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PubMed2001

Fatty acid composition of lysophosphatidic acid and lysophosphatidylinositol in plasma from patients with ovarian cancer and other gynecological diseases.

OBJECTIVE: We previously reported that plasma levels of total lysophosphatidic acid (LPA) represented a potential biomarker for ovarian cancer and other gynecological cancers [1]. However, total LPA is composed of different LPA species with distinct fatty acid chains. The major objective of the current study, therefore, was to determine whether one or more specific fatty acid LPA species was associated with disease or disease staging. If this was determined, these species could be useful in further improving the sensitivity and/or specificity of this biomarker for the diagnosis and/or prognosis of the disease. Because lysophosphatidylinositol (LPI) co-migrates with LPA, this study represents the analysis of combined molecular species from both lysolipid classes. METHODS: The patient population, sample collection, and analyses have been reported previously [1]. Lipids were hydrolyzed from the LPA band on thin-layer chromatography plates. The following individual fatty acid species were analyzed by gas chromatography: palmitic acid (16:0), stearic acid (18:0), oleic acid (18:1), linoleic acid (18:2), arachidonic acid (20:4), and docosahexaenoic acid (22:6). The LPA/LPI fatty acid composition levels were analyzed and compared with disease status. RESULTS: Distinct plasma LPA/LPI fatty acid chain species were not associated with ovarian or other gynecological cancers, compared to patients with benign gynecological disease or healthy controls. However, an increased presence of unsaturated fatty acids in plasma LPA/LPI was found in patients with late-stage or recurrent ovarian cancer and possibly with other gynecological cancers. CONCLUSIONS: Analysis of individual fatty acid species present in plasma LPA/LPI do not appear to enhance the sensitivity or specificity of total LPA/LPI as a marker for gynecological cancer detection. However, our results suggest that increased LPA/LPI species with unsaturated fatty acid chains may be associated with late-stage or recurrent ovarian cancer.

Adult↗
PubMed1985

Hydroxyeicosatetraenoic acids and other unsaturated fatty acids inhibit endotoxin-induced thromboplastin activity in human monocytes.

Human peripheral blood monocytes possessed increased thromboplastin activity when exposed to 10 micrograms/ml of bacterial endotoxin for 2 h. The effects of endotoxin were strongly inhibited by 10-20 microM of several unsaturated fatty acids: arachidonic, dihomo-gamma-linolenic, linoleic, linolenic and oleic acids. Two saturated fatty acids, arachidic and stearic acids, produced minimal inhibition at 20 microM. Three lipoxygenase-derived hydroxyfatty acids were also inhibitory, with IC50 values of 10 microM (5- and 12-hydroxyeicosatetraenoic acids) and 20 microM (15-hydroxyeicosatetraenoic acid). Leukotriene B4, 1 nM to 1 microM, was inactive. None of the fatty acids affected the ability of standard thromboplastin to shorten the clotting time of normal plasma or affected the activity of endotoxin as measured by a Limulus clotting assay.

Arachidonic Acid↗
PubMed2002

Saturated triglycerides and fatty acids activate neutrophils depending on carbon chain-length.

BACKGROUND: Unsaturated fatty acids are known as neutrophil activators. In the present study we investigated whether saturated triglycerides and fatty acids may also contribute to the previously observed activation of neutrophils by nutritional lipid emulsions. Furthermore we tested the hypothesis that carbon-chain length is of importance in this respect. MATERIALS AND METHODS: Neutrophils (1 x 10(6) mL(-1)) were isolated from the blood of nine volunteers. Chemiluminescence was used to evaluate neutrophil activation, characterized by the production of oxygen radicals by neutrophils during incubation with 1 mmol L(-1) saturated fatty acid (6-20 carbon) or triglycerides (6-12 carbon fatty acid), dissolved in aqueous medium by preparing micelles with dipalmitoyl phosphatidylcholine (DPPC). Results were expressed as means +/- SEMs of the overall luminescence signal relative to the signal of cells incubated in medium. RESULTS: Similar to a positive control, the polyunsaturated fatty acid arachidonic acid (C20 : 4), the triglycerides tricaproin (TC6 : 0), tricaprylin (TC8 : 0) and trilaurin (TC12 : 0) as well as the fatty acids lauric acid (C12 : 0), palmitic acid (C16 : 0), stearic acid (C18 : 0) and arachidic acid (C20 : 0) all induced oxygen radical production in neutrophils, while the medium-chain triglyceride tricaprin (TC10 : 0) and fatty acids caproic acid (C6 : 0), caprylic acid (C8 : 0) and capric acid (C10 : 0) exerted no clear effects, similar to negative controls (DPPC and glycerol). CONCLUSIONS: Besides their (poly)-unsaturated counterparts, saturated triglycerides and fatty acids also activate neutrophils. Carbon chain-length is pivotal in the interaction of fatty acids and triglycerides and cells of the immune system.

Adult↗
PubMed2004

Impact of long chain fatty acids on glucose fermentation under mesophilic conditions.

The effects of three long chain fatty acids (LCFAs) on glucose fermentation at 37 degrees C were examined during this study. Linoleic acid (LA) was more inhibitory than oleic acid (OA) and stearic acid (SA). During glucose fermentation, the carbon flow was diverted towards the production of more reduced volatile fatty acids (VFAs) in cultures fed with unsaturated LCFAs. In cultures inoculated with LA and OA, butyrate was produced with elevated levels observed in cultures inoculated with LA. Propionate degradation was unaffected by the presence of SA; however, elevated levels and longer removal times were observed in cultures receiving LA and OA. Acetate accumulation indicated the acetoclastic methanogenic population was affected only by OA and LA.

Biodegradation, Environmental↗
PubMed2006

The influence of tin compounds on the dynamic properties of liposome membranes: a study using the ESR method.

The influence of organic and inorganic compounds of tin on the dynamic properties of liposome membranes obtained in the process of dipalmitoylphosphatidylcholine (DPPC) sonication in distilled water was investigated. This was carried out by means of the spin ESR probe method. The probes were selected in such a way as to penetrate different areas of the membrane (a TEMPO probe, 5-DOXYL stearic acid, 16-DOXYL stearic acid). Four compounds of tin were chosen: three organic ones, (CH(3))(4)Sn, (C(2)H(5))(4)Sn and (C(3)H(7))(3)SnCl, and one inorganic one, SnCl(2). The investigated compounds were added to a liposome dispersion, which was prepared prior to that. The concentration of the admixture was changed within the values from 0 to 10%-mole in proportion to DPPC. The studies indicated that the chlorides of tin display the highest activity in their interaction with liposome membranes. Since these compounds have ionic form in a water solution, the obtained result can mean that this form of admixture has a considerable influence on its activity. Furthermore, it was found that there is a slightly stronger influence of tin compounds with a longer hydrocarbon chain on changes in the probes' spectroscopic parameters.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed2000

Determination of the fatty acid composition of saponified vegetable oils using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

A method using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) for the determination of the fatty acid composition of vegetable oils is described and illustrated with the analysis of palm kernel oil, palm oil, olive oil, canola oil, soybean oil, vernonia oil, and castor oil. Solutions of the saponified oils, mixed with the matrix, meso-tetrakis(pentafluorophenyl)porphyrin, provided reproducible MALDI-TOF spectra in which the ions were dominated by sodiated sodium carboxylates [RCOONa + Na]+. Thus, palm kernel oil was found to contain capric acid, lauric acid, myristic acid, palmitic acid, oleic acid, and stearic acid. Palm oil had a fatty acid profile including palmitic, linoleic, oleic, and stearic. The relative percentages of the fatty acids in olive oil were palmitoleic (1.2 +/- 0.5), palmitic (10.9 +/- 0.8), linoleic (0.6 +/- 0.1), linoleic (16.5 +/- 0.8), and oleic (70.5 +/- 1.2). For soybean oil, the relative percentages were: palmitoleic (0.4 +/- 0.4), palmitic (6.0 +/- 1.3), linolenic (14.5 +/- 1.8), linoleic (50.1 +/- 4.0), oleic (26.1 +/- 1.2), and stearic (2.2 +/- 0.7). This method was also applied to the analysis of two commercial soap formulations. The first soap gave a fatty acid profile that included: lauric (19.4% +/- 0.8), myristic (9.6% +/- 0.5), palmitoleic (1.9% +/- 0.3), palmitic (16.3% +/- 0.9), linoleic (5.6% +/- 0.4), oleic (37.1% +/- 0.8), and stearic (10.1% +/- 0.7) and that of the second soap was: lauric (9.3% +/- 0.3), myristic (3.8% +/- 0.5), palmitoleic (3.1% +/- 0.8), palmitic (19.4% +/- 0.8), linoleic (4.9% +/- 0.7), oleic (49.5% +/- 1.1), and stearic (10.0% +/- 0.9). The MALDI-TOFMS method described in this communication is simpler and less time-consuming than the established transesterification method that is coupled with analysis by gas chromatography/mass spectrometry (GC/MS). The new method could be used routinely to determine the qualitative fatty acid composition of vegetable oils, and, when fully validated by comparison with standard analytical methodologies, should provide a relatively fast quantitative measurement of fatty acid mixtures and/or soap formulations that contain saturated and unsaturated hydrocarbon moieties.

Esterification↗
PubMed2001

Effect of cholesterol on miscibility and phase behavior in binary mixtures with synthetic ceramide 2 and octadecanoic acid. Infrared studies.

The three main lipid components of the stratum corneum, namely ceramides, free fatty acids and cholesterol, play a fundamental role in the maintenance of the skin barrier. The current investigation is aimed toward understanding the miscibility and intermolecular interactions of these lipids. Toward this end, Fourier transform infrared spectroscopic studies of the three possible equimolar binary mixtures of cholesterol, a synthetic non-hydroxylated fatty acid N-acyl sphingosine with a C18 chain length (N-stearoylsphingosine, approximating human ceramide 2), and stearic acid were undertaken. The thermotropic responses of the methylene stretching and scissoring vibrations were used to evaluate chain conformation and packing respectively. Selective perdeuteration, of either the stearic acid or the ceramide acid chains, permitted separate and simultaneous evaluation of the conformational order and packing properties of the sphingosine chain, the amide linked fatty acid chains and/or the stearic acid chain. Whereas cholesterol mixed well with ceramide at physiological temperatures, the stearic acid was miscible with the cholesterol only at relatively high temperatures where the fatty acid is disordered. A complex interaction between stearic acid and ceramide was detected. A separate fatty acid-rich phase persisted until at least 50 degrees C, whereas at higher temperatures the components appear to be quite miscible. However, a preferential association of the fatty acid with the ceramide base chain is indicated. None of the binary systems studied exhibit miscibility and interactions resembling those in the ternary mixtures of these substances, which is widely used to model stratum corneum. The role of cholesterol in controlling the miscibility characteristics in the ternary system is evident.

Cholesterol↗
PubMed2005

Final amended report on the safety assessment of Octyldodecyl Stearoyl Stearate.

Octyldodecyl Stearoyl Stearate is an ester that functions as a skin-conditioning agent and viscosity-increasing agent. It is reported to be used in 105 cosmetic products at concentrations from 2% to 15%. In an isolated human skin permeation and penetration study, 0.005% of the applied dose permeated the skin, around 3% was found in the epidermis, around 1.5% was in tape stripped skin layers, and around 95% stayed in the material applied to the skin. A formulation having 20.6% Octyldodecyl Stearoyl Stearate was classified as minimally to mildly irritating in an in vitro ocular irritation assay. Several tests of products containing from 7.5% to 12.7% Octyldodecyl Stearoyl Stearate using rabbits produced minimal to mild ocular irritation. One test of 100% Octyldodecyl Stearoyl Stearate (a trade compound) and another of 10% Octyldodecyl Stearoyl Stearate in corn oil using rabbits produced no ocular irritation. Tests using rabbits demonstrated that Octyldodecyl Stearoyl Stearate at use concentrations was non- to mildly irritating to skin; only one study reported moderate irritation. Octyldodecyl Stearoyl Stearate was not mutagenic, with or without S-9 activation, in an Ames test and did not produce a significant increase in micronucleated cells in a mouse in vivo study. In clinical single-insult patch tests at use concentrations, Octyldodecyl Stearoyl Stearate was nonirritating to mildly irritating; in a cumulative irritation study, it caused mild irritation. Octyldodecyl Stearoyl Stearate was nonsensitizing in clinical tests. Because few toxicity data were available on Octyldodecyl Stearoyl Stearate, summaries of data from existing safety assessments of related ingredients (Octyl Dodecanol, Stearic Acid, and Octyl Stearate) were included. Undiluted Octyl Dodecanol was nontoxic during acute oral and dermal studies using rats and guinea pigs. Stearic Acid was nontoxic to rats during acute oral studies, but caused toxicity during subchronic studies. Rabbits treated topically with the acid were not affected adversely, and mild erythema and slight induration were observed when Stearic Acid was administered intradermally to guinea pigs and rabbits. Octyl Stearate had very low acute oral toxicity in rats and mice. Octyl Dodecanol produced only transient mild ocular irritation in rabbits when administered at concentrations up to 100%. Octyl Dodecanol (30% and 100%) was nonirritating to skin in one study using rabbits. In another study using multiple species, 100% Octyl Dodecanol (described as technical grade) caused severe skin irritation in rabbits, moderate irritation in guinea pigs and rats, and no irritation in swine. Stearic Acid was non- to moderately irritating in animal studies, and did not cause photosensitization. In studies using rabbits, undiluted Octyl Stearate caused slight, transient ocular irritation, and minimal skin irritation. Stearic Acid did not induce mitotic crossovers and aneuploidy in Saccharomyces cerevisiae, and was nonmutagenic in the Ames test. In a feeding study using mice, Stearic Acid was noncarcinogenic at doses up to 50 g/kg/day. Mice given subcutaneous injections of the acid had low incidences of carcinomas, sarcomas, and lymphomas. In clinical studies, concentrations of up to 100% Octyl Dodecanol were non- to mildly irritating, nonsensitizing, nonphototoxic, and nonphotosensitizing. Stearic Acid was nonirritating at concentrations up to 100%, and at concentrations up to 13% it was nonsensitizing and nonphotosensitizing. Octyl Stearate (7.6%) in formulation was nonirritating, nonsensitizing, and nonphotosensitizing. Based on skin permeation and penetration data, the Panel does not expect any significant amount of Octyldodecyl Stearoyl Stearate to be systemically available. There is no evidence of systemic toxicity associated with any of the related chemicals reviewed in previous safety assessments. None of the available toxicology or clinical data suggest a concern about adverse skin reactions to Octyldodecyl Stearoyl Stearate, or to any of the related chemicals. There is no evidence of ocular toxicity, except for a mild, transient ocular irritation associated with Octyldodecyl Stearoyl Stearate and the related chemicals. Overall, Octyldodecyl Stearoyl Stearate was considered safe as used in cosmetics.

Animals↗
PubMed1999

[Retention behavior of solutes on liquid chromatographic column packed with dynamically modified zirconia].

Zirconia was dynamically modified with stearic acid, beta-cyclodextrin and sodium dodecylsulfonate, separately, to form liquid chromatographic packings. The chromatographic behaviors of aromatic hydrocarbons, acidic compounds (phenol, nitrophenols and benzoic acids) and basic compounds (aniline, nitroanilines and toluidines) were investigated on these modified zirconia packings with a mixture of methanol/water as the mobile phase. On stearic acid modified zirconia, aromatic hydrocarbons and the basic compounds exhibit symmetrical peaks. The retention time of these solutes decreases with increasing the concentration of methanol in the mobile phase. When the mobile phases with stearic acid were used, the retention time of these solutes has a maximum with variation of stearic acid concentration (0-1.0 mmol/L) in the mobile phase. However, the acidic compounds such as nitrophenols and benzoic acids are strongly adsorbed and can not be eluted from the column with the mobile phases. No leaking of stearic acid on the modified zirconia was found after 3000 column volumes of the methanol/water mobile phase were used. The results showed that the stearic acid modified zirconia can be used as a stationary phase for reversed-phase liquid chromatography. On beta-cyclodextrin modified zirconia, aromatic hydrocarbons and basic compounds exhibit shorter retention time than those on the stearic acid modified zirconia under the same mobile phase composition, however, nitrophenols can be eluted but give unsymmetrical peaks. On sodium dodecylsulfonate modified zirconia packings, the basic compounds can not be retarded; Aromatic hydrocarbons and acidic compounds exhibit short retention time. The results can be ascribed to the weak adsorption of sodium dodecylsulfonate on the zirconia.

Adsorption↗
PubMed1976

Unsaturated fatty acid biosynthesis in Tetrahymena. Evidence for two pathways.

The ciliate Tetrahymena pyriformis synthesizes a wide variety of saturated and unsaturated fatty acids. Variations in growth temperature or the addition of sterols such as cholesterol or ergosterol alter the proportions of a number of unsaturated fatty acids. The pattern of substitution is complex when examined on the basis of individual fatty acids. A straightforward explanation is possible, however, if biosynthetic groupings are considered. Stearic acid gives rise to oleic, linoleic, and gamma-linolenic acids as shown by others. The environmental parameters influence the amounts of the unsaturated derivatives of stearic acid as a group and result in an increase or decrease in all members of this biosynthetic family in a fashion that depends on a particular set of conditions. The replacement of the stearate derivatives by unsaturated components that are derived from palmitic acid has been demonstrated. The addition of radiolabeled palmitic, palmitoleic, or stearic acids to the cells when coupled with radioisotope distribution measurements, isolation, and characterization of the acids, and the refeeding of key intermediates substantiates a second biosynthetic scheme for the synthesis of unsaturated acids in this ciliate. This novel pathway yields an unusual fatty acid, 18:2 delta6,11, as a major terminal product. Plamitic acid is the precursor for the members of both sequences. Palmitoleic acid can be desaturated further to produce two hexadecadienoates and a hexadecatrienoate. Further, palmitoleic acid (16:1 delta9) is elongated to cis-vaccenic acid (18:1 delta11) which is then desaturated to 18:2 delta6,11. Linoleic and gamma-linolenic acids were essentially unlabeled when [14C]palmitoleic acid was provided. Refeeding radiolabeled 18:2 delta6,11 to the cells revealed the extensive incorporation of this acid into the polar lipids and the absence of additional metabolites. [14C]Stearic acid addition to the cells results in extensive labeling of linoleic and gamma-linolenic acids, but not of 18:2 delta6,11. These observations confirm the existence of alternative and separate pathways for the synthesis of unsaturated fatty acids.

Animals↗
PubMed1994

The influence of dietary fatty acid composition on N-ethyl-N-nitrosourea-induced mammary tumour incidence in the rat and on the composition of inositol- and ethanolamine-phospholipids of normal and tumour mammary tissue.

This study has investigated the influence of dietary fatty acid composition on mammary tumour incidence in N-ethyl-N-nitrosourea (ENU)-treated rats and has compared the susceptibility to dietary fatty acid modification of the membrane phospholipids phosphatidylinositol (PI) and phosphatidylethanolamine (PE) from normal and tumour tissue of rat mammary gland. The incidence of mammary tumours was significantly lower in fish oil--(29%), compared with olive oil--(75%; P < 0.04) but not maize oil--(63%; P < 0.1) fed animals. No differences in PI fatty acid composition were found in normal or tumour tissue between rats fed on maize oil, olive oil or fish oil in diets from weaning. When normal and tumour tissue PI fatty acids were compared, significantly higher amounts of stearic acid (18:0) were found in tumour than normal tissue in rats given olive oil (P < 0.05). A similar trend was found in animals fed on maize oil, although differences between normal and tumour tissue did not reach a level of statistical significance (P < 0.1). In mammary PE, maize oil-fed control animals had significantly higher levels of linoleic acid (18:2n-6) than either olive oil- or fish oil-fed animals (P < 0.05, both cases) and levels of arachidonic acid were also higher in maize oil- compared with fish oil-fed animals (P < 0.05). In tumour-bearing animals no differences in PE fatty acid composition were found between the three dietary groups. When normal and tumour tissue PE fatty acids were compared, significantly lower amounts of linoleic acid (18:2n-6; P < 0.01) and significantly greater amounts of arachidonic acid (20:4n-6; P < 0.05) were found in tumour than normal tissue of rats fed on maize oil. The present study shows that the fatty acid composition of PI from both normal and tumour tissue of the mammary gland is resistant to dietary fatty acid modification. The PE fraction is more susceptible to dietary modification and in this fraction there is evidence of increased conversion of linoleic acid to arachidonic acid in tumour compared with normal tissue. Lower tumour incidence rates in rats given fish oils may in part be due to alteration in prostanoid metabolism secondary to displacement of arachidonic acid by eicosapentaenoic acid, but PE rather than PI would appear to be the most likely locus for diet-induced alteration in prostanoid synthesis in this tissue. Effects of dietary fatty acids other than on the balance of n-6 and n-3 fatty acids, and on prostanoid metabolism, should also be considered. The significance of increased stearic acid content of PI in tumours of olive oil-fed animals and the possible influence of dietary fatty acids on the capacity for stearic acid accumulation requires further study.

Animals↗
PubMed1977

Raman spectra of some saturated, unsaturated and deuterated C18 fatty acids in the HCH-deformation and CH-stretching regions.

We have analyzed the Raman spectra of stearic acid and two deuterated derivatives thereof, 2,2-dideutero stearic acid and 18,18,18-trideutero stearic acid, as well as of four unsaturated, C18 acids, (cis,-9; cis, cis-9,12, cis, cis, cis-9,12,15; and trans, trans-9,12) in their solid and liquid states. The different spectra of stearic acid and the two deuterated derivatives exhibit distinctive HCH-deformation and CH-stretching features for CH2 residues adjacent to CO2H or CH3 residues. Unsaturated hydrocarbon chains reveal additional features attributed to CH2 residues adjacent to one or two HC=CH groups. The spectra of the various fatty acids in their solic or liquid states show that both the HCH-deformation and CH-stretching regions are very sensitive to chain architecture, the CH-stretching region most dramatically so. Evaluation of the spectral features in the two regions indicates that the detailed structure of the CH-stretching region depends strongly upon interaction, enhanced by Fermiresonance, between CH-stretching fundamentals and HCH-deformation overtones. The data further suggest that the differences between HCH-deformation, in the solid and liquid states, and the resulting altered interactions between CH-stretching fundamentals and HCH-deformation overtones, produce the large modifications of the CH-stretching region that accompany solid-liquid transitions. The results thus provide a basis for the changes in the CH-stretching region, that accompany order-disorder transitions in model and biological membranes.

Deuterium↗
PubMed1991

Lipid fluidity and composition of the erythrocyte membrane from healthy dogs and Labrador retrievers with hereditary muscular dystrophy.

Erythrocyte membranes and their liposomes were prepared from clinically normal dogs and Labrador retrievers with hereditary muscular dystrophy. The "static" and "dynamic" components of fluidity of each membrane were then assessed by steady-state fluorescence polarization techniques using limiting hindered fluorescence anisotropy and order parameter values of 1,6-diphenyl-1,3,5-hexatriene (DPH) and fluorescence anisotropy values of DL-2-(9-anthroyl)-stearic acid and DL-12-(9-anthroyl)-stearic acid, respectively. Membrane lipids were extracted and analyzed by thin-layer chromatography and gas chromatography. The results of these studies demonstrated that the lipid fluidity of erythrocyte membranes, and their liposomes, prepared from dystrophic dogs were found to possess significantly lower "static and dynamic components of fluidity" than control counterparts. Analysis of the composition of membranes from dystrophic dogs revealed a higher ratio of saturated fatty acyl chain/unsaturated chains (w/w) and lower double-bond index. Alterations in the fatty acid composition such as decrease in levels of linoleic (18:2) and arachidonic (20:4) acids and increase in palmitic (16:0) and stearic (18:0) acids were also observed in the membranes of dystrophic animals. These associated fatty acyl alterations could explain, at least in part, the differences in membrane fluidity between dystrophic and control dogs.

Animals↗
PubMed1987

Modulation of Na+-Ca2+ exchange and Ca2+ permeability in cardiac sarcolemmal vesicles by doxylstearic acids.

We examine the effects of 5-, 12- and 16-doxylstearic acids on the Na+-Ca2+ exchange and passive Ca2+ permeability of cardiac sarcolemmal vesicles. Stearic acid is a weak stimulator of Na+-Ca2+ exchange. A doxyl moiety potentiates stimulation with the order of increasing potency being 5-, 12- and then 16-doxylstearic acid. Stearic acid has little effect on vesicle Ca2+ permeability but again the doxylstearates are more effective. The sequence of potency is reversed, however, from that for increasing Na+-Ca2+ exchange. 5-Doxylstearic acid most markedly exchanges passive Ca2+ flux followed by the 12-, and then 16-doxylstearic acids. Methyl esters of the doxylstearates have no effect on either Na+-Ca2+ exchange or Ca2+ permeability. We model the results as follows. For a fatty acid to stimulate Na+-Ca2+ exchange activity, an anionic charge is required to interact with the exchanger protein at the membrane surface. Stimulation is potentiated by a perturbation (such as provided by a doxyl group) within the lipid bilayer. The perturbation is most effective at a location towards the center of the bilayer. To increase passive Ca2+ permeability an anionic charge is again essential. Disorder within the bilayer is also important, but now the most important site is near the membrane surface. Results of experiments with linolenic and gamma-linolenic acid and previous studies with other fatty acids also support this model.

Animals↗
PubMed1977

Fatty acid biosynthesis by a particulate preparation from germinating pea.

1. Fatty acid synthesis was studied in microsomal preparations from germinating pea (Pisum sativum). 2. The preparations synthesized a mixture of saturated fatty acids up to a chain length of C(24) from [(14)C]malonyl-CoA. 3. Whereas hexadecanoic acid was made de novo, octadecanoic acid and icosanoic acid were synthesized by elongation. 4. The products formed during [(14)C]malonyl-CoA incubation were analysed, and unesterified fatty acids and polar lipids were found to be major products. [(14)C]Palmitic acid represented a high percentage of the acyl-carrier protein esters, whereas (14)C-labelled very-long-chain fatty acids were mainly present as unesterified fatty acids. CoA esters were minor products. 5. The addition of exogenous lipids to the incubation system usually resulted in stimulation of [(14)C]malonyl-CoA incorporation into fatty acids. The greatest stimulation was obtained with dipalmitoyl phosphatidylcholine. Both exogenous palmitic acid and dipalmitoyl phosphatidylcholine increased the amount of [(14)C]-stearic acid synthesized, relative to [(14)C]palmitic acid. Addition of stearic acid increased the amount of [(14)C]icosanoic acid formed. 6. [(14)C]Stearic acid was elongated more effectively to icosanoic acid than [(14)C]stearoyl-CoA, and its conversion was not decreased by addition of unlabelled stearoyl-CoA. 7. Incorporation of [(14)C]malonyl-CoA into fatty acids was markedly decreased by iodoacetamide and 5,5'-dithiobis-(2-nitrobenzoic acid). Palmitate elongation was sensitive to arsenite addition, and stearate elongation to the presence of Triton X-100 or fluoride. The action of fluoride was not, apparently, due to chelation. 8. The microsomal preparations differed from soluble fractions from germinating pea in (a) synthesizing very-long-chain fatty acids, (b) not utilizing exogenous palmitate-acyl-carrier protein as a substrate for palmitate elongation and (c) having fatty acid synthesis stimulated by the addition of certain complex lipids.

Chelating Agents↗
PubMed2000

Construction and analytical application of a biosensor based on stearic acid-graphite powder modified with sweet potato tissue in organic solvents.

A biosensor based on stearic acid-graphite powder modified with sweet potato (Ipomoea batatas (L.) Lam.) tissue as peroxidase source was constructed and applied in organic solvents. Several parameters were studied to evaluate the performance of this biosensor such as stearic acid-graphite powder and tissue composition, type and concentration of supporting electrolyte, organic solvents, water/organic solvent ratio (% v/v) and hydrogen peroxide concentration. After selection of the best conditions, the biosensor was applied for the determination of hydroquinone in cosmetic creams in methanol. At the peroxidase electrode hydroquinone is oxidized in the presence of hydrogen peroxide and the radical formed was reduced back electrochemically at -180 mV vs Ag/AgCl (3.0 mol L(-1) KCl). The reduction current obtained was proportional to the concentration of hydroquinone from 6.2 x 10(-5) to 1.5 x 10(-3) mol L(-1) (r = 0.9990) with a detection limit of 8.5 x 10(-6) mol L(-1). The recovery of hydroquinone from two samples ranged from 98.8 to 104.1% and an RSD lower than 1.0% for a solution containing 7.3 x 10(-4) mol L(-1) hydroquinone and 1.0 x 10(-3) mol L(-1) hydrogen peroxide in 0.10 mol L(-1) tetrabutylammonium bromide methanol-phosphate buffer solution (95:5% v/v) (n = 10) was obtained.

Antioxidants↗
PubMed2004

Protective role of Phaseolus vulgaris on changes in the fatty acid composition in experimental diabetes.

The present investigation was carried out to evaluate the effect of Phaseolus vulgaris, an indigenous plant used in Unani and Ayurvedic medicine in India, on blood glucose, plasma insulin, cholesterol, triglycerides, free fatty acids, phospholipids, and fatty acid composition of total lipids in liver, kidney, and brain of normal and streptozotocin (STZ) diabetic rats. The results show that there was a significant increase in tissue cholesterol, triglycerides, free fatty acids, and phospholipids in STZ diabetic rats. The analysis of fatty acids showed that there was a significant increase in the concentrations of palmitic acid (16:1), stearic acid (18:0), and oleic acid (18:1) in liver, kidney, and brain, whereas the concentrations of linolenic acid (18:3) and arachidonic acid (20:4) were significantly decreased. Oral administration of the aqueous extract of P. vulgaris pods (200 mg/kg of body weight) for 45 days to diabetic rats decreased the concentrations of lipids and fatty acids, viz., palmitic, stearic, and oleic acids, whereas linolenic and arachidonic acids were elevated. Similarly, the administration of P. vulgaris pod extract (PPEt) to normal animals resulted in a significant hypolipidemic effect. These results suggest that PPEt exhibits hypoglycemic and hypolipidemic effects in STZ diabetic rats. It also prevents the fatty acid changes produced during diabetes. The effect of PPEt at 200 mg/kg of body weight was better than that of glibenclamide.

Animals↗