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The synthesis/hydrolysis of wax esters was studied in an aqueous solution using purified rat pancreatic lipase, porcine pancreatic carboxylester lipase, and Pseudomonas fluorescens lipase. The equilibrium between wax ester synthesis and hydrolysis favored ester formation at neutral pH. The synthesizing activities were measured using free fatty acid or triacylglycerol as the acyl donor and an equimolar amount of long-chain alcohol as the acyl acceptor. When oleic acid and hexadecanol emulsified with gum arabic were incubated with these lipases, wax ester was synthesized, in a dose- and time-dependent manner, and the apparent equilibrium ratio of palmityl oleate/free oleic acid was about 0.9/0.1. These lipases catalyzed the hydrolysis of palmityl oleate emulsified with gum arabic, and the apparent equilibrium ratio of palmityl oleate/free oleic acid was also about 0.9/0.1. The apparent equilibrium ratio of wax ester/free fatty acid catalyzed by lipase depended on incubation pH and fatty alcohol chain length. When equimolar amounts of trioleoylglycerol and fatty acyl alcohol were incubated with pancreatic lipase, carboxylester lipase, or P. fluorescens lipase, wax esters were synthesized dose-dependently. These results suggest that lipases can catalyze the synthesis of wax esters from free fatty acids or through degradation of triacylglycerol in an aqueous medium.

The esterification of five medium- and long-chain acetylenic alcohols (2-nonyn-1-ol, 10-undecyn-1-ol, 6-octadecyn-1-ol, 9-octadecyn-1-ol, and 13-docosyn-1-ol), seven olefinic alcohols (cis-3-nonen-1-ol, 10-undecen-1-ol, cis-6-octadecen-1-ol, cis-9-octadecen-1-ol, trans-9-octadecen-1-ol, trans-9, trans-11-octadecadien-1-ol, cis-9,cis-12-octadecadien-1-ol), and four short-chain unsaturated alcohols (allyl alcohol, 3-butyn-1-ol, 3-pentyn-1-ol, and cis-2-penten-1-ol) with pentanoic or stearic acid in the presence of various lipase preparations was studied. With the exception of 2-nonyn-1-ol, where Lipase AY-30 (Candida rugosa) was used as the biocatalyst, the esterification of C11, C18, and C22 acetylenic alcohols with pentanoic acid appeared to be generally unaffected by the presence of an acetylenic bond in the alcohol as relatively high yields of the corresponding esters (78-97%) were obtained. However, medium- and long-chain olefinic alcohols were discriminated by Lipase AY-30, Lipolase 100T (Rhizomucor miehei), and especially by porcine pancreatic lipase (PPL), when esterification was conducted with pentanoic acid. Esterification of medium- and long-chain acetylenic or olefinic alcohols with a long-chain fatty acid, stearic acid, was very efficient except when Lipase AY-30 and Lipolase 100T were used. Short-chain unsaturated alcohols were much more readily discriminated. 3-Pentyn-1-ol and 3-butyn-1-ol were difficult (

Euglena gracilis, a unicellular phytoflagellate, can accumulate a large amount of medium-chain wax esters under anaerobic growth conditions. Here we report the identification and characterization of two genes involved in the biosynthesis of wax esters in E. gracilis. The first gene encodes a fatty acyl-CoA reductase (EgFAR) involved in the conversion of fatty acyl-CoAs to fatty alcohols and the second gene codes for a wax synthase (EgWS) catalyzing esterification of fatty acyl-CoAs and fatty alcohols, yielding wax esters. When expressed in yeast (Saccharomyces cerevisiae), EgFAR converted myristic acid (14:0) and palmitic acid (16:0) to their corresponding alcohols (14:0Alc and 16:0Alc) with myristic acid as the preferred substrate. EgWS utilized a broad range of fatty acyl-CoAs and fatty alcohols as substrates with the preference towards myristic acid and palmitoleyl alcohol. The wax biosynthetic pathway was reconstituted by co-expressing EgFAR and EgWS in yeast. When myristic acid was fed to the yeast, myristyl myristate (14:0-14:0), myristyl palmitoleate (14:0-16:1), myristyl palmitate (14:0-16:0) and palmityl myristate (16:0-14:0) were produced. These results indicate EgFAR and EgWS are likely the two enzymes involved in the biosynthesis of medium-chain wax esters in E. gracilis.

The lipids of the gram-negative bacterium Marinobacter hydrocarbonoclasticus grown in a synthetic seawater medium supplemented with various hydrocarbons as the sole carbon source were isolated, purified, and their structures determined. The hydrocarbons were normal, iso, anteiso, and mid-chain branched alkanes, phenylalkanes, cyclohexylalkanes, and a terminal olefin. According to the sequential procedure used for lipid extraction, three pools were isolated: unbound lipids extracted with organic solvents (corresponding to metabolic lipids and to the main part of membrane lipids), OH- labile lipids [mainly ester-bound in the lipopolysaccharides (LPS)], and H+ labile lipids (mainly amide-bound in the LPS). Each pool contained FA, fatty alcohols, and beta-hydroxy acids. The proportions of these lipids in the unbound lipid pools were 84-98%, 1.1-11.6%, and 0.1-3.6% (w/w), respectively. The chemical structures of the lipids were strongly correlated with those of the hydrocarbons fed; analytical data suggested a metabolism essentially through oxidation into primary alcohol, then into FA and degradation via the beta-oxidation pathway. Sub-terminal oxidation of the hydrocarbon chains, alpha-oxidation of FA or double-bond oxidation in the case of the terminal olefin, were minor, although sometimes substantial, routes of hydrocarbon degradation. Cyclohexyldodecane did not support growth, likely because of the toxicity of cyclohexylacetic acid formed in the oxidation of the alkyl side chain. In the OH- and H+ labile lipid pools, beta-hydroxy acids, the lipophilic moiety of LPS, generally dominated (28-72% and 64-98%, w/w, respectively). The most remarkable feature of these cultures on hydrocarbons was the incorporation in LPS of beta-hydroxy acids with Codd, omega-unsaturated, iso, or anteiso alkyl chains in addition to the specific beta-hydroxy acid of M. hydrocarbonoclasticus, 3-OH-n-12:0. These beta-hydroxy acids were tolerated insofar as their geometry and steric hindrance were close to those of the 3-OH-n-12:0 acid.

The biosynthetic properties of wax esters in the liver were compared between two types of myctophid fishes having different body lipid composition, i.e., three triglyceride-rich species (Lampanyctus jordani, Diaphus theta, and Symbolophorus californiensis) and three wax ester-rich species (L. regalis, Stenobracius nannochir, and Stenobracius leucopsarus). n-Heptadecanol (17:0-ALC) and/or 10-cis-heptadecenoic acid (17:1-ACID) was incubated with liver homogenate of the six myctophid fishes and with co-factors such as NADPH and ATP for 2 to 5 h. Considerable amounts of wax esters with odd-numbered fatty acids and/or alcohols were produced in the liver homogenate of the wax ester-rich species. Stenobracius nannochir and L. regalis, which exclusively contained wax esters as neutral lipids, showed the highest activity of wax ester synthesis, followed by S. leucopsarus, which contained triglyceride as the minor constituent. Only trace amounts at most of odd-numbered fatty acids and alcohols were incorporated into the wax esters after incubation with the liver homogenates of the triglyceride-rich fishes. Active interchange between the fatty acids and the alcohols occurred during wax ester biosynthesis in the wax ester-rich fishes. The chain elongation and shortening of acyl moieties were also observed during incubation. These results suggested that the deposition of lipids in myctophid fishes is mainly due to their biosynthetic activities.

This report deals with the fluorometric determination of fatty alcohols generated by the reduction of the ester linkage of lipids with NaBH4, and with the limitations of the reduction method for assaying oxidized lipids. Optimum conditions for the fluorometric analysis of primary and secondary alcohols using 1-anthroyl nitrile were obtained. After reduction with NaBH4 in MeOH or in MeOH/benzene (8∶2, v/v), the formation of 1-hexadecanol from a variety of palmitic acid esters was measured fluorometrically by reverse-phase high-performance liquid chromatography (HPLC): From glycerides and methyl palmitate, 1-3% (w/w) 1-hexadecanol was produced and a trace was produced from cholesteryl palmitate (10 min, 21°C). 1-Hexadecanol was never generated from palmitic acid. Although considerable improvement occurred with the choice of the solvent for the NaBH4 reduction, the generation of primary alcohols from ester lipids usually seems inevitable.

The total lipids of eleven species of Myctophids caught at depths between 20 and 700 m in the northern Pacific Ocean were analyzed using silicic acid column chromatography (lipid classes) and capillary gas chromatography (fatty acid and fatty alcohol composition). The major components in the lipid classes were triacylglycerols or wax esters; triacylglycerols were the dominant acyl neutral lipids (68.1-96.1%) in eight species, and wax esters were found as the dominant lipid (85.5-87.9%) in three species. The major fatty acids and alcohols contained in the wax esters of the three fishes were 18:1n-9, 20:1n-9, 20:1n-11, and 22:1n-11 for fatty acids, and 16:0, 18:1, 20:1 and 22:1 for fatty alcohols. Fatty acids in the triacylglycerols ranging from C14 to C22 were predominantly of even chain length. The major components were 16:0, 16:1n-7, 18:1n-9, 20:1n-11, 22:1n-11, 20:5n-3 (icosapentaenoic acid), and 22:6n-3 (docosahexaenoic acid). In both the triacylglycerols and the wax esters, the major fatty components were monoenoic acids and alcohols. It is suggested from the lipid chemistry of the Myctophids that they may prey on the same organisms as the certain pelagic fishes such as saury and herring, because the large quantities of monoenoic fatty acids are similar to those of saury, herring, and sprats whose lipids originate from their prey organisms such as zooplanktons which are rich in monoenoic wax esters.

Geometric and positional isomers of [1-14C] octadecenoic acids have been synthesized by modifications of published procedures. Positional isomers of octadecynoic acids also have been synthesized to obtain the geometric and positional isomers of the unlabeled octadecenoic acid analogs. The syntheses were accomplished by coupling a haloalkyl compound with a substituted acetylene using n-butyl lithium in hexamethylphosphoramide. The coupled product, either a 17- or 18-carbon acetylenic alcohol, could be semihydrogenated and chain extended to afford a carboxy labeled derivative, could be partially hydrogenated and chain extended to afford a carboxyl labeled cis- or trans-octadecenoic acid in the former case. In the latter case, octadecynoic, cis-octadecenoic or trans-octadecenoic acids could be obtained by the appropriate reactions. The methods used in this study enabled the synthesis of 14C-labeled fatty acids in generally higher yields and by simpler reactions than were previously possible.

It is shown that the shorter chain (C14-C18) minor fatty alcohols in copepods, fish body lipids, and commercial fish oils are all qualitatively present, and quantitatively similar in proportions to acids found in the depot fats of capelin and mackerel, and in some herring. Although these fatty acids can be formed de novo in fish, copepod alcohols offer an alternative dietary source. Monoethylenic fatty alcohol details, especially for the 22:1 isomers, are reviewed, and the latter are discussed as precursors of the 22:1 fatty acids of fish depot fats, specifically of the dominant 22:1 omega 11 isomer.

14C-Labeled jojoba wax was injected subcutaneously into mice and14C was determined 1–90 days after application in several internal organs, in the skin and in the lipids extracted from the carcass. A control group of mice was similarly treated with triolein. The major part of the injected lipids was not absorbed or metabolized. Some label was found in the organs examined, but there was no accumulation of labeled lipids with time. About 20% of label derived from triolein was found in polar lipids, whereas only 2–4% of that derived from jojoba wax was found in this fraction. There was some (1–5%) incorporation of the label of jojoba wax into body triglycerides.

Previous studies have shown that ingested fatty alcohols are absorbed as fatty acids and fatty acid esters, particularly triglycerides. The present study was carried out to determine whether fatty alcohols are also transported as 0-alkyl glyceryl ethers, alk-1-enyl glyceryl ethers, and as wax esters. Oxidation of fatty alcohols to other lipids was assessed by using a mixture of [1-3H] hexadecanol and [1-14C] hexadecanol of predetermined ratio. The results indicate that the absorption of fatty alcohol, and of its transport forms, parallels the absorption of labeled fatty acids. Six to 25% of plasma radioactivity was present as 1-0-alkyl diacylglyceryl ethers with a smaller proportion of ether lipids in the phospholipid fraction. In addition, 4-13% of the ingested hexadecanol appeared in the plasma as a material having the chromatographic properties of wax ester. Fatty alcohols were not detected in the plasma as alk-1-enyl lipids.

In vivo studies have indicated that exogenous free fatty acids may serve as precursors of the free fatty alcohols ofEscherichia coli K-12. Following disruption of the cells, the enzymatic activity capable of catalyzing the reduction of long chain fatty aldehydes to fatty alcohols was localized in the 100,000 x g supernatant fraction. Nicotinamide adenine dinucleotide phosphate, reduced form, was the required cofactor. The product of the reaction was characterized rigorously as 1-hexadecanol when hexadecanal was the substrate. Three independent, but complementary, assay methods were developed to assay the aldehyde reductase activity. By employing these methods, an equivalence between nicotinamide adenine dinucleotide phosphate, reduced form, oxidation and 1-hexadecanol synthesis was established. Two protein fractions catalyzing the reduction of fatty aldehydes to fatty alcohols were detected in the 100,000 x g supernatant fraction following ammonium sulfate fractionation and diethylaminoethyl-cellulose chromatography. Enzymatic activity (70%) applied to the diethylamino-ethyl-cellulose column was eluted at a phosphate concentration of 0.115 M. The remaining 30% was eluted at a concentration of 0.23 M. Following sephadex chromatography, it was observed that the enzyme eluting at 0.115 M phosphate had an apparent mol wt of 250,000 Daltons while that eluting at 0.23 M had an apparent mol wt of 62,000 Daltons. The enzymes were similar with respect to substrate specificity, pH optima, ionic strength optima, and stability with respect to thiol inhibitors, suggesting different sized aggregates of similar subunits.

The effects of altering the chemical composition of the culture media and the oxygen content of the environment upon the lipid metabolism ofEscherichia coli K-12 were investigated. WhenE. coli cells were grown on the same culture medium but under aerobic and anaerobic conditions, an increase in the free fatty acids of anaerobically grown cells was observed with a disproportionate increase in the unsaturated fatty acids. When glucose was the sole carbon source, both fatty alcohols and hydrocarbons were detected as component lipids of these cells, whether growth occurred under aerobic or anaerobic conditions. Based upon this observation, acetate is considered the initial precursor for fatty alcohol and hydrocarbon biosynthesis. A possible metabolic pathway involving fatty alcohols in hydrocarbon synthesis has been postulated.

Frog liver microsomes catalyzed the hydroxylation of 1-dodecanol into the corresponding ω- and (ω-1)-hydroxy derivatives. The hydroxylation rate for 1-dodecanol was much lower than that for lauric acid. Both NADPH and O2 were required for hydroxylation activity. NADH had no effect on the hydroxylation. The hydroxylating system was inhibited 49% by CO at a CO∶O2 ratio of 4.0. The formation of ω-hydroxydodecanol was more sharply inhibited by CO than was the formation of (ω-1)-hydroxydodecanol, implying that more than one cytochrome P-450 was involved in the hydroxylation of 1-dodecanol and that CO has a higher affinity for the P-450 catalyzing the ω-hydroxylation. The formation of laurate during the incubation of 1-dodecanol with frog liver microsomes suggests that a fatty alcohol oxidation system is also present in the microsomes. NAD+ was the most effective cofactor for the oxidation of 1-dodecanol and NADP+ had a little effect. Pyrazole (an inhibitor of alcohol dehydrogenase) had a slight inhibitory effect on the oxidation and sodium azide (an inhibitor of catalase) had no effect.

A group of long chain alpha, omega-diols (C29 to C34) has been identified in the lipids of steer and human meibomian gland excreta (meibum). These new lipids were isolated from the steer meibum unsaponifiables. Proof of structure was provided by 1) the column chromatographic behavior and TLC of the diols and their diacetates; 2) GLC on glass capillary columns; 3) fragmentation patterns in GC-MS; 4) NMR data, and 5) ozonolysis studies of the unsaturates. Chain types for the steer sample were 51% straight monoenes, 8.5% straight saturates, 39% iso and anteiso saturates and 1.5% iso and anteiso unsaturates. GC for the human sample gave straight monoenes 83%, straight saturates 8%, and iso plus anteiso saturates 9%. Close correspondence of the alpha, omega-diol chain lengths and types with meibum omega-hydroxy fatty acids suggests a biochemical precursor relationship.

Free fatty acohols have been established as lipid components ofE. coli K-12. Using combined gas liquid chromatography-mass spectrometry, the major alcohols in aerobically grown cells were identified as 1-tetradecanol (18%), 1-hexadecanol (28%), 1-octadecanol (14%), and 2-pentadecanol (27%). Small amounts of 1-hexadecenol (3%), 2-tridecanol (8%), and 2-tetradecanol (1.5%) were also detected. Analysis of anaerobically grown cells has shown a selective decrease of the secondary alcohols. 2-Pentadecanol was present as only 7% of the total alcohol fraction, and only traces of 2-tridecanol and 2-tetradecanol were found. The major alcohols in anaerobic cells were 1-tetradecanol, 1-pentadecanol, 1-hexadecenol and 1-hexadecanol. The above observations strongly suggest two pathways for the synthesis of fatty alcohols inE. coli. One pathway synthesizes the primary alcohols and does not require molecular oxygen, and a separate pathway synthesizes the secondary alcohols and has a requirement for molecular oxygen.

Major lipid classes of the preputial gland of the mouse have been identified as wax ester, neutral plasmalogen, glyceryl ether diester and triglyceride. The chain lengths and degree of unsaturation in the aliphatic moieties of the alk-1-enyl and alkyl glyceryl ethers are similar to those of the fatty alcohols of the wax ester fraction. This lends support to the theory that long chain fatty alcohols can be direct precursors of the aliphatic chains of glyceryl ethers. The striking qualitative, as well as quantitative, similarities between the alkyl and alk-1-enyl moieties of the glyceryl ethers in the neutral lipid fraction suggest that they share a common pathway of biosynthesis or are interconvertible. Neutral plasmalogens and glyceryl ether diesters contain significant amounts of odd-numbered and branched fatty acids, unlike the fatty acids of the triglycerides; therefore, the biosynthesis of neutral plasmalogens and glyceryl ether diesters may not be related to the biosynthesis of triglycerides.

Cell free studies have shown that liver and intestine are the major sites of synthesis of triacyl glycerols inSqualus acanthias. The liver and to a lesser extent the intestine and stomach are major sites of wax ester synthesis. Muscle does not synthesize either triacyl glycerols or wax esters significantly. In vivo studies have shown that intravenously injected (3H) fatty alcohol is massively oxidized to (3H) fatty acid, the bulk of which appears in muscle. Liver appears to export both free fatty acids and triacyl glycerols to serum and thence to muscle. Free fatty acids, triacyl glycerols, wax esters and cholesteryl esters are all turned over within 48 hr inSqualus serum. The turnover of triacyl glycerols greatly exceeds the turnover of alkyl diacyl glycerols.

Trans-6-hexadecenoic acid was found in polar lipids, triglycerides, was esters and diacylglyceryl ethers of the sea anemoneMetridium dianthus from Passamaquoddy Bay. The corresponding alcomaquoddy Bay. The corresponding alcohol also apparently occurs in the wax esters of this species. The long-chain (C20, C22) monoethylenic alcohols reported for other species of sea anemones from neighboring waters were absent and the major alcohol and glyceryl ether chain both had 16∶0 structures. The isomers of C18 and C20 monoethylenic fatty acids in polar lipids and triglycerides were unusual in their high proportion of theω7 isomer. These two lipids also contained higher proportion of the polyunsaturated fatty acids than the others.

Three groups of diesters have been isolated and identified in the lipids of steer meibomian glands. The first group, designated as alpha Type I, with the abbreviated formula FA-alpha OHFA-FAlc, consisted of alpha-hydroxy fatty acids esterified to fatty acids and fatty alcohols in the approximate molar ratio 1:1:1. The second group, designated as omega Type I-St, with the abbreviated formula FA-omega OHFA-St, consisted of omega-hydroxy fatty acids esterified to fatty acids and sterols in the approximate molar ratio 1:1:1. The third group, designated as alpha, omega Type II, with the abbreviated formula FA-alpha, omega diol-FA, consisted of alpha, omega-diols esterified to 2 moles of fatty acids. The sum of the different diesters comprised about 9% of total steer meibomian lipids. Capillary GLC of the fatty acids of alpha Type I diesters showed the fatty acids to be a family with a two-cluster profile, one at C12 to C20 and the other at C21 to C31, with anteiso chains predominating. Fatty acids from omega Type I-St and alpha, omega Type II diesters gave mainly a one-cluster profile in the short chain region with prominent anteiso and C18:1 peaks. Fatty alcohols of alpha Type I diesters were mainly long chain, C23 to C30, with anteiso chains predominating, while the alpha-hydroxy fatty acids were short chain C13 to C18 acids with C16 predominating. The sterols in diesters omega Type I-St were cholesterol (approximately 60%), delta 7 cholestenol (approximately 35%) and an unidentified compound (approximately 5%) with a GLC retention time slightly longer than delta 7 cholestenol on SE-30 phase. The omega-hydroxy fatty acids and alpha, omega-diols both were of exceedingly long chain lengths, C29-C38, and showed similar GLC profiles. Two types of triesters comprising approximately 1% of total steer meibomian lipids have been isolated but incompletely characterized. In terms of molar ratios, one group of triesters gave fatty acids:omega-hydroxy fatty acids:alpha-hydroxy fatty acids:sterols + fatty alcohols as approximately 1:1:1:1. The other contained fatty acids, alpha-hydroxy fatty acids and alpha, omega-diols in what appears to be a complex mixture of several triesters. Diesters omega Type I and alpha, omega Type II also were found in human meibum. Hitherto these two diesters have not been found in any animal tissue.

Wax esters were isolated from commercial orange roughy (Hoplostethus atlanticus) oil by column chromatography and fractionated by argentation thin layer chromatography. Following transesterification, the resultant fatty acid methyl esters and fatty alcohols were analyzed by gas chromatography. Both acyl- and alkyl-moieties were mainly of the monoene structure within the 16:1-22:1 range. After derivatization, the positions of the double bonds of even numbered fatty acid and fatty alcohol isomers were located by chromatography-mass spectrometry and compared. Results of these positional analyses indicate that the primary desaturation reactions takes place in the delta 9 position of pre-existing (C14 to C24) acyl chains. It is proposed that acyl components from 18:1 are subjected to chain elongation to form a mixture of 24:1 isomers as the final product. Apart from the 24:1 acyl moiety of the wax esters, in which the double bond was almost exclusively in the delta 15 position, de novo biosynthetic reactions on acids and alcohols appear to yield related acyl- and alkyl-moieties of resynthesized wax esters.

Isolated bovine meibomian glands incorporated exogenous [1-14C]acetate into lipids. Thin layer chromatographic analysis of the lipids showed that wax esters and sterol esters contained 61% of the total label. Radio gas liquid chromatographic analysis of the acid and alcohol moieties of both ester fractions showed the label was distributed equally between the two portions of the ester in both cases. Cholesterol and 5-alpha-cholest-7-en-3 beta-ol were the major labeled sterols, and anteiso-C25, anteiso-C27 and anteiso-C23 were the most highly labeled alcohols. The major labeled fatty acids in the wax esters were anteiso-C15, n-C16, anteiso-C17 and n-C18:1, whereas anteiso-C25 and anteiso-C27 were the major labeled acids in the sterol esters. The diester region with 6% of the total label contained labeled fatty acids and fatty alcohols each with anteiso-C25 as the major component and omega-hydroxy acids in which n-C32:1 was the major labeled component. The triglyceride fraction which contained 8% of the total lipids was composed of labeled fatty acids similar to those found in both sterol and wax ester fractions. Chromatographic analyses of the labeled lipids derived from exogenous labeled isoleucine showed that anteiso-branched products were preferentially labeled. The labeled triglyceride fraction derived from [U-14C] isoleucine also contained esterified C15, C13, C11, C9, C7 and possibly shorter anteiso-branched acids.

The skin, skeleton and a fat-filled swim bladder of the orange roughly (Hoplostethus atlanticus) each contained greater than 20% lipid by wet weight which was almost entirely wax esters. These had carbon numbers of 34-40 consistent with the major fatty acid being 18:1 and the major fatty alcohols being 16:0, 18:1, 20:1 and 22:1. In contrast, the liver and the roe contained appreciable quantities of glycerolipids with 18:1 and 22:6 as the major fatty acids.

The arylsulfonate esters of linoleyl, stearyl, and decyl alcohols were found to reduce significantly the accumulation of cholesterol in the plasma and livers of White Carneau pigeons subjected to a diet of Purina pigeon pellets coated with 0.25% cholesterol and 10% lard when fed for periods ranging from 9--12 months; no effects were observed in normocholesterolemic pigeons. These compounds produced no toxic side effects and were found to significantly attenuate the development of aortic atherosclerosis. The effect on aortic atherosclerosis was most likely the result of the lowering of plasma cholesterol concentrations. Linoleyl p-toluenesulfonate appeared to be the most effective of the three arylsulfonates tested, both with respect to the reduction of plasma and liver cholesterol accumulation and attenuation of the atherosclerotic process.

The liquid wax obtained from the seeds of the arid-land shrub jojoba (Simmondsia chinensis) is finding increasing use in skin treatment preparations. The fate of this wax upon reaching the digestive tract was studied.14C-Labeled wax was administered intragastrically to mice, and the distribution of the label in the body was determined as a function of time. Most of the wax was excreted, but a small amount was absorbed, as was indicated by the distribution of label in the internal organs and the epididymal fat. The label was incorporated into the body lipids and was found to diminish with time.Lipids 17: 169–171. 1982.

Ozonolysis studies of the monoenes of the fatty chain types in lipids of steer meibomian gland excreta (meibum) have confirmed earlier structural assignments based on gas liquid chromatography (GLC) retention data and have assisted in assigning complete structures to a group of recently identified omega-hydroxy fatty acids. The omega-hydroxy acids include straight-chain monoenoic acids (85%), saturated anteiso and iso acids (13%), monoenoic acids of the latter group (1%) and, finally, saturates of the normal monoenoic acids (1%). All the fatty chains of meibum can be biosynthesized by a unified process of chain buildup to primary chain lengths of 12:0-20:0 for the straight evens, with 16:0 predominating, 13:0-21:0 for the straight odds with 17:0 predominating, i16:0 to i28:0 for the iso and ai17:0 to ai29:0 for the anteiso chain types; then delta 9 desaturation of each of these chain types: and finally chain elongation of 1-10 C2 units. Some chain degradation may also occur. The meibum lipid components involved are unsubstituted fatty acids, alpha-OH fatty acids, alpha-OH fatty acids, omega-OH fatty acids, fatty alcohols and some other lipid components incompletely characterized. The carbon skeletons are straight even, straight odd, iso and anteiso except that the alpha-OH fatty acids are only straight even and straight odd and these chains are not elongated. All fatty chains are almost entirely saturated and monoenoic, the polyenes occurring in only trace amounts. Biosynthesis of the fatty chains of human meibum evidently occurs similarly, except that considerably more 18:0 than 16:0 fatty acids are built up by the fatty acid synthetase, before desaturation and extension.

The lower jaw fat of the Amazon River dolphinInia geoffrensis contains 52.8% wax ester, 44.7% triglyceride and 2.5% diacyl glyceryl ether, while its dorsal blubber fat is >98% triglyceride. Examination of the intact lipids, the derived fatty acids and the derived fatty alcohols by gas chromatography reveals that the blubber triglycerides show characteristics of freshwater fish fats, but the jaw fat lipids have several distinctive features. Jaw fat wax esters, triglycerides and diacyl glyceryl ethers are all rich in C10, C12 and C14 fatty acids and contain no polyunsaturated acids. The fatty alcohols in the wax esters are over 90% saturated. The major carbon numbers in the jaw fat triglycerides (C38–C46) are considerably lower than those of the blubber triglycerides (C48–C54). The possible adaptation of the jaw lipids for use in the underwater echolocation process of this dolphin is discussed.

Small quantities of long chain fatty alcohols (esterified or free or both) were found in four normal tissues (about 0.01% of total neutral lipids) and three neoplasms (about 0.3% of total neutral lipids). The major chain lengths (16∶0, 18∶0 and 18∶1) of the fatty alcohols in both normal and neoplastic cells qualitatively resemble the O-alkyl chain lengths of glyceryl ethers. Our data showing that long chain fatty alcohols occur in vivo support the biological significance of the metabolic pathway that uses fatty alcohols as a substrate for the alkyl chain in glyceryl ether biosynthesis.

The literature is surveyed on two types of diester lipid that occur on the skin surfaces of animals: Type 1, a hydroxy fatty acid of which the hydroxyl group and the carboxyl group are esterified respectively with another fatty acid and a fatty alcohol, and Type 2, and alkane α,β-diol of which each OH group is esterified with a fatty acid. New data presented here show that the cow, rabbit and cat produce Type 1, whereas the dog, mouse, guinea pig and baboon produce Type 2 diesters. Each occurs as a major component of the surface lipid. The homologue distribution is given for Type 1 diesters of cow, rabbit and cat as well as the Type 2 diesters of dog and mouse. Distribution of long chain fatty acids of Type 1 diesters parallels that of the fatty alcohols suggesting a biogenetic relation between the two types of compounds. GLC of total diesters for the cow suggests that the components are assembled randomly during biosynthesis. Molecular weight of these diesters are in the range of those of natural triglycerides composed mainly of C16 and C18 fatty acids.

A convenient method for the synthesis of acetals of fatty aldehydes and fatty alcohols by transacetatlation between fatty aldehyde dimethyl acetals and fatty alcohols is described. The acetals undergo decomposition to the alk-1-enyl alkyl ethers during GLC. Equimolar mixtures of fatty aldehydes and fatty alcohols show hemiacetal structure as evidenced by IR spectra in KBr discs but are dissociated completely into their components in solution and during TLC. They do not undergo dehydration and conversion to alk-1-enyl alkyl ethers during GLC under conditions of dealcoholization of acetals but are dissociated into aldehydes and alcohols.