Chain Aliphatic Acids Research Articles

Esterification of Long Chain Aliphatic Acids with Long Chain Alcohols Catalyzed by Multi-valent Metal Salts

Abstract Some typical multi-valent metal salts, such as chloride, nitrate, sulfate, and acetate of Fe(III), Al(III), Ga(III), In(III), Zr(IV), Hf(IV), Zn(II), Co(II), Ni(II), Mn(III), Cr(III), and Cu(II) have catalytic acitivties for the esterification of saturated and unsaturated long chain aliphatic acids with long chain aliphatic alcohols. These catalysts were sponteneously separated from the reaction mixtures, and could be subjected to the recycle use for the further reactions.

An Efficient Method for Determination of the Degree of Substitution of Cellulose Esters of Long Chain Aliphatic Acids

The determination of the degree of substitution (DS) of fatty acid cellulose esters, representing a broad range of substituents (C6, C12, C18 and C22), was performed by alkaline hydrolysis of the ester groups and the quantification of fatty acids by gas chromatography-mass spectrometry (GC-MS) as their trimethylsilyl derivatives. The method was optimized and compared with established techniques for the DS determination (elemental analysis and alkaline hydrolysis/titrimetry). The results demonstrated that alkaline hydrolysis/GC-MS is a rapid, reliable and powerful method for analysis of fatty acid cellulose esters, particularly when different acyl substituents are present.

Efficient Esterification of Long Chain Aliphatic Carboxylic Acids with Alcohols over ZrOCl2·8H2O Catalyst

Direct condensation of equimolar amounts of long chain carboxylic acids and alcohols could be achieved by using zirconyl chloride as an efficient catalyst. ZrOCl 2 .8H 2 O showed high activity for esterification between primary acids and alcohols; however, it was less active in the combination of branched acid and secondary alcohols to give the corresponding esters.

ZrOCl2·8H2O catalysts for the esterification of long chain aliphatic carboxylic acids and alcohols. The enhancement of catalytic performance by supporting on ordered mesoporous silica

ZrOCl2·8H2O is an efficient catalyst for the esterification of long chain carboxylic acids with long chain primary and secondary alcohols. Supporting ZrOCl2·8H2O on ordered mesoporous silica enhances the catalytic activity of the esterification. The esters of C10–C18 normal acid and alcohol are obtained in high yield by supported ZrOCl2·8H2O on MCM-41 although the yield of the esters decreases with the chain length of acids and alcohols. The esterification of less reactive branched acids and secondary alcohols gives excellent to good yield of the corresponding esters over supported catalysts. Zirconium cation cluster [Zr4(OH)8(H2O)16]8+ is suggested as the catalytic active species. The enhancement of catalytic performance by supporting on MCM-41 is due to increased contact between substrate and catalyst because the cation cluster is highly dispersed over MCM-41 with high surface area. The hydrophobic properties of mesoporous silica accelerate the removal of water during the esterification by controlling hydrated water in the cluster. The catalyst is recyclable without significant loss of activity.

Studies on transport properties of short chain aliphatic carboxylicacids in electrodialytic separation

An electrodialysis process was employed to investigate the concentration of formic, acetic and propionic acid solutions under different experimental conditions. In this process interpolymer-type ion-exchange membranes were used due their high chemical stability and durability. The effects of concentration, electric current and time on the electrodialysis process were studied. A mathematical equation representing the water transport behavior of the electrodialysis process for concentrating acids under the influence of different current densities was developed. This equation is valid for any electrodialysis process with ion-exchange membranes used under similar operating conditions. The reliability of the water transport equation was tested through comparison with the experimental data. Results indicate that electrodialysis is an effective method for concentrating shorter chain aliphatic carboxylic acid solutions. Ionic transportation, power consumption and current efficiency data reveal the following trend of the electrodialysis process's efficiency during concentration of carboxylic acid solutions: formic acid > acetic acid > propionic acid.

Comparison of mesophilic and thermophilic feruloyl esterases: Characterization of their substrate specificity for methyl phenylalkanoates

The active sites of feruloyl esterases from mesophilic and thermophilic sources were probed using methyl esters of phenylalkanoic acids. Only 13 out of 26 substrates tested were significant substrates for all the enzymes. Lengthening or shortening the aliphatic side chain while maintaining the same aromatic substitutions completely abolished activity for both enzymes, which demonstrates the importance of the correct distance between the aromatic group and the ester bond. Maintaining the phenylpropanoate structure but altering the substitutions of the aromatic ring demonstrated that the type-A esterase from the mesophilic fungus Fusarium oxysporum (FoFaeA) showed a preference for methoxylated substrates, in contrast to the type-B esterase from the same source (FoFaeB) and the thermophilic type-B (StFaeB) and type-C (StFaeC) from Sporotrichum thermophile, which preferred hydroxylated substrates. All four esterases hydrolyzed short chain aliphatic acid (C 2–C 4) esters of p-nitrophenol, but not the C 12 ester of laurate. All the feruloyl esterases were able to release ferulic acid from the plant cell wall material in conjunction with a xylanase, but only the type-A esterase FoFaeA was effective in releasing the 5,5′ form of diferulic acid. The thermophilic type-B esterase had a lower catalytic efficiency than its mesophilic counterpart, but released more ferulic acid from plant cell walls.

Antimicrobial activity and chemical investigation of Brazilian Drosera

The antimicrobial activity of three different extracts (hexanic, ethyl acetate, methanol) obtained from Brazilian Drosera species (D. communis, D. montana var. montana, D. brevifolia, D. villosa var. graomogolensis, D. villosa var. villosa, Drosera sp. 1, and Drosera sp. 2 ) were tested against Staphylococcus aureus (ATCC 25923), Enterococcus faecium (ATCC23212), Pseudomonas aeruginosa (ATCC27853), Escherichia coli (ATCC11229), Salmonella choleraesuis (ATCC10708), Klebsiella pneumoniae (ATCC13883), and Candida albicans (a human isolate). Better antimicrobial activity was observed with D. communis and D. montana var. montana ethyl acetate extracts. Phytochemical analyses from D. communis, D. montana var. montana and D. brevifolia yielded 5-hydroxy-2-methyl-1,4-naphthoquinone (plumbagin); long chain aliphatic hydrocarbons were isolated from D. communis and from D. villosa var. villosa, a mixture of long chain aliphatic alcohols and carboxylic acids, was isolated from D. communis and 3b-O-acetylaleuritolic acid from D. villosa var. villosa.

Protective effect of D-003 on experimental spinal cord ischemia in rabbits

D-003 is a natural mixture of long chain aliphatic acids isolated and purified from sugar cane wax. It possesses antiplatelet and antithrombotic effects as well as decreases plasma and serum levels of thromboxane B 2 (TxB 2), meanwhile significantly and markedly raises prostacyclin (PgI 2) levels in rats. This study was undertaken to investigate the effects of D-003 on spinal cord injury in rabbits. New Zealand rabbits were treated during 10 days with D-003 (25 and 200 mg kg −1) and ASA (2 mg kg −1) before spinal cord ischemia. Animals were subjected to 20 min of aortic occlusion and 24 h of reperfusion. Clinical symptoms and histopathological changes of spinal cord were observed.The PgI 2 levels in thoracic aorta were quantified by bioassay. D-003 (25 and 200 mg kg −1) significantly increased the mean scores reached 4 h after reperfusion, although no dose relation was observed. Twenty-four hours after reperfusion, no deaths occurred in both sham and D-003 treated groups, meanwhile in positive controls and ASA the mortality rate was 38.5% and 7.69% respectively. In addition, 100% of sham, 69% and 77% of rabbits treated with D-003 at 25 and 200 mg kg −1, respectively, did not show histopathological changes. By the contrary, 100% of positive control animals showed severe damage and ASA-treated rabbits showed only a partial protection. Animals treated with both doses of D-003 showed PgI 2 levels significantly larger than those of positive and negative controls, an effect dose-related, while ASA 2 mg kg −1 did not change PgI 2 values. The increase of PgI 2 levels achieved in the D-003 treated animals could be an important mechanism in the protection against the spinal cord ischemia.

Gas chromatographic–mass spectrometric study of the oil fractions produced by microwave-assisted pyrolysis of different sewage sludges

The pyrolysis of sewage sludge was studied in a microwave oven using graphite as microwave absorber. The pyrolysis temperature ranged from 800 to 1000 °C depending on the type of sewage sludge. A conventional electrical furnace was also employed in order to compare the results obtained with both methods. The pyrolysis oils were trapped in a series of condensers and their characteristics such as elemental analysis and calorific value were determined and compared with those of the initial sludge. The oil composition was analyzed by GC–MS. The oils from the microwave oven had n-alkanes and 1-alkenes, aromatic compounds, ranging from benzene derivatives to polycyclic aromatic hydrocarbons (PAHs), nitrogenated compounds, long chain aliphatic carboxylic acids, ketones and esters and also monoterpenes and steroids. The oil from the electric oven was composed basically of PAHs such as naphthalene, acenapthylene, phenanthrene, fluoranthene, benzo[ a]anthracene, benzofluoranthenes, benzopyrenes, indenepyrene, benzo[ ghi]perylene, and anthanthrene. In contrast, these compounds were not produced in the case of microwave-assisted pyrolysis.

Influence of π-stacking along with hydrogen bonding interactions in the recognition of monocarboxylic acids

The new receptors 1 and 2 have been designed and synthesized where phenyl and naphthalene rings have been introduced in place of aliphatic chain in receptor 3 to achieve the π-stacking interactions. These receptors show higher association constants with aromatic over aliphatic carboxylic acids compared to receptor 3 which preferably recognizes long chain aliphatic acid.

Preliminary evaluation of the cytotoxic and genotoxic potential of D-003: Mixture of very long chain fatty acids.

D-003 is a mixture of very long chain aliphatic acids purified from sugar cane wax, wherein octacosanoic acid represents the major component. Previous experimental studies have shown that D-003 inhibits platelet aggregation in rodents. Also, its lowers total (TC) and low-density lipoprotein cholesterol (LDL-C) in normocholesterolemic rabbits in a dose-dependent manner and inhibits cholesterol biosynthesis in fibroblast cultures. The present study was performed to investigate the in vitro cytotoxic and genotoxic potential effects of D-003 assessed through two tests: the neutral red (NR) assay and the Ames test. Positive and negative controls were included in each experimental series. Compared with controls, no cytotoxicity was evident after 24 and 72 h of treatment with doses up to 1,000 microg/ml in the NR assay. On the other hand, D-003 (5-5,000 microg/plate) did not increase the frequency of reverse mutations in the Ames test in both alternatives with or without S9 mix metabolic activation and a pre-incubation step. The positive control chemicals included in each experiment, namely, treatment with sodium dodecyl sulphate (SDS) in the NR assay and sodium azide (NaAz), 2-aminofluorene (AF), and dimethylnitrosamine (DMNA) in the Ames test, induced the expected changes, such as a decrease in optical density (OD) values in the NR assay and an increase in the frequency of reverse mutations in the Ames test. The present results indicate that D-003 did not show evidence of cytotoxic or genotoxic potential in tests able to detect the ability of chemicals to disrupt cells (NR assay) or to induce gene mutations (Ames test).

In Vivo Genotoxic Evaluation of D-003, a Mixture of Very Long Chain Aliphatic Acids.

D-003 is a mixture of very long chain aliphatic acids purified from sugar cane wax with cholesterol-lowering effects. The present study was undertaken to investigate the in vivo cytotoxic and genotoxic potential of D-003 using three established assays: bone marrow micronucleus, sperm morphology, and single cell gel electrophoresis (Comet) assay. In a first experimental series, CEN/NMRI mice (6-8 animals per sex per group) were administered D-003 by gastric gavage at 5, 50, or 500 mg/kg for 90 days, then sacrificed 24 hours after the last administration. The effects on bone marrow micronucleus were evaluated only in female mice. D-003 (5-500 mg/kg) did not increase the frequency of micronucleated polychromatic erythrocytes, nor the ratio of polychromatic to normochromatic erythrocytes, compared with the controls. The assessment of the effects on sperm morphology showed that D-003 did not change the sperm count or the frequency of all types of abnormal head shapes, compared with the controls. In a second series, the micronucleus assay was performed in mice of both sexes given 2,000 mg/kg for 6 days. Likewise, in this series, neither cytotoxic nor genotoxic effects were found. Finally, five male Sprague-Dawley rats were treated with D-003 (1,250 mg/kg) by oral gavage for 90 days, and Comet assay on liver cells was performed. No single-strand breaks or alkali-labile site induction on DNA was observed. These results indicate that D-003 does not show evidence of cytotoxic or genotoxic activity on either somatic or germ cells in rodents.

Characterization of plant beta-ureidopropionase and functional overexpression in Escherichia coli.

Pyrimidine bases are rapidly catabolized in growing plant tissues. The final enzyme of the catabolic pathway, beta-ureidopropionase (beta-UP; EC 3.5.1.6), was partially purified from the shoots of etiolated maize (Zea mays) seedlings. The enzyme had a K(m) for beta-ureidopropionate (the substrate derived from uracil) of 11 microM. Only one enantiomer of racemic beta-ureidoisobutyrate (derived from thymine) was processed with a K(m) of 6 microM. The enzyme was inactivated by dialysis against 1,10-phenanthroline and activity could be partially restored by addition of Zn(2+). Maize beta-UP was very sensitive to inactivation by iodoacetamide. This could be prevented by addition of substrate, indicating the presence of an active site Cys. The enzyme was strongly inhibited by short chain aliphatic acids and aryl propionates, the most potent inhibitor of which was 2-(2, 6-dinitrophenoxy)-propionate (I(50) = 0.5 microM). A gene for Arabidopsis beta-UP encodes a polypeptide of 405 amino acids and has about 55% homology with the enzymes from other eukaryotic organisms. Several highly conserved residues link the plant beta-UP with a larger class of prokaryotic and eukaryotic amidohydrolases. An Arabidopsis cDNA truncated at the N terminus by 14 residues was cloned and overexpressed in Escherichia coli. The recombinant enzyme (43.7 kD) was soluble, functional, and purified to homogeneity with yields of 15 to 20 mg per 30 g fresh weight of E. coli cells. The recombinant enzyme from Arabidopsis and the native enzyme from maize had molecular masses of approximately 440 kD, indicating the enzyme is a decamer at pH 7.

Dehydration and dehydroxylation of alumina gels prepared from tri-sec-butoxyaluminium modified with short chain aliphatic acids

The dehydration and dehydroxylation of alumina gels prepared from the hydrolysis of tri-sec-butoxyaluminium (ASB) at both 25 and 90°C, unmodified and modified with short chain aliphatic acids has been studied using a combination of differential thermal analysis (DTA) and thermogravimetry. The alumina phase in the gel was found to be dependent upon the temperature of hydrolysis and the modifying acid. The gels formed at 25°C from unmodified ASB contained alumina as gibbsite and at 90°C from the unmodified ASB a mixture of gibbsite and boehmite, whereas those gels formed from ASB at 25°C and modified with short chain aliphatic acids were amorphous. In DTA of the modified gels, the exotherms from the combustion of the aliphatic acid groups masked the endotherms of dehydration and dehydroxylation of the gels. Neither DTA nor thermogravimetric analysis (TGA) could determine the dehydroxylation temperature range. The application of differential thermogravimetric analysis (DTGA) enabled these temperatures to be obtained. DTGA of the gels formed from the acid modified ASB showed complex ‘endograms’. Infrared spectroscopy was used to determine the molecular structures of the acetic acid modified gels.

An NMR Conformational Analysis of Cyclic Bradykinin Mimics. Evidence for a β-Turn

A detailed NMR study is carried out in acetonitrile/water solutions on three novel cyclic bradykinin antagonist analogues, BKM-824, BKM-870, and BKM-872, to examine their solution structures, and to correlate the structures with bradykinin antagonist and anti-cancer activities. The solution structures of the cyclic peptides are correlated with the structural data for known linear bradykinin antagonists. The sequences are: BKM-824 c[Ava-Igl-Ser-DF5F-Oic- Arg] where Ava is 5-aminovaleric acid, Igl is α-(2-indanyl)glycine, F5F is pentafluorophenylalanine, and Oic is (2S,3aS,7aS)-octahydroindole-2-carboxylic acid; BKM-870; c[DArg-Arg-Add-DF5F-Oic-Arg] where Add is 12-aminododecanoic acid; and BKM-872; c[DArg-Arg-Eac-Ser-DF5F-Oic-Arg] where Eac is 6-aminocaproic acid. BKM-824 was the only peptide within this series that possessed a discernable solution structure. The NMR data indicate the presence of a type I β-turn between residues F5F4 and Ava1, a C-terminal-like end. Molecular dynamics calculations show that a type I β-turn from DF5F4 to Ava1 does exist although the turn was somewhat distorted. This result differs from the structures seen in linear bradykinin antagonists, which usually possess a type II II′β-turn at the C-terminal end and the presence of a defined turn is correlated with bradykinin antagonist activity. There is no solution structure for BKM-870 and BKM-872 but a correlation between the primary sequence Argterminal-DArg1-Arg2-long chain aliphatic amino acid and anti-cancer activity is evident.

Influence of synthetic sheep urine on the microbial biomass, activity and community structure in two pastures in the Scottish uplands.

The impact of urine on the microbial biomass, activity and community structure was compared in the soil beneath two pastures in the Scottish uplands; Fasset, a natural Agrostis capillaris–Festuca ovina–Galium saxatile grassland and Strathfinella, a semi-natural grassland, improved with fertiliser addition. Community level physiological profiles (CLPP) were used to characterise the microbial communities. The utilisation of sugars, oligosaccharides, alcohols, carboxylic acids, long chain aliphatic acids, acidic, basic and neutral amino acids, amide N, phenolic acids and long chain aliphatic acids was used to compare the soils and the impact of synthetic urine addition. In the untreated soils, the utilisation of all the substrates decreased from the first week in May through to October. Averaged over all times and urine treatment, the potential utilisation of all substrates except for phenolic acids, long chain aliphatic acids and carboxylic acids was greater in the improved and more intensively grazed Strathfinella site. When averaged over all sample times, urine increased the utilisation of sugars, oligosaccharides, basic amino acids and amide N and the increases were greater in the unimproved, less intensively grazed, Fasset soil than that at Strathfinella. The effect of urine tended to be greatest during the period between 2 and 5 weeks after urine addition when utilisation of alcohols, acidic and neutral amino acids was also increased. Microbial biomass C in the control soils was 155.9 and 112.7 g C m−2 at Fasset and Strathfinella, respectively. Values did not change significantly with time and were unchanged by the addition of urine. However, urine addition significantly increased basal respiration rates at Fasset and decreased them at Strathfinella. Urine also increased bacterial numbers in both soils, but had no consistent effect on fungi or yeasts. The significance of these findings for studies of soil microbial community structure and activity in grazed upland grasslands is discussed.

Degradation of cellulosic materials under the alkaline conditions of a cementitious repository for low and intermediate level radioactive waste: Part I: Identification of degradation products

In order to assess the potential role of cellulose degradation products as metal-binding chelates in a repository for radioactive waste, different cellulosic materials (pure cellulose, cotton, tissues and recycling paper) were degraded under the chemical conditions of cement pore water (pH 13.3). The degradation products formed were characterised using different separation techniques (HPIEC, HPAEC, GC-MS, MS/MS) and by high resolution 1H-NMR spectroscopy. The main degradation products of pure cellulose are the diastereomeric α-isosaccharinic acid (α-ISA) and β-isosaccharinic acid (β-ISA), which accounted for ∼80% of total dissolved organic carbon formed. Minor components are short chain aliphatic acids such as formic acid, acetic acid, lactic acid and threonic acid comprising less than 10% of total dissolved organic carbon. The degradation of the other cellulosic materials resulted in lower amounts of α-ISA and β-ISA and in higher yields of small organic acids (acetic acid) and of unidentified compounds. The combination of the different MS and NMR techniques unequivocally shows the structural identity of β-ISA.

Ozonation of Lignin Rich Solid Fractions from Corn Stalks

Various kinds of solid materials containing lignin were obtained by fractionation (autohydrolysis and organosolvolysis) of corn (Zea mays) stalks. These materials were further ozonated in order to observe the behaviour of their constituent polymers, particular attention being paid to lignin, and the evolution of the water soluble reaction products during oxidation. An optimal moisture content for these materials of 60% was found, which led to the highest degree of solubilization during ozone treatment. Results indicate that lignin is the most severely affected polymer, followed by hemicelluloses and finally by cellulose. The ozonation of autohydrolyzed material involved its gradual delignification, the elimination of lignin being more easy at the beginning of the reaction than at the end. The following acids were identified by GC/MS and injection of standards in GC/FID: glycolic, oxalic, malonic, glyoxylic, glyceric, p-hydroxybenzoic and malic. In addition, p-hydroxybenzaldehyde and vanillin were also identified. During the ozonation of lignin-containing lignocellulosic materials in moistened solid state, ozone rapidly oxidized the initially generated oxyaromatics and transformed them into short chain aliphatic carboxylic acids.

Hydrophobicity of residue351 of the G protein Gi1 alpha determines the extent of activation by the alpha 2A-adrenoceptor.

Cysteine351 is the site for pertussis toxin-catalyzed ADP-ribosylation in the G protein Gi1 alpha. Alteration of this residue, or the equivalent cysteine in other Gi-family G proteins, has been used to examine specific interactions between receptors and these G proteins. However, no systematic analysis has been performed to determine the quantitative effect of such alterations. To address this we mutated cysteine351 of Gi1 alpha to all other possible amino acids. Each of the G protein mutants was transiently coexpressed along with the porcine alpha 2A-adrenoceptor in HEK 293/T cells. Following pertussis toxin treatment of the cells, membranes were prepared and the capacity of the agonist UK14304 to stimulate the binding of [35S]GTP gamma S to the modified G proteins was measured. A spectrum of function was observed. The presence of either a charged amino acid or a proline at this position essentially attenuated agonist regulation. The wild-type G protein did not result in maximal stimulation by agonist. The presence of certain branched chain aliphatic amino acids or bulky aromatic R groups at amino acid351 resulted in substantially greater maximal stimulation by the alpha 2A-adrenoceptor than that achieved with the wild-type sequence. The degree of activation of the forms of Gi1 alpha correlated strongly with the octanol/water partition coefficient of the amino acid at residue351. Variation in EC50 values for agonist-induced stimulation of binding of [35S]GTP gamma S to the mutant G proteins also correlated with the octanol/water partition coefficient. These results define a central role for hydrophobicity of this residue in defining productive receptor-G protein interactions.

Aniline mineralization by AOP's: anodic oxidation, photocatalysis, electro-Fenton and photoelectro-Fenton processes

The aniline degradation in acidic medium of pH≈3 under photocatalytic and electrochemical conditions has been investigated. The efficiency for substrate mineralization in each process has been comparatively analysed by the decrease in TOC of aniline solutions. Particular emphasis has been made on the role of Fe(II) ions and H 2O 2. The electrochemical experiments performed in the presence of both species (electro-Fenton conditions) leads to a fast aniline mineralization, which is notably increased by UVA irradiation (photoelectro-Fenton process). In photocatalysis with TiO 2 suspensions, the presence of H 2O 2 and Fe(II) ions in solution notably increases the aniline degradation rate at the initial stages of the process, whereas the opposite effect occurs at long irradiation times. Benzoquinone, hydroquinone, nitrobenzene, phenol and 1,2,4-benzenetriol were detected as intermediates by HPLC in both, electrochemical and photocatalytic experiments. Short chain aliphatic acids, such as maleic and fumaric acids, were only found in the electrochemical experiments. Ammonium ions (75–80% of initial nitrogen) were generated in all solutions tested. A general reaction pathway that accounts for aniline mineralization to CO 2 involving those products is proposed.