The Uptake of Trehalose Glycolipids by Macrophages Is Independent of Mincle

Trehalose glycolipids play an important role in the pathogenesis of Mycobacterium tuberculosis and are used as adjuvants for vaccines; however, much still remains unanswered about the mechanisms through which these glycolipids exert their immunomodulatory potential. Recently, the macrophage‐inducible C‐type lectin Mincle was determined to be the receptor for trehalose glycolipids, yet the role played by Mincle in glycolipid uptake is unknown. Accordingly, we developed several fluorescent trehalose glycolipid reporter systems that can be used to study the uptake of soluble trehalose glycolipids and glycolipid‐coated particles by macrophages. Our studies revealed that, although Mincle is essential for the activation of macrophages by trehalose glycolipids, the receptor does not play a role in the uptake of these glycolipids or of glycolipid‐coated particles.     

Design of Trehalose-Based Amide/Sulfonamide C-type Lectin Receptor Signaling Compounds

Mincle agonists have been shown to induce inflammatory cytokine production, such as tumor necrosis factor-alpha (TNF) and promote the development of a Th1/Th17 immune response that might be crucial to development of effective vaccination against pathogens such as Mycobacterium tuberculosis. As an expansion of our previous work, a library of 6,6′-amide and sulfonamide α,α-d -trehalose compounds with various substituents on the aromatic ring was synthesized efficiently in good to excellent yields. These compounds were evaluated for their ability to activate the human C-type lectin receptor Mincle by the induction of cytokines from human peripheral blood mononuclear cells. A preliminary structure–activity relationship (SAR) of these novel trehalose diamides and sulfonamides revealed that aryl amide-linked trehalose compounds demonstrated improved activity and relatively high potency cytokine production compared to the Mincle ligand trehalose dibehenate adjuvant (TDB) and the natural ligand trehalose dimycolate (TDM) inducing dose-dependent and human-Mincle-specific stimulation in a HEK reporter cell line.     

α-sulfonated fatty acid esters: II. Solution behavior of α-sulfonated fatty acid polyethylene glycol esters

Sodium α-sulfonated, fatty acid polyethylene glycol monoesters [C _m H_2m+1CH(SO₃Na)COO(C₂H₄O) _n H] and diesters [C _m H_2m+1CH(SO₃Na)COO(C₂H₄O) _n COCH(SO₃Na)C _m H_2m+1], wherem=10–16 andn=1–35, were prepared by esterification of α-sulfonated, fatty acids with polyethylene glycols, followed by neutralization with NaOH. Crude products were purified by reversed-phase column chromatography on an octadecyl-modified silica gel. Characteristic solution behavior of these α-sulfonated fatty acid esters was, examined, and the following features were observed. All monoesters prepared in this work had Krafft points below 0°C and also possessed good calcium stabilities. Critical micelle concentrations of the monoesters increased monotonously, as a rule, with an increase in the number of oxyethylene units. These results suggest that the polyethylene glycol residue of the monoester behaves as a hydrophile. On the other hand, diesters possessed high water solubility, low foamability, and critical micelle concentrations that were lower by a factor of ten compared to those of the monoesters.     

Leaf wax ofPortulaca oleracea

Wax coating the leaves and stems ofPortulaca oleracea consists of hydrocarbons (21%), esters (53%), acids (2%), alcohols (4%), diol monoesters (2%), and unidentified material (15%). Lesser amounts of esterified and free β-amyrin and lupeol, stigmast-4-en-3-one and free diols also are present. The principal component of the hydrocarbons is C₃₃. The C₄₀-C₅₆ esters are C₂₂-C₂₈ alcohol esters of C₂₀-C₂₆ acids; free alcohols are C₂₂-C₃₀; free acids are C₁₆-C₃₆; diols of diol monoesters and free diols are C₂₀-C₂₆. Presented at the AOCS Meeting, Ottawa, September 1972. NRCC No. 14037.     

A Simple Glycolipid Mimic of the Phosphatidylinositol Mannoside Core from Mycobacterium tuberculosis Inhibits Macrophage Cytokine Production

Glycolipids from Mycobacterium tuberculosis have a profound impact on the innate immune response of the host. Macrophage‐inducible C‐type lectin (Mincle) is a pattern‐recognition receptor that has been shown to bind trehalose dimycolate (TDM) from the mycobacterium and instigate intracellular signalling in the immune cell. There are structural similarities between the structures of TDM and phosphatidyl inositol mannoside (PIM). We thus hypothesized that these latter structures might also modulate an immune response in a similar manner. To test this, we synthesized a series of new mannose derivatives modified with fatty esters at the 6‐position and assessed the release of inflammatory cytokines in human U937 macrophages under the induction of lipopolysaccharides (LPS) after glycolipid treatment. The results showed that the amount of two major cytokines—tumour necrosis factor (TNF)‐α and interleukin (IL)‐6—released from LPS‐stimulated U937 cells decreased significantly when compared to a control upon treatment with the prepared glycolipids, thus indicating a reduction in cytokine production by the macrophages.     

Factors affecting analytical values of beeswax and detection of adulteration

Various factors that could affect analytical values for beeswax, and so also detection of adulteration, have been investigated. Ester value determination was checked using synthetic monoesters. Gas liquid chromatographic analysis of overheated wax confirmed that free acids decreased on heating and also showed loss of unsaturated hydrocarbons and of monoesters. The saponification cloud point detected as little as 1% of a paraffin mp 83 C (chain length C₂₀–C₆₀) but only 6% or more of a paraffin mp 53 C (chain length C₂₀–C₃₅). Gas liquid chromatographic analysis of the hydrocarbon fraction of waxes containing these paraffins detected 1% of either paraffin, but only the low melting paraffin was estimated accurately. The presence of 2.5% of carnauba wax in beeswax was detected and estimated by gas liquid chromatography. Issued as NRCC No. 13173.     

Lipase-catalyzed monoesterification of 1-O-hexadecylglycerol in organic solvents

A simple method is presented to esterify 1-O-hexadecyl-rac-glycerol using lipases in different organic solvents. The following fatty acids were used: C_14∶0, C_16∶0, C_18∶0, C_18∶1, and C_18∶2. Monoesterification was achieved by using a limiting amount of the fatty acid. Both the 1-O-hexadecyl-3-O-acylglycerol and the 2-O-acylglycerol were obtained in a total yield of 75% and a ratio of 7∶1 in dichloromethane after 3 d. Chromatographic data for the monoesters, useful for the identification of the natural products, are given (gas-liquid chromatography, thin-layer chromatography, reverse-phase thin-layer chromatography). The structure was confirmed by a chemical synthesis of 1-O-hexadecyl-2-O-hexadecanoylglycerol. The 3-O-glyceride was also formed by acyl migration, as the minor component. The monoesters were separated by column chromatography and characterized by ¹H and ¹³C nuclear magnetic resonance spectra.     

Distribution of monoesters resulting from the esterification of a mixture of glycols and triols

The distribution of monoesters resulting from the esterification of mixtures of C₃ to C₆ glycols and triols with lauric acid is reported. Glycols with two primary, two secondary, and one primary and one secondary, both vicinal and isolated, as well as triols with both vicinal and isolated hydroxyls, were investigated for their relative esterifiability. Nonvicinal glycols with only primary hydroxyls were found to have equal reactivity. Glycols and triols that have one secondary hydroxyl show a lower relative esterifi-ability than compounds with only primary hydroxyls. The reactivity is dependent on the position of the secondary hydroxyl in the mol-ecule. Esterifiabilities relative to 1,4 butanediol ranged from 0.228 for the secondary hydroxyl of 1,2,6 hexanetriol up to 1.591 for the isolated primary hydroxyl of 1,2,4 butanetriol. 1 Presented at the AOCS Meeting, Philadelphia, October 1966.     

Comparison of some commercial waxes by gas liquid chromatography

Volatile components (hydrocarbons, monoesters, free acids as methyl esters and free alcohols as acetates) of seven unhydrolyzed commercial waxes-ouricury, carnauba, Chinese insect, lac, esparto, candelilla and Japan wax—have been analyzed and compared by gas liquid chromatography. Though appreciable portions of the waxes were nonvolatile, the results were sufficient to distinguish the seven waxes completely. Methanolysis products were analyzed directly by gas liquid chromatography, and the results agreed with those previously obtained for hydrolysis products of these waxes. Ouricury wax gave 18% C₂₄−C₃₄ αω-diols and 4% C₂₄−C₃₂ ω-hydroxy acids, in addition to 28% C₂₀−C₃₂ aciods and 17% C₂₂−C₃₄ alcohols, on methanolysis. NRCC No. 13387.     

Decarboxylative (4+1) Oxidative Annulation of Malonate Monoesters with 2‐Vinylpyridine Derivatives

A novel N‐iodosuccinimide‐mediated decarboxylative (4+1) oxidative annulation between 2‐vinylpyridine derivatives and malonate monoesters was developed. It offers a new way to construct indolizine derivatives by utilizing malonate monoesters as a C₁ unit. The alkyl 2,2‐diiodoacetate was found to be the active reaction intermediate during the transformation.

     

The Minimum Activation Peptide from ilvH Can Activate the Catalytic Subunit of AHAS from Different Species

Acetohydroxyacid synthases (AHASs), which catalyze the first step in the biosynthesis of branched‐chain amino acids, are composed of a catalytic subunit (CSU) and a regulatory subunit (RSU). The CSU harbors the catalytic site, and the RSU is responsible for the activation and feedback regulation of the CSU. Previous results from Chipman and co‐workers and our lab have shown that heterologous activation can be achieved among isozymes of Escherichia coli AHAS. It would be interesting to find the minimum peptide of ilvH (the RSU of E. coli AHAS III) that could activate other E. coli CSUs, or even those of ## species. In this paper, C‐terminal, N‐terminal, and C‐ and N‐terminal truncation mutants of ilvH were constructed. The minimum peptide to activate ilvI (the CSU of E. coli AHAS III) was found to be Δ_N14–Δ_C89. Moreover, this peptide could not only activate its homologous ilvI and heterologous ilvB (CSU of E. coli AHAS I), but also heterologously activate the CSUs of AHAS from Saccharomyces cerevisiae, Arabidopsis thaliana, and Nicotiana plumbaginifolia. However, this peptide totally lost its ability for feedback regulation by valine, thus suggesting different elements for enzymatic activation and feedback regulation. Additionally, the apparent dissociation constant (K_d) of Δ_N14–Δ_C89 when binding CSUs of different species was found to be 9.3–66.5 μM by using microscale thermophoresis. The ability of this peptide to activate different CSUs does not correlate well with its binding ability (K_d) to these CSUs, thus implying that key interactions by specific residues is more important than binding ability in promoting enzymatic reactions. The high sequence similarity of the peptide Δ_N14–Δ_C89 to RSUs across species hints that this peptide represents the minimum activation motif in RSU and that it regulates all AHASs.     

Hydrolysis and biodegradation studies of surface-active esters

Base-catalyzed hydrolysis, biodegradation, and enzyme-catalyzed hydrolysis of a series of four monoesters of tetra(ethylene glycol) have been investigated. The surfactants varied in substitution on the α-carbon of the acyl chain, from no substitution, to 2-methyl, to 2-ethyl, and on to 2,2-dimethyl. All surfactants were based on C₈-acids except the methyl-substituted, which was based on a C₇-acid. The hydrolysis was investigated using ¹H nuclear magnetic resonance. The surfactants showed a pronounced difference in stability with respect to type of substitution in the vicinity of the ester bond. In alka-line hydrolysis the most significant difference in reactivity lay between the surfactant with an ethyl group and the surfactant with a methyl group in the α-position of the acyl chain. However, in the biodegradation studies these surfactants broke down at almost exactly the same rate as the nonsubstituted surfactant. In the biodegradation test, the disubstituted surfactant deviated considerably. Two lipases, from Mucor miehei (MML) and Candida antarctica B (CALB), were used in the enzyme-catalyzed hydrolysis. The surfactant with no substitution was found to hydrolyze much faster than the other surfactants, and the hydrolytic activity of MML, but not CALB, increased in the presence of surfactant micelles.     

Direct Access to Medium‐Chain α,ω‐Dicarboxylic Acids by Using a Baeyer–Villiger Monooxygenase of Abnormal Regioselectivity

Baeyer–Villiger monooxygenases (BVMOs) are versatile biocatalysts in organic synthesis that can generate esters or lactones by inserting a single oxygen atom adjacent to a carbonyl moiety. The regioselectivity of BVMOs is essential in determining the ratio of two regioisomers for converting asymmetric ketones. Herein, we report a novel BVMO from Pseudomonas aeruginosa (PaBVMO); this has been exploited for the direct synthesis of medium‐chain α,ω‐dicarboxylic acids through a Baeyer–Villiger oxidation–hydrolysis cascade. PaBVMO displayed the highest abnormal regioselectivity toward a variety of long‐chain aliphatic keto acids (C₁₆–C₂₀) to date, affording dicarboxylic monoesters with a ratio of up to 95 %. Upon chemical hydrolysis, α,ω‐dicarboxylic acids and fatty alcohols are readily obtained without further treatment; this significantly reduces the synthetic steps of α,ω‐dicarboxylic acids from renewable oils and fats.     

Synthesis and chemical hydrolysis of surface-active esters

A series of four homologous pure nonionic surfactants, all monoesters of tetra(ethylene glycol), were synthesized. The ester surfactants varied in the degree of substitution on the α-carbon of the acyl chain, from no substitution to 2-methyl, to 2-ethyl, and on to 2,2-dimethyl. All surfactants were based on C₈-acids except the 2-methyl-substituted, which was based on a C₇-acid. The ester surfactants were characterized by critical micelle concentration (CMC) and cloud point. Base-catalyzed hydrolysis was investigated by using ¹H NMR and tensiometry. The surfactants showed a pronounced difference in hydrolytic reactivity; the nonsubstituted surfactant was 90 times more reactive than the disubstituted, and the reactivity of the methyl-substituted surfactant was 14 times more reactive than the ethyl-substituted. Hydrolysis studies above the CMC revealed that the ester bond of the aggregated surfactant is protected from attack by hydroxide ions; thus, only surfactants in monomeric form are being cleaved.     

Synthesis,Quantum Chemical Calculations and Properties of Nonionic and Nonionic–Anionic Surfactants Based on Fatty Alkyl Succinate

Two surfactants based on maleic anhydride were synthesized by esterification with fatty alcohols C₁₀, C₁₂ and C₁₄ to produce half esters [I–III]. Nonionic surfactant monoesters [I–III]a–c synthesized by ethoxylation of [I–III] with different moles of ethylene oxide [6, 8 and 10] in the presence of K10 clay as an untraditionally catalyst. The later products were sulfonated to produce nonionic–anionic surfactants [IV–VI]a–c. The structures of synthesized surfactant were elucidated by FTIR and ¹H-NMR data. Their surface activity and biodegradability were determined. All the synthesized surfactants showed good surface activity and biodegradability, but anionic-nonionic type has better effect than nonionic one. Quantum chemical calculations were utilized to explore the electronic structure and stability of these compounds. Computational studies have been carried out at the PM3 semiempirical molecular orbitals level, to establish the highest occupied molecular orbital–lowest unoccupied molecular orbital, ionization potential energy and ESP mapping of these compounds. Also, the absorption, distribution, metabolism, elimination and toxic properties were studied to gain a clear view of the oral bioavailability of these compounds.     

Activities of γ-Al2O3-Supported Metal Oxide Catalysts in Propane Oxidative Dehydrogenation

The activities of metal oxide catalysts in propane oxidative dehydrogenation to propene have been studied. The catalysts are M/-Al₂O₃ (where M is an oxide of Cr, Mn, Zr, Ni, Ba, Y, Dy, Tb, Yb, Ce, Tm, Ho or Pr). Both transition metal oxides (TMO) and rare-earth metal oxides (REO) are found to catalyze the reaction at 350-450 °C, 1 atm and a feed rate of 75 cm³/min of a mixture of C₃H₈, O₂ and He in a molar ratio of 4:1:10. Among the catalysts, Cr-Al-O is found to exhibit the best performance. The selectivity to propene is 41.1% at 350 °C while it is 54.1% at 450 °C. Dy-Al-O has the highest C₃H₆ selectivity among the REO. At 450 °C, the other catalysts show C₃H₆ selectivity ranging from 16.2 to 37.7%. In general TMO show higher C₃H₆ selectivity than REO, which, however, show higher C₂H₄ selectivity. An attempt is made to correlate propane conversion and selectivity to C₃H₆ with metal-oxygen bond strength in the catalysts. For the TMO a linear correlation is found between the standard aqueous reduction potential of the metal cation of the respective catalyst and its selectivity to propane at 11% conversion. No such correlation has been found in the case of REO. Analyses of the product distributions suggest that for TMO propane activation the redox mechanism seems to prevail while the REO activate it by adsorbed oxygen.     

Perfluoroalkylated fatty acid monoesters of trehalose and sucrose for biomedical applications: Remarkable emulsifying properties of 6-O-[3′-(perfluorooctyl) propanoyl]-trehalose

A new series of perfluoroalkylated fatty acid monoesters of α,α-trehalose and sucrose has been evaluated with respect to their physicochemical and biological properties for possible biomedical use. These water-soluble compounds strongly reduce the water surface tension and fluorocarbon/water interfacial tension. As co-surfactants in perfluorodecalin/Pluronic F-68 type emulsions they significantly increase the stability of these emulsions. Remarkably stable concentrated perfluorodecalin-in-water (50% w/v) emulsions were obtained when the C₈F₁₇CH₂CH₂C(O)-α,α-trehalose monoester was used as the sole surfactant, while no emulsion could be obtained with its maltoside analogue. No significant effect on the growth and viability of Namalva cell cultures and no hemolytic activity on human erythrocytes at concentrations up to 50 g/L were detected for these amphiphiles in spite of their high surface activity. The LD₅₀ was found to be in the range of 250–375 mg/kg of body weighti.v. in mice.     

Biotechnology and oleochemicals: Changing patterns

Biotechnology will have a broad impact on the oleochemicals industry. Only a narrow range of this interface is discussed: (a) the use of organic solvents in the enzymatic synthesis of lipid derivatives, (b) the effect of the chemical nature of the feedstock on the production of microbial monoesters, and (c) temperature as a determinant of the level of unsaturation in biosynthetic lipids. Interest in running enzymatic reactions in high concentrations of organic solvents is increasing. The implications of such processes for the oleochemical industry is illustrated by examples of ester synthesis and interesterification of oils and fats. The dramatic effect of feedstock chemistry on the final monoester product mix produced byAcinetobacter sp. HO1-N is also discussed. Products resulting from usingn-alkanes (C₁₆−C₂₀), acetic and propionic acids and, most recently, ethanol and propanol, are illustrated. They range from a monoester mix resembling sperm oil to one similar to jojoba oil. In general, temperature inversely affects biolipid unsaturation: the low the temperature, the greater the unsaturation. The major function of this response is to preserve fluidity and function in biological membranes. The effect is universal in nature, occurring in animals, plants and microorganisms. Controlled laboratory studies have supported these observations made in nature. We have investigated the effect of temperature on the unsaturation of monoesters produced by the bacterium,Acimetobacter sp. HO1-N. The inverse relationship between temperature and unsaturation is clearly shown. The enzymatic basis for these results and the possibility of chemical or genetic modification of plants and microorganisms to produce more or less unsaturated lipids is briefly discussed. Organic solvents, feedstock chemistry and temperature stress in biocatalysis are but three of the variables at the interface of biotechnology and the oleochemicals industry that will cause changing patterns.     

Soap-based detergent formulations: XV. Amino esters of α-sulfo fatty acids

Amphoteric surfactants were prepared either by direct esterification of α-sulfo fatty acids with various alkanolamines or by rearrangement of the corresponding alkanolamides of the α-sulfo fatty acids to the amino esters with the aid of aqueous hydrochloric acid. The α-sulfo fatty acid monoesters of diethanolamine could be prepared only via the rearrangement method. The amino esters in the C₁₆−C₁₈ range possessed limited water solubility whereas α-sulfolaurate esters were soluble at room temperature. The amino esters were found to be stable to acid hydrolysis; however, they were generally not stable to alkali, by which they were either hydrolyzed or rearranged to the corresponding amide. Only the esters of isopropanolamine and diglycolamine were stable to alkali. Surface active properties of the esters were determined. The lime soap dispersant requirements of the compounds were slightly poorer than those of the corresponding amides. The compounds were good cotton detergents by themselves as well as in combination with soap and a silicate builder. The overall surface active properties of the amino esters were greatly inferior to those of the sulfobetaines previously reported. This indicates that an effective amphoteric lime soap dispersant should have its anionic group located at the very end of the molecule and the cationic group somewhat farther away, instead of the reverse. Presented at the AOCS Meeting, Philadelphia, September 1974.     

Friction properties of vegetable oils

Vegetable oils are a renewable and an environmentally friendly alternative to petroleum-based oils in lubrication and other important application areas. Vegetable oils fall into two broad chemical categories: triesters (or TG) and monoesters. Most vegetable oils are triesters of glycerol with FA, whose characteristics are dependent on the chemistry and composition of the FA residues. A small percentage of vegetable oils are monoesters of long-chain FA and fatty alcohols of varying chemistries. In this work, the free energy of adsorption (ΔG _ads) of safflower (SA), high-oleic safflower (HOSA), and jojoba (JO), methyl oleate (MO), and methyl palmitate (MP) on steel were investigated. SA and HOSA are TG of vegetable oils with FA residues of radically different degrees of unsaturation. JO is a monoester vegetable oil. ΔG _ads is one of the major factors affecting the boundary friction properties of lubricant ingredients. ΔG _ads was found to increase in the order: HOSA≤SA<JO<MO≤MP. The results are consistent with the degree of functionality and other chemical properties of the oils studied.