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PubMed2005

Relationships between oxidative stability, triacylglycerol composition, and antioxidant content in olive oil matrices.

In olive oils, relationships between oxidative stability, glyceridic composition, and antioxidant content were investigated. Lipid matrices, obtained by purification of olive and high-oleic sunflower oils, were spiked with hydroxytyrosol, alpha-tocopherol, and mixtures of them and then subjected to oxidation in a Rancimat apparatus at 100 degrees C. At the same concentration of antioxidants, induction time (IT) decreased as the unsaturation rate of the matrix increased, but only fair correlations were found with fatty acid composition. Oxidative susceptibility (OS(TAG)) was calculated as a function of the relative oxidation rate of the triacylglycerols, and a linear relationship-IT (h) = (a + b)OS(TAG)-between induction time and this parameter showed a good correlation coefficient (r > 0.990, p < 0.001). In the case of matrices with a single antioxidant, origin ordinate (a) and slope (b) can be calculated as a function of the antioxidant concentration. In matrices spiked with mixtures of hydroxytyrosol and alpha-tocopherol, a simple relationship between the coefficients a and b and the concentration of antioxidants cannot be established because additive and subtractive effects occur depending on the relative concentrations of both antioxidants. However, approximate values for these coefficients can be obtained, allowing the estimation of the oil stability. In various olive oils, an acceptable agreement was found between the IT experimentally determined and that calculated from the oil composition. These results confirmed that the Rancimat stability of olive oils mainly depends on triacylglycerol composition and concentrations of o-diphenols and alpha-tocopherol.

Antioxidants↗
PubMed2007

HPLC separation and NMR structural elucidation of sn-1,2-, 2,3-, and 1,3-diacylglycerols from olive oil as naphthylethylurethane derivatives.

In this study, sn-1,2-, sn-2,3-, and sn-1,3-diacylglycerols were isolated from olive oil, and their urethane derivatives (urethanes) were prepared. Normal-phase high-performance liquid chromatography (NP-HPLC) separation of the urethane isomers was performed and the separate classes were studied by nuclear magnetic resonance (NMR). The use of 1H NMR and homo- and heteronuclear 2D techniques provided a great amount of information in a very short time, particularly when a high-field NMR instrument (700 MHz) was used. Particularly diagnostic for this kind of compound was the glyceridic moiety that presents typical chemical shifts both for carbon and hydrogen. These studies show the usefulness of NMR spectroscopy to recognize clearly the sn-1,3- and, moreover, sn-1,2- with respect to sn-2,3-diacylglycerols, although very minor differences occur between them.

Chromatography, High Pressure Liquid↗
PubMed1998

Determination of the (13)C Content of Glycerol Samples of Different Origin.

The average carbon isotope value (delta(13)C) of 63 samples of glycerol from over 30 different sources has been determined. The results indicate that it is possible to distinguish the glycerol obtained from the glycerides produced in plants following C-3 and C-4 carbon fixation pathways. The samples obtained from animal sources seem to reflect the composition of the material consumed, as well as that produced by sugar fermentation.

Journal Article↗
PubMed1999

Analytical evaluation of virgin olive oil of first and second extraction.

Virgin olive oils from percolation (first extraction) have been compared with the corresponding oils from centrifugation (second extraction). The former were characterized by (i) higher contents of total phenols, o-diphenols, hydroxytyrosol, tyrosol-aglycons, tocopherols, trans-2-hexenal, total volatiles, and waxes; (ii) higher values of resistance to autoxidation and of turbidity; (iii) higher sensory scores; (iv) higher ratios of campesterol/stigmasterol, trans-2-hexenal/hexanal, and trans-2-hexenal/total volatiles; (v) lower contents of chlorophylls, pheophytins, sterols, and aliphatic and triterpene alcohols; (vi) lower alcoholic index and color indices; (vii) similar values of acidity, peroxide index, and UV (ultraviolet) spectrophotometric indices; (viii) similar percentages of saturated and unsaturated fatty acids, triglycerides, and diglycerides; and (ix) similar values of glyceridic indices. Stigmastadienes, trans-oleic, trans-linoleic, and trans-linolenic acid isomers were not detected in the two genuine oil kinds. Hence, the qualitative level of the first extraction oil was superior to the second extraction one.

Food Handling↗
PubMed2000

Isolation, purification, and characterization of a cold-active lipase from Aspergillus nidulans.

Aspergillus nidulans WG312 strain secreted lipase activity when cultured in liquid media with olive oil as carbon source. Highest lipase productivity was found when the mycelium was grown at 30 degrees C in a rich medium. The new enzyme was purified to homogeneity from the extracellular culture of A. nidulans by phenyl-Sepharose chromatography and affinity binding on linolenic acid-agarose. The lipase was monomeric with an apparent M(r) of 29 kDa and a pI of 4.85 and showed no glycosylation. Kinetic of enzyme activity versus substrate concentration showed a typical lipase behavior, with K(M) and K(cat) values of 0.28 mM and 494 s(-)(1) and 0.30 mM and 320 s(-)(1) for the isotropic solution and for the turbid emulsion, respectively. All glycerides assayed were hydrolyzed efficiently by the enzyme, but this showed preference toward esters of short- and middle-chain fatty acids. The optimum temperature and pH for the lipolytic activity were 40 degrees C and 6.5, with high activity in the range 0-20 degrees C and reduced thermal stability.

Aspergillus nidulans↗
PubMed1986

A lymphotropic prodrug of L-dopa: synthesis, pharmacological properties, and pharmacokinetic behavior of 1,3-dihexadecanoyl-2-[(S)-2-amino-3-(3,4-dihydroxyphenyl)prop anoyl] propane-1,2,3-triol.

A glyceride derivative of L-Dopa, 1,3-dihexadecanoyl-2-[(S)-2-amino-3-(3,4-dihydroxyphenyl)propan oyl] propane-1,2,3-triol (1), was synthesized and tested as an orally administrable prodrug endowed with lymphotropic properties. In the oxotremorine and reserpine tests, 1 exhibited an anti-Parkinsonian activity of longer duration than L-Dopa. The time course of concentration of 1 in the intestinal lymph of rat was determined and compared to that of L-Dopa. The results clearly demonstrate that 1 is selectively absorbed from the intestinal tract by the lymphatic route without any chemical or enzymatic degradation. In the blood of rats and mice, 1 functions as a prodrug to release L-Dopa by hydrolysis. In comparison with L-Dopa itself, higher L-Dopa levels for a longer period of time were observed as well as much more favorable L-Dopa/dopamine ratios. Ultimately, studies using mice show that the administration of 1 brings about a prolonged increase of L-Dopa and dopamine levels in the brain, without initial transient peak in concentration observed after an equimolecular dose of L-Dopa.

Administration, Oral↗
PubMed1983

1,3-dipalmitoylglycerol ester of chlorambucil as a lymphotropic, orally administrable antineoplastic agent.

A glyceride derivative of chlorambucil (2), 1,3-dipalmitoyl-2-[4-[bis (2-chloroethyl)amino]benzenebutanoyl]glycerol (1), was synthesized and tested as an orally administrable antineoplastic drug endowed with lymphotropic properties. A significantly higher efficacy (increased life span) and a reduced toxicity of 1, relative to 2, were apparent when both compounds given per os were evaluated against P388 leukemia subcutaneously implanted in mice, a situation where the tumor cells disseminate along the lymphatic route. In order to assess the selective absorption of 1 by the intestinal lymphatic system after oral administration, we determined plasma and intestinal lymphatic concentrations and compared them with that obtained with 2. The results clearly demonstrate that the esterification of 2 to a diacylglycerol moiety brings about considerably higher levels in the lymph and reduces plasma levels. Moreover, pharmacokinetic and biological data suggest that 1 is most probably acting by itself rather than as a prodrug of chlorambucil.

Administration, Oral↗
PubMed2005

Negative dipole potentials of uncharged langmuir monolayers due to fluorination of the hydrophilic heads.

The dipole potential, affecting the structure, functions, and interactions of biomembranes, lipid bilayers, and Langmuir monolayers, is positive toward the hydrocarbon moieties. We show that uncharged Langmuir monolayers of docosyl trifluoroethyl ether (DFEE) exhibit large negative dipole potentials, while the nonfluorinated docosyl ethyl ether (DEE) forms films with positive dipole potentials. Comparison of the Delta V values for these ethers with those of the previously studied(37-39) monolayers of trifluoroethyl ester (TFEB) and ethyl ester of behenic acid (EB) shows that the reversal of the sign of Delta V causes the same change Delta(Delta V) = -706 +/- 16 mV due to fluorination of heads. The Delta V values of both TFEB and EB films differ by -122 +/- 16 mV from those of DFEE and DEE monolayers, respectively, with the same density. Such quantitative coincidence points to a common mechanism of reversal of the sign of the dipole potential for the ether and ester films despite the different structure of their heads. The mechanical properties and phase behaviors of these monolayers show that both fluorinated heads are less hydrated, suggesting that the change of the sign of Delta V could, at least partially, be related to different hydration water structure. The same negative contribution of the carbonyl bond in both TFEB and EB films contrasts with the generally accepted positive contribution of the C(delta+)=O(delta-) bond in condensed Langmuir monolayers of fatty acids, their alcohol esters, glycerides, and phospholipids but concurs with the theoretical analysis of Delta V of stearic acid monolayers. Both results question the literature values of the molecular dipole moments of these substances calculated via summation of bonds and atomic group contributions. Mixed monolayers of DFEE and DEE show smooth monotonic variation of Delta V from +450 to -235 mV, indicating a way for adjustment of the sign and magnitude of the dipole potential at the membrane-water boundary and regulation of such membrane behaviors as binding and translocation rate of hydrophobic ions and ion-carriers, adsorption and penetration of amphiphilic peptides, polarization of hydration water, and short-range repulsion. The interaction of the hydrophobic ions tetraphenylboron TPhB- and tetraphenylphosphonium TPhP+ with DFEE and DEE monolayers qualitatively follows the theory of binding of such ions to lipid bilayers, but the shifts Delta(Delta V) from the values obtained on water are much smaller than those for DPPC monolayers. This difference seems to be due to the solid (polycrystalline) character of the DFEE and DEE films that hampers the penetration of TPhB- and TPhP+ in the monolayers and reduces the attractive interaction with the hydrophobic moiety. This conclusion orients the future synthesis of amphiphiles with fluorinated heads to those which could form liquid-expanded Langmuir monolayers.

Chemical Phenomena↗
PubMed2006

Interaction between the conjugated polyelectrolyte poly{1,4-phenylene[9,9-bis(4-phenoxybutylsulfonate)]fluorene-2,7-diyl} copolymer and the lecithin mimic 1-O-(l-Arginyl)-2,3-O-dilauroyl-sn-glycerol in aqueous solution.

In this paper, the interaction between the water-soluble conjugated polyelectrolyte poly{1,4-phenylene[9,9-bis(4-phenoxybutylsulfonate)]fluorene-2,7-diyl} copolymer and the amino acid glyceride conjugate 1-O-(L-arginyl)-2,3-O-dilauroyl-sn-glycerol dichlorohydrate (a mimic for the phospholipid lecithin) has been studied in aqueous solution by electronic spectroscopy (absorption and fluorescence) and small-angle neutron scattering (SANS). A significant increase in the polymer fluorescence and blue shift in its emission are observed on association with the surfactant. This is suggested to be due to breakup of polymer aggregates. In addition, the spectroscopic and photophysical data suggest this is followed by the vesicle to ribbon transition characteristic of this surfactant, leading to incorporation of single chains of the polymer within mixed polymer-surfactant aggregates. Support for this comes from preliminary SANS measurements, from which evidence for polymer dissolution and formation of two-dimensional structures has been obtained.

Journal Article↗
PubMedDate not supplied

Plant anticancer agents. XIX Constituents of Aquilaria malaccensis.

The stem bark of the Thai tree Aquilaria malaccensis (Thymelaeaceae) has afforded 1,3-dibehenyl-2-ferulyl glyceride (3), which is novel, and 12-O-n-deca- 2, 4, 6-trienoylphorbol-13-acetate (4). The structures of these cytotoxic compounds were elucidated by their spectral and chemical parameters.

Animals↗
PubMed2002

NMR-based metabonomic studies on the biochemical effects of commonly used drug carrier vehicles in the rat.

The biochemical effects of a series of commonly used drug carrier vehicles were investigated using (1)H NMR spectroscopic and pattern recognition based metabonomic analysis. Animals were treated by oral gavage with six dosage vehicles: 0.5% (w/v) sodium carboxymethylcellulose/0.2% (v/v)tween; microemulsion (consisting of propylene glycol, ethanol, cremophor, and corn oil glycerides); labrafil [consisting of poly(ethylene glycol) 300 esterified with oleic acid] (30%)/corn oil (70%); 0.1 M sodium phosphate buffered water; poly(ethylene glycol) 300 and 0.5% methocel. Urine samples (n = 7) collected over a 96 h period post administration were analyzed using 600 MHz (1)H NMR spectroscopy, and principal components analysis of the spectral data was used to analyze these data. Of the six vehicles studied, three (labrafil/corn oil, PEG 300 and microemulsion) gave rise to strong vehicle-related signals in the (1)H NMR spectra of urine and were, therefore, deemed to be less suitable for NMR-based toxicity studies. To investigate any biochemical consequences of vehicle dosing, PCA was used to analyze spectral regions that did not contain vehicle-related signals, i.e., the NMR-detectable endogenous metabolite profile. PEG 300 and labrafil/corn oil induced changes in the biochemical composition of urine including increased concentrations of dicarboxylic acids, creatinine, taurine, and sugars, indicating that these vehicles were bioactive in their own right and that this might confound interpretation of biochemical effects of weakly toxic drugs dosed in these carriers. This study shows the importance of selecting appropriate vehicles for NMR-based metabonomic studies with a view to minimizing the possibility of vehicle resonances obscuring endogenous compound peaks. Furthermore, we have shown that at least two of the commonly used drug carrier vehicles caused metabolic perturbations in the urine profile. These alterations in the biochemical profile reflect vehicle-induced changes in the physiological status of the organism that may obscure the pharmacologic or toxicologic effects of drugs.

Administration, Oral↗
PubMed2000

Sterol carrier protein-2 suppresses microsomal acyl-CoA hydrolysis.

Although sterol carrier protein 2 (SCP-2) has long been regarded primarily as a sterol transfer protein, its actual physiological function is not known. The recent discovery that SCP-2 binds long chain fatty acyl-CoAs (LCFA-CoAs) with high affinity suggests additional roles for SCP-2 in cellular utilization of LCFA-CoAs for synthesis of glycerides and cholesterol esters. Concomitant to these anabolic pathways, LCFA-CoAs are also degraded by cellular hydrolases. The purpose of the work presented herein was to determine if SCP-2 altered the aqueous pool of LCFA-CoA by (i) extracting LCFA-CoA from microsomal membranes, and (ii) protecting LCFA-CoA from microsomal hydrolase activity. The data demonstrated for the first time that SCP-2 increases the aqueous pool of oleoyl-CoA by increasing the aqueous/membrane distribution oleoyl-CoA by 2.4-fold. In addition, SCP-2 inhibited the hydrolysis of oleoyl-CoA by microsomal acyl-CoA hydrolase 1.6-2.4 fold, depending on the concentration of oleoyl-CoA. By simultaneously extracting LCFA-CoA from membranes and inhibiting LCFA-CoA degradation SCP-2 may potentiate LCFA-CoA transacylation and modulate the role of LCFA-CoAs as intracellular signaling molecules.

Acyl Coenzyme A↗
PubMed2000

Preparation of biodegradable insulin nanocapsules from biocompatible microemulsions.

PURPOSE: To prepare poly(ethyl 2-cyanoacrylate) nanocapsules containing insulin by interfacial polymerization of spontaneously forming, biocompatible microemulsions. METHODS: A pseudo-ternary phase diagram of a mixture of medium chain glycerides (caprylic/capric triglycerides and mono-/diglycerides), a mixture of surfactants (polysorbate 80 and sorbitan mono-oleate) and water was constructed. Polarizing light microscopy was used to identify combinations forming microemulsions. Microemulsions were characterized by conductivity and viscosity to select systems suitable for the preparation of poly(ethyl 2-cyanoacrylate) nanocapsules by interfacial polymerization. Nanocapsules were prepared by addition of 100 mg of ethyl 2-cyanoacrylate to a stirred water-in-oil microemulsion containing 1 g of water, 7.6 g of oil, and 1.4 g of surfactant. The nanocapsules formed were characterized by photon correlation spectroscopy, freeze fracture transmission and scanning electron microscopy. Insulin nanocapsules were prepared by using an aqueous solution of insulin (100 units/ml) as the dispersed phase of the microemulsion. The entrapment and the release of insulin from the nanocapsules were determined. RESULTS: Three regions were identified in the pseudo-ternary phase diagram; a microemulsion region, a region in which liquid crystalline structures were present and a coarse emulsion region. All systems in the microemulsion region were water-in-oil dispersions. Poly(ethyl 2-cyanoacrylate) nanocapsules having a mean particle size of 150.9 nm were formed upon interfacial polymerization of the microemulsion. Nanocapsules were found to have a central cavity surrounded by a polymer wall. In excess of 80% of the insulin present in the microemulsion was encapsulated upon interfacial polymerization. CONCLUSIONS: Interfacial polymerization of spontaneously forming water-in-oil microemulsions represents a convenient method for the preparation of poly(alkylcyanoacrylate) nanocapsules suitable for the entrapment of bioactive peptides.

Absorbable Implants↗
PubMed1991

Polymorphic behavior of sprayed lipid micropellets and its evaluation by differential scanning calorimetry and scanning electron microscopy.

Considering the importance of polymorphism occurring in solid dosage forms causing instability, the polymorphic behavior of spray-dried and -congealed lipid micropellets was examined by differential scanning calorimetry and scanning electron microscopy. The results showed that both of the spraying processes exert an important effect on their polymorphic and crystallization properties. In spray-drying, due to the rapid solvent evaporation, the obtained lipid micropellets possess an unstable polymorphic form. This unstable form transforms gradually toward a stable form by storage at elevated temperatures. The same modifications were observed with spray-congealed lipid micropellets. The type of glyceride (composition, chain length), solvent and drugs (estradiol cypionate, medroxyprogesterone acetate) and, further, the presence of a stabilizing agent such as lecithin affect the polymorphic transition and its rate.

Calorimetry, Differential Scanning↗
PubMed1990

Bile salt-fatty acid mixed micelles as nasal absorption promoters of peptides. I. Effects of ionic strength, adjuvant composition, and lipid structure on the nasal absorption of [D-Arg2]kyotorphin.

Bile salts and synthetic surfactants have been used to promote nasal absorption of peptide drugs. Although a marked increase in nasal absorption has been achieved, this may not be adequate and the possibility of adjuvant-induced membrane toxicity exists. The present study employs a rat in situ nasal perfusion technique and mixed micelles between sodium glycocholate (NaGC) and various lipids as potential nasal absorption enhancers of a stable model dipeptide, [D-Arg2]kyotorphin. NaGC alone enhanced the nasal absorption of the dipeptide in a concentration-dependent manner. When linoleic acid was added to form mixed micelles with NaGC, the absorption was further enhanced (P less than 0.01). The effect of mixed micelles was synergistic and much greater than with single adjuvants. Increasing ionic strength was found to increase the adjuvant activity of both NaGC and NaGC-lipid mixed micelles. Structure of the lipid component of the mixed micelles also affected the adjuvant potency. Oleic acid, a cis-unsaturated fatty acid, was more effective than elaidic acid, the trans-isomer, whereas cis-linoleic acid and trans-linolelaidic acid were equally effective (alpha = 0.05). Mixed micelles of mono-glycerides such as monoolein and monolinolein were also more effective than NaGC alone (alpha = 0.05). Micellar solubilization of these polar lipids by NaGC appears to be important for nasal absorption enhancement to occur. Reversal of the membrane permeability was also observed within approximately 20-40 min after removal of the adjuvants from the rat nasal cavity. These observations are similar to the effects of mixed micelles on the rectal mucosa and may involve the same mechanism.

Adjuvants, Pharmaceutic↗
PubMed1993

Phenytoin-lipid conjugates: chemical, plasma esterase-mediated, and pancreatic lipase-mediated hydrolysis in vitro.

Phenytoin-lipid conjugates obtained by covalent binding of hydroxymethylphenytoin to diacylglycerides and to 3-acyloxy-2-acyl-oxymethylpropionic acids formed dispersions with a particle size of 10-200 microns when briefly sonicated in a sodium taurodeoxycholate-containing ethanol-water mixture. In contrast to the corresponding bis-deacyl derivatives, the lipids were not significantly hydrolyzed in aqueous buffers and in plasma. Incubation with pancreatic lipase yielded primarily the bis-deacyl compounds, which are comparable to monoglycerides, and subsequently liberated phenytoin. The glyceride-derived prodrugs were better substrates for the enzyme than the 3-acyloxy-2-acyloxymethyl-propionic acid derivatives. It is concluded that the phenytoin lipid conjugates are hydrolyzed by pancreatic lipase in a similar manner as natural triglycerides.

Chromatography, High Pressure Liquid↗
PubMed1999

Studies on the cytosolic phospholipase A2 in immortalized astrocytes (DITNC) revealed new properties of the calcium ionophore, A23187.

Besides playing an important role in the maintenance of cell membrane phospholipids, phospholipases A2 (PLA2) are responsible for the release of arachidonic acid (AA) which is a precursor for prostaglandin biosynthesis. The cytosolic PLA2 has been the focus of recent studies, probably due to its ability to respond to protein kinases and changes in intracellular calcium levels. In this study, we examined agents for stimulation of the cytosolic phospholipase A2 in immortalized astrocytes (DITNC). Incubation of DITNC cells with [14C]arachidonic acid (AA) resulted in a time-dependent uptake of the label into phospholipids (PL) and neutral glycerides. In prelabeled cells, release of labeled AA could be stimulated by calcium mobilizing agents such as calcium ionophore A23187 (4-20 microM) and thimerosal (100 microM), and by phorbol myristate acetate (PMA, 100 nM), an agent for activation of protein kinase C. The release of AA could also be stimulated by ATP (200 microM), probably through activation of the purinergic receptor but not by glutamate (1 mM). The stimulated release of AA was dependent on extracellular Ca2+ and was inhibited by mepacrine (50 microM), a non-specific PLA2 inhibitor. Western blot analysis further confirmed the presence of an 85 kDa cPLA2 in both membrane and cytosol fractions of these cells and stimulation by A23187 resulted in translocation of this protein to the membrane fraction. Besides labeled fatty acids, A23187 also stimulated the concomitant release of labeled PL into the culture medium and this event was accompanied by the increased release in lactate dehydrogenase (LDH). Results thus revealed that besides activation of cPLA2, the calcium ionophore A23187 is capable of perturbating cell membrane integrity.

Animals↗
PubMed1977

Krameria, free fatty acids and oil-collecting bees.

Vogel's report of the production of glycerides rather than nectar as rewards gathered by bees described an association involving several genera of insects and numerous plant families. We report here that members of the Krameriaceae produce floral lips more unusual than those described by Vogel. Our data also provide evidence that the oils of Krameria are collected by bees of only one genus, Centris (Anthophoridae), and used, mixed with pollen, as larval food.

Animals↗