Threshold protective effect of deuterated polyunsaturated fatty acids on peroxidation of lipid bilayers.

Autoxidation of polyunsaturated fatty acids (PUFAs) damages lipid membranes and generates numerous toxic by-products implicated in neurodegeneration, aging, and other pathologies. Abstraction of bis-allylic hydrogen atoms is the rate-limiting step of PUFA autoxidation, which is inhibited by replacing bis-allylic hydrogens with deuterium atoms (D-PUFAs). In cells, the presence of a relatively small fraction of D-PUFAs among natural PUFAs is sufficient to effectively inhibit lipid peroxidation (LPO). Here, we investigate the effect of various D-PUFAs on the stability of liposomes under oxidative stress conditions. The permeability of vesicle membranes to fluorescent dyes was measured as a proxy for bilayer integrity, and the formation of conjugated dienes was monitored as a proxy for LPO. Remarkably, both approaches reveal a similar threshold for the protective effect of D-PUFAs in liposomes. We show that protection rendered by D-PUFAs depends on the structure of the deuterated fatty acid. Our findings suggest that protection of PUFAs against autoxidation depends on the total level of deuterated bi-sallylic (CD2 ) groups present in the lipid bilayer. However, the phospholipid containing 6,6,9,9,12,12,15,15,18,18-d10 -docosahexaenoic acid exerts a stronger protective effect than should be expected from its deuteration level. These findings further support the application of D-PUFAs as preventive/therapeutic agents in numerous pathologies that involve LPO.

Eleostearic phospholipids as probes to evaluate antioxidants efficiency against liposomes oxidation.

Regardless of the applications: therapeutic vehicle or membrane model to mimic complex biological systems; it is of a great importance to develop simplified, reproducible and rapid model assays allowing for a relevant assessment of the liposomal membrane oxidation and therefore antioxidant activity of selected molecules. Here, we describe a new and high-throughput assay that we called "Vesicle Conjugated Autoxidizable Triene (VesiCAT)". It is based on specific UV absorbance spectral properties of a new phospholipid probe, synthesized with natural conjugated eleostearic acid extracted from Tung oil. The VesiCAT assay has been developed with two different radical generators (2,2'-azobis(2-amidinopropane) dihydrochloride; AAPH and 2,2'-azobis(2,4-dimethylvaleronitrile); AMVN), producing a constant flux of oxidant species, either in membrane or in aqueous phase. This method appears very efficient in assessing the effect of various pure antioxidant molecules in their ability to preserve liposomes from oxidative degradation. In addition, the AAPH- and AMVN-induced oxidations offer the possibility of extracting different but complementary information with respect to the antioxidants efficacy.

Isoprenoid-phospholipid conjugates as potential therapeutic agents: Synthesis, characterization and antiproliferative studies.

The aim of this research was to extend application field of isoprenoid compounds by their introduction into phospholipid structure as the transport vehicle. The series of novel isoprenoid phospholipids were synthesized in high yields (24-97%), their structures were fully characterized and its anticancer activity was investigated in vitro towards several cell lines of different origin. Most of synthesized compounds showed a significantly higher antiproliferative effect on tested cell lines than free terpene acids. The most active phosphatidylcholine analogue, containing 2,3-dihydro-3-vinylfarnesoic acids instead of fatty acids in both sn-1 and sn-2 position, inhibits the proliferation of colon cancer cells at 13.6 µM.

Fitosomas: un desarrollo tecnológico para mejorar la biodisponibilidad de los extractos vegetales / Phytosomas: um desenvolvimento tecnológico para melhorar a biodisponibilidade de extractos de plantas / Phytosomes: a technological development to improve the bioavailability of herbal extracts

Las plantas son una fuente inestlmable de nutrientes y princpios actívos con propledades muy lnteresantes para la salud. Lamentablemente, el organismo humano tiene dificultad para absorber algunos de ellos. Por ello, aportar y transportar hasta las células del organlsmo estas sustanclas, en cantidad suficiente para que realicen su acción, no siempre es posible, ya que en algunos casos el consumo de cantidades relativamente elevadas de extracto (o lngrediente actlvo) puede tener efectos adversos. Para solventar este problema se han realizado diversas investlgaciones tecnológicas. Entre ellas destaca el desarrollo que ha llevado a la obtencion de "fitosomas", proceso patentado mediante el cual un extracto vegetal estandarizado, una fraccion del mismo, o sus componentes, se unen a fosfolípldos (principalmente fosfatidilcolina) para obtener un complejo molecula-lípido. Este complejo exhibe un mejor perfil farmacocinético y farmacodinámlco y por tanto mejora de forma probada mediante ensayos, su biodisponibilidad. Un ejemplo ampliamente estudiado es el fitosoma de silibina (AU)

Plants are a valuable source of nutrients and active ingredients with interesting health properties. Unfortunately, the human body can have difficulties in absorbing some of them. Therefore, it is not always possible make these substances available to the body cells in sufficient active amount, since in some cases the administration of relatively large amounts of extract (or active ingredient) can cause adverse effects. To solve this problem several technological improvements have been studied. Among them, the development of "phytosomes", which are obtained thanks to a patented process in which a standardized herbal extract, a fraction thereof, or their constituents, are binded to phospholipids (mainly phosphatidylcholine) to obtain a lipid—molecule complex. This complex exhibits better pharmacokinetic and pharmacodynamic profile and it has shown to improve bioavailability. An extensively studied example is the silybin phytosome (AU)

As plantas sao uma valiosa fonte de nutrientes e constituintes activos com propriedades muito interessantes para a saude. Lamentavelmente, o organismo humano tem dificuldade em absorver alguns deles. Por isso, transportar e disponibilizar as celulas do organismo estas substancias em quantidade suficiente para que realizem a sua acgao nem sempre e possivel, uma vez que em alguns casos 0 uso de quantidades relativamente elevadas de extracto (ou da substancia activa) pode ter efeitos adversos. Para resolver este problema realizaram-se varias investigaçoes tecnológicas. Entre elas, destaca-se o desenvolvimento que conduziu a obtengao de "fitossomas", processo patenteado mediante o qual um extracto vegetal padronizado, uma fracçao do mesmo, ou os seus componentes, se unem a fosfolípidos (principalmente fosfatidilcolina) para se obter um complexo molecula-lípido. Este complexo exibe um melhor perfil farmacocinetico e farmacodinamico e, portanto, melhora de forma comprovada mediante ensaios, a sua biodisponibilidade. Um exemplo amplamente estudado e o fitossoma de silibina (AU)

Lipase-catalyzed preparation of phospholipids containing n-3 polyunsaturated fatty acids from soy phospholipids.

To utilize n-3 polyunsaturated fatty acid (PUFA) for a wide range of applications, we prepared phospholipids (PLs) containing PUFAs as constituent fatty acids (PUFA-PLs) via commercially available lipase OF-mediated transacylation with PL from soy (Soy-PL) and ethyl ester of PUFA (PUFA-Et). In a preliminary study to evaluate PUFA-incorporation (wt%) on phosphatidylcholine (PC), we observed that dehydration of Soy-PL is critical. PUFA-incorporation in PLs increased with acyl ratio and time. Finally, maximum PUFA-incorporation (47.1 ± 2.1 wt%) was obtained using the following reaction conditions: 2.0 mmol of Soy-PL, a PUFA-Et/Soy-PL acyl ratio of 7, 13 mL of hexane, 2.2 × 10(5) U of lipase OF, 500 rpm of agitation, a temperature of 37°C, and 72 h of reaction time. The analysis of fatty acid composition at the sn-2 position of obtained PL revealed that PUFAs incorporated into Soy-PL localized to the sn-2 position of the PL molecule in spite of using lipase OF whose positional specificity is random for triacylglycerol.

Clickosomes--using triazole-linked phospholipid connectors to fuse vesicles.

Two complementary artificial diether phospholipids were synthesized that can undergo a Cu(I)-catalyzed Huisgen-Sharpless click reaction. The resulting lipid can bridge the membranes of large unilamellar vesicles and cause their aggregation and ultimately their fusion.

Uranium(VI) complexes with phospholipid model compounds--a laser spectroscopic study.

We present the complex formation of the uranyl ion (UO(2)(2+)) in the aqueous system with phosphocholine, O-phosphoethanolamine and O-phosphoserine. These phosphonates (R-O-PO(3)(2-)) represent the hydrophilic head groups of phospholipids. The complexation was investigated by time-resolved laser-induced fluorescence spectroscopy (TRLFS) at pH=2-6. An increase of the fluorescence intensity, connected with a strong red-shift of about 8 nm compared to the free uranyl ion, indicates a complex formation between UO(2)(2+) and the phosphonates already at pH=2. Even at pH=6 these complexes prevail over the uranyl hydroxide and carbonate species, which are generated naturally at this pH. At pH=4 and higher a 1:2 complex between uranyl and O-phosphoserine was found. Complexes with a metal-to-ligand ratio of 1:1 were observed for all other ligands. Fluorescence lifetimes, emission maxima and complex stability constants at T=22+/-1 degrees C are reported. The TRLFS spectra of uranyl complexes with two phosphatidic acids (1,2-dimyristoyl-sn-glycero-3-phosphate and 1,2-dipalmitoyl-sn-glycero-3-phosphate), which represent the apolaric site of phospholipids, show in each case two different species.

Syntheses of new model compounds related to an antigenic epitope from Bupleurum falcatum L. and their distributions in various ganglioside-phospholipid monolayers.

6-N-[2-(Tetradecyl)hexadecanamido]hexyl beta-D-glucopyranosyluronic acid-(1-->6)-beta-D-galactopyranosyl-(1-->6)-beta-D-galactopyranoside (1) and its clustering compound (2) carrying a tetravalent sugar unit, which are new model compounds related to a major antigenic epitope from antiulcer pectic polysaccharide of Bupleurum falcatum L., were synthesized and the distributions of 1 and 2 in mixed ganglioside (GM1, GD1a or GT1b)/phospholipid (DPPC) monolayers were observed using atomic force microscopy (AFM). AFM images showed that 1 was distributed in the GM1, GD1a and GT1b region of the mixed monolayers, in which 1 was miscible with GD1a. Specific distribution of 1 was observed in the mixed GM1/DPPC monolayer. Compound 2 was miscible with GM1, while 2 formed associations with GD1a and GT1b in the mixed monolayers. The distribution mode of 1 and 2 was different among the mixed ganglioside/DPPC monolayers.

[PAF-antagonists with phospholipid structure. 2. Phospholipids with heteroarene head groups and variations of the phosphorus-nitrogen distance; synthesis, characterization and structure-activity relationships]. / PAF-Antagonisten mit Phospholipidstruktur. 2. Mitteilung: Phospholipide mit Heteroarenkopfgruppen und verlängerter Phosphor-Stickstoff-Distanz; Synthese, Charakterisierung und Struktur-Wirkungs-Vergleich.

A series of 27 PAF-analogues with heteroarene head groups and variation of the P-N-distance on the C-3-position of the backbone were synthesized, and the PAF-antagonistic activity on human blood platelets in vitro was evaluated. Investigation of structure-activity relationships revealed that PAF-antagonistic activity is strongly influenced by the 4-(Dimethylamino)-pyridine as polar head base and the distance between phosphate group and onium center. Maximal activity was observed with a chain length of 3 or 4 methylene groups. Among the compounds tested, 1-O-Hexadecyl-2-n-propylpropan-1,3-diol-3-phosphoric acid-4'-[4-(dimethylamino)pyridinium]butylester was the most effective inhibitor in the in vitro assay (KB = 0.3 mumol/l).