共查询到20条相似文献,搜索用时 0 毫秒
1.
Cuticular lipids cover nearly all parts of insect and are the chief agent for restricting water loss. The structure of insect
epicuticles is reviewed, with emphasis on the role of cuticular lipids and the metabolism of cuticular lipids. The chemical
composition of insect cuticular lipids are discussed with particular emphasis on the types in which hydrocarbons, was esters
and fatty alcohols predominate. What little evidence is available on the biosynthesis of insect cuticular lipids is discussed.
One of six papers to be published from the Symposium on Natural Waxes, presented at the AOCS Meeting, San Francisco, April
1969. 相似文献
2.
The cuticular hydrocarbons of the Mormon cricket,Anabrus simplex, are all saturated and consist of n-alkanes (29+%), 3-methylalkanes (12%), internally branched monomethylalkanes (26+%),
and dimethylalkanes (28+%). The principal n-alkane is the C29 component, with a range from C23 to C33. The 3-methylalkanes range from C28 to C32, and the internally branched monomethyl-and dimethylalkanes range from C29 to C39. When the branched alkanes ofA. simplex are compared to those from other insects in the order Orthoptera, interesting patterns of methyl branching are observed.
Scientific Journal Series 631, Agricultural Experiment Station, University of Montana, Bozeman, Montana 59715. 相似文献
3.
The major hydrocarbons found in the surface lipids of the cockroachesLeucophaea maderae andBlatta orientalis have been identified asn-heptacosane, 11-methylheptacosane, 13-methylheptacosane and 3-methylheptacosane. The hydrocarbons from the two genera of
cockroaches are qualitatively identical and quantitatively similar. 相似文献
4.
Incorporation of18O2 and H2 18O into the secondary alcohol moiety of wax esters in the grasshopperMelanoplus sanguinipes was determined by mass spectrometry. Results of this study show that oxygen-18 from18O2 was incorporated into the secondary alcohol, whereas no incorporation of oxygen-18 from H2 18O was detected. The data suggest that the reaction, which hydroxylates n-alkanes at or near the center of the carbon chain, involves a mixed function oxidase type enzyme. 相似文献
5.
Larry L. Jackson 《Lipids》1970,5(1):38-41
The major cuticular hydrocarbons of the cockroachesPeriplaneta australasiae, Periplaneta brunnea andPeriplaneta fuliginosa aren-tricosane,cis-9-tricosene, 3-methyltricosane, 11-methyltricosane and 13-methylpentacosane. There are as yet unexplained quantitative differences
between the hydrocarbon compositions of males and females ofP. australasiae andP. fuliginosa, cis-9-tricosene being a major hydrocarbon of the males only. A series of mono-methyl internally branched hydrocarbons ranging
in chain length from 23 to 26 carbons with the methyl branch on the 13th carbon from one end was observed. Minor quantities
of other hydrocarbons have been identified. 相似文献
6.
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. 相似文献
7.
Thomas K. Miwa 《Journal of the American Oil Chemists' Society》1971,48(6):259-264
HCl-catalyzed ethanolysis followed by saponification readily surmounts the resistance of long chain wax esters to direct hydrolysis
by alkali. Additionally, choosing ethyl instead of methyl esters allows baseline separations between long-chain alcohols and
corresponding esters in gas liquid chromatographic (GLC) analysis of total alcohol and acid components before saponification.
Liquid wax esters were analyzed on a temperature-programmed 3% OV-1 silicone column. Geographical and genetic effects on the
variability of jojoba oil composition were investigated with five different seed samples. Major constituents in jojoba seed
oil from shrubs in the Arizona deserts, as indicated by GLC analyses of oil, ethanolysis product, isolated fatty alcohols
and methyl esters of isolated fatty acids, were C40 wax ester 30%, C42 wax ester 50% and C44 wax ester 10%; octadecenoic acid 6%; eicosenoic acid 35%, docosenoic acid 7%, eicosenol 22%, docosenol 21% and tetracosenol
4%. Oil from smaller leaved prostrate plants growing along California’s oceanside showed a slight tendency toward higher molecular
size than oils from the California desert and Arizona specimens. The wax esters are made up of a dispro-portionately large
amount of docosenyl eicosenoate and are not a random combination of constituent acids and alcohols.Lunaria annua synthetic wax ester oil was used as a model for evaluating the analytical procedures.
Presented at the AOCS Meeting, Chicago, September 1970
No. Utiliz, Res. Dev. Div., ARS, USDA. 相似文献
8.
Acyl-CoA: alcohol transacylase activity was demonstrated in cell-free homogenates of developing jojoba seeds. The optimal
pH was 8.0–8.1. Under optimal conditions, wax formation had a nearly linear relationship with extract concentration; the time
course of wax formation was also linear up to 30 min.cis-11-Eicosenol was the most effective alcohol substrate whereas tetradecanol, octadecanol, dodecanol,cis-9-octadecanol, andcis-13-eicosenol gave progressively lower activities. Either saturated or unsaturated acyl-CoA with 18 or 20 C-atoms had similar
activity. The enzyme was fairly stable at 0 C, less stable at RT and labile above 30 C. Differential centrifugation showed
that the 12,000 × g fat pad was the most active in wax formation; to maximize the activity, a 12,000 × g supernatant appeared
to be necessary. This factor in the supermatant was thermolabile and nondialyzable. 相似文献
9.
Mangesh G. Kulkarni Sudhirprakash B. Sawant 《Journal of the American Oil Chemists' Society》2001,78(7):719-723
The primary aliphatic alcohols n-octanol, n-decanol, and n-dodecanol have been converted to their corresponding symmetrical esters by using HBr and H2O2 in the absence of a solvent. The reaction was carried out at 30, 40, and 50°C and at mole ratios of alcohol to HBr of 1∶0.1,
1∶0.2, 1∶0.3, and 1∶0.5. The rate of the reaction was found to increase with increase in the reaction temperature and concentration
of HBr. The maximal conversion of n-octanol was 72% at 40°C and a mole ratio of n-octanol to HBr of 1∶0.5. The kinetics of the reaction have been established, and the reaction was found to be first-order
with respect to alcohol and bromine concentration in the organic phase, and second-order with respect to both. The second-order
rate constants for n-octanol, n-decanol, and n-dodecanol are 27.08, 32.58, and 37.42 mL mol−1 min−1, respectively, at 40°C. The activation energy for the esterification reaction of n-octanol was found to be 16.32 kcal mol−1. 相似文献
10.
Mangesh G. Kulkarni Sudhirprakash B. Sawant 《European Journal of Lipid Science and Technology》2002,104(7):387-393
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. 相似文献
11.
Chromatography of stearyl oleate and cholesteryl oleate on thin layer plates coated with magnesium hydroxide-celite, 1:1,
or magnesia-celite, 1:1, showed that magnesium hydroxide had better resolving power for the separation of these wax ester
and steryl ester model compounds than did magnesia, an adsorbent which has been used previously for this separation. By means
of high pressure liquid chromatography on magnesium hydroxide, wax esters and steryl esters from the skin surface lipids of
human, rat and monkey were separated completely and without hydrolysis. 相似文献
12.
Open-tubular gas chromatography was carried out on fatty acids and alcohols obtained from wax esters of the orange roughy,Hoplostethus atlanticus, caught at sea off New Zealand. The major (above 5%) components were 16∶1(n−7), 18∶1(n−9) and (n−7), 20∶1(n−9) and (n−7),
and 22∶1(n−11, n−13) as fatty acids, and 16∶0, 18∶0, 18∶1(n−9), 20∶1(n−9) and (n−7), and 22∶1(n−11, n−13) as fatty alcohols.
The total percentages of the minor components were 10% in the acids and 26% in the alcohols. The 22∶1/20∶1 ratio of the fatty
alcohols obtained in this study was less than 1.0, although the ratio for the Atlantic orange roughy has been reported as
being greater than 1.0. The contents of polyenes were as low as 2.48% in the acids and 0.95% in the alcohols, but their compositions
showed some specific features. The percentages of the C16−C22 dienes in the total polyenes were remarkably high, 57.7% of these acids and 53.1% of these alcohols. The most important dienes
were 18∶2(n−6) in the acids and 20∶2(n−6) in the alcohols. 相似文献
13.
Marianne Lilja Hallberg Daobin Wang Magnus Härröd 《Journal of the American Oil Chemists' Society》1999,76(2):183-187
Wax esters were transesterified from fatty acid methyl esters of rapeseed and a fatty alcohol (1-hexadecanol, 16:0). The amounts of both the substrates were fixed to 0.1 mmol and an immobilized enzyme, Lipozyme, was used as catalyst. The experiment was performed following a statistic central composite design with five variables. The enzyme/lipid ratio was varied between 0.3–0.9 of the substrate weight and the enzyme was equilibrated to different water activities varying from 0.11 to 0.44. A temperature range of 50–80°C was investigated and the reaction time lasted up to 40 min. A solvent, isooctane, constituted 0–30% of the substrate weight. The first experimental series was performed in small closed test tubes. In the second series the caps of the test tubes were off to evaporate the methanol produced during the reaction. The highest initial reaction rate was 9.6 gwax esters/genzyme · h. It appeared when: the enzyme/lipid ratio was low, 0.3, the temperature was high, 80°C; no isooctane was present; and the water activity was below 0.11. The initial reaction rate was independent of the caps on the test tubes. With the large amount of enzyme the yield of wax esters was above 70% after 10 min in both experimental series. In the reaction with caps, the reaction reached equilibrium at 83% after 20 min at 80°C. However, without caps the continuous evaporation of methanol increased the equilibrium constantly, and after 40 min at 80°C a yield of 90% was reached. 相似文献
14.
Mauro Amelio Renzo Rizzo Flavio Varazini 《Journal of the American Oil Chemists' Society》1993,70(8):793-796
To detect adulteration of olive oil with solvent-extracted oils, the determination of the wax ester content has become more
important during recent years. Hence, a greater number of wax ester analyses need to be performed by quality control laboratories.
The most common method in use requires a liquid chromatographic (LC) separation of the less polar fraction, which contains
the wax esters, from the glyceride matter on a hand-filled silica gel column. The aim of this project was to verify the possibility
of replacing LC with high-performance liquid chromatography by taking advantage of the greater reliability and repeatability
of this technique, as well as of the possibility of making the separation automatic. The paper describes how to perform the
analysis and the statistical test that was carried out; furthermore, a comparison has been made with the usual method and
results are in good agreement. 相似文献
15.
Hypercholesterolemic rats, fed 1% cholesterol and 0.5% glycocholate, were treated with arylsulfonates in various ways to observe
the pattern of cholesterol elimination. Dietary linoleyl p-toluene-sulfonate (LTS) hastened return to normocholesterolemia
and lowered hepatic cholesterol either with or without continued cholesterol feeding. LTS administered via the portal vein
significantly lowered plasma cholesterol in 48 hr; ethyl linoleate and monoolein produced no lowering. LTS administered via
the portal vein to glycocholate-infused rats increased the biliary excretions of label from [4-14C]cholesterol administered intracardially and also increased total bile acid excretion 21% without increased bile volume when
compared to similar injection of ethyl linoleate. No change in biliary excretion of cholesterol was seen. Bile acid kinetics
were studied by using isotopic dilution techniques. Cholate turnover was enhanced by feeding oleyl p-toluenesulfonate (OTS)
and oleylp-(n-decyl)-benzenesulfonate (ODS) as suggested by a 16–35% decrease in half-life in both normal and hypercholesterolemic rats.
Rats consuming a grain-based colony diet had a 54% increase in cholate synthesis when OTS was included in the diet. The composition
of bile was changed when either OTS or ODS was fed; an increase in chenodeoxycholate was noted. This change was gradual with
OTS but rapid with ODS and paralleled enhanced decay of chenodeoxycholate specific radioactivity in response to treatment.
ODS and OTS also increased14CO2 expiration from oral [26-14C] cholesterol in hypercholesterolemic rats. Dietary OTS and ODS elevated hepatic free cholesterol in hypercholesterolemic
rats; ODS also elevated plasma free cholesterol and increased cholesteryl ester hydrolase activity in the liver. The data
suggest that arylsulfonates stimulate cholesterol catabolism, in addition to the reported inhibition of cholesterol absorption
[Lipids 12:819 (1977)].
Published as Journal Paper No. 6699, A.E.S., Purdue University. 相似文献
16.
E. W. Bell L. E. Gast F. L. Thomas R. E. Koos 《Journal of the American Oil Chemists' Society》1977,54(6):259-263
Synthetic wax esters with properties similar to those of sperm whale oil have been prepared entirely from soybean and linseed
oils. the synthesis required: (a) selective hydrogenation of the oils with copper-on-silica gel catalyst, (b) hydrogenolysis
of fatty acids to fatty alcohols with copper-cadmiumchromium catalyst, and (c) esterification of hydrogenolysis products to
yield predominantly long chain fatty esters which contained unsaturation in both the alcohol and acid moieties. Similarity
of physical and chemical properties indicate that these wax esters are possible replacements for sperm oil. After sulfurization,
the wax esters also have potential as extreme pressure lubricant additives. 相似文献
17.
Previous attempts at separating nonpolar lipid esters (including wax esters, sterol esters, and methyl esters) have achieved
only limited success. Among the several normal-phase methods tested, a single recent report of a method employing an alumina
column at 30°C with a binary gradient system was the most promising. In the current study, modification of the alumina method
by increasing the column temperature to 75°C improved the separation of standards of wax esters and sterol esters. Elevated
column temperature also enhanced the separation of FAME with differing degrees of unsaturation. Evidence was also presented
to indicate that the method similarly separated phytosterol esters, based on their levels of unsaturation. With the increased
interest in phytosterol- and phytostanol esterenriched functional foods, this method should provide a technique to characterize
and compare these products. 相似文献
18.
Conversion of oils into gels generally involves altering the chemical characteristics of the liquid. We describe here the
gelling of vegetable oils, essential oils, and hydrocarbons at ambient temperature, without changing the chemical characteristics
of the liquids, using saturated FA having carbon chain lengths of 10 to 31. The gelling ability of the added FA increased
linearly with their chain lengths. Structure-function studies demonstrated that the carboxyl group, position of an additional
hydroxyl group, and acyl chain length played an important role in gelation. Long-chain saturated fatty alcohols, wax esters,
and dicarboxylic acids also had the ability to gel plant oils and hydrocarbons. 相似文献
19.
J. Busson-Breysse M. Farines J. Soulier 《Journal of the American Oil Chemists' Society》1994,71(9):999-1002
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. 相似文献
20.
Picolinyl derivatives are used for structural determination of FA by GC-MS. Although they provide reliable diagnostic fragments,
the usual multistep methodologies applied for their preparation require TAG hydrolysis or acid chloride formation prior to
picolinyl synthesis. These reaction conditions may result in the presence of artifact molecules in the samples and thus compromise
analytical quality and accuracy. To address these problems, a rapid, simple and quantitative methodology for the synthesis
of FA picolinyl esters from intact lipids was developed. It involves their transesterification under basecatalyzed conditions
using 3-potassiooxamethylpyridine in methylene chloride. The catalyst was prepared by proton exchange between potassium tert-butoxide and anhydrous 3-hydroxymethylpyridine. Mild reaction conditions allowed complete derivatization of TAG and phospholipids
in 2 min at room temperature, and of FAME in 15 min at 45°C. The proposed procedure, which can be used on a routine basis,
was applied to Ipomoae imperialis seed lipids and used to confirm occurrence of γ-linoleic acid at a level of 0.9%. 相似文献