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At least 847 records · Page 47Linked to original sources
PubMed1975

Analogs of natural lipids. I. Synthesis and properties of tris-homoacyl derivatives of cyclopentane- 1,2,3-triols.

A new series of analogs of triglycerides has been synthesized, in which the glycerol moiety is replaced by each of the three isomeric cyclopentanetriols. For each of the isomeric cyclopentane-1,2,3-triols (1,2,3/0; DL-1,2/3; and 1,3/2), the tris-homoacyl derivatives of octanoic, decanoic, lauric, myristic, palmitic, stearic, and dihydrosterculic acids were prepared by treatment of the respective triols with the appropriate acyl chloride in pyridine. The dihydrosterculates were prepared by fusing the triols with a mixture of the acyl anhydride and the corresponding potassium salt. It is proposed that because of restricted rotation of the carbon-carbon bonds the cyclopentanoid compounds are analogs of specific rotamers of triglycerides. Infrared spectra (KBr discs) obtained at room temperature show differences in crystal structure from series to series. A band near 720 cm-minus 1 (CH2 rock) is doubled in the 1,2,3/0 and 1,2/3 series and is single in the 1,3/2 series and the triglycerides. In each spectrum with a doublet at 720 cm-minus 1, a band near 1470 cm-minus 1 (CH2 bend) is doubled also. A strong band at 890 cm-minus 1 present in the triglyceride spectra is weak or missing from the spectra of the analogs. A band at 1418 cm-minus 1 (bending of CH2 adjacent to C equal to 0) present in the triglyceride spectra is demonstrable only in the 1,2,3/0 derivatives in comparison with the other three series. In all series the dihydrosterculates show a decrease in apparent polarity, relative to the stearates, significantly greater than expected from the introduction of an additional carbon atom. The potential utility of the analogs as probes of the effects of conformation on the physical properties and enzymatic susceptibility of glycerides is discussed.

Alcohols↗
PubMedDate not supplied

The components of ethereal and methanolic extracts from the fruits of Celastrus tatarinovii (Rupr.).

The ethereal extract contains the glycerides of saturated: hexadecanoic, octadecanoic, tetradecanoic, dodecanoic and eicosanoic, and of unsaturated: octadecaenoic, octadecadienoic, octadecatrienoic acids. From the neutral fraction n-nonacosane was isolated beside to beta- and gamma-sitosteroles, a triterpene compound, crystalline mixture of unidentified compounds and amorphous substance with haemolytic properties. From methanolic extract five heterosides derivatives of kaempferol and quercetin were obtained.

Fatty Acids↗
PubMedDate not supplied

Oral immunisation of chickens using cholera toxin B subunit and Softigen as adjuvants results in high antibody titre in the egg yolk.

Oral immunisation by gavage of laying hens with human immunoglobulin G (IgG) combined with a number of potential adjuvants was performed. The resulting immunospecific egg yolk (IgY) antibodies were quantified by ELISA. The following adjuvants were tested: A Poly(lactide-co-glycolide) (PLG) microspheres, Cholera toxin B-subunit (CTB), CTB conjugated with glutaraldehyde, Dimethyl dioctadecyl ammonium bromide (DDA), and Softigen (pegylated C8/C10 mono/di glyceride). Hens in a positive control group were immunised with human IgG in saline emulsified with an equal volume of Freund's Incomplete Adjuvant. High titres of immunospecific IgY antibodies against human IgG were recorded in the eggs from the chickens immunised orally with the antigen combined with glutaraldehyde conjugated CTB and in the chickens immunised with the antigen combined with Softigen. The present results show that invasive technique related stress could be eliminated/reduced in polyclonal antibody producing animals.

Adjuvants, Immunologic↗
PubMed2006

[Application of gas chromatography in research of biodiesel processing].

Applications of gas chromatography in the research of biodiesel processing are reviewed with 27 references, including the analysis of fatty acid methyl esters (FAME) in the reaction products and final biodiesel, the determination of mono-, di- and tri-glycerides, the contents and distribution of free fatty acids, and the determination of trace methanol in biodiesel. The effects of various factors for analysis of the reaction products are discussed, such as injection mode, column type and silylation. A method for the determination of trace methanol in biodiesel products with dual-columns and pressure backflush system is proposed. 1-Propanol was used as the internal standard. After methanol and 1-propanol entered the analytical column through pre-column, the pressure was changed to backflush the heavy components through the split vent. A polar PEG-20M column was applied for the analysis of the contents and distribution of FAME in biodiesels from 8 different vegetable oils.

Biofuels↗
PubMedDate not supplied

[Effect of pyridoxine on patterns of lipid metabolism in patients with alimentary obesity].

Studies of patients with alimentary-metabolic obesity, which were treated with pyridoxine and were maintained on a reduced diet, revealed a normalizing effect of the vitamin on some patterns of lipid metabolism. In patients, treated with pyridoxine, body weight, content of total lipids, cholesterol, phospholipids, glycerids and beta-lipoproteins in blood serum were decreased more distinctly as compared with patients, which were only maintained on a reduced diet. In hyperlipidaemia the positive effect of pyridoxine was more pronounced than in the cases with normal content of lipids in blood.

Body Weight↗
PubMed1976

Alterations in lipid constituents during growth of Mycobacterium smegmatis CDC 46 and Mycobacterium phlei ATCC 354.

Phospholipids of Mycobacterium phlei ATCC 354 and Mycobacterium smegmatis CDC 46 consist of cardiolipin, phosphatidyl ethanolamine, tri-acylated dimannophosphoinositide, tetra-acylated dimannophosphoinositide and tetra-acylated pentamannosphosphoinositide. A comparative study of lipid patterns of M. phlei ATCC 354 and of M. smegmatis CDC 46 in relation to age of culture revealed higher total lipid level and increased activity of malate-vitamin K reductase, a phospholipid requiring enzyme, during the early logarithmic growth phase of the former. No appreciable change occurred in the latter. The high total lipid content coincides with an increase in phospholipid, brought about apparently by the increase in malate-vitamin K reductase. Changes in cardiolipin and phosphatidyl ethanolamine appeared to be unique to M. phlei ATCC 354. However, in both bacterial species, a decrease in glyceride and a progressive increase in tuberculostearic acid with a concomitant decrease in oleic acid, occurred with ageing.

Cardiolipins↗
PubMed1985

[Comparative biochemical effects of the injection of cyclic and linear forms of vertebrate somatostatin on the honeybee in vivo. II. Blood lipids].

The linear and cyclic forms of vertebrate somatostatin were injected to worker honeybees at the rate of 50 ng per individual, and their effects on the lipemia were compared between themselves and with those of saline injection over a 3 hrs period. Both hormonal forms elicit a global decrease of the levels of phospholipids, steroids, fatty acids, diacyl and triacyl glycerol, by contrast with hyperlipemic effects induced by the injection of saline alone. The kinetics of variations show a remarkable phase concordance between the respective effects of both hormonal forms, with strong positive correlations in the case of phospholipids, fatty acids and glycerides. The linear and cyclic forms of somatostatin thus show similar effects counteracting the results of the release of endogenous hormones following the stress associated to the microsyringe stinging.

Animals↗
PubMed1987

Differences in lipid characteristics of autologous human melanoma cell lines with distinct biological properties.

Significant differences in lipid composition were found when six established human melanoma cell lines were compared. A pair of cell lines was initiated from a superficial spreading melanoma and the lymph node of the same patient; four others were also autologous, three of which originated from the same nodular melanoma and the other from its metastasis. Cell lines varied in pigmentation level and ability to grow in nude mice. Cell lines contained similar amounts of total cholesterol, glycerides, and phospholipids but different amounts of free cholesterol and cholesterol esters. In particular, the molar ratio of free cholesterol to phospholipid was increased in highly tumorigenic cell lines. No changes in phospholipid profiles were noted among cell lines, except an increase in sphingomyelin with a concomitant decrease in phosphatidylcholine in one cell line compared to the profiles of its counterpart cell line. The saturated-to-unsaturated fatty acid ratios in phosphatidylcholine and phosphatidylethanolamine were similar in all cell lines, but the monounsaturated-to-polyunsaturated fatty acid ratio in phosphatidylcholine was increased in highly tumorigenic cell lines. A significant variation in the latter ratio in phosphatidylethanolamine was also observed in the pair of autologous cell lines. These changes were unrelated to a depletion in linoleic acid in culture medium. Results obtained by fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene were consistent with the differences in lipid composition between two autologous cell lines. The present results indicate that two lipid characteristics were significantly changed in highly tumorigenic cell lines as compared to cell lines with low tumorigenicity, but no correlation was found between either pigmentation level or origin (primary or metastatic) and lipid composition.

Cell Line↗
PubMed1986

[Dynamics of changes in the lipid composition of bile in patients with alimentary obesity during treatment].

In the bile of patients with alimentary obesity, the content of primary (cholic) bile acids is reduced, that of secondary (deoxycholic) acids is increased, and the quota of glycine-bound cholates is lowered. This points to the distress of the cholate-synthesizing, glyco-conjugating, and hydroxylating function of liver cells. In addition, the bile of obese persons is characterized by a low content of free fatty acids associated with an increase in the amount of total lipids, glycerides, and phospholipids. The treatment of obesity by the subcaloric diet and graded physical exercise brings about positive changes in the content of cholic and deoxycholic acids in the bile and gives rise to the enhanced excretion of all lipid fractions, cholesterol in particular, with the bile to the intestine, thereby raising the bile lithogenic potential.

Bile↗
PubMed1986

A case of adiposis dolorosa: lipid metabolism and hormone secretion.

The present report describes a 53-year-old non-obese man with adiposis dolorosa whose pain was dramatically relieved by the intravenous injection of lidocaine. The patient showed a paradoxical response of growth hormone to thyrotropin-releasing hormone. In addition, in-vitro studies on adipose tissue metabolism revealed the reduced glucose conversion to neutral glycerides in painful adipose tissue. These abnormalities may be related in some ways to the pathogenesis of this disorder.

Adipose Tissue↗
PubMed1971

Estradiol- and testosterone-induced alterations in phosphatidylcholine and triglyceride synthesis in hepatic endoplasmic reticulum.

Pathways of phosphatidylcholine and triglyceride biosynthesis were studied in hepatic endoplasmic reticulum from castrated and noncastrated male rats pretreated with estradiol or testosterone. In vitro measurements of hepatic microsomal enzymes which catalyze phosphatidylcholine biosynthesis revealed a significant increase in the specific activity of the enzyme governing phosphatidylcholine biosynthesis by the sequential methylation of phosphatidylethanolamine in the estradiol-treated castrate animals. The specific activity of phosphorylcholine-glyceride transferase was decreased by estradiol treatment in both castrate and noncastrate animals. The specific activity of diglyceride acyltransferase, which catalyzes triglyceride biosynthesis, was decreased by estradiol pretreatment in both castrate and noncastrate animals and was increased by testosterone in the castrate animals. The changes in specific activity of the enzymes governing phosphatidylcholine biosynthesis may account for the previously noted increased in vivo incorporation of methyl groups of l-methionine into hepatic phosphatidylcholine in female and estradiol-treated animals; the data suggest that in female and estradiol-treated rats a greater proportion of hepatic phosphatidylcholine is synthesized by the stepwise methylation of phosphatidylethanolamine. The decrease in diglyceride acyltransferase specific activity seen after estradiol administration may account for the lipotropic-like effect of estradiol.

Acyltransferases↗
PubMed1966

Synthesis and characterization of 1- and 2-monoglycerides of anteiso fatty acids.

The branched-chain fatty acids D-(+)-12-methyltetradecanoic acid (C(15) anteiso) and D-(+)-14-methylhexadecanoic acid (C(17) anteiso) were isolated from the lipids of Listeria monocytogenes and their 1- and 2-monoglycerides were prepared. Reaction intermediates and products were purified without isomerization by column chromatography. Thin-layer chromatography on Florisil impregnated with boric acid and nuclear magnetic resonance were used in characterizing the 1- and 2-monoglycerides. The value of the latter method for analyzing glyceride structure is discussed.

Chemical Phenomena↗
PubMed1969

Evidence for separate monoglyceride hydrolase and triglyceride lipase in post-heparin human plasma.

Post-heparin plasma contains an enzyme or enzymes with both triglyceride lipase (TGL) and monoglyceride hydrolase (MGH) activities. A simple and reproducible radioactive assay for measurement of MGH activity was developed and used, with a previously reported assay for TGL, to study lipolysis in plasma. After the injection of heparin, enzymatic activity against both tri- and monoglycerides appeared and disappeared from plasma at approximately the same rates. However, in contrast to TGL activity, MGH activity was: (a) much greater, (b) considerably less heat-sensitive, (c) unaffected by three inhibitors (NaCl, protamine, and pyrophosphate), (d) not influenced by radical changes in fat and carbohydrate content of the diet, and (e) normal in familial Type I hyperlipoproteinemia. The dichotomy between MGH and TGL activities in patients with genetic deficiency of TGL constitutes strong evidence that these are two different enzymes. The findings further indicate that when post-heparin lipolytic activity is measured for the purpose of detecting TGL deficiency, it may be necessary to perform the assay with a substrate free from partial glycerides.

Diet↗
PubMed1979

Enzyme-substrate interaction in lipid monolayers. II. Binding and activity of lipase in relation to enzyme and substrate concentration and to other factors.

With the limited stirring procedure used in the present work, substrate and enzyme together form a segregated and well-defined system on the surface. The lipase molecules responsible for the lipolysis are only those that are adsorbed on the glyceride monolayer. After a study of the stirring procedure, two series of systematic experiments were done: a) the bulk concentration of the enzyme was varied with different constant surface concentrations of the substrate, and b) the surface concentration of the substrate was varied with different constant bulk concentrations of the enzyme. The influence of the surface concentration of substrate on a) the rate of lipolysis, V,; b) the enzyme activity, a,; and c) the enzyme adsorption, Ze, were each determined by a different procedure. The values obtained verify the enzymic activity equation (a = V/Ze). The roles of other factors (Ca2+ ions, and pH) which govern the adsorption of the enzyme and its specific activity were also studied in preliminary experiments.

Adsorption↗
PubMed1979

Interfacial structure and lipase action. Characterization of taurodeoxycholate-didecanoylglycerol monolayers by physical and kinetic methods.

Surface pressure-area isotherms for 1,3-didecanoyl-glycerol (dicaprin) were determined as a function of the concentration of taurodeoxycholate in the subphase. Analysis of these curves indicates that, from 0.05 to 0.80 mM bile salt, surface structure is dependent only on the surface concentration of the diglyceride. The limiting areas for dicaprin in the presence and absence of bile salt were about 38 A2/molecule. Subjecting the monolayers to hydrolysis by pancreatic lipase yielded kinetic data which, together with the physical studies, support a model for monolayer glyceride molecules undergoing discrete changes of state. In the absence of bile salt, the relatively expanded state exhibits an area of 75 A2/diglyceride molecule and is not a substrate for pancreatic lipase B. The more condensed state exhibits an area of 38 A2/diglyceride molecule and is hydrolyzed at a rate proportional to its concentration in the monolayer. Taurodeoxybholate at 0.05 to 0.60 mM shifts the apparent area of the expanded state to 360 A2/diglyceride molecule.

Animals↗
PubMed1972

Inhibition of lipid synthesis by clofibrate: comparative study of human skin, rat skin, and rat liver in vitro.

The effects of clofibrate (ethyl p-chlorophenoxyisobutyrate) on lipid synthesis by human skin were studied in vitro. The drug was found to inhibit lipid synthesis from [1-(14)C]acetate or [U-(14)C]glucose. While the synthesis of all classes of lipids was suppressed, inhibition of sterol synthesis was more pronounced than that of fatty acids and glycerides. By comparison, sodium p-chlorophenoxyisobutyrate was less effective as an inhibitor. The addition of glucose to the incubation medium enhanced lipid synthesis from both [1-(14)C]acetate and [U-(14)C]glucose. The inhibitory effect of clofibrate could be partially reversed by increasing the glucose concentration in the incubation medium. Rat skin and rat liver were studied similarly, using [1-(14)C]-acetate as a tracer for lipid synthesis, and the inhibitory effect of clofibrate was also demonstrated. Of the three tissues studied, human skin was the most sensitive to the drug and yielded more reproducible results.

Acetates↗
PubMed1970

Liquid-gel chromatography on lipophilic-hydrophobic Sephadex derivatives.

Hydrophobic long-chain alkyl ethers of Sephadex have been synthesized and tested for use in liquid chromatography. With columns prepared in such polar solvents as methanol, reversed-phase systems are obtained where compounds separate in order of decreasing polarity. In such non-polar solvents as heptane, straight-phase systems are formed, and separations occur in order of increasing polarity. The retention volume of a compound is determined mainly by its polarity, the type and degree of substitution of Sephadex, and the nature of the solvent system. Examples are given of straight-and reversed-phase separations of waxes, fatty acids, glycerides, glycerol ethers, sterols, bile acids, and hormonal steroids. The Sephadex derivatives are simple to make, the columns are easy to prepare, and they can be used over long periods of time. Liquid-gel chromatography on alkyl ethers of Sephadex is a mild separation technique and should be a useful complement to other chromatographic methods.

Bile Acids and Salts↗