Cutins of Malus pumila fruits and leaves

The cutins of fruits and leaves of four apple cultivars have been analysed using TLC, GLC and GC-MS. They are similarly composed of saturated, monounsaturated and diunsaturated fatty, hydroxy-fatty and epoxyhydroxy-fatty acids. The most abundant monomers are 18-hydroxyoctadeca-9,12-dienoic, 10,16-dihydroxyhexadecanoic, 9,10-epoxy-18-hydroxyoctadec-12-enoic, 9,10-epoxy-18-hydroxyoctadecanoic and 9,10,18-trihydroxyoctadecanoic acids. The fruit cutins have high contents of epoxides (35–40%) and unsaturated components ( > 40%) and C₁₈ compounds predominate over C₁₆. The leaf cutins contain smaller amounts of unsaturated components than the fruits and higher proportions of C₁₆ compounds. The adaxial leaf cutin differs in composition from the abaxial. 10,16-Dihydroxyhexadecanoic and 9,10-epoxy-18-hydroxoctadecanoic acids are the major constituents (each ca. 30%) of the adaxial leaf cutin and 10,16-dihydroxyhexadecanoic acid (55–65%) predominates in the abaxial.     

Epoxyoctadecanoic acids in plant cutins and suberins

Three C₁₈ epoxy acids occur in plant cutins and suberins. 9,10-Epoxy-18-hydroxyoctadecanoic acid is a common constituent of both cutins and suberins whilst 9,10-epoxy-18-hydroxyoctadec-12-enoic acid is also present in some cutins. 9,10-Epoxyoctadecane-1,18-dioic acid occurs more commonly in suberins. Epoxy acids may comprise up to 60% of the total monomers obtained from some polymers. The epoxy compounds are readily converted into their corresponding alkoxyhydrin alkyl esters on depolymerization of cutin or suberin by alcoholysis. The chromatographic and MS properties of the alkoxyhydrin derivatives enable them to be readily distinguished from other cutin and suberin hydroxyfatty acids and to be used for the qualitative and quantitative determination of epoxy acids in the polymers.     

Reaction of hematin with allylic fatty acid hydroperoxides: identification of products and implications for pathways of hydroperoxide-dependent epoxidation of 7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene

Reaction of 10-hydroperoxyoctadec-8-enoic acid (10-OOH-18:1) (50 microM) with hematin (0.5 microM) in sodium phosphate buffer containing Tween 20 (200 microM) generates 10-oxooctadec-8-enoic acid, 10-oxodec-8-enoic acid (10-oxo-10:1), and 10-hydroxyoctadec-8-enoic acid in relative yields of 79, 4, and 17%, respectively. The product profile and relative distribution are unaffected by 1 mM butylated hydroxyanisole. Approximately 5% of the hydroperoxide isomerizes from the 10- to the 8-position. 10-Oxo-10:1 most likely arises via beta-scission of an intermediate alkoxyl radical to the aldehyde and the n-octyl radical. To test this, 10-hydroperoxyoctadeca-8,12-dienoic acid was reacted with hematin under identical conditions. 10-Oxooctadeca-8,12-dienoic acid, 10-oxodec-8-enoic acid, and 10-hydroxyoctadeca-8,12-dienoic acid are formed in relative yields of 50, 45, and 5%, respectively. The product ratios are constant with time and hydroperoxide to catalyst ratio and unaffected by inclusion of phenolic antioxidants. The higher yield of 10-oxo-10:1 from 10-OOH-18:2 compared to 10-OOH-18:1 is due to the higher rate of beta-scission of the intermediate alkoxyl radical from the former to the resonance-stabilized octenyl radical. Two products of reaction of the 2-octenyl radical with O2, octenal and octenol, were detected in 10% yield relative to 10-oxo-10:1. Inclusion of 7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene (BP-7,8-diol) led to epoxidation by both 10-OOH-18:1 and 10-OOH-18:2. Studies with isotopically labeled hydroperoxide or O2 indicated approximately 65% of the epoxide oxygen was derived from O2 and 35% from hydroperoxide oxygen, consistent with the involvement of peroxyl free radicals as the oxidizing agents. The available evidence indicates that hematin reduces the fatty acid hydroperoxides homolytically to alkoxyl radicals that are oxidized to ketones, reduced to alcohols, or undergo beta-scission to aldehydes. Carbon radicals generated during these reactions couple to O2, generating peroxyl free radicals that epoxidize BP-7,8-diol. The smaller percentage of epoxidation that results from hydroperoxide oxygen may arise from oxidation of the hydroperoxide group to peroxyl radicals or from heterolytic cleavage of the hydroperoxide to alcohol and an iron-oxo complex.     

Determination of structure and composition of suberin from the roots of carrot, parsnip, rutabaga, turnip, red beet, and sweet potato by combined gas-liquid chromatography and mass spectrometry

Suberin from the roots of carrots (Daucus carota), parsnip (Pastinaca sativa), rutabaga (Brassica napobrassica), turnip (Brassica rapa), red beet (Beta vulgaris), and sweet potato (Ipomoea batatas) was isolated by a combination of chemical and enzymatic techniques. Finely powdered suberin was depolymerized with 14% BF₃ in methanol, and soluble monomers (20-50% of suberin) were fractionated into phenolic (<10%) and aliphatic (13-35%) fractions. The aliphatic fractions consisted mainly of ω-hydroxyacids (29-43%), dicarboxylic acids (16-27%), fatty acids (4-18%), and fatty alcohols (3-6%). Each fraction was subjected to combined gas-liquid chromatography and mass spectrometry. Among the fatty acids very long chain acids (>C₂₀) were the dominant components in all six plants. In the alcohol fraction C₁₈, C₂₀, C₂₂, and C₂₄ saturated primary alcohols were the major components. C₁₆ and C₁₈ dicarboxylic acids were the major dicarboxylic acids of the suberin of all six plants and in all cases octadec-9-ene-1, 18-dioic acid was the major component except in rutabaga where hexadecane-1, 16-dioic acid was the major dicarboxylic acid. The composition of the ω-hydroxyacid fraction was quite similar to that of the dicarboxylic acids; 18-hydroxy-octadec-9-enoic acid was the major component in all plants except rutabaga, where equal quantities of 16-hydroxyhexadecanoic acid and 18-hydroxyoctadec-9-enoic acid (42% each) were found. Compounds which would be derived from 18-hydroxyoctadec-9-enoic acid and octadec-9-ene-1, 18-dioic acid by epoxidation, and epoxidation followed by hydration of the epoxide, were also detected in most of the suberin samples. The monomer composition of the six plants showed general similarities but quite clear taxonomic differences.     

Free radical oxidation (autoxidation) of alkenones and other lipids in cells of Emiliania huxleyi

Cells of the coccolithophorid Emiliania huxleyi strain CS-57 grown under an atmosphere of air+0.5% CO(2) showed oxidative damage after 10 days growth with concomitant and major changes to the lipid composition. The fatty acid profile was strongly altered and lacked appreciable amounts of the polyunsaturated fatty acids (PUFA: C(18:5), C(18:3) and C(22:6)) typical of healthy cells. Oxidation products of these PUFA could not be detected, but monounsaturated fatty acids proved to be good indicators of oxidative processes. The presence (after NaBH(4)-reduction) of a high proportion of 11-hydroxyoctadec-cis-9-enoic and 8-hydroxyoctadec-cis-9-enoic acids showed that the degradation of oleic acid involved mainly free radical oxidation processes (70-75% autoxidation and 20-25% photooxidation). We also detected large amounts of degradation products of the oxidation product 9,10-epoxyoctadecanoic acid including diols, methoxyhydrins and chlorohydrins. These oxidative effects were found in all the lipid classes examined. Products included significant amounts of chlorophyll side-chain autooxidation products Z- and E-3,7,11,15-tetramethylhexadec-3-ene-1,2-diols and Z-and E-3,7,11,15-tetramethylhexadec-2-ene-1,4-diols, while phytyldiol was present in relatively low proportions. Delta(5)-3beta,7-epimeric unsaturated steroidal diols arising from the autooxidation of the Delta(5) double bond of epi-brassicasterol and minor amounts of Delta(4)-3beta,6-diols were also detected. Long-chain unsaturated ketone (alkenone) content per cell was much higher in the presence of 0.5% CO(2) likely due to carbon storage under these conditions. The proportions of di- and tri-unsaturated alkenones was relatively stable throughout the growth cycle in the absence of additional CO(2), but not when grown with 0.5% CO(2). The detection of characteristic alkenone autoxidation products in cells grown under these latter conditions allowed us to attribute the significant increase in index observed to the involvement of free radical oxidation processes.     

Characterization of triacylglycerols from overwintering prepupae of the alfalfa pollinator Megachile rotundata (Hymenoptera: Megachilidae)

Alfalfa leafcutting bees, Megachile rotundata (F.), overwinter as prepupae. The internal lipids were extracted from prepupae that had been wintered at 4 degrees C for 7 months. Megachile rotundata prepupae possessed copious quantities of internal lipids (20% of the fresh weight) that were extracted with CHCl3/methanol (2:1). Transmission electron microscopy revealed that lipids were stored within very large intracellular vacuoles. Separation by silica chromatography revealed that 88% of the internal lipids were triacylglycerols. Ester derivatives of fatty acids from triacylglycerol components were analyzed by gas chromatography-mass spectrometry and 15 fatty acid constituents were identified. The majority (76%) of the triacylglycerol fatty acids were unsaturated fatty acids. The major triacylglycerol fatty acid constituent (30%) was the C16 monounsaturated fatty acid, palmitoleic acid (16:1, hexadec-9-enoic acid), with substantial amounts of linolenic acid (18:3, octadec-9,12,15-trienoic acid, 15%), palmitic acid (16:0, hexadecanoic acid, 14%) and oleic acid (18:1, octadec-9-enoic acid, 13%). Palmitoleic acid as the major fatty acid of an insect is an unusual occurrence as well as the presence of the 16-carbon polyunsaturated fatty acids, 16:2 and 16:3. The major intact triacylglycerol components were separated and identified by high performance liquid chromatography-mass spectrometry. A complex mixture of approximately 40 triacylglycerol components were identified and major components included palmitoyl palmitoleoyl oleoyl glycerol, palmitoyl palmitoleoyl palmitoleoyl glycerol, myristoyl palmitoleoyl palmitoleoyl glycerol, myristoleoyl palmitoyl palmitoleoyl glycerol, and palmitoyl palmitoleoyl linolenoyl glycerol. The function of these internal lipids and their relevance to winter survival and post-wintering development of M. rotundata is discussed.     

Use of an unsaturated fatty acid auxotroph of Saccharomyces cerevisiae to modify the lipid composition and function of mitochondrial membranes

KD115 (ol1), an unsaturated fatty acid auxotroph of S. cerevisiae, was grown in a semi-synthetic medium supplemented with 3.3 x 10(-4) M palmitoleic (cis 16:1) or palmitelaidic (trans 16:1) acids. The parent strain S288C was studied as a control. The lipid composition (fatty acids, neutral lipids, and phospholipids), respiratory activity (O2 consumption), and ultrastructure were compared in mutant yeast grown with each unsaturated fatty acid supplement. The fatty acid supplement represented 70-80% of the yeast fatty acids. Yeast grown in trans 16:1 contained more squalene, a higher ratio of phosphatidylethanolamine (PE) to phosphatidylcholine (PC), and had 10-20% of the respiratory activity compared to the same yeast grown in cis 16:1. The mitochondrial morphology of yeast in each growth supplement was notably different. The use of mixtures of cis and trans 16:1 in different proportions revealed that the PE/PC ratio, the squalene content, the respiratory defect, and the mitochondrial morphology were all similarly dependent on the fraction of trans 16:1 in the mixtures. As little as 10-20% of cis 16:1 in the mixture was sufficient to abrogate the physiological effects of trans 16:1 on each of the parameters noted above. The combined effects of high content of trans unsaturated fatty acid and the altered phospholipid composition seem to account for the decrease in lipid fluidity, the defective structure and function of the mitochondrial membrane.     

Cytotoxic clerodane diterpenes from Glossocarya calcicola

Three clerodane diterpenes were isolated and identified from leaf extract of Glossocarya calcicola. Compound has been characterised as (rel)-10betaH-trans-12xi-(2-methylbut-2(E)-enoyl)-1beta-(isobutanoyl)-6alpha,13xi-dihydroxyclerodan-4(20),8(18)-dien-7,15-dione-15,16-oxide, to which we have assigned the trivial name calcicolin-A. The other two compounds had the same skeletal structure and C-12 substituent but in compound, the C-1 esterifying group becomes 2-methylbut-2(E)-enoic acid and in it becomes 2-methylbutanoic acid. Although anti-insect activity was not observed for G. calcicola, cytotoxicity against insect and human carcinoma cell lines was detected.     

Aliphatic composition of cutin from inner seed coat of apple

Lithium aluminum deuteride reduction released aliphatic monomers from the inner seed coat fraction but not from the outer seed coat fraction of mature apples. These monomers were identified by GC/MS and the results indicate that the inner coat of apple seed contains a cutin polymer with the major monomer acids being 18-hydroxyoctadec-9-enoic (31%), 9,10-epoxy-18-hydroxyoctadecanoic (28%) and 9,10,18-trihydroxyoctadecanoic (20 %). The monomer composition of this seed coat cuticular polymer was very similar in seeds taken from freshly harvested fruit and in those taken from fruit which had been stored at 4° for 6 months.     

Suberins of Malus pumila stem and root corks

The suberin contents of the isolated superficial cork layers of Malus pumila stems and root ranged from 15 to 35% of the dry weight. The qualitative composition of the aliphatic monomers obtained after alkaline depolymerization of the extractive-free corks was similar but some quantitative differences were found according to cultivar and age of the cork layer. 1-Alkanols (mainly 22:0, 24:0 and 26:0), alkanoic acids (mainly 22:0 and 24:0), α, ω-alkanedioic acids (mainly 16:0, 18:1 (9) and 18:0) and ω-hydroxyalkanoic acids (mainly 18:1 (9) and 22:0) were major constituents of all the samples examined and together they comprised 40–50% of the total monomeric mixture. The remainder was composed mainly of 9,10-epoxy-18-hydroxy-and 9,10,18-trihydroxyoctadecanoic acids. The corresponding dibasic acids, 9,10-epoxy- and 9,10-dihydroxyoctadecane-1,18-dioic, were minor components as were C₁₆ and C₁₈ dihydroxyalkanoic acids (mainly 10,16-dihydroxyhexadecanoic and 10,18-dihydroxyoctadecanoic acids, respectively). The root suberin dittered from that of the stem in containing larger amounts of 9,10-epoxy- 18-hydroxyoctadecanoic and 18-hydroxyoctadec-9-enoic acids.     

Heterologous expression of a fatty acid hydroxylase gene in developing seeds of<Emphasis Type="Italic"> Arabidopsis thaliana</Emphasis>

Expression of a cDNA encoding the castor bean ( Ricinus communis L.) oleate Delta12-hydroxylase in the developing seeds of Arabidopsis thaliana (L.) Heynh. results in the synthesis of four novel hydroxy fatty acids. These have been previously identified as ricinoleic acid (12-hydroxy-octadec- cis-9-enoic acid: 18:1-OH), densipolic acid (12-hydroxy-octadec- cis-9,15-enoic acid: 18:2-OH), lesquerolic acid (14-hydroxy-eicos- cis-11-enoic acid: 20:1-OH) and auricolic acid (14-hydroxy-eicos- cis-11,17-enoic acid: 20:2-OH). Using mutant lines of Arabidopsis that lack the activity of the FAE1 condensing enzyme or FAD3 ER Delta-15-desaturase, we have shown that these enzymes are required for the synthesis of C20 hydroxy fatty acids and polyunsaturated hydroxy fatty acids, respectively. Analysis of the seed fatty acid composition of transformed plants demonstrated a dramatic increase in oleic acid (18:1) levels and a decrease in linoleic acid (18:2) content correlating to the levels of hydroxy fatty acid present in the seed. Plants in which FAD2 (ER Delta12-desaturase) activity was absent showed a decrease in 18:1 content and a slight increase in 18:2 levels corresponding to hydroxy fatty acid content. Expression of the castor hydroxylase protein in yeast indicates that this enzyme has a low level of fatty acid Delta12-desaturase activity. Lipase catalysed 1,3-specific lipolysis of triacylglycerol from transformed plants demonstrated that ricinoleic acid is not excluded from the sn-2 position of triacylglycerol, but is the only hydroxy fatty acid present at this position.     

Thiafatty acids as tracers to investigate biosynthetic pathways of lepidopteran sex pheromones

In order to investigate the potential utility of thiafatty acids as tracers for biosynthetic studies of moth sex pheromones, a series of thiatetradecanoic acids, namely 8-, 9-, 10-, 11-, 12- and 13-thiatetradecanoic, were prepared and their metabolism was investigated in pheromone glands of Spodoptera littoralis. Analysis by gas chromatography coupled to mass spectrometry of extracts from pheromone glands treated with the above acids showed that only 8-thiatetradecanoic acid and 13-thiatetradecanoic acid were metabolized by desaturation and were incorporated into the sex pheromone biosynthetic pathway. 13-Thiatetradecanoic acid was converted into (E)- and (Z)-13-thiatetradec-11-enoic acids, (Z,E)-13-thiatetradeca-9,11-dienoic acid, 11-thiadodecanoic acid, (E)- and (Z)-11-thiadodec-9-enoic acids and 15-thiahexadecanoic acid. 8-Thiatetradecanoic acid gave rise to two monoenoic thiafatty acids and two dienoic thiafatty acids, which were assigned to (Z)- and (E)-8-thiatetradec-11-enoic acids, (Z,E)-8-thiatetradeca-9,11-dienoic acid and (E,E)-8-thiatetradeca-10,12-dienoic acid. The other thiafatty acids tested, 9-, 10-, 11- and 12-thiatetradecanoic acids, were not metabolized by desaturation, although the corresponding products of beta-oxidation and chain elongation were detected. The occurrence of sulfoxides was not detected in this case, in disagreement with results on the metabolism of some thiaacids previously reported by other authors in yeast, Saccharomyces cerevisiae.     

Production of butter fat rich in trans10-C18:1 for use in biomedical studies in rodents

Trans fatty acids are suspected to be detrimental to health, particularly to cardiovascular function. Trans fatty acids include a wide range of fatty acids, with isomers of C18:1, conjugated and non-conjugated C18:2 as major components. A vaccenic acid (trans11-C18:1) + rumenic acid (cis9,trans11-CLA)-rich butter has been shown previously to exhibit health beneficial effects, but less is known concerning another trans-C18:1 present in hydrogenated vegetable oil-based products and sometimes in milk fat, the trans10-isomer. The present experiment was conducted to produce butters from milk of variable fatty acid composition for use in biomedical studies with rodents, with the overall aim of evaluating the specific effect of trans10-C18:1 and trans11-C18:1 + cis9,trans11-CLA on cardiovascular function. Milks from lactating dairy cows fed two types of maize-based diets supplemented (5% of dry matter)--or not--with sunflower oil were collected, and used to manufacture butters either rich in trans10-C18:1 (14% of total fatty acids, 64.5% of fat content) or rich in trans11-C18:1 + cis9,trans11-CLA (7.4 and 3.1% of total fatty acids, respectively, 68.5% of fat content), or with standard fatty acid composition (70% of fat content). Additionally, total saturated fatty acid percentage was reduced by more than one third in the enriched butters compared with the standard butter. An understanding of the role of nutrition on milk fatty acid composition in cows allows for the production of dairy products of variable lipid content and composition for use in biomedical studies in animal models and human subjects.     

灵芝液态深层发酵产物中10种不饱和脂肪酸类化合物的鉴定

通过规模化液态深层发酵获得灵芝发酵产物,采用多种硅胶色谱柱层析及重结晶的方式,从中分离得到10个化合物.通过核磁、质谱等波谱分析,鉴定出这些化合物均属于含羟基或酮基的不饱和脂肪酸类化合物,分别为(9S,10R,11E,13R)-9,10,13-trihydroxyoctadec-11-enoic acid(1)和(9S...     

The constituent cutin acids of cranbury cuticle

Purified cutin from cranberry (Vaccinium macrocarpon, var. Howes) skin was selectively degraded, and the cutin acids, as methyl esters, separated by TLC into seven classes including monobasic acids, dibasic acids, monohydroxy monobasic acids, monohydroxy epoxymonobasic acids, vic-dihydroxy dibasic acids, dihydroxy monobasic acids and trihydroxy monobasic acids. Of the 41 components identified in cranberry cutin by GLC and MS analysis, 18-hydroxyoctadec-cis-9-enoic acid (9·4%), 18-hydroxy-cis-9,10-epoxyoctadecanoic acid (7·5%), 10,16-dihydroxyhexadecanoic acid (16·7%) and threo-9,10,18-trihydroxyoctadecanoic acid (43·7%) were shown to be the major constituents.     

Trans fatty acids promote the growth of some Lactobacillus strains

Five Lactobacillus strains (2 L. gasseri, 2 L. plantarum and 1 L. reuteri) were cultured in modified MRS medium containing fatty acids (FAs) instead of Tween 80 for 24 h at 37 degrees C, to learn the effect of saturated and unsaturated FAs on the Lactobacillus growth. Free FAs included palmitic (16:0), palmitoleic (c9-16:1), stearic (18:0), oleic (c9-18:1), elaidic (t9-18:1), cis-vaccenic (c11-18:1), vaccenic (t11-18:1), linoleic (c9, c12-18:2), conjugated linoleic (c9, t11- and t10, c12-18:2), alpha-linolenic (c9, c12, c15-18:3), alpha-eleostearic (c9, t11, t13-18:3), eicosapentaenoic (20:5), and docosahexaenoic (22:6) acids. Among free FAs, oleic acid stimulated the growth of all Lactobacillus strains, whereas palmitoleic acid had almost no affect on the Lactobacillus growth. Saturated FAs such as stearic and palmitic acids inhibited or did not affect the Lactobacillus growth. Polyunsaturated FAs such as alpha-linolenic, eicosapentaenoic and docosahexaenoic acids strongly inhibited the Lactobacillus growth at 7.6 x 10(-4) m. Octadecenoic acids such as oleic, elaidic, cis-vaccenic and vaccenic acids remarkably promoted the growth of L. gasseri, regardless of the different double bond positions and configurations. When oleic or cis-vaccenic acid was incubated with L. gasseri, the FAs was transformed to cyclopropane FAs (methyleneoctadecanoic acids) after incorporation into the cells. On the other hand, trans FAs such as elaidic and vaccenic acids incorporated into the cells were not converted to another FAs. Conjugated linoleic and alpha-eleostearic acids having a trans double bond promoted the Lactobacillus growth. The growth of L. gasseri was also stimulated by trans-rich free FAs from hydrogenated canola and fish oils. These results showed that octadecenoic acid and trans FAs had strong promotion activities for the Lactobacillus growth due to their incorporation into membrane lipids.     

Polar lipid and fatty acid profiles – Re-vitalizing old approaches as a modern tool for the classification of mycoplasmas?

A set of 20 Mollicutes strains representing different lines of descent, including the type species of the genus Mycoplasma, Mycoplasma mycoides, Acholeplasma laidlawii and a strain of Mesoplasma, were subjected to polar lipid and fatty acid analyses in order to evaluate their suitability for classification purposes within members of this group. Complex polar lipid and fatty acid profiles were detected for each examined strain. All strains contained the polar lipids phosphocholine-6'-alpha-glucopyranosyl-(1'-3)-1, 2-diacyl-glycerol (MfGL-I), 1-O-alkyl/alkenyl-2-O-acyl-glycero-3-phosphocholine (MfEL), sphingomyelin (SphM), 1-O-alkyl/alkenyl-glycero-3-phosphocholine (lysoMfEL), the unknown aminophospholipid APL1 and the cholesterol Chol2. A total of 19 strains revealed the presence of phosphatidylethanolamine (PE) and/or phosphatidylglycerol (PG), and the presence of diphosphatidylglycerol (DPG) was detected in 13 strains. The unknown aminolipid AL1 was found in the extracts of 17 strains. Unbranched saturated and unsaturated compounds predominated in the fatty acid profiles. Major fatty acids were usually C16:0, C18:0, C18:1 omega9c and 'Summed feature 5' (C18:2 omega6, 9c/C18:0 anteiso). Our results demonstrated that members of the M. mycoides cluster showed rather homogenous polar lipid and fatty acid profiles. In contrast, each of the other strains was characterized by a unique polar lipid profile and significant quantitative differences in the presence of certain fatty acids. These results indicate that analyses of both polar lipid and fatty acid profiles could be a useful tool for classification of mycoplasmas.     

Low Resolution Mass Spectra of Some Unsaturated δ-Lactones

Mass spectra of the δ-lactones of the following 5-hydroxy-2-enoic acids were determined: 5-hydroxyhex-2-enoic acid (I), 5-hydroxyoct-2-enoic acid (II), 5-hydroxydec-2-enoic acid (III), 5-hydroxydodec-2-enoic acid (IV), 5-hydroxy-8-methylnon-2-enoic acid (V), 5-hydroxy-6-ethyloct-2-enoic acid (VI), 5-hydroxy-5, 6, 6-trimethylhept-2-enoic acid (VII), and 5-hydroxy-5-methylnon-2-enoic acid (VIII). The following modes of fragmentation are consistent with observed m/e values, metastable peaks, and established modes of breakdown in compounds containing similar atomic groupings:—1. Loss of side chain, resulting in ions at m/e 97 for I-VI and at m/e 111 and 153 for VII and VIII (diagnostic peaks); 2. 1,4-Rupture of the ring giving an ion at m/e 68 (diagnostic peak) which loses CO to give m/e 40; 3. Loss of CO from m/e 97 fragment to give m/e 69 which breaks down further to m/e 41→m/e 39; 4. 1, 4-Rupture of m/e 111 and m/e 153 fragments to give m/e 43 and 85, further breakdown of m/e 85→57→41→39; 5. Loss of H₂O from the molecular ion providing there is a hydrogen atom on C₅ and the side chain is at least 3 carbon atoms in length, further loss of H₂O when the side chain is equal to C5 or C7; 6. Loss of CO₂ from the molecular ion of I, IV-VIII; 7. Loss of CO from all molecular ions; 8. Loss of 2×28 from the molecular ions of III, IV, V, VI; 9. Loss of (18 + 28) from the molecular ion of III, IV, V, VI; 10. Loss of 60 from the molecular ion of II, III, IV, V, VI; 11. Formation of M + 1 ion (169) of VII and VIII; 12. Formation of M + 1 ion (143) of saturated δ-octalactone and loss of H₂O from this M + 1 ion.     

Polyphthienoyl trehalose, glycolipids specific for virulent strains of the tubercle bacillus

Phthienoic acids constitute a family of dextro-rotary odd-numbered unsaturated fatty acids isolated exclusively from virulent strains of human and bovine tubercle bacilli. In the bacterial cell they are not free and a search for their linked form in complex wall lipids of Mycobacterium tuberculosis (strain Canetti) showed that they esterified trehalose. Structural elucidation of the major phthienoyl trehalose showed the occurrence of five acyl residues located at 2, 2', 3', 4 and 6' positions of trehalose. The acyl substituents were mainly 2,4,6-trimethyl tetracos-2-enoic acid (C27 phthienoic acid) accompanied by its homologs. In addition to these branched fatty acids, straight-chain C16 and C18 acyls composed about 20% of the substituents. The proposed structure is a new one, both for the mycobacterial-specific glycolipid and for the substituted positions on trehalose. Other minor acyl trehaloses were detected in M. tuberculosis (strain Canetti), differing from the major component by the occurrence of an additional hydroxy fatty acid (3-hydroxy-2,4,6-trimethyl tetracosanoic acid) or by the number of acyl substituents. The major glycolipid presented a weak activity in vitro on mitochondrial oxidative phosphorylation. These glycolipids and phthienoic acids could serve as virulence indicators.     

Biochemical effects of the hypoglycaemic compound pent-4-enoic acid and related non-hypoglycaemic fatty acids. Fatty acid oxidation

1. The effects of the hypoglycaemic compound, pent-4-enoic acid, and of four structurally related non-hypoglycaemic compounds (pentanoic acid, pent-2-enoic acid, cyclopropanecarboxylic acid and cyclobutanecarboxylic acid), on the oxidation of saturated fatty acids by rat liver mitochondria were determined. 2. The formation of (14)CO(2) from [1-(14)C]palmitate was strongly inhibited by 0.01mm-pent-4-enoic acid. 3. The inhibition of oxygen uptake was less than that of (14)CO(2) formation, presumably because fumarate was used as a sparker. 4. The oxidation of [1-(14)C]-butyrate, -octanoate or -laurate was not strongly inhibited by 0.01mm-pent-4-enoic acid. 5. The other four non-hypoglycaemic compounds did not inhibit the oxidation of any saturated fatty acid when tested at 0.01mm concentration, though they all inhibited strongly at 10mm. 6. The oxidation of [1-(14)C]-myristate and -stearate, but not of [1-(14)C]decanoate, was strongly inhibited by 0.01mm-pent-4-enoic acid. 7. The oxidation of [1-(14)C]palmitate was about 50% carnitine-dependent under the experimental conditions used. 8. The percentage inhibition of [1-(14)C]palmitate oxidation by pent-4-enoic acid was the same whether carnitine was present or not. 9. Acetoacetate formation from saturated fatty acids was inhibited by 0.1mm-cyclopropanecarboxylic acid to a greater extent than their oxidation. 10. The other compounds tested inhibited acetoacetate formation from saturated fatty acids proportionately to the inhibition of oxidation. 11. Possible mechanisms for the inhibition of long-chain fatty acid oxidation by pent-4-enoic acid are discussed. 12. There was a correlation between the ability to inhibit long-chain fatty acid oxidation and hypoglycaemic activity in this series of compounds.