Fatty Acid Radicals Research Articles

Phospholipids of the seeds ofPhaseolus vulgaris

Six homogeneous fractions have been isolated from the total phospholipids of the seeds of the kidney bean, and their ratios and fatty acid compositions and the position distributions of the fatty acid radicals in the main fractions have been determined.

Polyglycerol esters composition: Theoretical random distribution versus HPLC analysis

AbstractProduct composition of polyglycerol esters, prepared from a direct alkaline polymerization of glycerol followed by esterification with stearic or oleic acids, has been studied. The internal product composition, as analyzed by high performance liquid chromatography (HPLC), shows clearly that in contradiction to what has been published recently, the fatty acid radicals arenot distributed at random among all available hydroxyl groups, and thus, any theoretical calculation on the product composition could not be correct. The product composition of the crude material indicates clearly that the internal positions (secondary hydroxyls) of the glycerol polymer are esterified with greater difficulty than the primary hydroxyl groups.

An electron spin resonance study of .gamma.-irradiated frozen aqueous solutions containing N-acetylamino acids

The results of ..gamma.. irradiation of a number of N-acetylamino acids at 77 K in frozen D/sub 2/O and H/sub 2/O solutions are reported. The radicals produced by the irradiation, their relative amounts, and their stability were studied as a function of temperature. The results found for ices of N-acetylalanine illustrate the reaction mechanisms found. At low temperatures (120 K) the peptide anion and decarboxylated species dominate the spectrum. Upon warming to 190 K the anion converts to the amide and fatty acid radical by secondary deamination: CH/sub 3/CO/sup -/NDCH(CH/sub 3/)CO/sub 2//sup -/ + D/sup +/ ..-->.. CH/sub 3/COND/sub 2/ + .CH(CH/sub 3/)CO/sub 2//sup -/. Further warming to 220 K results in abstraction of the intermediate radicals from the parent compound to form the ..cap alpha..-carbon radical: CH/sub 3/CHCO/sub 2//sup -/ + CH/sub 3/CONDCH(CH/sub 3/)CO/sub 2//sup -/ ..-->.. CH/sub 3/CH/sub 2/CO/sub 2//sup -/ + CH/sub 3/CONDCCH/sub 3/CO/sub 2//sup -/. Results found for N-acetylglutamic acid show similar reactions and also show evidence for electron attachment to the two carboxyl groups as well as the peptide linkage. An investigation as a function of pD shows that the site of electron attachment is strongly pD dependent with the carboxyl groups being favored atmore » low pD and the peptide linkage favored at high pD. 9 figures, 1 table.« less

Molecular composition of the N-acylphosphatidylethanolamine of the cotton plant of variety S-6029

An N-arylphosphatidylethanolamine has been isolated from the total phospholipids of the cotton plant of variety S-6029. The composition and the position distribution of the fatty-acid radicals has been studied with the aid of enzymatic hydrolysis with phospholipase A1 (from the fungusRhisophus microsporus UzLT-1) and by alkaline and acid hydrolyses. From the results obtained, the possible molecular composition of the N-acylphosphatidylethanolamine has been calculated by Coleman's method. The total number of all the molecular species amounted to 720.

Structure-Dependent Feature of Electron Transport in Langmuir Multilayer Assemblies

Abstract The behavior of dc and ac conductivities is studied in the Langmuir multilayer films sandwiched between aluminium electrodes. The structure-dependence of conductivities has been systematically examined on different film structures constructed by the Molecular Assembly Technique. The constituent monolayers used were Cd salts of fatty acids CH3-(CH2)n-2-COOH with n = 16, 18, 20 and a mixture (C16)x-(C20)1–x. The structure dependent aspects are summarized in the following items, which are reasonably interpreted by the model based on the hopping or thermally assisted tunneling of electrons via localized states assumed at each monolayer interface: 1) exponential decrease of dc conductivity with increasing chain length of the fatty acid radical: 2) the same exponential variation of dc conductivity for mixed monolayers; 3) reduction of dc conductivity caused by one single C20 monolayer introduced into C16 multilayer system; 4) frequency-dispersion of conductivity in heterogeneous multilayer assemblies i...

PULSE RADIOLYSIS STUDIES IN MODEL LIPID SYSTEMS: FORMATION AND BEHAVIOR OF PEROXY RADICALS IN FATTY ACIDS

Abstract— Radiolytic formation and peroxidation of fatty acid radicals have been investigated by pulse radiolysis techniques in oleate, linoleate, linolenate and arachidonate systems. A strong absorption band at 280 nm associated with conjugated radicals, Rconj, formed in polyunsaturated fatty acid moieties has been used as a probe for kinetic processes occurring at doubly allylic sites in the hydrocarbon chain. Formation of Rconj by O‐ has been found to be more efficient than the less selective OH radical. Peroxidation of Rconj is shown to be somewhat slower, (kR+ O2˜ 3 × 108M‐1 s‐1), than O2 reactions with radicals in oleate (kR+ O2= 1 × 109M‐1 s‐1). Peroxy radicals generated in these reactions disappear slowly by essentially second order processes (2kRO1˜ 107M‐1 s‐1). The superoxide radical, O‐2, shows little if any reactivity towards 0.01 M linolenate or arachidonate over periods of 20 s.

Interesterification of edible oils

AbstractTypes of interesterification discussed are (a) interchange between a fat and free fatty acids, in which the most important reaction is the introduction of acids of low mol wt into a fat with higher fatty acids; (b) interchange between a fat and an alcohol, e.g., with glycerol, in order to produce emulsifiers like monoglycerides; (c) rearrangement of fatty acid radicals in triglycerides, the so‐called transesterification which in recent years has taken on the same importance as hydrogenation or fractionation. In natural fats, the fatty acid radicals are not usually randomly distributed but become so by rearrangement; the distinctive physical properties of natural fats and oils can be changed within limits by this transesterification. Well‐known examples are cocoa butter, palm oil, and lard. More important is the transesterification of a mixture of different fats and oils; e.g., the combination of hydrogenation and interesterification allows the production of a solid fat with high linoleic acid content. The composition of glycerides after random interesterification can be calculated by formulas.Distinct from random is such directed interesterification. This is done by working at low temperatures that glycerides with higher melting point crystallize from the reaction mixture. Directed interesterification can be combined with fractionation, for instance, to get a higher yield of liquid fraction from palm oil than is obtained by fractionation alone.The transesterification process can be performed in a batch or continuously. A small amount of metallic sodium or sodium ethylate is used as catalyst, which is destroyed by water or acid and removed after the reaction.

Application of chromatographic methods in biogeochemical investigations : Determination of the structures of sapropelites by thermal decomposition

Sapropelite was subjected to standard laboratory low-temperature carbonization and its decomposition products (oil) were analysed by combining various chromatographic techniques. The sample of neutral oil (500 mg) was separated by preparative thin-layer chromatography into groups of compounds —paraffins, olefins, etc. Subsequently, the composition of each group was determined by temperature-programmed gas-liquid chromatography. The presence of fragments of material of biological origin in the structure of the sapropelite was demonstrated, i.e. paraffins and ketones of odd carbon number and 1-olefins of even carbon number. Besides the analysis of the Esthonian oil shale “Kukersite”, as an example of the practical use of the method, a total of fifteen sapropelites were investigated, and in most cases the presence of unchanged fatty acid radicals in the structure could be indicated.

A comparison of triglycerides from aphids and their cornicle secretions

Direct mass spectrometry of extracts showed that body triglycerides from 30 species of aphids contained the same fatty acid radicals, C 6 (hexanoyl), C 6:2 (sorboyl), C 14 (myristoyl), and C 16 (palmitoyl) as did the cornicle secretions, but in many species the proportions of hexanoyl and/or palmitoyl triglycerides were greater in the body. When cornicle secretions were collected progressively so as to draw increasingly upon body fat reserves, their composition changed gradually towards that of the body extracts. All summer forms of Myzus persicae had similar body triglycerides, even when selected for resistance to organophosphorus insecticides, or bred for 3 months on an artificial diet. The composition of body triglycerides was also independent of colour in two aphid species in which pink and green forms were compared. Body extracts contain enough triglycerides for their composition to be determined in single aphids and the use of body extracts allows examination of aphids lacking cornicles and of specimens that do not give cornicle secretion because of low body turgor. Although, as in the case of cornicle secretions, the triglyceride composition of body extracts was not well correlated with taxonomic position, body extracts provide a second chemical characteristic that can be used to define a particular species.

The chemical processes accompanying the hydrogenation of fats

1. The hydrogenation of fats is accompanied by the migration of double bonds in the fatty-acid radicals, mainly by one place in the direction of the methyl or the carboxyl group. In dienic acids, the double bonds migrate mainly towards one another, with the formation of conjugated systems. 2. The migration of the double bonds takes place by two different mechanisms based on the principles of the multiplet theory of heterogeneous catalysis.

The question of the formation of isomeric fatty acids in the low-temperature hydrogenation of cottonseed oil in solvents

The hydrogenation of cottonseed oil in hexane and ethanol is accompanied by geometrical and positional isomerizations in the fatty-acid radicals.

Hydroxy Sulfonated Fatty Acid Esters as Surface Active Agents V: Surfactants Containing More Than One Hydrophilic Group

AbstractHydroxy sulfonated fatty acid esters having the general formula RCOOCH2CHOHCH2SO3M (where M is alkali or other metal and R a fatty acid radical) have been synthesized using sulfonated oleic acid, sulfated ricinoleic acid and sulfated‐sulfonated ricinoleic acid. Comparative evaluation of their properties have been described and the effect of increasing number of hydrophilic groups and their position in the surfactant molecule discussed.

The role of lipids in membrane transport in Mycoplasma laidlawii.

AbstractPulse labeling of metabolizing cells ofMycoplasma laidlawii, strain B with14C‐glucose results in rapid turnover of the glucose moiety in carotenyl glucoside and phosphatidyl glucose. Pulse labeling also occurs in the fatty acid radicals of carotenyl esters. No labeling of phosphatidyl glycerol, carotenol or monoglucosyl diglyceride occurs. No turnover of14C occurs in diglucosyl diglyceride. Rapid turnover of32P in phosphatidyl glucose, but not in phosphatidyl glycerol, also occurs. The rate of14CO2 evolution is equivalent to the rate of disappearance of14C in total lipids of cells prelabeled with14C‐glucose. β‐Glucosidase inhibition results in inhibition of glucose utilization. The reverse effect is not seen. A theory involving lipids as carriers in the transport of glucose into the cell and acetate, the end product of glucose metabolism, out of the cell is presented. This theory is compatible with known information concerning membrane structure, membrane transport and metabolism in Mycoplasmas.

Keeping properties of edible oils. III. identity of trace materials adsorbed from peanut oil by chromatography on alumina

AbstractA peanut oil of improved quality was obtained by replacing active earth bleaching in the refining process by treatment with alumina. To determine which components of the oil were removed and modified by this treatment, the material adsorbed on the alumina was examined. Off‐flavor precursors were not concentrated, but chemical modification of precursors had taken place. Alumina treatment probably owes its effectiveness in part to removal of off‐flavor precursors and pro‐oxidants, and in part to suppression of undesirable side reactions which occur in bleaching earths. Hydroperoxides originally present in the oil were almost entirely destroyed on the alumina, and the adsorbate was found to be enriched in oxidized, hydroxylated, and unsaponifiable material. The presence of glycer‐ides containing both saturated and ॅ,ॆ unsat‐urated (and possibly traces of a,ॆ, े, ै diunsat‐urated) aldehyde groups was demonstrated. The adsorbate also contained a considerable proportion of glycerides containing polar groups, e.g. hydroxyl, in the fatty acid radicals; the bulk of these appeared to be hydroxydienoic acid. Gas liquid chromatography (GLC) of the methyl esters of the fatty acids of the adsorbate was used to detect simple oxidized fatty acids such as keto, epoxy, and hydroxy acids. Adsorption on alumina may prove to be a powerful tool for the isolation of aldehydoglycerides and glycerides of hydroxy‐acids from oils and fats.

Migration of an Acyl group in glycerol derivatives: III. An investigation of Fischer's method for the preparation of αγ‐diglycerides

AbstractHeating of a monoacid diacylglycerol‐α‐iodohydrin or diacylglycerol‐β‐iodohydrin with silver nitrite or silver nitrate in a mixture of alcohol and water leads to an (equilibrium) mixture of the corresponding αβ‐and αγ‐diglycerides. Preparation of a monoacid αγ‐diglyceride in a good yield by this method, which is due to E. Fischer, is possible only if the acyl group of the diacylglycerol‐iodohydrin has a strong tendency towards migration in acid medium, thus, for instance, if it is a fatty acid radical.

Rheology of Cocoa Butter. IV. Further Studies of “Omega” Crystallinity

SUMMARYAn X‐ray diffraction study was made of several plastic fats, including lard, butterfat, oleomargarine, and hydrogenated vegetable shortenings. Their liquid contents were varied by altering the holding temperature. Separate mixtures were made of cocoa butter or tristearin with corn oil, tributyrin, or trioctanoin, and their diffraction patterns were obtained. The crystal form (omega), previously described for oxidized cocoa butter, was found in the first group of fats and in the corn oil‐tristearin mixture. Omega crystallinity was not related to the solid‐liquid ratio of the fats or to differences in molecular length in the constituent fatty acid radicals. Omega crystallinity seemed to be related to a general difficulty in crystallization, probably due to steric hindrances.

Nonconjugated linseed vinyl ether by vinyl transetherification. Preparation procedure

AbstractAn improved procedure is described for preparing nonconjugated linseed vinyl ether monomer by transetherification of linseed alcohol with ethyl vinyl ether. By use of a mercuric acetate‐oxalic acid catalyst mixture, an excess of ethyl vinyl ether, a reaction temperature of 45°C., and an evaporation, water‐extraction procedure for continuous removal of by‐product ethanol as the reaction proceeds, 91% of the linseed alcohol was converted to the fatty vinyl ether in 6 1/2 hrs. When mercuric acetate was used alone, more catalyst was required; at 90°C, and above, the over‐all rate and yield were reduced by partial deactivation of the catalyst. This reduction was attributed to a side reaction wherein the mercuric salt was added to the fatty acid radical at points of unsaturation. All the various methods that were compared for purifying the linseed monomer produced a product of polymerization quality. While vacuum distillation, followed by an alumina adsorption treatment, gave a monomer of the highest purity, a monomer, vacuum‐distilled only, should be of suitable polymerization quality for many purposes.

Solubility and swelling of alkali soaps in organic solvents

1. 1. The ideal solubility curve of sodium palmitate has been calculated from published heat of transition data. The solubility curves of sodium palmitate in hydroxylic solvents were then found to approach the ideal curve fairly closely, whereas the high degree of nonideality of the solution of soda soap in hydrocarbons became quite conspicuous. 2. 2. The swelling of lithium, sodium, and potassium soap crystals in various organic solvents was measured microscopically. It was found that sodium stearate crystals dissolve or disintegrate but do not swell in hydroxylic solvents at temperatures above 80°C., swell slightly in aliphatic hydrocarbons and high-boiling aliphatic esters, and swell considerably in aromatic hydrocarbons. The degree of swelling at a given temperature and in 1,1-diphenylethane (the strongest swelling agent found) increases continuously from sodium laurate to stearate, decreases as double bonds and hydroxyl groups are introduced into the fatty acid radical, and is much smaller for lithium and potassium stearates than for sodium stearate. All of the observed swelling data could be correlated with the sum of the heats of transition up to the temperature at which the swelling is measured: the larger Σ t Δ H i , the greater the extent of swelling. Swelling of soaps in solvents is thus due to the thermal loosening of the crystal lattice.

The study of aluminum soap‐hydrocarbon systems: Effect of additives and metathesis

SummaryMany additives have pronounced and manifold effects on the behavior of aluminum soaps‐hydrocarbon systems. Some additives accelerate the formation of jellies, other retard it. Some thicken the jellies, others liquefy them. The mechanism of the action of additives is probably manifold, too. One of the many possible mechanisms is that of metathesis between the fatty acid radical of the soap and acidic additives. The actual occurrence of such metathesis is demonstrated by both qualitative observations of a variety of systems and by the preparation in benzene of aluminum dibenzoate from the dilaurate.

Role of the Hydroxyl Group in the Gelation of Aluminium Soaps in Hydrocarbons

IN most of the early investigations, aluminium soaps were prepared by aqueous metathesis between a soluble soap and an aluminium salt. As pointed out by McBain1, the result of reaction between a weak acid and a weak base is not likely to produce a stable salt. The tendency of aqueous solutions of aluminium salts to precipitate aluminium hydroxide over a range of pH is well known, so some at least of soap prepared by aqueous metathesis is likely to consist of fatty acid adsorbed on to precipitated aluminium hydroxide. Analogous to the alumino silicates, alums, etc., one could associate a co-ordination number of four or six with aluminium, giving many different possibilities of co-ordination with fatty acid radical, undissociated fatty acid and water. When the effect of pH, heat and method of preparation on such a heterogeneous system2 is considered, it is not surprising that results are difficult to duplicate.