩺2. Although this work does not define
the biosynthetic pathway for platelet activating factor, it does show that there is ample precursor present to support its
synthesis by a deacylation-reacylation pathway. 相似文献
11.
In mammalian systems, platelet-activating factor, 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine, (PAF) is rapidly inactivated by a deacetylation/reacylation system that produces 1-O-alkyl-2-acyl-sn-glycero-3-phosphocholine which is highly enriched in arachidonic acid. There is some evidence that n−3 fatty acids may have
an impact on this system in humans but the nature of this impact is unclear. In rainbow trout, n−3 fatty acids are known to
be essential dietary components which are derived through the food chain. Substantial quantities of n−3 fatty acids are found
in trout membrane phospholipids. We show here that in sharp contrast to mammalian cells, trout cells acylate lyso platelet-activating
factor, alkyl-GPC, 1-O-alkyl-2-lyso-sn-glycero-3-phosphocholine, (lyso-PAF) with a high degree of specificity for n−3 fatty acids. When [3H]lysoPAF was incubated with these cells, only three molecular species of alkylacylglycerophosphocholine were produced, and
92% contained n−3 fatty acids. Since isolated membranes yielded similar results, it appears that the acylation proceedsvia a coenzyme A-independent transacylase as found in mammalian systems. 相似文献
12.
Colantonio S Simpson JT Fisher RJ Yavlovich A Belanger JM Puri A Blumenthal R 《Lipids》2011,46(5):469-477
Since its introduction as an ionization technique in mass spectrometry, matrix-assisted laser desorption ionization (MALDI)
has been applied to a wide range of applications. Quantitative small molecule analysis by MALDI, however, is limited due to
the presence of intense signals from the matrix coupled with non-homogeneous surfaces. The surface used in nano-structured
laser desorption ionization (NALDI) eliminates the need for a matrix and the resulting interferences, and allows for quantitative
analysis of small molecules. This study was designed to analyze and quantitate phospholipid components of liposomes. Here
we have developed an assay to quantitate the DPPC and DC8,9PC in liposomes by NALDI following various treatments. To test our method we chose to analyze a liposome system composed of
DPPC (1,2-dipalmitoyl-sn-glycero-3-phosphocholine) and DC8,9PC (1,2-bis(tricosa-10,12-diynoyl)-sn-glycero-3-phosphocholine), as DC8,9PC is known to undergo cross-linking upon treatment with UV (254 nm) and this reaction converts the monomer into a polymer.
First, calibration curves for pure lipids (DPPC and DC8,9PC) were created using DMPC (1,2-dimyristoyl-sn-glycero-3-phosphocholine) as an internal standard. The calibration curve for both DPPC and DC8,9PC showed an R2 of 0.992, obtained using the intensity ratio of analyte and internal standard. Next, DPPC:DC8,9PC liposomes were treated with UV radiation (254 nm). Following this treatment, lipids were extracted from the liposomes and
analyzed. The analysis of the lipids before and after UV exposure confirmed a decrease in the signal of DC8,9PC of about 90%. In contrast, there was no reduction in DPPC signal. 相似文献
13.
Hans D. Schick Wolfgang E. Berdel Michael Fromm Ulrich Fink Ulrich Jehn Kurt Ulm Anneliese Reichert Hansjörg Eibl Clemens Unger Johann Rastetter 《Lipids》1987,22(11):904-910
The effects of 2-lysophosphatidylcholine (2-LPC), the alkyl lysophospholipid derivatives (ALP) 1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphocholine (ET-18-OCH3) and 1-O-hexadecyl-sn-glycero-3-phospho-trimethyl-ammonio-hexanol, the 2-acetamide analog of platelet-activating factor (PAF) 1-O-octadecyl-2-acetamide-sn-glycero-3-phosphocholine, the thioether lysophospholipid derivative (TLP) BM 41.440 and the ether-linked lipoidal amine CP-46,665 on tritiated thymidine uptake and trypan blue dye exclusion were tested in vitro in various freshly explanted cell samples from human nonneoplastic bone marrow and human leukemias. In both assay systems, a dose range of 1–20 μg/ml of the compounds was tested after 24, 48 and 72 hr of coincubation with the cells. The trypan blue dye exclusion revealed statistically significant preferential cytotoxicity in leukemic cells for three compounds with the order of quantitative selectiveness: ET-18-OCH3>BM41.440>2-acetamide analog of PAF. CP-46,665 was the most toxic compound, but did not reveal significant differences between nonneoplastic bone marrow and leukemic cells when added in concentrations greater than 1 μg/ml. The trimethyl-ammoniohexanol compound showed only minor activity in the majority of tests, when added at concentrations <20 μg/ml. 2-LPC was rather ineffective. The tritiated thymidine uptake showed only preferential antiproliferative effects towards leukemic cells of ET-18-OCH3 and, sometimes, within the dose time frame tested of BM 41.440. All compounds tested except 2-LPC and the trimethyl-ammonio-hexanol compound were active also in this assay (inhibition of uptake>50% of the controls). Based on these results, ET-18-OCH3 and BM 41.440 are recommended for experimental bone marrow purging. 相似文献
14.
Etsuo Hasegawa Yoh-ichi Matsushita Kiyoshi Eshima Hiroyuki Ohno Eishun Tsuchida 《Polymer Bulletin》1986,15(5):397-403
Summary Polymerizable glycerophosphocholines containing one or two 2,4-hexadienyloxy groups at the terminal of the acyl chains were prepared. Those were 1-[11-(2,4-hexadienyloxy)undecanoyl]-2-0-alkyl-rac-glycero-3-phosphocholines 1, 1-acyl-2-[11-(2,4-hexadienyloxy)undecanoyl]-sn-glycero-3-phosphocholines 2 and 1,2-bis[11-(2,4-hexadienyloxy)undecanoyl]-sn-glycero-3-phosphocholine 3. Those having one hexadienyloxy group formed small unilamellar vesicles. One having two groups formed lipid bilayers, but not unilamellar vesicles. 1 and 2 could form stable microcapsules (polymerized vesicles) with the diameters ranging from 20 to 40 nm. 相似文献
15.
Racemic heavy isotope analogs of 1-O-alkyl-sn-glycero-3-phosphocholine (lysoPAF) and 1-O-alkyl-2-O-acetyl-sn-glycero-3-phosphocholine (PAF) were prepared for use as internal standards to facilitate quantitative studies based on mass
spectrometry. Starting from pentadencane-1,15-diol andrac-glycerol-1,2-acetonide, a convergent synthesis of 1-O-[16′-2H3]hexadecyl and 1-O-[18′-2H3]octadecylrac-glycero-3-phosphocholine and their acetyl derivatives is described. Three deuterium atoms were introduced at the terminal
position of the 1-O-alkyl group by displacement of thep-toluensulfonyl group from 1-O-alkyl-15′-p-toluensulfonate and 1-O-alkyl-17′-p-toluensulfonate with [2H3]-methylmagnesium iodide. The 1-O-alkyl-17′-p-toluensulfonate was obtained by reaction of the 1-O-alkyl-15′-p-toluensulfonate with allylmagnesium bromide, followed by reductive ozonolysis and treatment withp-toluenesulfonyl chloride. The hydroxyl group at C-2 was protected by a benzyl group and removed at a late stage in the synthesis.
This provided the corresponding lysoderivatives or allowed preparation of racemic PAF by subsequent acetylation of the free
hydroxy group. The phosphocholine moiety was introduced at glycerol C-3 by reaction with bromoethyldichlorophosphate and trimethylamine.
The synthetic compounds were analyzed by FAB/MS and GC/NICIMS. They were shown to contain less than 0.6% protium impurity. 相似文献
16.
Marie-Aude Rouet-Mayer Olga Valentova Elizabeth Simond-Côte Jean Daussant Claudine Thévenot 《Lipids》1995,30(8):739-746
Using the spectrofluorimetric method described by Wittenaueret al. [Wittenauer, L.A., Shirai, K., Jackson, R.L., and Johnson, J.D. (1984)Biochem. Biophys. Res. Commun. 118, 894–901] for phospholipase A2 (PLA2) measurement, we have detected a phospholipase activity in Ailsa Craig and in mutantrin tomatoes at their normal harvest time (mature green stage). This activity in Ailsa Craig tomatoes increased at the beginning
of fruit ripening (green-orange stage) and then decreased slowly. The decrease in activity, however, was greater when ripening
occurred after tomato picking at normal harvest time than when ripening occurred on tomato plants. This phospholipase activity
was always higher inrin tomatoes than in normal ones. Thin-layer chromatography of compounds obtained after incubation of tomato extract demonstrated
a decrease in the substrate 1-acyl-2-{6[(7-nitro-2,1,3, benzoxadiazol-4-yl)amino]-caproyl}-sn-glycero-3-phosphocholine (C6-NBD-PC), and an increase in one product (NBD-aminohexanoic acid), but failed to detect the second product (1-acyl-sn-glycero-3-phosphocholine). We, therefore, developed a new one-step method for separation and quantification of a mixture
of phospholipids and other lipids, using straight-phase-high-performance liquid chromatography with light-scattering detection.
This method detected another fatty acid-releasing activity in enzyme extract from green-orange tomatoes. This lipolytic enzyme
(or family of enzymes) slowly produced free fatty acids when 1-oleoyl-sn-glycero-3-phosphocholine was added as substrate. The production of fatty acids was stoichiometric and more rapid when 1-oleoyl-sn-glycero-3-phosphate and 1-oleoyl-sn-glycerol were used as substrates. On the other hand, the same tomato extract was unable to hydrolyze 1,2-dioleoyl-sn-glycero-3-phosphate and 1,2-dioleoyl-sn-glycerol. Crude tomato extract exhibited lipid acyl hydrolase activity according to the definition of Galliard [Galliard,
T. (1979), inAdvances in the Biochemistry and Physiology of Plant Lipids (Appelqvist, L.A., and Liljenberg, C. eds.), pp. 121–132, Elsevier, Amsterdam]. But in order to demonstrate whether tomato
extract contains PLA2 activity and/or lysophospholipase activity, further work on purified tomato extract will be necessary. 相似文献
17.
J. T. Tsiepe B. B. Mamba Inamuddin Alaa S. Abd-El-Aziz A. K. Mishra 《Journal of Inorganic and Organometallic Polymers and Materials》2018,28(2):467-480
The aim of this present work is to investigate the adsorption capacity, kinetics and mechanism of arsenite ion removal onto beta-Cyclodextrin–Chitosan–Fe3O4 nanocomposite (β-CD–CS–Fe3O4 nanocomposite) from aqueous solutions. Iron oxide nanoparticles (Fe3O4) were synthesized using the co-precipitation method and the nanocomposite was successfully prepared via the solution-blending method. The analysis to determine arsenite ion adsorption was carried out using ICP-MS by varying pH, contact time and arsenite concentration parameters. The sorption of arsenite was found to be dependent on pH, time and arsenite initial concentrations. The adsorption equilibrium was reached in the first 20 min with the maximum uptake of 96%. Adsorption data were fitted well to the Langmuir isotherm describing a monolayer adsorption mechanism and pseudo-second-order models for kinetic study. It was established that the β-CD–CS polymer blend grafted with Fe3O4 nanoparticles enhanced the adsorption capacity because of the complexation abilities of the multiple OH and NH2 groups in the polymer backbone with metal ions. Subsequently, the mechanism of adsorption was investigated by studying the physicochemical properties of the adsorbent and the adsorbed species using the FTIR, TGA, DSC, XRD, SEM and TEM techniques. The characterizations before and after incorporations of the β-CD–CS composite with Fe3O4 nanoparticles showed well-improved properties for better adsorption of arsenite (As(III)) ions. 相似文献
18.
Chiew-Hwee YeoSharif Hussein Sharif Zein Abdul Latif AhmadDavid S. McPhail 《Ceramics International》2012,38(1):561-570
The aim of this paper is to synthesise calcium phosphate (CaP) nanoshells by controlling their particle size and shape using negatively charged liposomes (1,2 dioleoyl-sn-glycero-3 phosphate sodium salt (DOPA) and 1,2-dipalmitoyl-sn-glycero-3-phosphate sodium salt (DPPA)) as a template. The morphology, particle size, size distribution and zeta potential properties of DOPA and DPPA liposome templates were determined. The results showed that both DOPA and DPPA formed spherical nanoshell structures to be used as templates for the synthesis of CaP nanoshells. By using the DOPA template, spherical CaPs structures with a mean particle size of 197.5 ± 5.8 nm were successfully formed. In contrast, needle or irregularly shaped CaP particles were observed when using the DPPA template. 相似文献
19.
In this study, the 1-O-alkyl-2-acyl-sn-glycero-3-phosphocholine content of human platelets was determined. The distribution of arachidonate among the 1,2-diacyl,
1-O-alkyl-2-acyl, and 1-O-alk-l′-enyl-2-acyl classes of choline- and ethanolamine-containing phosphoglycerides was also assessed. The major platelet
phospholipids were choline-containing phosphoglycerides (38%), ethanolamine-containing phosphoglycerides (25%) and sphingomyelin
(18%), with smaller amounts of phosphatidylserine (11%) and phosphatidylinositol (4%). In addition to the diacyl class, the
choline-linked fraction was found to contain both 1-O-alkyl-2-acyl (10%) and 1-O-alk-l′-enyl-2-acyl (9%) species. The ethanolamine-linked fraction, on the other hand, had an elevated level of the 1-O-alk-l′-enyl-2-acyl (60%) species and a small amount of the 1-O-alkyl-2-acyl component (4%). The major fatty acyl residues found in all classes of the choline and ethanolamine phospholipids
were 16∶0, 18∶0, (Δ9), 18∶2(n−6) and 20∶4(n−6). The 1-O-alk-l and 1-O-alk-l′-enyl fraction of the ethanolamine-linked phospholipids also contained substantial amounts of 22∶4(n−6), 22∶5(n−3)
and 22∶6(n−3) acyl chains. Arachidonate comprised 44% of the acyl residues in thesn-2 position of 1-O-alkyl-2-acyl-sn-glycero-3-phosphocholine. Corresponding values for the diacyl and 1-O-alk-l′-enyl-2-acyl species were 23% and 25%, respectively, based on all 20∶4(n−6) being linked to thesn-2 position of all classes. In the ethanolamine-linked phosphoglycerides, arachidonate constituted 60%, 20% and 68% of the
acyl groups in thesn-2 position of the 1,2-diacyl, 1-O-alkyl-2-acyl and 1-O-alk-l′-enyl-2-acyl classes, respectively. The content of 1-O-alkyl-2-acyl-sn-glycero-3-phosphocholine appears sufficient to support the synthesis of platelet activating factor by a deacylation-reacylation
pathway in platelets. Our findings also demonstrate that human platelets contain a significant amount of 1-O-alkyl-2-arachidonyl-sn-glycero-3-phosphocholine that could possibly serve as a precursor of both platelet activating factor and bioactive arachidonate
metabolites. 相似文献
20.
The time course of hydrolysis of a mixed phospholipid substrate containing bovine liver 1,2-diacyl-sn-glycero-3-phosphocholine (PC) and 1,2-diacyl-sn-glycero-3-phosphoethanolamine (PE) catalyzed byCrotalus adamanteus phospholipase A2 was measured before and after peroxidation of the lipid substrate. The rate of hydrolysis was increased after peroxidation
by an iron/adenosine diphosphate (ADP) system; the presence of iron/ADP in the assay had a minimal inhibitory effect. The
rate of lipid hydrolysis was also increased after the substrate was peroxidized by heat and O2. Similarly, peroxidation increased the rate of hydrolysis of soy PC liposomes that did not contain PE. In order to minimize
interfacial factors that may result in an increase in rate, the lipids were solubilized in Triton X-100. In mixtures of Triton
with soy PC in the absence of PE, peroxidation dramatically increased the rate of lipid hydrolysis. In addition, the rate
of hydrolysis of the unoxidizable lipid 1-palmitoyl-2-[1-14C]oleoyl PC incorporated into PC/PE liposomes was unaffected by peroxidation of the host lipid. These data are consistent
with the notions that the increase in rate of hydrolysis of peroxidized PC substrates catalyzed by phospholipase A2 is due largely to a preference for peroxidized phospholipid molecules as substrates and that peroxidation of host lipid does
not significantly increase the rate of hydrolysis of nonoxidized lipids. 相似文献