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Showing papers in "Lipids in 1986"


Journal ArticleDOI
01 Apr 1986-Lipids
TL;DR: In this article, a comparison of the effects of a polyunsaturated vegetable oil (corn oil) containing linoleate with a fish oil (menhaden oil) derived from linolenic acid showed that higher dietary levels of corn oil increased the yield of DMBA-induced mammary tumors.
Abstract: High fat diets promote the development of mammary tumors induced in rats by 7,12-dimethylbenz(a)anthracene (DMBA), and polyunsaturated fats are more effective than saturated fats. This difference is related to the linoleic acid content of polyunsaturated vegetable oils, but the amount of linoleate required for maximum tumor promotion appears to be higher than indicated by earlier experiments. Comparison of the effects of a polyunsaturated vegetable oil (corn oil) containing linoleate with a fish oil (menhaden oil) containing polyunsaturated fatty acids derived from linolenic acid showed that higher dietary levels of corn oil increased the yield of DMBA-induced mammary tumors, while corresponding levels of menhaden oil had an inhibitory effect. This is further evidence that promotion of mammary tumorigenesis by polyunsaturated vegetable oils may be mediated by prostaglandins or other biologically active eicosanoids derived from n-6 fatty acids.

245 citations


Journal ArticleDOI
01 Sep 1986-Lipids
TL;DR: Fast atom bombardment (FAB) desorption in combination with collisional activation allows for characterization of fragmentation and determination of structural features of the fatty acid chain.
Abstract: Fast atom bombardment (FAB) desorption of phosphatidylserine and various phosphatidylcholines produces a limited number of very informative negative ions Especially significant is the formation of (M-H)− ions for phosphatidylserine, a compound which does not yield informative high mass ions by other ionization methods Phosphatidylcholines of not yield (M-H)− ions but instead produce three characteristic high mass ions, (M-CH 3 + _−, [M-HN(CH3) 3 + ]− and [M-HN(CH3 3 + -C2H2]− Both classes of lipids also yield anions attributed to the carboxylate components of these complex lipids FAB desorption in combination with collisional activation allows for characterization of fragmentation and determination of structural features Collisional activation of the carboxylate anion fragments from the complex lipids is especially informative Structural characterization of the fatty acid chain can be achieved as the released saturated carboxylate anions undergo a highly specific 1,4-elimination of H2, which results in the losses of the elements of CH4, C2H6, C3H8in a fashion entirely consistent with the chemistry of carboxylate anions desorbed from free fatty acids These CnH2n+2 losses begin at the alkyl terminus and progress along the entire alkyl chain Modified fatty acids undergo a similar fragmentation; however, the modification affects the series of CnH2n+2 losses in a manner which permits determining the type of modification and its location on the fatty acid chain

173 citations


Journal ArticleDOI
01 Feb 1986-Lipids
TL;DR: Limited trials showed that the method can be applied satisfactorily to cow's and goat's milks, but for highly pure globules a deeper buffer column than that used with human milk is required because of their much higher casein content.
Abstract: The traditional procedure for isolating milk fat globules involves repeated cycles of centrifuging to obtain globules and redispersion of them in fresh buffer to eliminate other milk components. We have evaluated a simpler, less manipulative method whereby globules are centrifuged out of the milk and through an overlying buffer layer. Human milk samples ranging from 0.1 to 35 ml were centrifuged at 1500×g for 20 min after deposition under a suitable quantity of buffer. This yielded purified globules, in less time, which could be dispersed more satisfactorily than those by the traditional procedure. Protein, phospholipid and cholesterol contents of globules by the two methods were quite similar. A lower protein content (10.4 vs 13.2 mg/g of lipid) was characteristic of globules prepared by the multiple wash method. However, large differences could not be seen in gel electrophoresis patterns of the proteins. By using plastic centrifuge tubes, tube freezing and cleavage just below the globule layer enables clean separation of globule and nonglobule phases for analysis of milk component distributions. Macro (5 to 35 ml of sample) and micro (200 μl or less) versions of the method are described. Limited trials showed that the method can be applied satisfactorily to cow's and goat's milks, but for highly pure globules a deeper buffer column than that used with human milk is required because of their much higher casein content.

165 citations


Journal ArticleDOI
01 Jan 1986-Lipids
TL;DR: The physical data obtained for the adducts provide structural information on the possible mode of crosslinking of proteins and nucleic acids induced by this lipid metabolite.
Abstract: Malondialdehyde reacts readily with amino acids to form adducts containing vinylogous amidine linkages. Crosslinking reactions between nucleic acid bases, and amino acids induced by malondialdehyde also have been investigated. The physical data obtained for the adducts provide structural information on the possible mode of crosslinking of proteins and nucleic acids induced by this lipid metabolite.

146 citations


Journal ArticleDOI
01 Feb 1986-Lipids
TL;DR: Results suggest that the smolt lipid, is involved intimately with either the cause of the dermal lesion or is a defense mechanism, possibly mediated through oxygenase activity.
Abstract: In Atlantic Canada the Atlantic salmonSalmo salar change from the parr stage to the smolt stage while still in fresh water, preparatory to migration to salt water. In some stocks this takes place during the second overwintering. In several hatcheries where the water temperature drops to 0–0.5 C and the ponds ice over, there is a high incidence of erosion of the dorsal and pectoral fins and sometimes of the caudal fin. No disease organism has been identified, and the lesions heal over in most cases. Dietary fatty acids were thought, to be a factor. A detailed study of lipid recoveries and classes has shown that in the skins of abnormal fish the total lipid, is 7.8% compared to 4.7% in control fish.

141 citations


Journal ArticleDOI
01 May 1986-Lipids
TL;DR: The quantitative analysis of phospholipid molecular species containing polyenoic fatty acids is described, and the derivatives of alkenylacyl molecular species from platelet phosphatidylethanolamine were resolved concomitantly with diacyl Molecular species.
Abstract: The quantitative analysis of phospholipid molecular species containing polyenoic fatty acids is described. Dinitrobenzoyl derivatives of diacylglycerols prepared from phospholipids were separated into individual molecular species by reversed-phase high performance liquid chromatography (HPLC) using a combination of two solvent systems and were quantified at 254 nm. Thirty-six molecular species were resolved from the phosphatidylcholines of rat hearts, human platelets and Chinese hamster V79-R cells. The derivatives of alkenylacyl molecular species from platelet phosphatidylethanolamine were resolved concomitantly with diacyl molecular species.

128 citations


Journal ArticleDOI
01 Apr 1986-Lipids
TL;DR: It is suggested that α-tocopherol at high concentrations influences the mechanism of autoxidation of edibleOil under storage conditions and a mechanism in which chromanoxy radical participates is proposed.
Abstract: In order to understand the effect of α-tocopherol on the autoxidation mechanism of edible oil under storage conditions, methyl linoleate was allowed to autoxidize at 50 C in bulk phase without any radical initiator. The reaction was monitored by determining the production of four isomeric hydroperoxides (13-cis,trans; 13-trans,trans; 9-cis,trans; 9-trans,trans) by high performance liquid chromatographic analysis after reduction. In the absence of α-tocopherol, the rate of autoxidation depended on the sample size, and the duration of the induction period was affected by the initial level of hydroperoxides. However, the distribution of c-t and t-t hydroperoxide isomers remained constant during the propagation period regardless of the sample size. The addition of α-tocopherol at 0.1 and 1.0% caused a linear increase in the amount of hydroperoxides and elevated the distribution of the c-t isomers. The rate of hydroperoxidation appeared to be governed by the initial concentration of α-tocopherol rather than the sample size or the initial hydroperoxide level. This peroxidizing effect of α-tocopherol was suppressed by the presence of ascorbyl palmitate. A mechanism in which chromanoxy radical participates is proposed for the effect of α-tocopherol on lipid autoxidation in bulk phase. It is therefore suggested that α-tocopherol at high concentrations influences the mechanism of autoxidation of edible oil.

125 citations


Journal ArticleDOI
01 Apr 1986-Lipids
TL;DR: Total MDA excretion increased in response to conditions which stimulate lipid peroxidation in vivo, including vitamin E deficiency, Fe or CCl4 administration, and enrichment of the tissues with PUFA, as well as in animals fasted or fed MDA-free diets.
Abstract: Interest in malondialdehyde (MDA) metabolism stems from its formation as a product of lipid peroxidation in the diet and in the tissues; its reactivity with functional groups of nucleic acid bases, proteins and phospholipids; its mutagenicity in bacteria, and its reported skin and liver carcinogenicity in animals. Administration of the Na enol salt of MDA in the drinking water of mice over a range of 0.1-10.0 micrograms/g/day for 12 mo produced dose-dependent hyperplastic and neoplastic changes in liver nuclei and increased mortality at the highest level but produced no gross hepatic tumors. Addition of MDA to the medium of rat skin fibroblasts grown in culture caused nuclear abnormalities at concentrations as low as 10(-6) M despite an uptake of only 4%. [1,3-14C]MDA was rapidly oxidized to [14C]acetate in rat liver mitochondria and to 14CO2 in vivo; however, approximately 10% of the radioactivity was recovered in the urine. Chromatographic analysis of rat urine revealed the presence of several compounds which yield MDA on acid hydrolysis. Total MDA excretion increased in response to conditions which stimulate lipid peroxidation in vivo, including vitamin E deficiency, Fe or CCl4 administration, and enrichment of the tissues with PUFA. N-acetyl-e-(2-propenal)lysine was identified as a major urinary metabolite of MDA in rat and human urine. This compound is derived primarily from N-alpha-(2-propenal)lysine released in digestion as a product of reactions between MDA and the epsilon-amino groups of N-terminal lysine residues in food proteins. However, its presence in the urine of animals fasted or fed MDA-free diets indicates that it is also formed in vivo.(ABSTRACT TRUNCATED AT 250 WORDS)

117 citations


Journal ArticleDOI
01 Nov 1986-Lipids
TL;DR: The results of these analyses suggest that even when the traditional Aboriginal diet contained a high proportion of animal foods it would have been low in fat with a highportion of PUFA and thereby could have protected Aborigines against cardiovascular diseases and related conditions through a combination of factors: low energy density, low saturated fat and relatively high PUFA content.
Abstract: Australian Aborigines develop high frequencies of diabetes and cardiovascular diseases when they make the transition to an urban lifestyle. The composition of the traditional diet, particularly its lipid components, is a most important aspect of the hunter-gatherer lifestyle that would bear on the risk of these diseases. We have examined the fat content and fatty acid composition of a variety of animal foods eaten traditionally by Aborigines from different regions of Australia. The muscle samples of the wild animals from all over Australia were uniformly low in fat (less than 2.6% wet weight) with a high proportion of polyunsaturated fatty acids (greater than or equal to 20% PUFA). Liver samples had a higher range of fat content (5-10% wet weight) but were also rich in PUFA (33-42%). Depot fat samples varied widely in their PUFA content (5-40%). In terms of their PUFA composition the foods tended to fall into three groups: (i) those rich in both n-3 and n-6 PUFA, which included land-based, coastal and freshwater animals; (ii) those rich in n-3 PUFA, i.e., marine species; (iii) those rich in n-6 PUFA, mainly land-based species. The results of these analyses suggest that even when the traditional Aboriginal diet contained a high proportion of animal foods it would have been low in fat with a high proportion of PUFA and thereby could have protected Aborigines against cardiovascular diseases and related conditions through a combination of factors: low energy density, low saturated fat and relatively high PUFA content.

109 citations


Journal ArticleDOI
01 Oct 1986-Lipids
TL;DR: The pyrrolidide and picolinyl ester derivatives of the fatty acids in two natural lipid samples rich in unsaturated fatty acids, pig testis lipids and cod liver oil were satisfactorily resolved on capillary columns of fused silica coated with stationary phases of varying polarity.
Abstract: The pyrrolidide and picolinyl ester derivatives of the fatty acids in two natural lipid samples rich in unsaturated fatty acids, pig testis lipids and cod liver oil were satisfactorily resolved on capillary columns of fused silica coated with stationary phases of varying polarity. The picolinyl esters, in particular, when subjected to gas chromatography-mass spectrometry on a column containing a cross-linked methyl silicone, gave distinctive mass spectra, which could be interpreted in terms of both the numbers and positions of the double bonds.

102 citations


Journal ArticleDOI
01 Dec 1986-Lipids
TL;DR: The results suggest that TBA value as an index of lipid peroxides in the lungs of animals may be regulated mainly by the contents of VE and NPSH, the composition ratio and the reactivity of each polyunsaturated fatty acid in lung phospholipid fraction.
Abstract: Marked species differences in thiobarbituric acid reactant value (TBA value) in normal lung tissue of five species of animals were found. The order of the values was mouse greater than hamster greater than rat greater than guinea pig greater than rabbit, and the value for mice was 3.6 times higher than that for rabbit. The vitamin E (VE) and nonprotein sulfhydryls (NPSH) contents in lungs varied widely among the five animal species. Species differences were also observed on polyunsaturated fatty acid composition in lung phospholipids. The peroxidizability index (PI), which shows the relative rate of peroxidation reaction, was calculated from the composition ratio and the reactivity of each polyunsaturated fatty acid, and the PI was found to be significantly correlated to the TBA value in lungs (r = 0.853, p less than 0.001). The PI value was normalized by the contents of VE and/or NPSH. Finally, the log-value of PI, normalized by the log values of the reciprocals of VE and NPSH, log(PI/VE X NPSH), showed the highest correlation coefficient (r = 0.907, p less than 0.001). Normalization by the activities of antioxidative protective enzymes in lungs did not show any significant correlation against TBA value. These results suggest that TBA value as an index of lipid peroxides in the lungs of animals may be regulated mainly by the contents of VE and NPSH, the composition ratio and the reactivity of each polyunsaturated fatty acid in lung phospholipid fraction.

Journal ArticleDOI
01 Oct 1986-Lipids
TL;DR: The results showed that animals fed higher proportions of POL consistently contained higher levels of dihomo-γ-linolenic acid (DGLA) and lower levels of arachidonic acid (AA), suggesting that EPA but not DHA in fish oil exerts an inhibitory effect on the conversion of DGLA to AA.
Abstract: The interrelations between linoleic acid (LA) metabolites and fish oil fatty acids were studied. Sprague-Dawley rats (200-220 g) were fed a fat-free semisynthetic diet supplemented with 10% (by weight) of different combinations of evening primrose oil (EPO), a rich source of LA and gamma-linolenic acid, and polepa (POL), a marine oil rich in eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids. The combinations of supplement were as follows: 9% EPO-1% POL, 8% EPO-2% POL, 7% EPO-3% POL, 6% EPO-4% POL and 5% EPO-5% POL. After two weeks on the respective diets, the animals were killed, and the fatty acid compositions of liver and plasma phospholipids were examined. The results showed that animals fed higher proportions of POL consistently contained higher levels of dihomo-gamma-linolenic acid (DGLA) (p less than 0.05), a metabolite of LA and GLA, and lower levels of arachidonic acid (AA) (p less than 0.01), a metabolite of DGLA through delta-5-desaturation. Thus, an inverse relationship between AA/DGLA ratio and EPA levels was found to exist (r = -0.765 in plasma and -0.792 in liver). However, there was no such relationship between AA/DGLA ratio and DHA levels. This result suggested that EPA but not DHA in fish oil exerts an inhibitory effect on the conversion of DGLA to AA.

Journal ArticleDOI
01 Jan 1986-Lipids
TL;DR: Results obtained indicate a primary effect of mevinolin on phytosterol accumulation, whereas other endproducts of the multibranched isoprenoid pathway, such as ubiquinone in the mitochondria or chlorophylls and carotenoids in the plastids, are less or not at all affected.
Abstract: Hydroxymethylglutaryl-CoA reductase (HMGR) regulates the synthesis of mevalonic acid (MVA), the precursor of the myriad of isoprenoid compounds functional in plant cells, with phytosterols representing one class of major importance. Recently, it has shown possible to solubilize and purify the membrane-bound enzyme from a heavy membrane fraction (P 16,000×g) isolated from a cell-free homogenate of etiolated radish seedlings. What is presently known about the molecular and kinetic properties of radish HMGR is reported. Mevinolin, a highly specific competitive inhibitor of HMGR, has been valuable as a research tool in studying the regulatory role of HMGR activity for the growth and development of intact seedlings and cell cultures. The results obtained indicate a primary effect of mevinolin on phytosterol accumulation, whereas other endproducts of the multibranched isoprenoid pathway, such as ubiquinone in the mitochondria or chlorophylls and carotenoids in the plastids, are less or not at all affected. This and other data can be interpreted to mean that the organelles are autonomous in their capacity to synthesize MVA. Since the mevinolin-induced drop in free sterol accumulation is paralleled by significant plant growth retardation, a rate-limiting role of HMGR activity for phytosterol synthesis and normal development of plants is suggested.

Journal ArticleDOI
01 Nov 1986-Lipids
TL;DR: Rats fed rice bran oil at 10% level for a period of eight weeks showed significantly lower levels of total cholesterol, low density lipoprotein and very low density cholesterol, both on cholesterol-containing and cholesterol-free diets.
Abstract: Rats fed rice bran oil at 10% level for a period of eight weeks showed significantly lower levels of total cholesterol, low density lipoprotein and very low density lipoprotein cholesterol, both on cholesterol-containing and cholesterol-free diets. High density lipoprotein cholesterol was increased but triglyceride showed a decrease that was not statistically significant. Liver cholesterol and liver triglycerides were also reduced. Fecal excretion of neutral sterols and bile acids was increased after ingestion of rice bran oil.

Journal ArticleDOI
01 Jan 1986-Lipids
TL;DR: 2-aza-2,3-dihydrosqualene and its derivatives strongly inhibited the cyclases, the site of the enzyme responsible for binding to the inhibitor is quite sensitive to the steric hindrance, and the degree of the inhibitory activity is greater in higher plants than in rat liver or fungi.
Abstract: The 2,3-oxido squalene (SO) cyclases represent a group of enzymes which convert SO into polycyclic triterpenoids such as lanosterol, cycloartenol, cucurbitadienol and beta-amyrin Taking into account the postulated model of the enzymatic cyclization of SO, we have investigated the possibility of designing compounds that would be selective and potent inhibitors of SO cyclases Due to the fundamental role of sterols in animal, higher plant and fungal tissues, these inhibitors might behave as very selective (ipocholesterolemic, antifungal or phytotoxic) drugs Our first approach was the synthesis and biological evaluation of 2-aza-2,3-dihydrosqualene and its derivatives which, being protonated at physiological pH, would present some similarities to the C-2 carbon ion generated by the opening of the oxirane ring of SO Microsomes from different sources (germinated pea cotyledons, maize seedlings, rat liver and yeasts) were utilized to determine the inhibition values (I50: concentration of inhibitor producing 50% inhibition at a given substrate concentration) From the results obtained so far we conclude that 2-aza-2-dihydrosqualene and its derivatives strongly inhibited the cyclases, the site of the enzyme responsible for binding to the inhibitor is quite sensitive to the steric hindrance, and the degree of the inhibitory activity is greater in higher plants than in rat liver or fungi

Journal ArticleDOI
01 Dec 1986-Lipids
TL;DR: The low incidence of cardiovascular disease in Greenland Eskimos appears to be due to their high intake of seal, whale and fish, and n-3 fatty acids are considered essential dietary components since they cannot be synthesized in the body and appear necessary for normal vision and probably other body functions.
Abstract: The low incidence of cardiovascular disease in Greenland Eskimos appears to be due to their high intake of seal, whale and fish. The lipids of these marine animals lower serum triglyceride and cholesterol levels and help to prevent blood clotting. The latter effect has been related to a change in the balance of prostacyclin and thromboxane as a result of replacing n-6 polyunsaturated fatty acids in the body by n-3 polyunsaturated fatty acids present in marine lipids. Dietary fish oils have also been shown to inhibit development of mammary, pancreatic, intestinal and prostatic tumors in experimental animals. This effect may likewise be due to changes in the production of prostaglandins or related compounds. The involvement of prostaglandins and leukotrienes in immune responses has led to studies on the effects of fish oil on various chronic diseases associated with abnormalities of the immune system. Some of these diseases, such as multiple sclerosis and psoriasis, are also relatively uncommon in Eskimos. Preliminary results of these studies are encouraging, but more work is required to assess the usefulness of dietary fish oils in treatment of these diseases. In addition to their apparent therapeutic value, n-3 fatty acids are considered essential dietary components since they cannot be synthesized in the body and appear necessary for normal vision and probably other body functions.

Journal ArticleDOI
01 Jan 1986-Lipids
TL;DR: The potent inhibitors described are powerful tools to control in vivo the sterol profile of plant cells and therefore to study the structural and functional roles of sterols in cell membranes and could be of value in plant protection.
Abstract: Several enzymes of plant sterol biosynthesis involve during their catalysis postulated or demonstrated carbocationic high energy intermediates (HEI). The aim of this study was to interfere with plant sterol biosynthesis by means of rationally designed species able to mimic these carbocationic HEI. It has been demonstrated previously that the design of transition state (TS) or HEI analogues could lead to powerful and specific inhibitors of enzymes. We applied this approach to the following target enzymes: 2,3-epoxy-2,3-dihydroqualene cyclase, AdoMet-cycloartenol-C-24-methyltransferase (AdoMet CMT), cycloeucalenol-obtusifoliol isomerase (COI) and Δ8-Δ7-sterol isomerase. Very potent inhibitors have been obtained in the four cases. As an example, analogues of cycloartenol substituted at C-25 by a charged heteroatom (N, As, S) have been synthesized and shown to be able to mimic the C-25 carbocationic HEI involved in the reaction catalyzed by the AdoMet CMT. These compounds were shown to be very potent and specific inhibitors of this enzyme both in vitro (Ki=2.10−8 M, Ki/Km=10−3) and in vivo. The potent inhibitors described are powerful tools to control in vivo the sterol profile of plant cells and therefore to study the structural and functional roles of sterols in cell membranes. Moreover, these compounds constitute leader molecules of a new class of rationally designed inhibitors which could be of value in plant protection.

Journal ArticleDOI
01 Apr 1986-Lipids
TL;DR: The data suggest that caloric intake is a more stringent determinant of tumor growth than fat intake.
Abstract: The experiments reported are part of our effort to dissociate the tumor-enhancing effects of dietary fat and high caloric intake. Rats either were fed ad libitum diets containing 4% corn oil or their calories were restricted by 40% and their diets contained 13.1% corn oil. Incidence of 7,12-dimethylbenz(a)anthracene (DMBA)-induced mammary tumors was 80% in rats fed ad libitum and 20% in those fed the calorie-restricted diets. Incidence of 1,2-dimethylhydrazine (DMH)-induced colon tumors was 100% in rats fed ad libitum and 53% in those whose caloric intake was restricted by 40%. The tumor yield (tumors per tumor-bearing rat) was significantly lower in rats on caloric restriction. In another series, rats were fed diets containing 5, 15 or 20% corn oil ad libitum or were fed calorie-restricted (by 25%) diets which provided 20 or 26.6% corn oil (therefore, the same absolute amount of fat was consumed in each of the pair-fed groups). Tumor incidence and tumor yield in the two calorie-restricted groups were similar to those seen in the rats fed 5% fat ad lititum; tumor burden (total g of tumor) was 45–65% lower in the calorie-restricted rats. The data suggest that caloric intake is a more stringent determinant of tumor growth than fat intake.

Journal ArticleDOI
01 Jan 1986-Lipids
TL;DR: In this paper, the configurations of C-24 of the alkylsterols were examined by high resolution(1)H NMR and(13)C NMR spectroscopy.
Abstract: The major sterols of the seeds ofBenincasa cerifera, Cucumis sativus, Cucurbita maxima, C. pepo andTrichosanthes japonica and of the mature plant tissues (leaves and stems) ofCitrullus battich, Cucumis sativus andGynostemma pentaphyllum of the family Cucurbitaceae were 24-ethyl-Δ(7)-sterols which were accompanied by small amounts of saturated and Δ(5)-and Δ(8)-sterols. The 24-ethyl-Δ(7,22),Δ(7,25(27)) and Δ(7,22,25(27))-sterols constituted the predominant sterols for the seed materials, whereas the 24-ethyl-Δ(7) and Δ(7,22)-sterols were the major ones for the mature plant tissues. The configurations of C-24 of the alkylsterols were examined by high resolution(1)H NMR and(13)C NMR spectroscopy. Most of the 24-methyl- and 24-ethylsterols examined which lack a Δ(25(27))-bond (i.e., 24-methyl-, 24-methyl-Δ(22)-, 24-ethyl- and 24-ethyl-Δ(22) sterols) were shown to occur as the C-24 epimeric mixtures in which the 24α-epimers predominated in most cases. The 24-ethylsterols which possess a Δ(25(27)) (i.e., 24-ethyl-Δ(25(27))-and 24-ethyl-Δ(7,22,25(27))-sterols) were, on the other hand, composed of only 24β-epimers. The Δ(8)-sterols identified and characterized were four 24-ethyl-sterols: 24α-and 24β-ethyl-5α-cholesta-8,22-dien-3β-ol, 24β-ethyl-5α-cholesta-8,25(27)-dien-3β-ol and 24β-ethyl-5α-cholesta-8,22,25(27)-trien-3β-ol. This seems to be the first case of the detection of Δ(8)-sterols lacking a 4-methyl group in higher plants, and among the four Δ(8)-sterols the latter two are considered to be new sterols. The probable biogenetic role of the Δ(8)-sterols and the possible biosynthetic pathways leading to the 24α- and 24β-alkylsterols in Cucurbitaceae are discussed.

Journal ArticleDOI
01 Jan 1986-Lipids
TL;DR: Results imply that a critical mass of sterol is associated with sorghum for floral induction, reaching a plateau level that surpassed the sterol content as flowering progressed.
Abstract: Sterol composition and biosynthesis have been examined in seeds, germinating seeds and blades from fally matured leaves ofSorghum bicolor in various stages of development'from seedlings (seven-day plants) to flowering (66-day) plants. The profile of the dominant free sterols of seeds was similar to that of leaf blades; both contained cholesterol, 24α-methylcholesterol (campesterol), 24β-methylcholesterol (dihydrobrassicasterol), 24α-ethylcholesterol (sitosterol) and 24α-ethylcholesta-5,22-dienol (stigmasterol). Sufficient sterol intermediates were identified in the plant to indicate separate post-cycloartenol pathways to sterolic end products. The total free sterol content of the seed (μg/seed) increased somewhat during the 20 hr germination period. However, as the plant developed (seven to 48 days), there was a logarithmic increase in the leaf blade sterol content (μg/leaf blade) which plateaued at the onset of floral differentiation (ca. day 41). Over the next 18 days (48 to 66 days-period of inflorescense development), the sterol content rapidly decreased. In the early stages of plant development, the leaf blade pentacyclic triterpenoid (PT) content was negligible. With the onset of floral differentiation, PT content increased logarithmically, reaching a plateau level that surpassed the sterol content as flowering progressed. These results imply that a critical mass of sterol is associated with sorghum for floral induction. Sterol loss from the leaves of the flowering plants presumably was compensated for by the diversion of 2,3-oxidosqualene (SO) from sterol synthesis to PT production. Additional feeding and trapping experiments with [2-(14)C]mevalonic acid, [2-(3)H]cycloartenol, [24-(3)H]lanosterol [4-(14)C]sitosterol and [4-(14)C]cholesterol fed to germinating seeds and leaves from flowering plants demonstrated that sorghum possessed a cycloartenolbased pathway; germinating seeds synthesized 24-alkylsterols but not cholesterol, although cholesterol was identified in both dry and germinating seeds by gas chromatography-mass spectroscopy (GC-MS); and mature leaves synthesized cholesterol and 24α-alkylsterols but not 24β-methylcholesterol.

Journal ArticleDOI
01 Jun 1986-Lipids
TL;DR: The products of cholesterol autoxidation (oxysterols) in heated animal food fat were determined qualitatively and quantitatively to evaluate their toxicity and those of the foods in which they occur.
Abstract: The products of cholesterol autoxidation (oxysterols) in heated animal food fat were determined qualitatively and quantitatively to evaluate their toxicity and those of the foods in which they occur. Samples of beef tallow were taken from deep-fat fryers while they were in use. The oxysterols were identified and assayed by gas liquid chromatography and thin layer chromatography on Chromarods with flame ionization detection (TLC-FID). The two methods were compared and the TLC-FID method was found more convenient for a rapid estimation of autoxidation. Of the original cholesterol, 25% was destroyed during cooking and partly transformed into 3β-5-6β-trihydroxy-5α-cholestane, 7α-hydroxy-, 7β-hydroxy-, 7-oxo-cholesterol, 7-oxo-cholesta-3-5-diene and cholesterol epoxides. Certain other oxysterols were present in smaller quantities.

Journal ArticleDOI
01 Feb 1986-Lipids
TL;DR: The results show that the LMW compounds fromMLHPO autoxidation are more easily absorbed in rat tissues than polymer and MLHPO.
Abstract: To study the toxicity of low molecular weight (LMW) compounds formed during the autoxidation of oils,14C-labeled primary monomeric compounds (methyl linoleate hydroperoxides) and secondary oxidation products, i.e., polymer and LMW compounds prepared from autoxidized methyl [U-14C]linoleate hydroperoxides (MLHPO) were orally administered to rats, and their radioactive distributions in tissues and organs were compared. The polymeric fraction consisted mainly of dimers of MLHPO. For the LMW fraction, 4-hydroxy-2-nonenal, 8-hydroxy methyl octanoate and 10-formyl methyl-9-decenoate were identified as major constituents by gas chromatography-mass spectrometry (GC-MS) after chemical reduction and derivatization. When LMW compounds were administered to rats,14CO2 expiration and the excreted radioactivity in urine in 12 hr were significantly higher than those from polymer or MLHPO administration. Maximum14CO2 expiration appeared 2–4 hr after the dose of LMW compounds. Radioactivity of the upper part of small intestines six hr after the dose of LMW compounds was higher than the values from administered polymer or MLHPO. The remaining radioactivity in the digestive contents and feces 12 hr after administration of LMW compounds was much lower than the values observed from administered polymer or MLHPO. Among internal organs, the liver contained the highest concentration of radioactivities from polymer, MLHPO and LMW fractions, and an especially higher level of radioactivity was found in liver six hr after the administration of LMW compounds. Six hours after the dose of LMW compounds, a relatively higher level of radioactivity also was detected in kidney, brain, heart and lung. These results show that the LMW compounds from MLHPO autoxidation are more easily absorbed in rat tissues than polymer and MLHPO.

Journal ArticleDOI
01 May 1986-Lipids
TL;DR: In this paper, the authors used fast atom bombardment (FAB) and tandem mass spectrometry (MS-MS) to distinguish between straight chain and anteiso-branched fatty acids.
Abstract: Branched fatty acids can be distinguished from isomeric straight chain fatty acids by collisionally activating the (M-H)− ions desorbed by using fast atom bombardment (FAB) mass spectrometry (MS). In particular, an acid with iso- fatty branching can be readily distinguished from one containing anteiso- branching; the latter undergoes loss of the elements of CH4 and C2H6 but not C3H8. These decompositions are another example of remote charge site fragmentation. Mixtures of homologs and isomers can be investigated by using the combination of FAB and tandem mass spectrometry (MS-MS).

Journal ArticleDOI
01 Jun 1986-Lipids
TL;DR: It is suggested that the plasma cholesteryl and plant steryl esters in phytosterolemia originate from both synthesis in plasma via the lecithin-ch cholesterol acyl transferase and synthesis in tissues via the acylCoA-cholesterol acyltransferase.
Abstract: The bulk of the plasma plant sterol in phytosterolemia occurs in the esterified form and is carried mostly in the low and high density lipoproteins We have determined the fatty acid composition of the individual plasma steryl esters from a newly discovered subject with phytosterolemia and xanthomatosis For this purpose the intact steryl esters were subject to high temperature gas liquid chromatography (GLC) on a polar capillary column, which separated the major esters on the basis of molecular weight and degree of unsaturation of the fatty acids The saturated and unsaturated sterols esterified to saturated, monoenoic, dienoic and tetraenoic fatty acids were identified by GLC analysis of the sterol moieties of the corresponding AgNO3-TLC fractions of the steryl esters The GLC results were confirmed by reversed phase high performance liquid chromatography combined with mass spectrometry via direct liquid inlet interface It was found that, in general, each fatty acid was esterified to the same complement of sterols, and that the esterified sterols possessed a composition comparable to that of the free plasma sterols, which was comprised of about 75% cholesterol, 6% campesterol, 4% 22,23-dihydrobrassicasterol and 15% β-sitosterol The fatty acid composition of the steryl esters differed from that of the 2-position of the plasma phosphatidylcholines, which contained significantly less palmitic and oleic and more linoleic acid On the basis of these results and a review of the literature it is suggested that the plasma cholesteryl and plant steryl esters in phytosterolemia originate from both synthesis in plasma via the lecithin-cholesterol acyltransferase and synthesis in tissues via the acylCoA-cholesterol acyltransferase

Journal ArticleDOI
01 Apr 1986-Lipids
TL;DR: It was concluded that the reactions of the mushroom hydroperoxide lyase cannot be explained by the heterolytic rearrangement mechanism, which was proposed for the corresponding plant enzyme.
Abstract: The pathway for the oxidative cleavage of linolenic acid was investigated using a protein fraction from mushrooms (Psalliota bispora) as the enzyme source. Incubation of the protein fraction with linolenic acid resulted in 1,Z-5-octadien-3(R)-ol and Z-2,Z-5-octadien-1-ol (in a 3∶2 ratio) and 10-oxo-E-8-decenoic acid (10-ODA). Experiments with molecular oxygen-18 indicated that the oxygen in the hydroxy group of both octadienols originates from the gaseous phase and not from water. The protein fraction was incubated with the individual 9-, 10-, 12-, 13-, 15- and 16-hydroperoxide isomers of linolenic acid. Only the 10-hydroperoxy-E-8,Z-12,Z-15-octadecatrienoic acid (10-HPOT) served as substrate, and was cleaved into the two octadienols and the 10-ODA. This result suggests that in the oxidation of linolenic acid by the mushroom fraction the 10-HPOT is an intermediate cleaved by a hydroperoxide lyase into the octadienols and the 10-ODA. Model experiments in which the methyl esters of both 10-hydroperoxy-E-8,Z-12-octadecadienoic acid (10-HPOD) and 10-HPOT were treated with the Lewis acid BF3 yielded only various C9 compounds. It was therefore concluded that the reactions of the mushroom hydroperoxide lyase cannot be explained by the heterolytic rearrangement mechanism, which was proposed for the corresponding plant enzyme. β-Scission of the 10-HPOD and the 10-HPOT explains the reactions of the mushroom hydroperoxide lyase and is discussed in detail.

Journal ArticleDOI
01 Jan 1986-Lipids
TL;DR: The measured fatty acid content in the total phospholipids derived from the plasma, red cells, buffy coat cells, neutrophils, monocytes and lymphocytes of 27 allergic patients and 21 normal controls suggest that atopic leukocytes may have altered essential fatty acid metabolism.
Abstract: We previously have found that monocytes from patients with allergic rhinitis and/or asthma produce less PGE2 than cells from normal subjects in response to a histamine-induced lymphokine. In order to investigate this observation further, we measured the fatty acid content in the total phospholipids derived from the plasma, red cells, buffy coat cells, neutrophils, monocytes and lymphocytes of 27 allergic patients and 21 normal controls. There were no substantial differences between atopics and normals in the fatty acid analyses carried out for plasma and red cells. However, linoleic acid (18∶2n−6) levels were elevated significantly in the buffy coat fraction, while arachidonic acid (20∶4n−6) levels were reduced. Measurement of fatty acid levels after fractionation of the buffy coat population into neutrophils and monocytes yielded similar elevations in 18∶2n−6 and reduced 20∶4n−6. In contrast, lymphocytes appeared to have the reverse pattern, i.e., significantly reduced 18∶2n−6 and elevated 20∶4n−6 levels. These data suggest that atopic leukocytes may have altered essential fatty acid metabolism.

Journal ArticleDOI
01 Jan 1986-Lipids
TL;DR: Results support the supposition that oxysterols may regulate sterol biosynthesis at the cellular level and include the inhibitory effects of 9α, 11α-epoxycholest-7-en-3β-ol cholest
Abstract: As a class of compounds, oxysterols have demonstrated a wide variety of biological properties. Due to the general interest in these compounds, new methods of chemical synthesis have been developed to provide them for biological investigation. The specific inhibition by oxysterols of cholesterol biosynthesis in mammalian cells has been shown to result primarily from a decrease in cellular levels of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase activity. Recent evidence suggests these cellular responses may be mediated by an oxysterol binding protein found in the cytosol of many lines of cultured cells. In certain instances, oxysterols have been shown to be produced in biological systems. These results support the supposition that oxysterols may regulate sterol biosynthesis at the cellular level. Included herein are the inhibitory effects of 9α, 11α-epoxycholest-7-en-3β-ol cholest-8-en-3β-ol-7-one and cholest-8-en-3β-ol-11-one on HMG-CoA reductase activity and their relative affinities for a cytosolic binding protein.

Journal ArticleDOI
01 Feb 1986-Lipids
TL;DR: Dietary BC increased A and E levels in liver and in the mitochondrial and lysosomal fractions while the plasma E level was decreased, and the increase in E resulted in a large increase in the molar ratio of E to polyunsaturated fatty acids.
Abstract: Studies were conducted examining the subcellular distribution of β-carotene (BC), α-tocopherol (E) and retinol (A) in livers of control and BC-fed male White Leghorn chicks. Chicks were fed Cornell B chick starter diet with or without the addition of 0.5 g BC/kg diet. A first study involved liver fractionation by differential centrifugation in 0.25 M sucrose followed by high performance liquid chromatographic (HPLC) analyses of all fractions for quantitation of BC, E and A. A second study employed both intravenous injection of Triton WR-1339 four days prior to sacrifice and centrifugation in 1.0 M sucrose to separate mitochondria from lysosomes more efficiently. Fraction purity was assessed by marker enzyme analyses. Results showed that (i) chick liver accumulated BC; (ii) BC-fed chicks had higher concentrations of BC in all fractions relative to controls, and (iii) the mitochondrial fraction contained the highest concentration of BC, followed by lysosomes, microsomes and nuclei, respectively. Plasma BC increased more than fivefold in BC-fed chicks. Dietary BC increased A and E levels in liver and in the mitochondrial and lysosomal fractions while the plasma E level was decreased. Plasma A changed little with BC feeding. While dietary BC had no effect on fatty acid composition of subcellular fractions, the increase in E resulted in a large increase in the molar ratio of E to polyunsaturated fatty acids. The incorporation of BC and increased amounts of E into cellular mebranes presumably would result in increased resistance to peroxidative damage.

Journal ArticleDOI
01 Nov 1986-Lipids
TL;DR: It is suggested that dietary 18∶3ω3 can modulate the level of precursor of diene prostaglandins (PG) but not that of triene PG in the rat brain, and imply that dietary 19∶2ω6 and eicosatrienoic acid are rapidly converted mainly to 22∶6ω3 without being accumulated.
Abstract: Weanling male rats were fed hydrogenated coconut oil to induce essential fatty acid (EFA) deficiency. After 15 weeks, the rats were divided into six groups. Five groups were fed graded amounts of purified linolenate (18∶3ω3) with a constant amount of linoleate (18∶2ω6) for six weeks. Fatty acid composition was determined in brain lipids. Increasing dietary 18∶3ω3 resulted in a decrease in arachidonic acid (20∶4ω6), docosatetraenoic acid (22∶4ω6) and docosapentaenoic acid (22∶5ω6), whereas 18∶2ω6 and eicosatrienoic acid (20∶3ω6) were increased both in total lipids and phospholipids. These results suggest that dietary 18∶3ω3 exerts its inhibitory effect mainly on the desaturation of 20∶ω6 to 20∶4ω6 in brain lipids. Linolenate was undetectable in brain lipids from any dietary treatments. The levels of eicosapentaenoic acid (20∶5ω3) in groups receiving dietary 18∶3ω3 were not different from that of the group receiving no 18∶3ω3. These results indicate that, in the brain, 18∶3ω3 is rapidly converted mainly to 22∶6ω3 without being accumulated and imply that dietary 18∶3ω3 can modulate the level of precursor of diene prostaglandins (PG) but not that of triene PG in the rat brain.

Journal ArticleDOI
01 Dec 1986-Lipids
TL;DR: This study shows that the hypolipidemic drug clofibrate induces the lauric acid ω-hydroxylase activity in Vicia and soybean seedlings, and suggests that cl ofibrates induces preferentially the l Lauric acidπ�-Hydroxylating isozyme in plants.
Abstract: Recently, we have found in plant microsomes two laurate hydroxylases that catalyze the terminal hydroxylation or the in-chain hydroxylation of the fatty acid. These two hydroxylases, which are both cytochrome P-450 enzymes, are never found in the same plant. This study shows that the hypolipidemic drug clofibrate induces the lauric acid ω-hydroxylase activity inVicia and soybean seedlings. The marked increase in activity (>20-fold) produced by clofibrate was dose-dependent but was not paralleled by an enhancement of bulk cytochrome P-450 or cinnamic acid 4-hydroxylase. Compounds related to clofibrate by structure (2,4-dichlorophenoxyacetic acid) or effects (diethylhexyl-phthalate) also stimulated the ω-hydroxylating system in these plants. In contrast, the lauric acid in-chain hydroxylase from Jerusalem artichoke tubers was induced less than cinnamic acid 4-hydroxylase activity and bulk cytochrome P-450 in tissues incubated in clofibrate solution. This suggests that clofibrate induces preferentially the laurate ω-hydroxylating isozyme in plants.