Chain Aliphatic Aldehydes Research Articles

Comprehensive Insights into the Production of Long Chain Aliphatic Aldehydes Using a Copper-Radical Alcohol Oxidase as Biocatalyst

The oxidation of alcohols is a cornerstone reaction in chemistry, notably in the flavor and fragrance industry where long-chain aliphatic aldehydes are major odorant compounds. In a context where greener alternatives are sought after, biocatalysis holds many promises. Here, we investigated the ability of the alcohol oxidase from Colletotrichum graminicola (CgrAlcOx)—an organic cofactor-free enzyme belonging to the copper-radical oxidase (CRO) class—to convert industrially relevant long-chain aliphatic alcohols. CgrAlcOx is a competent catalyst for the conversion of octan-1-ol when supported by the accessory enzymes peroxidase and catalase. Detailed examination of the products revealed the occurrence of an overoxidation step leading to the production of carboxylic acid for some aliphatic aldehydes and benzaldehyde derivatives. The partition between aldehyde and acid products varied upon substrate properties (chain length and propensity to form geminal-diols) and enzyme specificity and could be tuned by controlling the reaction conditions. In silico analyses suggested an inhibitory binding mode of long-chain aliphatic geminal-diols and a substrate-induced fit mechanism for a benzyl alcohol derivative. By demonstrating their natural ability to perform long-chain aliphatic alcohol oxidation, the present study establishes the potential of fungal CRO-AlcOx as promising candidates for the green production of flavor and fragrance compounds.

Valorisation of bark lipophilic fractions from three Portuguese Salix species: A systematic study of the chemical composition and inhibitory activity on Escherichia coli

Salix (Salicaceae) species bark extracts are traditionally consumed due to their anti-inflammatory and analgesic benefits, mainly attributed to phenolic compounds. However, this biomass could be further exploited calling upon other extractive components, namely the lipophilic fraction. Hence, the present study highlights, for the first time, the chemical characterisation and the inhibitory effect of S. viminalis L., S. atrocinerea Brot. and S. fragilis L. bark lipophilic dichloromethane extracts against the Gram-negative bacterium Escherichia coli. Gas chromatography-mass spectrometry allowed the identification and quantification of 63 compounds, from which 36 were reported for the first time in these Salix species, namely 15 aromatic compounds, 4 fatty acids, 4 long chain aliphatic alcohols, 1 diterpene, 4 pentacyclic triterpenes, 4 tocopherols, 3 long chain aliphatic aldehydes and 1 sterol. Long chain aliphatic aldehydes represent the prevalent family, with triacontanal as the major component in S. fragilis L. and S. atrocinerea Brot. barks. Additionally, β-sitosterol was the major component identified in S. viminalis L. bark lipophilic extract, followed by lupeol. This last extract exhibited the highest inhibitory effect against E. coli viability, being probably related with these bioactive components. In contrast, aromatic compounds were detected at high abundances in S. atrocinerea Brot. and S. fragilis L. barks, with piceol as the predominant component. These findings can contribute to valorise bark of the three endogenous Portuguese Salix species, based on their chemical composition and biological properties.

A sialic acid aldolase from Peptoclostridium difficile NAP08 with 4-hydroxy-2-oxo-pentanoate aldolase activity.

Sialic acid aldolases (E.C.4.1.3.3) catalyze the reversible aldol cleavage of N-acetyl-d-neuraminic acid (Neu5Ac) to from N-acetyl-d-mannosamine (ManNAc) and pyruvate. In this study, a sialic acid aldolase (PdNAL) from Peptoclostridium difficile NAP08 was expressed in Escherichia coli BL21 (DE3). This homotetrameric enzyme was purified with a specific activity of 18.34U/mg for the cleavage of Neu5Ac. The optimal pH and temperature for aldol addition reaction were 7.4 and 65°C, respectively. PdNAL was quite stable at neutral and alkaline pH (6.0-10.0) and maintained about 89% of the activity after incubation at pH 10.0 for 24h. After incubation at 70°C for 15min, almost no activity loss was observed. The high thermostability simplified the purification of this enzyme. Interestingly, substrate profiling showed that PdNAL not only accepted ManNAc but also short chain aliphatic aldehydes such as acetaldehyde, propionaldehyde and n-butyraldehyde as the substrates. This is the first example that a sialic acid aldolase is active toward aliphatic aldehyde acceptors with two or more carbons. The amino acid sequence analysis indicates that PdNAL belongs to the NAL subfamily rather than 4-hydroxy-2-oxopentanoate (HOPA) aldolase, but it is interesting that the enzyme possesses the activity of HOPA aldolase.

Identification of human semiochemicals attractive to the major vectors of onchocerciasis.

BackgroundEntomological indicators are considered key metrics to document the interruption of transmission of Onchocerca volvulus, the etiological agent of human onchocerciasis. Human landing collection is the standard employed for collection of the vectors for this parasite. Recent studies reported the development of traps that have the potential for replacing humans for surveillance of O. volvulus in the vector population. However, the key chemical components of human odor that are attractive to vector black flies have not been identified.Methodology/Principal FindingsHuman sweat compounds were analyzed using GC-MS analysis and compounds common to three individuals identified. These common compounds, with others previously identified as attractive to other hematophagous arthropods were evaluated for their ability to stimulate and attract the major onchocerciasis vectors in Africa (Simulium damnosum sensu lato) and Latin America (Simulium ochraceum s. l.) using electroantennography and a Y tube binary choice assay. Medium chain length carboxylic acids and aldehydes were neurostimulatory for S. damnosum s.l. while S. ochraceum s.l. was stimulated by short chain aliphatic alcohols and aldehydes. Both species were attracted to ammonium bicarbonate and acetophenone. The compounds were shown to be attractive to the relevant vector species in field studies, when incorporated into a formulation that permitted a continuous release of the compound over time and used in concert with previously developed trap platforms.Conclusions/SignificanceThe identification of compounds attractive to the major vectors of O. volvulus will permit the development of optimized traps. Such traps may replace the use of human vector collectors for monitoring the effectiveness of onchocerciasis elimination programs and could find use as a contributing component in an integrated vector control/drug program aimed at eliminating river blindness in Africa.

Recognition at the leaf surface.

Recognition at the leaf surface.

Chromatographic determination of aliphatic aldehydes in human serum after pre-column derivatization using 2,2′-furil, a novel fluorogenic reagent

A novel, highly sensitive and selective fluorimetric liquid chromatographic method for simultaneous determination of medium chain aliphatic aldehydes was developed. The method was based on the derivatization of aliphatic aldehydes with 1,2-di(2-furyl)-1,2-ethanedione (2,2′-furil), a novel fluorogenic reagent, to form highly fluorescent difurylimidazole derivatives. The fluorescence derivatives were separated in less than 20min on a reversed-phase ODS column using an isocratic elution with a mixture of methanol–water (80:20, v/v%). The detection limits were from 0.19 to 0.50nM (1–10fmol/injection) at a signal-to-noise ratio (S/N) of 3. This method was successfully applied for monitoring of aliphatic aldehydes in healthy human sera by a simple pretreatment procedure without interferences from serum constituents.

The Influence of Process Conditions on the Chemical Composition of Pine Wood Catalytic Pyrolysis Oils

Pine wood samples were used as model feedstock to study the properties of catalytic fast pyrolysis oils. The influence of two commercial zeolite catalysts (BASF and SudChem) and pretreatment of the pine wood with sodium hydroxide on pyrolysis products were investigated. The pyrolysis oils were first fractionated using column chromatography and characterized using GC-MS. Long chain aliphatic hydrocarbons, levoglucosan, aldehydes and ketones, guaiacols/syringols, and benzenediols were the major compounds identified in the pyrolysis oils. The catalytic pyrolysis increased the polycyclic hydrocarbons fraction. Significant decreases in phthalate derivatives using SudChem and long chain aliphatics using BASF catalyst were observed. Significant amounts of aromatic heterocyclic hydrocarbons and benzene derivatives were formed, respectively, using BASF and SudChem catalysts. Guaiacyl/syringyl and benzenediols derivatives were partly suppressed by the zeolite catalysts, while the sodium hydroxide treatment enriched phenolic derivatives. Zeolite catalyst and sodium hydroxide were employed together; they showed different results for each catalyst.

Accelerated hydrothermal degradation of fibres of Phormium tenax (New Zealand flax)

Solid-phase microextraction (SPME)–gas chromatography (GC)–mass spectrometry (MS) has been applied to the analysis of acetic acid and furfural that are emitted from the fibres of Phormium tenax (Xanthorrhoeaceae) [New Zealand flax] during degradation. Accelerated hydrothermal ageing of fibres of the Ruawai cultivar of P. tenax for 55 days at 70 °C resulted in the production of acetic acid at a level greater or equal to 1.65 mg g–1 fibre. This corresponds to only 8.5% of the acetyl groups present in the fibres. These groups are an important source of acetic acid, which is capable of damaging the fibres. The rate of production of acetic acid suggests that a heritage object made from the fibres of P. tenax, that was stored in damp ambient conditions, would undergo significant deterioration after a relatively short period. Other volatile products released during ageing included furfural, a series of short to medium chain aliphatic aldehydes that were derived from the oxidation of long chain unsaturated fatty acids on the fibres and a small group of products that were derived from carotenoids. The levels of furfural were determined to be approximately 0.75% of the potential production but at these levels, furfural could contribute to unpleasant odours from unventilated items. Fibres from six cultivars of P. tenax were found to release acetic acid and furfural all at the same rate. The levels of acetic acid that can be generated from these fibres are sufficiently high that low moisture levels and continuous change of air is required to minimize degradation of cultural objects that are made from these fibres and displayed in museum halls.

A glutathione-based system for defense against carbonyl stress in Haemophilus influenzae

BackgroundadhC from Haemophilus influenzae encodes a glutathione-dependent alcohol dehydrogenase that has previously been shown to be required for protection against killing by S-nitrosoglutathione (GSNO). This group of enzymes is known in other systems to be able to utilize substrates that form adducts with glutathione, such as aldehydes.ResultsHere, we show that expression of adhC is maximally induced under conditions of high oxygen tension as well as specifically with glucose as a carbon source. adhC could also be induced in response to formaldehyde but not GSNO. An adhC mutant was more susceptible than wild-type Haemophilus influenzae Rd KW20 to killing by various short chain aliphatic aldehydes, all of which can be generated endogenously during cell metabolism but are also produced by the host as part of the innate immune response.ConclusionsThese results indicate that AdhC plays a role in defense against endogenously generated reactive carbonyl electrophiles in Haemophilus influenzae and may also play a role in defense against the host innate immune system.

Synthesis of lipid II phosphonate analogues

Simple analogues of lipid II were synthesized from 3,4,6-tri-O-acetyl-2-acetamido-2-deoxy-1-thio-β-d-glucopyranose using conjugate addition onto ethylidene bisphosphonate and subsequent Wadsworth–Horner–Emmons reaction with long chain aliphatic aldehydes.

Determination of Linear Short Chain Aliphatic Aldehyde and Ketone Vapors in Air Using a Polystyrene-coated Quartz Crystal Nanobalance Sensor

A polystyrene coated quartz crystal nanobalance (QCN) sensor was developed for use in the determination of a number of linear short-chain aliphatic aldehyde and ketone vapors contained in air. The quartz crystal was modified by a thin-layer coating of a commercial grade general purpose polystyrene (GPPS) from Tabriz petrochemical company using a solution casting method. Determination was based on frequency shifts of the modified quartz crystal due to the adsorption of analytes at the surface of modified electrode in exposure to various concentrations of analytes. The frequency shift was found to have a linear relation to the concentration of analytes. Linear calibration curves were obtained for 7-70 mg l(-1) of analytes with correlation coefficients in the range of 0.9935-0.9989 and sensitivity factors in the range of 2.07-6.74 Hz/mg l(-1). A storage period of over three months showed no loss in the sensitivity and performance of the sensor.

Two Lysine Residues in the Bacterial Luciferase Mobile Loop Stabilize Reaction Intermediates

Bacterial luciferase catalyzes the reaction of FMNH(2), O(2), and a long chain aliphatic aldehyde, yielding FMN, carboxylic acid, and blue-green light. The most conserved contiguous region of the primary sequence corresponds to a crystallographically disordered loop adjacent to the active center (Fisher, A. J., Raushel, F. M., Baldwin, T. O., and Rayment, I. (1995) Biochemistry 34, 6581-6586; Fisher, A. J., Thompson, T. B., Thoden, J. B., Baldwin, T. O., and Rayment, I. (1996) J. Biol. Chem. 271, 21956-21968). Deletion of the mobile loop does not alter the chemistry of the reaction but decreases the total quantum yield of bioluminescence by 2 orders of magnitude (Sparks, J. M., and Baldwin, T. O. (2001) Biochemistry 40, 15436-15443). In this study, we attempt to localize the loss of activity observed in the loop deletion mutant to individual residues in the mobile loop. Using alanine mutagenesis, the effects of substitution at 15 of the 29 mobile loop residues were examined. Nine of the point mutants had reduced activity in vivo. Two mutations, K283A and K286A, resulted in a loss in quantum yield comparable with that of the loop deletion mutant. The bioluminescence emission spectrum of both mutants was normal, and both yielded the carboxylic acid chemical product at the same efficiency as the wild-type enzyme. Substitution of Lys(283) with alanine resulted in destabilization of intermediate II, whereas mutation of Lys(286) had an increase in exposure of reaction intermediates to a dynamic quencher. Based on a model of the enzyme-reduced flavin complex, the two critical lysine residues are adjacent to the quininoidal edge of the isoalloxazine.

Novel and recurrent ALDH3A2 mutations in Italian patients with Sjögren–Larsson syndrome

Sjögren-Larsson syndrome (SLS; MIM#270200) is an autosomal recessive neurocutaneous disease caused by mutations in the ALDH3A2 gene for fatty aldehyde dehydrogenase (FALDH), a microsomal enzyme that catalyzes the oxidation of medium- and long- chain aliphatic aldehydes fatty acids. We studied two unrelated Italian SLS patients with ichthyosis, developmental delay, spastic diplegia and brain white matter disease. One patient was homozygous for a novel ALDH3A2 insertion mutation (c.767insA) in exon 5. The other SLS patient was a compound heterozygote for two previously reported mutations: a slice site mutation (c.1094C > T; S365L) in exon 7. Analysis of fibroblast RNA by RT-PCR indicated that the spice-site mutation caused skipping of exons 2 and 3. The c.1094C > T mutation, previously associated with two ALDH3A2 haplotypes, was found on a third distinct haplotype in our patient, which indicates that arose independently in this kindred. These results add to understanding of the genetic basis of SLS and will be useful for DNA diagnosis of this disease.

Critical Role of Glu175 on Stability and Folding of Bacterial Luciferase: Stopped-flow Fluorescence Study

Bacterial luciferase is a heterodimeric enzyme, which catalyzes the light emission reaction, utilizing reduced FMN (FMNH2), a long chain aliphatic aldehyde and O(2), to produce green-blue light. This enzyme can be readily classed as slow or fast decay based on their rate of luminescence decay in a single turnover. Mutation of Glu175 in alpha subunit to Gly converted slow decay Xenorhabdus Luminescence luciferase to fast decay one. The following studies revealed that changing the luciferase flexibility and lake of Glu-flavin interactions are responsible for the unusual kinetic properties of mutant enzyme. Optical and thermodynamics studies have caused a decrease in free energy and anisotropy of mutant enzyme. Moreover, the role of Glu175 in transition state of folding pathway by use of stopped-flow fluorescence technique has been studied which suggesting that Glu175 is not involved in transition state of folding and appears as surface residue of the nucleus or as a member of one of a few alternative folding nuclei. These results suggest that mutation of Glu175 to Gly extended the structure of Xenorhabdus Luminescence luciferase, locally.

Purification and Characterization of a Dehydrogenase Catalyzing Conversion of Nα-Benzyloxycarbonyl-L-Aminoadipic-δ-Semialdehyde to Nα-Benzyloxycarbonyl-L-Aminoadipic Acid from Rhodococcus sp. AIU Z-35-1

The enzyme catalyzing conversion of N alpha-benzyloxycarbonyl-L-aminoadipic-delta-semialdehyde (N alpha-Z-L-AASA) to N alpha-benzyloxycarbonyl-L-aminoadipic acid (N alpha-Z-L-AAA) in Rhodococcus sp. AIU Z-35-1 was identified, and its characteristics were revealed. This reaction was catalyzed by a dehydrogenase with a molecular mass of 59 kDa. The dehydrogenase exhibited enzyme activity on not only N alpha-Z-L-AASA but also N alpha-Z-D-AASA and short chain aliphatic aldehydes, but not on aromatic aldehydes and alcohols. The apparent Km values for N alpha-Z-L-AASA, N alpha-Z-D-AASA and NAD+ were estimated to be 3.8 mM, 14.1 mM and 0.16 mM, respectively. The NH2 terminal amino acid sequence of this enzyme exhibited a similarity to those of a piperidein-6-carboxylate dehydrogenase from Streptomyces clavuligerus and a putative dehydrogenase from Rhodococcus sp. RHA 1, but not to those of other microbial aldehyde dehydrogenases.

Ethyl(benzothiazol‐2‐ylsulfonyl)acetate: A New Reagent for the Stereoselective Synthesis of α,β‐Unsaturated Esters from Aldehydes.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Ethyl (benzothiazol-2-ylsulfonyl)acetate: a new reagent for the stereoselective synthesis of α,β-unsaturated esters from aldehydes

The title reagent engaged in the modified Julia olefination with aldehydes under mild reaction conditions (DBU, CH(2)Cl(2), rt or -78 degrees C) to yield alpha,beta-unsaturated esters; aryl aldehydes and aliphatic aldehydes possessing significant chain branching elements gave trans alkene products with high stereoselectivity (E : Z up to >98 : 2), while straight chain aliphatic aldehydes gave cis products preferentially (Z : E up to 92 : 8).

Spatial representation of odorant structure in the moth antennal lobe: a study of structure-response relationships at low doses.

How odorant structure and concentration are spatially represented within the primary olfactory integration center, the antennal lobe (AL) or olfactory bulb (OB) in invertebrates and vertebrates, respectively, is currently a topic of high interest. Here, we show the spatial representation of odorant structure in the antennal lobe of the moth Spodoptera littoralis by imaging calcium activity evoked by straight chain aliphatic alcohols and aldehydes at low doses. Activity patterns of a given odor were most similar to compounds with the same functional group, differing in chain length by only one carbon atom. A chain length dependency was present as the most activated glomerulus in the lobe shifted from a medial to a lateral position with increasing chain length of the molecule. Statistical analysis revealed that in both classes of chemicals the chain length of the molecule was represented in a similar way. No topographically fixed domains were observed for any of the classes. However, activity patterns evoked by lower chain length molecules were spatially more distinct than patterns evoked by higher chain length molecules. The number of activated glomeruli for both classes of chemicals increased with increasing chain length to reach a maximum at eight or nine C atoms followed by a decrease as the chain length further increased.

Distribution of volatile compounds in the pulp, cloud, and serum of freshly squeezed orange juice.

The quantitative distribution of volatile compounds in the pulp, cloud, and serum of a freshly squeezed orange juice (cv. Naveline) was measured. Juice monoterpene and sesquiterpene hydrocarbons were primarily recovered from the pulp (74.0 and 87.2%, respectively) and cloud (7.3 and 14.9%, respectively). Esters and monoterpene alcohols were mainly found in the serum (90.4 and 84.1%, respectively). Long chain aliphatic aldehydes tend to concentrate in the pulp. The relative proportions of individual volatile compounds were similar in the pulp and cloud. Pulp and cloud alcohol insoluble residues exhibited similar compositions; half of them are made of nonwall proteins, and the rest are made of cell wall materials. Pulp and cloud total and neutral lipids had similar fatty acids distributions, although the cloud was much richer in total lipids than the pulp. No relationship was found between the retention of aroma compounds in the pulp or cloud and their AIR and lipid content or composition.

Surface-active cobalt cage complexes: synthesis, surface chemistry, biological activity, and redox properties

Amphiphilic cobalt(III) cage complexes with bridgehead octyl, dodecyl and hexadecyl hydrocarbon chain substituents have been synthesized simply by co-condensation of formaldehyde and long chain aliphatic aldehydes with the tripodal cobalt(III) hexaamine complex, [Co(sen)]3+ {sen = 4,4′,4″-ethylidynetris(3-azabutan-1-amine)}. The synthetic methodology was also used to prepare a novel chiral surfactant by capping the Λ-(−)D-[Co(sen)]3+ stereoisomer. The cobalt(III) cage complexes with octyl to hexadecyl substituents are all surface active and reduce the surface tension of water to levels approaching those of organic solvents. The dodecyl substituted cage complex forms aggregates in aqueous solution with a critical micelle concentration of (1.3 ± 0.1) × 10−3 mol dm−3 at 25.00 °C. The surfactant cage complexes are biologically active and are lethal at millimolar levels to the tapeworm Hymenolepis diminuta, and the parasitic eukaryote, Tritrichomonas foetus, in vitro. The biological activity of these surfactants appears to involve insertion of the paraffin tail into the organism's exterior membrane and consequent incorporation of the highly charged head-group, which perturbs the normal membrane potential and leads to disintegration of the membrane and death of the organism. The cobalt(III) cage head-group of these surfactants also undergoes a chemically reversible one-electron reduction to the corresponding cobalt(II) cage complex and the construction of oriented films of such redox reagents should be feasible. The reduction potential of the cobalt(III)/(II) couple is shifted from −0.72 to −0.61 V (vs. saturated calomel electrode) by replacing a bridgehead hydrocarbon chain substituent with an alkoxy substituent. The shift in potential correlates with the electrochemical polar substituent constants of alkyl versus alkoxy chains.