Structure of some intact lipids of petrel stomach oils

The stomach or proventricular oils from 16 species of petrel have been analyzed and the carbon number distributions of the wax esters, triglycerides, and diacylglyceryl ethers are reported. The wax esters have been fractionated further into less and more polar species. To determine whether any intermolecular specificity existed, carbon number distributions for each lipid class were calculated, assuming random esterifications. The triglyceride and diacylglyceryl ether compositions observed were all found to agree closely with those calculated. The wax esters from three petrel species were found to have greater proportions of the middle range species with carbon numbers 34–38 than calculated. However, most of the lipids examined had random structures which have been found to be characteristic of marine sources. The results in general support the belief that the oils are derived directly from dietary sources rather than synthesis by the proventricular glands.     

Analysis of the wax ester fraction of olive oil and sunflower oil by gas chromatography and gas chromatography-mass spectrometry

The wax ester fractions of solvent-extracted sunflower oil and “extra virgin” olive oil were obtained by solid-phase extraction and subsequently subjected to gas-chromatographic and gas chromatographic-mass spectrometric analysis. The comprehensive qualitative analysis of these fractions, which was carried out by the interpretation of mass spectral data, revealed several types of wax esters. In olive oil, shortchain, even-numbered wax esters, saturated and unsaturated long-chain, even-numbered wax esters, benzyl esters, and the diterpenic esters phytyl and geranylgeranyl ester (the latter as a minor component) are present. With the exception of benzyl esters, all these esters occur in sunflower oil as well, but in considerably different amounts compared to those in olive oil. Whereas unsaturated wax esters are present in a negligible amount, diterpenic esters, mainly geranylgeranyl esters, represent the major part of the wax ester fraction.     

Jojoba wax: Its esters and some of its minor components

A lack of reliability in the usual determinations of fatty acids and fatty alcohols of jojoba wax prompted us to propose an original method of hydrolysis and extraction, making it possible to better determine the composition of fatty acids and alcohols of the wax. High-performance liquid chromatography fractionation of the wax allowed isolation of four main classes of esters (which differed by their partition number). The detailed study of these ester classes emphasized the way acids and alcohols are connected, and fourteen distinct esters were thus identified. Some triacylglycerols, free fatty alcohols and other minor components of jojoba wax were found and quantitated. Seven sterols were identified, four for the first time.     

Molecular analysis of intact preen waxes of Calidris canutus (Aves: Scolopacidae) by gas chromatography/mass spectrometry

The intact preen wax esters of the red knot Calidris canutus were studied with gas chromatography/mass spectrometry (GC/MS) and GC/MS/MS. In this latter technique, transitions from the molecular ion to fragment ions representing the fatty acid moiety of the wax esters were measured, providing additional resolution to the analysis of wax esters. The C₂₁−C₃₂ wax esters are composed of complex mixtures of hundreds of individual isomers. The odd carbon-numbered wax esters are predominantly composed of even carbon-numbered n-alcohols (C₁₄, C₁₆, and C₁₈) esterified predominantly with odd carbon-numbered 2-methyl fatty acids (C₇, C₉, C₁₁, and C₁₃), resulting in relatively simple distributions. The even carbon-numbered wax esters show a far more complex distribution due to a number of factors: (i) Their n-alcohol moieties are not dominated by even carbon-numbered n-alcohol moieties are not dominated by even carbon-numbered n-alcohols esterified with odd carbon-numbered 2-methyl fatty acids, but odd and even carbon-numbered n-alcohols participate in approximately equal amounts; (ii) odd carbon-numbered methyl-branched alcohols participate abundantly in these wax ester clusters; and (iii) with increasing molecular weight, various isomers of the 2,6-, 2,8-, and 2,10-dimethyl branched fatty acids also participate in the even carbon-numbered wax esters. The data demonstrate that there is a clear biosynthetic control on the wax ester composition although the reasons for the complex chemistry of the waxes are not yet understood.     

Synthesis and analysis of phytyl and phytenoyl wax esters

An efficient procedure for preparing phytenic acid methyl ester, free of isomers, from phytol is reported. Phytyl phytenate and other isoprenoid wax esters were synthesized. Gas liquid chromatography of these wax esters and other compounds related to phytol and phytenic acid is described. The alkyl constituents of isoprenoid wax esters can be analyzed after alkaline methanolysis and the acyl constituents after acidic methanolysis. The applicability of these methods to natural mixtures was demonstrated with wax esters from mosses which contained both types of isoprenoids and with wax esters from healthy and frost damaged grass which contained phytol, but not phytenic acid.     

Zur Kenntnis der Wachsbaustein des Montanwachses II: Hydroxysäuren

Constituents of Montan Wax II: Hydroxy Acids The group of hydroxy acids which occur in a large number of natural waxes as condensing component of the ester wax part were found in Montan wax as well and were studied closely. The methyl esters of the total acids were treated with succinic anhydride and the resulting hydrogen succinates of the methyl esters of hydroxy acids separated by means of an anion exchanger.     

A process for the preparation of food-grade rice bran wax and the determination of its composition

A two-step method was developed for the preparation of food-grade wax. The first step involved the solventdefatting of crude wax, which gave a dark brown, dry, powdered wax with a m.p. of 75–79°C. The major impurity in the defatted wax was the dark brown resinous matter. In the second step, the resinous matter was removed by bleaching with sodium borohydride in isopropanol. This step yielded a pale yellow, odorless wax with purity higher than 99% and with a m.p. of 80–83°C. The resinous matter was a mixture of aliphatic aldehydes, fatty alcohols, and FA. High-temperature GC analysis of the purified rice bran wax indicated that it contained 11 major and 9 minor types of saturated wax esters. The major and minor peaks contained C₄₄–C₆₄ and C₄₅–C₅₉ wax esters, respectively. Rice bran wax was mainly a mixture of saturated esters of C₂₂ and C₂₄ FA and C₂₄ to C₄₀ aliphatic alcohols, with C₂₄ and C₃₀ being the predominant FA and fatty alcohol, respectively. The alcohol portion of the wax esters also contained small amounts of branched and odd carbon number fatty alcohols.     

Physico‐chemical properties of wax esters synthesised from corresponding alcohols using hydrobromic acid and hydrogen peroxide action

Symmetrical wax esters were prepared directly from the C₁₄–C₂₂ alcohols using HBr and H₂O₂. Conversion of alcohol up to 98% was obtained. Physical properties such as melting point, refractive index, viscosity and specific gravity were determined for these wax esters at different temperatures. The physical properties of the synthetic wax esters were compared with those of some commercial samples of wax esters. The physical properties of the wax esters can be manipulated by starting with commercially available mixtures of alcohols.     

Molecular species of wax esters in jaw fat of atlantic bottlenose dolphin,Tursiops truncatus

The jaw fat of the Atlantic bottlenose dolphin (Tursiops truncatus) contains unusual wax esters which can be separated into short chain (<C₂₄) and long chain (>C₂₄) fractions by thin layer chromatography. The short chain wax esters (28 wt. %) have been characterized as a 72∶24∶4 mixture of isovaleroyl, isobutoryl, and 2-methylbutyrol, esters of C₁₄–C₁₈ n- and iso-alcohols. The intact <C₂₄ esters have been resolved into individual molecular species by gas liquid chromatography on open-tubular polyester columns. The long chain wax esters (12 wt. %) contain C₁₀–C₂₂ n- and iso-acids esterified to the same C₁₄–C₁₈ n- and iso-alcohols. Gas liquid chromatography of the intact, hydrogenated >C₂₄ esters on a short JXR column has characterized them according to carbon number and the number of methyl branches they contain.     

Fatty Acid Specificity of Candida cylindracea Lipase

Candida cylindracea lipase (SIGMA) was tested against triglycerides (TG) and wax esters (WE) of marine origin as substrates. Under the same conditions, wax esters were hydrolysed at a lower rate than the triglycerides. The C₁₄ to C₁₈ saturated and monounsaturated fatty acids were preferentially hydrolysed whereas the longer chain monoenes (20:1 and 22:1) and particularly the polyunsaturated fatty acids (18:4,20:5 and 22:6) were resistant to the hydrolysis in triglycerides as well as in wax esters. No specificity was demonstrated for the fatty alcohols in the wax esters.     

The fatty acids of wax esters and sterol esters from vernix caseosa and from human skin surface lipid

Separation of sterol esters from wax esters in the lipids of vernix caseosa and adult human skin surface was accomplished by column chromatography on MgO. The fatty acids of the sterol esters and wax esters of both samples were separated into saturates and monoenes, and examined in detail by gas liquid chromatography (GLC). The saturated fatty acids of the wax esters of vernix caseosa and of adult human skin surface were remarkably similar. They ranged in chain length from at least C₁₁ to C₃₀, six skeletal types being present: straight even, straight odd, iso, anteiso, other monomethyl branched and dimethyl branched. A large number of patterns of monoenes were observed, each pattern consisting of desaturation of a specific chain at Δ6 or Δ9 plus its extension or degradation products. The mole per cent of the total Δ6 and Δ9 patterns of wax ester fatty acid monoenes of vernix caseosa were 87% and 12%, respectively, and 98% and 1%, respectively, for adult human skin surface lipid. The sterol ester fatty acids of vernix caseosa were much different from those of adult human skin surface: vernix caseosa saturates were largely branched and of lengths greater than C₁₈, whereas the saturates of adult human surface lipid resembled the wax ester fatty acids. Of the vernix caseosa monoene patterns, the mole per cent was 30% Δ6 and 70% Δ9, whereas of the adult human skin surface sterol ester fatty acids 89% were Δ6 and 11% Δ9. Chain extension was particularly pronounced in the sterol ester fatty acid monoenes of vernix caseosa amounting to 7–8 C₂ units in some cases. The fatty acids of the sterol esters of both vernix caseosa and adult human skin surface appear to be derived from the sebaceous gland and from the keratinizing epidermis, but those of the wax esters are from the sebaceous glands only.     

Melting points of synthetic wax esters

Saturated, monoenoic and dienoic wax esters, C₂₆−C₄₀, have been synthesized from even-numbered fatty alcohols and acids. In homologous series of saturated esters, the increments of melting points follow a regular trend except for those esters which have an acid moiety two carbon atoms shorter than the alcohol moiety. These wax esters have melting points higher than interpolation would predict. Monoenoic wax esters with the double bond in the alcohol chain have melting points about 10 C higher than their isomers with the double bond in the acid chain.     

Alkoxy-Acyl combinations in the wax esters from winterized sperm whale oil by gas chromatography-mass spectrometry1

Wax esters from winterized sperm whale oil were separated according to degree of unsaturation and then analyzed by gas chromatography-mass spectrometry. The combinations of fatty alcohols and acids making up the wax esters of each chain length were determined. Octadecenyl octadecenoate was the most abundant wax ester (14%), followed by octadecenyl hexadecenoate (10%). Over 240 different wax esters were detected and quantitated. Presented at the AOCS Meeting in San Francisco, 1979.     

Improved method for the determination of wax esters in vegetable oils

In this work, a modified International Olive Council (IOC) method for wax determination involving a double‐adsorbent layer of silica gel and silver nitrate‐impregnated silica gel is presented (SN method). Column chromatography by the SN method did not show retention of wax esters standards with an even number of carbon atoms (C34–C44), observing recovery percentages higher than 90% even for unsaturated wax esters. All wax fractions were lower by the SN method than by the IOC method, resulting in a percentage decrease in the total wax content (olive oils: 20–50%, crude sunflower oil: 38%, crude soybean oil: 58% and crude grape seed oil: 13%). Olive oils analysed by the SN method showed increases of up to 27% in C40 relative percentage with respect to the IOC method. Additionally, decreases were observed by the SN method in the relative percentages for odd‐carbon atom waxes for the seed oils in comparison to the IOC method (crude sunflower oil: 27%, crude soybean oil: 28% and crude grape seed oil: 13%). The main advantages of the proposed modification consist in its easy implementation and a better determination of wax esters (C34–C60) by controlling their complete recovery and removing interfering substances. The method is suitable for quality control and for authentication of olive oil and seed oils as well as in processing monitoring. Practical applications: The proposed method is useful in the quality, authentication and processing control of fruit and seed oils. Moreover, it can be an important tool for vegetable oil industries to control the efficiency of the wax separation process to prevent turbidity in the refined oil.     

Über die katalytische Dehydrierung gesättigter und ungesättigter Fettalkohole unter Esterbildung,Teil I: Ergebnisse mit verschiedenen Alkoholen und Katalysatoren und der Einfluß der Reaktionsbedingungen

Formation of Esters in the Catalytic Dehydrogenation of Saturated and Unsaturated Fatty Alcohols, Part I: Results with Various Alcohols and Catalysts, and the Effect of Reaction Conditions Symmetrical wax esters, i. e. those having the same number of C-atoms in the acidic and alcoholic moieties are formed during dehydrogenation of saturated and unsaturated fatty alcohols in the liquid phase with modified copper-zinc oxide catalysts. Yields upto 90% of esters are obtained under suitable conditions of reaction (temperature, pressure, catalyst concentration). Saturated and unsaturated wax esters are obtained as waxy substances having definite melting points by various treatments of the reaction product like distillation or crystallization. Other reactions which occur apart from esterification, such as the formation of acid, hydrocarbon, ketone and higher esters as well as isomerization of double bonds of the unsaturated fatty alcohols were investigated.     

Fatty alcohols in capelin,herring and mackerel oils and muscle lipids: II. A comparison of fatty acids from wax esters with those of triglycerides

The fatty acids recovered from the triglycerides and wax esters of common northwest Atlantic copepods are compared with the fatty acids of wax esters recovered intact from certain fish skin and body lipid, and from commercial fish oils. The fish species, herring, capelin and mackerel, all feed on copepods, and many resemblances of the copepod lipid fatty acids to those of a previous analysis of similar copepods suggest that the basic dietary fat input for these fish may be quite constant. The two copepod fatty acid analyses differed quantitatively in triglyceride 20∶1 and 22∶1 and also in 20∶5ω3 and 22∶6ω3, confirming the primary role of the wax esters in copepods. Selectivity factors are discussed in comparing the copepod wax ester fatty acids with the fatty acids of the wax esters recovered intact from the fish lipids and oils. The basic role of copepods in supplying all types of fatty acids to fish depot fats is considered to be strongly supported by these findings.     

Über Naturwachse XVI: Gas-Chromatographie der Wachsester

Natural Waxes XVI: Gas Chromatography of Wax Esters The authors have applied the method of high temperature gas chromatography of wax esters in the study on relationship between position of ester group in the carbon chain on the retention volumes of isomeric esters. In esters containing one double bond variations in retention data were observed. Gas chromatography and mass spectroscopy revealed that inspite of its apparent simplicity, spermaceti-ester is actually a complex mixture of esters, since each gas chromatographic peak, corresponding to a definite carbon number, contains a mixture of isomeric esters. These esters differ from each other only with respect to position of their ester group.     

Trennung halbsynthetischer Montanwachse in Gruppenkomponenten und physikalischchemische sowie rheologische Eigenschaften der Wachssäure-Glykolester-Systeme

Separation of Semisynthetic Montana Wax into Component Groups and Physico-Chemical as well as Rheological Properties of Wax Acids and Glycol Ester Systems Crude montana wax Romonta, acid wax R, as well as two ester waxes MR-150B and KPS were separated into their component groups. Two methods of separation were employed, namely, chromatography and extraction. Using these methods free wax acids, esters, alcohols and hydrocarbons were separated. Purity of each fraction was determined in the same manner. One part of the separated acids was esterified with ethylene glycol and from the reaction product six wax esters were synthesized. Slip point, penetration and rheological properties of these six wax esters were studied.     

Wax ester fraction of edible oils: Analysis by on‐line LC‐GC‐MS and GC×GC‐FID

The wax ester fraction of various plant oils was isolated by normal‐phase HPLC (NPLC) on‐line coupled to GC via the on‐column interface and applying concurrent eluent evaporation. The esters were analyzed by on‐line NPLC‐GC‐MS and by comprehensive two‐dimensional GC with flame ionization detection (GC×GC‐FID) off‐line combined with NPLC‐GC. GC×GC‐FID enables to group the various classes of wax esters, in particular the phytol esters, geranylgeraniol esters and the straight‐chain esters of palmitic acids and the unsaturated C₁₈ acids. Optimization of the GC×GC columns and the conditions must take into account the limited thermostability of the diterpene esters. Chromatograms are shown for a range of oils, with particular focus on the various classes of wax esters in olive oil and the geranylgeraniol esters 22:0 and 24:0 in a variety of oils.     

Occurrence,function and biosynthesis of wax esters in marine organisms

Wax esters occur as a major lipid-type in at least 30 species of marine animals, distributed among 17 orders and 3 phyla. They are of limited usefulness as a chemotaxonomic character, since only in two suborders, the calanoid copepods, Calanoidei, and the toothed whales, Odontoceti, do the wax esters occur in all members so far examined. In bony fishes their occurrence in muscle correlates better with mesopelagic habitat and vertical migration patterns than with taxonomy. Homologs with 21 to 44 total carbon atoms have been reported, but the usual range for the wax esters in copepods and fish is C₃₀–C₄₂. In fishes the muscle wax esters contain predominantly one and two double bonds per molecule, while in roe lipids up to 65% of the homologs contain three or more double bonds. The component alcohols are saturated and monounsaturated, with 16∶0 and 18∶1 as the usual major constituents. The fatty acids are more diverse, but 18∶1 is most often the main component, and 16∶1 and 20∶1 are frequent major constituents; polyunsaturated acids make up 1–12% in fish muscle and whale oils and up to 45% in fish roe wax esters. Possible functions of the wax esters are for buoyancy, as energy reserves and for thermal insulation. In vitro, various tissues of marine bony fishes synthesize wax esters from long chain alcohols and fatty acids, without activation. A competing pathway for the long chain alcohols in vivo is their catabolic oxidation to the corresponding fatty acids. The key to the accumulation of wax esters is to be sought in the metabolism of the long chain alcohols, their biosynthesis and esterification vs. their catabolism. Presented at the 60th AOCS Annual Meeting, San Francisco, April 1969, as part of a Symposium on Natural Waxes.