Structure and composition of aliphatic constituents of potato tuber skin (suberin)

Potato tuber skin (suberin), isolated enzymatically, was depolymerized with BF₃-CH₃OH, and the structure and composition of the aliphatic monomers were determined by combined gas chromatography-mass spectrometry. 18-Hydroxyoctadec-9-enoic acid and octadec-9-ene-1,18-dioic acid were the major components. Products of epoxidation and subsequent hydration of the Δ⁹ double bond of these compounds, 10,16-dihydroxy hexadecanoic acid, and much smaller quantities of 9,16-dihydroxyhexadecanoic acid and 8,16-dihydroxyhexadecanoic acid also were present. The other significant feature of the monomer composition of potato skin was that it contained substantial quantities of C₂₀−C₂₈ fatty acids, fatty alcohols, and ω-hydroxy acids. Based upon these studies, a method of distinguishing between suberin and cutin and a biosynthetic pathway for suberin monomers are suggested. Scientific paper 4199, Project 2001, Agricultural Research Center, College of Agriculture, Washington State University, Pullman, Washington.     

Plant sn‐Glycerol‐3‐Phosphate Acyltransferases: Biocatalysts Involved in the Biosynthesis of Intracellular and Extracellular Lipids

Acyl‐lipids such as intracellular phospholipids, galactolipids, sphingolipids, and surface lipids play a crucial role in plant cells by serving as major components of cellular membranes, seed storage oils, and extracellular lipids such as cutin and suberin. Plant lipids are also widely used to make food, renewable biomaterials, and fuels. As such, enormous efforts have been made to uncover the specific roles of different genes and enzymes involved in lipid biosynthetic pathways over the last few decades. sn‐Glycerol‐3‐phosphate acyltransferases (GPAT) are a group of important enzymes catalyzing the acylation of sn‐glycerol‐3‐phosphate at the sn‐1 or sn‐2 position to produce lysophosphatidic acids. This reaction constitutes the first step of storage‐lipid assembly and is also important in polar‐ and extracellular‐lipid biosynthesis. Ten GPAT have been identified in Arabidopsis, and many homologs have also been reported in other plant species. These enzymes differentially localize to plastids, mitochondria, and the endoplasmic reticulum, where they have different biological functions, resulting in distinct metabolic fate(s) for lysophosphatidic acid. Although studies in recent years have led to new discoveries about plant GPAT, many gaps still exist in our understanding of this group of enzymes. In this article, we highlight current biochemical and molecular knowledge regarding plant GPAT, and also discuss deficiencies in our understanding of their functions in the context of plant acyl‐lipid biosynthesis.     

Molecular Cloning and Functional Analysis of GmLACS2-3 Reveals Its Involvement in Cutin and Suberin Biosynthesis along with Abiotic Stress Tolerance

Cutin and wax are the main precursors of the cuticle that covers the aerial parts of plants and provide protection against biotic and abiotic stresses. Long-chain acyl-CoA synthetases (LACSs) play diversified roles in the synthesis of cutin, wax, and triacylglycerol (TAG). Most of the information concerned with LACS functions is obtained from model plants, whereas the roles of LACS genes in Glycine max are less known. Here, we have identified 19 LACS genes in Glycine max, an important crop plant, and further focused our attention on 4 LACS2 genes (named as GmLACS2-1, 2, 3, 4, respectively). These GmLACS2 genes display different expression patterns in various organs and also show different responses to abiotic stresses, implying that these genes might play diversified functions during plant growth and against stresses. To further identify the role of GmLACS2-3, greatly induced by abiotic stresses, we transformed a construct containing its full length of coding sequence into Arabidopsis. The expression of GmLACS2-3 in an Arabidopsis atlacs2 mutant greatly suppressed its phenotype, suggesting it plays conserved roles with that of AtLACS2. The overexpression of GmLACS2-3 in wild-type plants significantly increased the amounts of cutin and suberin but had little effect on wax amounts, indicating the specific role of GmLACS2-3 in the synthesis of cutin and suberin. In addition, these GmLACS2-3 overexpressing plants showed enhanced drought tolerance. Taken together, our study deepens our understanding of the functions of LACS genes in different plants and also provides a clue for cultivating crops with strong drought resistance.     

Characterization of Betula pendula Outer Bark Regarding Cork and Phloem Components at Chemical and Structural Levels in View of Biorefinery Integration

Betula pendula outer bark includes a cork-rich periderm and a rhytidome, including periderm and phloem layers. Cork and phloem from the outer bark were chemically analyzed after fractioning into different particle sizes; coarser fractions were obtained in higher yields. Cork and phloem chemical composition were different: the coarse and medium fractions of cork were enriched in suberin (37.7–38.4%) and lipophilic extractives (31.1%); phloem fractions were enriched in lignin (32.2%) and polysaccharides (43.0%). Lipophilic and suberin extracts were analyzed by GC-MS. Triterpenes constitute the most abundant identified compounds (90.1–97.1% in cork, 76.1–90.2% in phloem), and betulin is the most representative (64.6–70.7%). The majority of the suberin monomers are ω-hydroxyacids, (55.2–83.9%); namely, 9,10-epoxy-18-hydroxyoctadecanoic, 9,10,18-trihydroxyoctadecanoic, and 22-hydroxydocosanoic acids. A chemical valorization of the cork component from B. pendula outer bark as an industrial residue is proposed based on the fractionated production of triterpenoids, suberinic acids, oligo/monosaccharides, and lignin.     

Lipid components that reduce protein solubility of soy protein isolates

A lipid fraction from a commercial soy protein isolate (SPI), previously found to be detrimental to SPI solubility, was analyzed by size-exclusion liquid chromatography, by high-performance liquid chromatography (HPLC), and for chemical composition. The molecular weight of most of this material was greater than 1,100 daltons. This lipid fraction was water-soluble yet required a strong nonpolar solvent mixture to elute it from a C₁₈ HPLC column. The lipid material was alkaline (pH 8.7) and composed of 3.0% nitrogen, 1.6% phosphorus, 17.5% nonvolatile crude fatty acids primarily hydroxylated), 10.4% long-chain bases, 9.9% hexuronic acid, 3.2% hexosamine, and 6.6% total sugar. The molecular weight, chemical composition, and physical characteristics (solubility characteristics, surfactant characteristics, and appearance) of this material were all similar to those reported for phytoglycolipid.     

Age Variation of Douglas-Fir Bark Chemical Composition

The chemical composition of Douglas-fir bark was analyzed at three stem height levels of trees with different ages from two geographical locations. Cork and phloem in the bark’s rhytidome were analyzed separately at stem bottom: extractives (49.8% and 17.0%, respectively), suberin (30.1% in cork) and hemicelluloses, namely arabinose content (25.3% and. 4.8% of all monomers, respectively). Suberin composition includes α,ω-alkanoic diacids (38.6%), ω-hydroxyalkanoic acids (25.6%), alkanoic acids (18.2%), alkanols (2.2%), and aromatics (8.8%). Bark’s chemical composition is age-related, namely regarding suberin content: at 45, 30 and, 17?years of age, bark contained respectively 25.4%, 2.6%, and 0.9% of suberin; 24.5%, 33.9%, and 29.8% of lignin; and 29.4%, 20.6%, and 25.7% of extractives. This difference is due to the small number of periderms and low cork content in barks with 30 or less years. When aiming at a cork-targeted valorization, the lower stem parts of mature Douglas-fir trees should be considered while the high content of polar extractives at all stem heights allows an overall potential valorization.     

Polyhydroxy fatty acids and their derivatives from plant oils

A novel process for the industrial production of hydroxylated fatty acids involves epoxidation of plant oils and their derivatives, followed by catalytic epoxy ring opening in the presence of water or other hydrogen donors, such as alcohols, diols, and amines. Depending on the starting material, epoxidation followed by opening of the oxirane ring leads to fatty acids that contain vicinal diol groups or to other substituted hydroxylated fatty acid derivatives. As an example for the preparation of a substituted hydroxylated fatty acid derivative, the reaction of epoxidized rapeseed oil with monobutylamine as hydrogen donor is described. Apart from the intended formation of hydroxyl groups with vicinal aminoalkyl groups, partial aminolysis of the ester compound was also observed. Another example describes the reaction of epoxidized rapeseed oil with different molar proportions of 1,4-butanediol as hydrogen donor. Depending on the molar proportion of the hydrogen donor, interesterification, or intermolecular ether formation were observed as side reactions. The properties of various technical hydroxylated fatty acids and their derivatives, prepared according to this novel process, are given, and potential applications of these products are suggested.     

Increased Lipid Peroxidation in LDL from Type-2 Diabetic Patients

Increased oxidative stress is associated with type-2 diabetes and related cardiovascular diseases, but oxidative modification of LDL has been partially characterized. Our aim was to compare the lipid and fatty acid composition as well as the redox status of LDL from diabetic patients and healthy subjects. First, to ensure that isolation of LDL by sequential ultracentrifugation did not result in lipid modifications, lipid composition and peroxide content were determined in LDL isolated either by ultracentrifugation or fast-protein liquid chromatography. Both methods resulted in similar concentrations of lipids, fatty acids, hydroxy-octadecadienoic acid (HODE) and malondialdehyde (MDA). Then, LDLs were isolated by ultracentrifugation from eight type-2 diabetic patients and eight control subjects. Compared to control LDL, diabetic LDL contained decreased cholesteryl esters and increased triglyceride concentrations. Ethanolamine plasmalogens decreased by 49%. Proportions of linoleic acid decreased in all lipid classes, while proportions of arachidonic acid increased in cholesteryl esters. Total HODE concentrations increased by 56%, 12- and 15-hydroxy-eicosatetraenoic acid by 161 and 86%, respectively, and MDA levels increased by twofold. α-Tocopherol concentrations, expressed relative to triglycerides, were lower in LDL from patients compared to controls, while γ-tocopherol did not differ. Overall, LDL from type-2 diabetic patients displayed increased oxidative stress. Determination of hydroxylated fatty acids and ethanolamine plasmalogen depletion could be especially relevant in diabetes.     

Lipids in the germ,endosperm and pericarp of the developing maize kernel

Acyl lipids were quantified in the germ, endosperm and pericarp of LG-11 maize kernels at eight stages of development from 9 to 87 days after pollination (DAP). Changes in the lipids are discussed in relation to morphological events in the developing kernel. Storage lipids (triglyceride, steryl ester) and membrane lipids (diacylphospholipids) accumulated in germ until 52-76 DAP, then decreased slightly without formation of lipid degradation products, lated in endosperm until 36-42 DAP and then decreased. Maximum values for galactosyldiglycerides and diacylphospholipids (nonstarch lipids) were reached at 16-23 DAP, and all decreased to very low values at maturity. Loss of these functional (membrane) lipids during the period of endosperm cell filling is unexpected. Starch contained 82% of the lysophospholipids and 64% of the free fatty acids in endosperm at 76 DAP. Endosperm lysophospholipids increased until 76 DAP and then decreased slightly, while free fatty acids increased continuously mostly inside starch granules at all stages of development, and any possible decrease after 76 DAP was masked by acids formed by hydrolysis of aleurone and endosperm nonstarch lipids from 52 DAP. In DAP, and phospholipids decreased after 42 DAP. Loss of these lipids is associated with senescence of most pericarp tissue. Triglycerides and steryl esters accumulated steadily to maturity, while the main accumulation of unsaponifiables occurred after 52 DAP about the time of suberin formation.     

The optical rotation of a major component of plant cutin

The major component of cutin from the fruit of both tomato and papaya, dihydroxypalmitate, is shown to have plain positive rotation and is, therefore, assigned L configuration in analogy to other known hydroxy fatty acids. Scientific paper no. 5150, College of Agriculture Research Center, Washington State University, Pullman, Washington 99164. This work was supported in part by Grants PCM 74-09351 and PCM 77-00927, from the National Science Foundation.     

Chemoenzymatic Synthesis of Fragrance Compounds from Stearic Acid

Fatty acids are versatile precursors for fuels, fine chemicals, polymers, perfumes, etc. The properties and applications of fatty acid derivatives depend on chain length and on functional groups and their positions. To tailor fatty acids for desired properties, an engineered P450 monooxygenase has been employed here for enhanced selective hydroxylation of fatty acids. After oxidation of the hydroxy groups to the corresponding ketones, Baeyer–Villiger oxidation could be applied to introduce an oxygen atom into the hydrocarbon chains to form esters, which were finally hydrolyzed to afford either hydroxylated fatty acids or dicarboxylic fatty acids. Using this strategy, we have demonstrated that the high-value-added flavors exaltolide and silvanone supra can be synthesized from stearic acid through a hydroxylation/carbonylation/esterification/hydrolysis/lactonization reaction sequence with isolated yields of about 36 % (for ω−1 hydroxylated stearic acid; 100, 60, 80, 75 % yields for the individual reactions, respectively) or 24 % (for ω−2 hydroxylated stearic acid). Ultimately, we obtained 7.91 mg of exaltolide and 13.71 mg of silvanone supra from 284.48 mg stearic acid.     

Antibiotic properties of porcupine quills

Porcupine quills possess antibiotic properties. The antibiotic activity is associated with free fatty acids (but not neutral lipids) coating the quills. Extracts of quill fatty acids strongly inhibited the growth of six grampositive bacterial strains. No growth inhibition was observed against four gram-negative strains. Free fatty acids made up 18.6% of total quill lipids in samples collected in the summer, and 5.5% of total lipid in samples collected in the winter. The fatty acids were separated and identified (as the methyl esters) by gas-liquid chromatography and mass spectroscopy. Major components of a complex mixture included 14-methylpentadecanoic, 9-hexadecenoic, hexadecanoic, and 9-octadecenoic acids. It is suggested that porcupines benefit from the quill fatty acids: evidence from healed fractures of major skeletal components (35.1% incidence in 37 skeletons examined) suggests that porcupines fall relatively frequently from trees. Quill antibiotics may limit self-injury suffered in such falls.     

Effect of tall oil fatty acids content on the properties of novel hyperbranched alkyd resins

Hyperbranched alkyd resins (HBRA) were synthesized by modification of hydroxylated hyperbranched polyester (HBP1‐4) with tall oil fatty acids (TOFA). The core is a hydroxylated hyperbranched polyester of fourth generation with OH groups in the periphery (18), which is endcapped with tall oil fatty acids. The occurrence of these reactions, HBP1‐4 and TOFA, was determined by making use of acid value, nuclear magnetic resonance, and hydroxyl values. The effects of TOFA and HBP1‐4 on properties of the HBRA resins were investigated by vapor pressure osmometry, differential scanning calorimetry, thermogravimetric analysis, friction resistance, and hardness. The resins with higher modification percentage (HBRA4) presented the best thermal and hydrolytic stability, but lower friction resistance and hardness. All HBRA resins presented amorphous characteristics, OH groups, and double bonds in the periphery. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Epoxidation and hydroxlation of rubber seed oil: one‐pot multi‐step reactions

Epoxidized and hydroxylated rubber seed oils were prepared by peroxyformic acid generated in situ by reacting formic acid and hydrogen peroxide with RSO, a renewable resource. The structural and physico‐chemical properties of RSO have been determined. The fatty acid composition showed a high content of polyunsaturated fatty acids. The modified products were characterized with regard to their structure and properties. The findings of this study revealed that both hydroxylated and epoxidized RSO can be prepared by one‐pot multi‐step reactions.     

Components of royal jelly: I. Identification of the organic acids

This present work characterizes the fatty acid constituents of the lipid fraction of royal jelly. Among the organic acids found after fractionation by thin layer chromatography of the corresponding methyl esters, the following compounds were identified by combined GC-MS: saturated and unsaturated linear fatty acids, saturated and unsaturated linear and branched dicarboxylic acids, mono-and dihydroxy acids. The most common characteristic of the organic acids was that most contained 8 or 10 carbon atoms, whether saturated or unsaturated, linear or branched.     

A Short Method for the Synthesis of Hydroxyoleic Acids

Enzymatic or microbiological oxidation of oleic acid can afford azelaic acid as a building block for bioplastics. However, during the oxidation, the formation of hydroxylated byproducts is observed. To better follow the oxidation reaction, the availability of reference compounds is of great importance. To this aim, the synthesis of a series of oleic acids hydroxylated at ω - 1, ω - 2, ω - 3 positions is described without the use of protecting groups. The final products are obtained by partial lactone reduction to hydroxyaldehyde followed by Grignard addition, selective oxidation of the primary hydroxyl group, and Wittig reaction.     

Synthesis of C20–38 Fatty Acids in Plant Tissues

Very-long-chain fatty acids (VLCFA) are involved in a number of important plant physiological functions. Disorders in the expression of genes involved in the synthesis of VLCFA lead to a number of phenotypic consequences, ranging from growth retardation to the death of embryos. The elongation of VLCFA in the endoplasmic reticulum (ER) is carried out by multiple elongase complexes with different substrate specificities and adapted to the synthesis of a number of products required for a number of metabolic pathways. The information about the enzymes involved in the synthesis of VLCFA with more than 26 atoms of Carbon is rather poor. Recently, genes encoding enzymes involved in the synthesis of both regular-length fatty acids and VLCFA have been discovered and investigated. Polyunsaturated VLCFA in plants are formed mainly by 20:1 elongation into new monounsaturated acids, which are then imported into chloroplasts, where they are further desaturated. The formation of saturated VLCFA and their further transformation into a number of aliphatic compounds included in cuticular waxes and suberin require the coordinated activity of a large number of different enzymes.     

Lipids of bovine thyroid

The lipid composition of the freshly slaughtered bovine thyroid tissue has been investigated. The phospholipid patterns of microsomal and mitochondrial fractions obtained from homogenates of bovine thyroids have also been determined. They resemble the phospholipid composition of the corresponding subcellular fractions from other tissues. The fatty acid composition of the various phospholipid species of these subcellular components have also been estimated by gas liquid chromatography. These analyses reveal that the fatty acids are not particularly characteristic of the subcellular organelle but tend to be characteristic of the lipid species. There is a high percentage of nervonic acid (C24∶1) in all the subcellular phospholipid species examined.     

Effect of dietary cyclopropene fatty acids on the octadecenoates of individual lipid classes of rat liver and hepatoma

The effect of dietary cyclopropene fatty acids on the concentration of octadecenoate chain positional isomers in individual lipid classes of normal liver, host liver, and hepatoma 7288CTC has been determined. The data revealed the following: (a) Saturated and monoene fatty acid percentages of liver phosphatidylcholines and phosphatidylethanolamines werenot affected, but the percentage of saturated fatty acids of the triglycerides and cholesteryl esters was increased while the monoene percentages decreased. (b) Oleate to vaccenate percentage ratios, previously shown to be characteristic of individual lipid classes, were completely disrupted. (c) Oleate concentrations of the two major liver phospholipids were elevated, and vaccenate levels were dramatically reduced. (d) Cyclopropene fatty acids appear to inhibit monoene elongation. (e) The elevated concentrations of oleate indicate that an alternate route of oleate biosynthesis must exist if the Δ9 desaturation is inhibited by cyclopropene fatty acids as reported previously. (f) In contrast to liver, oleate and vaccenate concentrations in hepatoma were not affected by the dietary cyclopropene fatty acids.     

Fatty acid synthesis in isolated spermatocytes and spermatids of mouse testis

In vitro incorporation of [1-¹⁴C] acetate into fatty acids and lipid classes of spermatocytes, round spermatids and condensing spermatids enriched by Staput 1×g sedimentation was measured by thin layer and gas radiochromatography. All three cell fractions showed the full range of de novo synthetase, elongation and desaturase activities necessary for biosynthesis of fatty acids characteristic of mouse testis, but synthesis of fatty acids of >16 carbons declined with progressive stages of differentiation. The magnitudes and patterns of distribution of fatty acid synthesis in the germinal cells were similar to those of whole testis incubated in vitro or injected in vivo with [¹⁴C] acetate. On the other hand, complex lipid synthesis was much more variable and incorporation into triacylglycerol was generally much lower in dispersed germinal cells than in whole testis in vitro or in vivo. Cells remained viable throughout the 15-hr incubation. Thus, isolated germinal cells are fully capable of synthesizing their constituent fatty acids, including the long-chain polyenoic acids which they accumulate, but the intratubular environment or association with Sertoli cells may be necessary for maintenance of adequate complex lipid synthesis.