Ester Type Research Articles

Identification and Expression Analysis of Lipoxygenase Gene in Bitter Gourd (Momordica charantia)

Background: Lipoxygenases (LOXs) are key enzymes in the unsaturated fatty acid oxidation reaction pathway and play an important regulatory role in the synthesis of fruit aroma volatiles. Methods: LOX gene family members were identified in the whole genome database of bitter gourd and analyzed bioinformatically. An RT-qPCR was used to analyze the expression differences in different tissues. Monoterpenes were determined by gas chromatography-mass spectrometry (GC-MS) technique. Results: A total of 12 LOX gene family members were identified in the genome. The expression of LOX genes varied significantly among the tissues of roots, stems, leaves, flowers, fruits, seeds and tendrils. A total of 29 monoterpenes were detected in the fruits of five different fruit colors of bitter gourd, mainly containing six types of alcohols, aldehydes, terpenes, ketones, esters and alkynes, with the highest relative content of alcohols. Conclusions: The present study provides a reference for further elucidation of the biological functions of the LOX gene in the synthesis pathway of aroma volatiles in bitter gourd.

Synthesis of Newly Ester Type Gemini Cationic Surfactants: Surface Properties, Fabric Softness and Antibacterial Properties

AbstractFour ester cationic Gemini surfactants (EDQ‐n, n represents the carbon number in the raw fatty acid of 12, 14, 16 and 18) were synthesized from fatty acid, N, N‐dimethylethanolamine and 1, 4‐dibromobutane by two‐step reaction of esterification and quaternization. Their surface activities at air/water interface were investigated. The application performance such as water solubility, antistatic property, fabric softness, fabric whiteness, biodegradability, and antibacterial activities were tested and compared with traditional quaternary ammonium salt. The results showed that the γcmc increases with increasing the hydrophobic chain length and EDQ‐12 presented the highest surface activity. The diffusion coefficients calculated from the Ward‐Tordai equation indicates the adsorption process is a mixed‐diffusion kinetic adsorption mechanism. The water solubility of EDQ‐n is higher than dioctadecyl dimethyl ammonium chloride (D1821) and ester quaternary ammonium salt (Esterquats). The fabric softness and whiteness properties of EDQ‐16 and EDQ‐18 are similar to D1821 and Esterquats, which can significantly reduce the cotton fabric softness and have no significant difference in whiteness retention. EDQ‐n demonstrated more readily biodegradation(>90 %) than D1821(0 %) after seven days. In addition, EDQ‐12 and EDQ‐14 show excellent antibacterial activities against Staphylococcus aureus and Escherichia coli in comparison with conventional bacteriostatic agent didecyl dimethyl ammonium chloride (DDAC).

Assessing Aquatic Baseline Toxicity of Plastic-Associated Chemicals: Development and Validation of the Target Plastic Model.

We developed a Target Plastic Model (TPM) to estimate the critical plastic burden of organic toxicants in five types of plastics, namely, polydimethylsiloxane (PDMS), polyoxymethylene (POM), polyacrylate (PA), low-density polyethylene (LDPE), and polyurethane ester (PU), following the Target Lipid Model (TLM) framework. By substituting the lipid-water partition coefficient in the TLM with plastic-water partition coefficients to create TPM, we demonstrated that the biomimetic nature of these plastic phases allows for the calculation of critical plastic burdens of toxicants, similar to the notion of critical lipid burdens in TLM. Following this approach, the critical plastic burdens of baseline (n = 115), less-inert (n = 73), and reactive (n = 75) toxicants ranged from 0.17 to 51.33, 0.04 to 26.62, and 1.00 × 10-6 to 6.78 × 10-4 mmol/kg of plastic, respectively. Our study showed that PDMS, PA, POM, PE, and PU are similar to biomembranes in mimicking the passive exchange of chemicals with the water phase. Using the TPM, median lethal concentration (LC50) values for fish exposed to baseline toxicants were predicted, and the results agreed with experimental values, with RMSE ranging from 0.311 to 0.538 log unit. Similarly, for the same data set of baseline toxicants, other widely used models, including the TLM (RMSE: 0.32-0.34), ECOSAR (RMSE: 0.35), and the Abraham Solvation Model (ASM; RMSE: 0.31), demonstrated comparable agreement between experimental and predicted values. For less inert chemicals, predictions were within a factor of 5 of experimental values. Comparatively, ASM and ECOSAR showed predictions within a factor of 2 and 3, respectively. The TLM based on phospholipid had predictions within a factor of 3 and octanol within a factor of 4, indicating that the TPM's performance for less inert chemicals is comparable to these established models. Unlike these methods, the TPM requires only the knowledge of plastic bound concentration for a given plastic phase to calculate baseline toxic units, bypassing the need for extensive LC50 and plastic-water partition coefficient data, which are often limited for emerging chemicals. Taken together, the TPM can provide valuable insights into the toxicities of chemicals associated with environmental plastic phases, assisting in selecting the best polymeric phase for passive sampling and designing better passive dosing techniques for toxicity experiments.

Substrate Characterization for Hydrolysis of Multiple Types of Aromatic Esters by Promiscuous Aminopeptidases.

Synthetic aromatic esters, widely employed in agriculture, food, and chemical industries, have become emerging environmental pollutants due to their strong hydrophobicity and poor bioavailability. This study attempted to address this issue by extracellularly expressing the promiscuous aminopeptidase (Aps) from Pseudomonas aeruginosa GF31 in B. subtilis, achieving an impressive enzyme activity of 13.7 U/mg. Notably, we have demonstrated, for the first time, the Aps-mediated degradation of diverse aromatic esters, including but not limited to pyrethroids, phthalates, and parabens. A biochemical characterization of Aps reveals its esterase properties and a broader spectrum of substrate profiles. The degradation rates of p-nitrobenzene esters (p-NB) with different side chain structures vary under the action of Aps, showing a preference for substrates with relatively longer alkyl side chains. The structure-dependent degradability aligns well with the binding energies between Aps and p-NB. Molecular docking and enzyme-substrate interaction elucidate that hydrogen bonding, hydrophobic interactions, and π-π stacking collectively stabilize the enzyme-substrate conformation, promoting substrate hydrolysis. These findings provide new insights into the enzymatic degradation of aromatic ester pollutants, laying a foundation for the further development and modification of promiscuous enzymes.

A General Electron Donor‐Acceptor Photoactivation Using Oxime Esters Enabled Divergent Thioetherifications†

Comprehensive SummaryThe EDA complex‐mediated reactions involving oxime esters have been few studied. Herein, an EDA complex formed by thiophenolate anion and oxime ester is reported for photoinduced divergent synthesis of thioethers, depending on different types of oxime esters. Operational simplicity, mild reaction conditions, and flexible options of leaving group demonstrate the generality and synthetic utility of this approach. Such an approach can also enable an interesting thiol‐catalysis for the synthesis of phenanthridines.

Preparation and Tribological Behaviors of Sulfur- and Phosphorus-Free Organic Friction Modifier of Amide–Ester Type

Preparation and Tribological Behaviors of Sulfur- and Phosphorus-Free Organic Friction Modifier of Amide–Ester Type

Synthesis of Sugar Esters Using Maize Seed Lipase as a Biocatalyst

This work is devoted to the extraction of a lipase from maize seeds obtained at low cost without extensive purification technology and used as a biocatalyst in the synthesis of various sugar esters as potential biosurfactants in the detergent industry. Indeed, several reactions have been carried out between different sugars - namely glucose, galactose, saccharose, lyxose, fructose and sorbitol - and stearic acid in a ratio of 2.5:1 in hexane at 50 °C. Kinetic monitoring of the target reactions was carried out by volumetric analysis in order to determine the conversions (C). The best results obtained were C = 76, 71 and 67% in the presence of glucose, lyxose and galactose, respectively. In addition, HPLC and TLC analyses revealed that for every sugar used two types of esters formed.

Comprehensive investigation on non-volatile and volatile compounds in Auricularia auricula from different regions by UPLC-MS/MS-based metabolomics and GC-IMS

Auricularia auriculata from two regions of China were studied for their metabolite fingerprints, metabolic pathways, and volatile organic compounds (VOCs) using UPLC-MS/MS and GC-IMS techniques in conjunction with multivariate statistical analysis approaches. A total of 881 metabolites were identified by UPLC-MS/MS, of which 39 compounds displayed significant differences. Acetyl-l-carnitine, N-acetyl-l-alanine, PC (18:3(9Z,12Z,15Z)/0:0), 4-fumaryl-acetoacetate, S-2-hydroxybutanedioic acid, and 4-guanidinobutyric acid belonged to the characteristic non-volatile metabolites. The umami-tasted amino acid, essential amino acid was abundant in Heilongjiang and Shaanxi province, respectively. KEGG pathway analysis indicated that differential metabolites were mainly enriched in lipid and amino acid metabolism. The GC-IMS study revealed 64 different types of VOCs, including acids, alcohols, aldehydes, esters, ketones, and other compounds. A. auricula from Shaanxi province was abundant in 2,3-pentanedione, 1-octen-3-one (dimer), 2-acetylfuran, beta-pinene (monomers, dimers) and alpha-pinene. While the primary distinctive VOCs of A. auricula from Heilongjiang province were butyl acetate, methyl acetate and propyl acetate. PCA and OPLS-DA allowed for clear differentiation between the A. auricula samples from the two regions. This research established foundations for investigating potential biomarkers for A. auricula and has important applications values for the creation and implementation of traceability systems within the edible mushroom industry.

Phthalates Boost Natural Transformation of Extracellular Antibiotic Resistance Genes through Enhancing Bacterial Motility and DNA Environmental Persistence.

The environmental dissemination of extracellular antibiotic resistance genes (eARGs) in wastewater and natural water bodies has aroused growing ecological concerns. The coexisting chemical pollutants in water are known to markedly affect the eARGs transfer behaviors of the environmental microbial community, but the detailed interactions and specific impacts remain elusive so far. Here, we revealed a concentration-dependent impact of dimethyl phthalate (DMP) and several other types of phthalate esters (common water pollutants released from plastics) on the natural transformation of eARGs. The DMP exposure at an environmentally relevant concentration (10 μg/L) resulted in a 4.8-times raised transformation frequency of Acinetobacter baylyi but severely suppressed the transformation at a high concentration (1000 μg/L). The promotion by low-concentration DMP was attributed to multiple mechanisms, including increased bacterial mobility and membrane permeability to facilitate eARGs uptake and improved resistance of the DMP-bounded eARGs (via noncovalent interaction) to enzymatic degradation (with suppressed DNase activity). Similar promoting effects of DMP on the eARGs transformation were also found in real wastewater and biofilm systems. In contrast, higher-concentration DMP suppressed the eARGs transformation by disrupting the DNA structure. Our findings highlight a potentially underestimated eARGs spreading in aquatic environments due to the impacts of coexisting chemical pollutants and deepen our understanding of the risks of biological-chemical combined pollution in wastewater and environmental water bodies.

Designing a new bio-active copper(II)-triazole ester type complex based on copper(II)-catalyzed reaction

The reaction of copper(II) nitrate trihydrate with N,Nʹ-cyclohexane-1,2-diylidene-bis(4-chlorobenzoylhydrazide) (LCl) in acetonitrile produced a mononuclear Cu(II) complex [CuII(TECl)2(NO3)2] (TECl: triazole-ester) (1). Triazole-ester is an intermediate compound formed during the oxidation of LCl by copper ion based on Cu(II) catalyzed click reaction. The organic ligand (LCl) and its complex (1) are characterized with different techniques. According to single crystal X-ray crystallography, complex 1 has been verified to possess a distorted square planar geometry and functions as a four-coordinate mononuclear copper(II) complex. Furthermore, the Cu(II) ion coordinates to the 1-N atoms of two monodentate (TECl) molecules, along with the N atoms of two monodentate nitrate ions. The optimization of geometry and other functional analyses was executed using density functional theory (DFT). Additionally, molecular electrostatic potential (MEP) and Hirshfeld surface analyses were conducted to scrutinize the reactive regions within the crystals. Employing molecular modeling software, the most suitable conformational bond between the prepared compounds (LCl and 1) and the urease enzyme is investigated to calculate the structure–activity relationship and binding energies. Moreover, comprehensive studies were performed on in vitro enzyme inhibition, pharmacokinetics, enzyme kinetic mechanism, and antimicrobial activity. These investigations revealed that the synthesized compounds exhibit a pronounced affinity for binding to the urease enzyme. Furthermore, the compounds demonstrate promising inhibitory potential against select bacterial strains and the urease enzyme, as evidenced by their MIC and IC50 values.

Principles of the pharmacology of local anesthetics

The development of local anesthetics revolutionized the performance of painful interventions. Local anesthetics have an effect on voltage-gated sodium channels in nerve fibers and modulate the conduction of impulses. With respect to the chemical structure, local anesthetics can be divided into amide and ester types. The structural differences of local anesthetics have an influence on the duration of action, the degradation pathways and specific side effects. Severe adverse events include cardiotoxicity and neurotoxicity. In addition to basic measures, such as the monitoring and securing of vital parameters, lipid infusion represents a treatment option in cases of intoxication. The recent developments of local anesthetics are particularly concerned with the reduction of toxicity and prolonging the duration of action.

Differences and distribution of quality components in Fu brick tea around fungal fermentation

The differences in and distributions of the quality components of Fu brick tea before and after flowering (also called fungal fermentation and known as “Fahua” in China) remain unclear, and the standard of judging quality by the number of golden flowers (GFs; yellow closed capsules of Eurotium cristatum spores) by consumers lacks a scientific foundation. In this study, Fu brick tea (AFT) was obtained from pre-flower raw dark tea (BFT) through the traditional processing of Fu brick tea. The AFT was then hand-selected and divided into pure tea (SFT) and GFs. It was found that the flavonoid, tea polyphenol, free amino acid, aqueous extract, and ester-type catechin content in the AFT were all significantly lower than in the BFT (p < 0.05); the content of 34 types of volatile compound was significantly higher (26 alkanes, 4 alkenes, 2 alcohols, 1 ester, 1 aldehyde) (p < 0.05), and the content of 14 types of volatile compound was significantly lower (6 alkanes, 4 alcohols, 2 esters, 1 ketone, 1 alkene) than in the BFT (p < 0.05). Furthermore, the content of 39 types of nonvolatile substances, including four carboxylic acids, three flavonoids, and D-Arabitol, amino acids and their derivatives, was significantly higher in the AFT (p < 0.05). The content of flavonoids and their derivatives, including 24 types of saturated alkanes and seven types of aldehydes and esters of volatile compounds (3 alkenes, 2 alcohols, 1 ester, and 1 aldehyde) (p < 0.05), was significantly higher in the SFT than in the GFs (p < 0.05). The GFs had significantly higher content of water-soluble leachate, maltose, glycosylated flavonoids, D-salicylose, and amino acids and their derivatives than the SFT (p < 0.05). Widdrol, linalool, N-octanal, and 25 other volatile compounds (9 alkenes, 9alcohols, s aldehydes, 1 ester, 1 alkane, 1 ketone, 1 Naphthalene) were detected only in the GFs.

Ester-related volatile compounds reveal the diversity and commonalities of different types of late-ripening peaches.

To recognize the key ester-related volatile compounds, 5 types of peaches including 54 late-ripening peach materials were examined by headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry and E-nose. Here, a large number of esters were identified to be released by ripe peach fruits and were mainly characterized by fruity, green, and fatty notes. The variety and content of esters had greatly changed within or between cultivars, indicating that the fruit volatiles were highly differentiated depending on the specific genotypes and cultivation conditions. The ester types showed that fatty acid-derived C6 alcohols and methyl-/ethyl- short-chain alcohol were the main ester precursors, which were more likely to be utilized and well selected by alcohol acyltransferases, whereas the preference of acyl donors was not observed. The common peach type, which exhibited a unique volatile profile, displayed broader diversity and more abundant characteristics in ester-related volatiles than the other four types. A total of 19 key esters were identified as the main components and the content of most esters showed no significant difference among different peach types. Some key esters had even been enriched in nectarines. Moreover, the multiple discriminant analysis revealed a possible relationship between peach types and the domestication of the peach evolution. This study investigated ester-related volatiles released by different types of peach fruits and can be further used to evaluate the peach qualities, providing an important reference for peach breeding and processing.

Self-healable, Tolerant Superaerophobic Coating for Improving Electrochemical Hydrogen Production.

Gas-evolving electrodes often suffer from the blocking of catalytic active sites-due to unwanted and unavoidable adhesion of generated gas bubbles, which elevates the overpotential for the electrochemical hydrogen evolution reaction (HER)- by raising the resistance of the electrode. Here, a catalyst-free and self-healable superaerophobic coating having ultra-low bubble adhesion is introduced for achieving significantly depleted overpotentials of 209 and 506mV at both low (50mAcm-2) and high (500mAcm-2) current densities, respectively, compared to a bare nickel-foam electrode. The optimized coating ensured an early detachment of the generated tiny (0.8±0.1mm) gas bubble-and thus, prevented the undesired rise in resistance of the coated electrode. The systematic association of physical (i.e., ionic interactions, H-bonding, etc.) cross-linkage, β-amino ester type covalent cross-linkage and reinforced halloysite nano clay enables the design of such functional material embedded with essential characteristics-including improved mechanical (toughness of 63.7kJm-3, and tensile modulus of 26kPa) property and chemical (extremes of pH (1 and 14), salinity, etc.) stability, rapid (<10min) self-healing ability (even at alkaline condition) and desired bubble-wettability (bubble contact angle of 158.2±0.2°) with ultralow force (4.2±0.4µN) of bubble adhesion.

Functional roles and localization of hydrolases in the Japanese mitten crab Eriocheir japonica

The Japanese mitten crab Eriocheir japonica inhabits rivers throughout Japan and is being cultivated for food. To conduct aquaculture efficiently, it is crucial to comprehend the physiological functions of the target organisms. However, there is a lack of fundamental information on Japanese mitten crabs. In this study, hydrolases were extracted from the midgut glands of Japanese mitten crabs and their metabolic activities were analyzed. An enzyme with hydrolytic activity was discovered within the cytosol of the midgut gland. Western blot analysis also revealed that the Japanese mitten crab contains a hydrolase with cross-reactivity to human carboxylesterase 1 (hCES1) antibodies. The substrate specificity of the S9 fraction of the midgut gland was investigated and, interestingly, it was revealed that it reacts well with indomethacin phenyl ester and fluorescein diacetate, which are substrates of hCES2, not substrates of hCES1. Furthermore, this enzyme was observed to metabolize the ester derivative of astaxanthin, which is a red pigment inherent to the Japanese mitten crab. These findings underscore the significance the midgut gland in the Japanese mitten crab as an important organ for metabolizing both endogenous and exogenous ester–type compounds.

Synthesis of C12-C18 Fatty Acid Isobornyl Esters.

Camphene, C12-C18 fatty acids, and titanium sulfate were used as raw materials to study the synthesis of long-chain fatty acid isobornyl esters. Products were analyzed quantitatively by gas chromatography (GC), characterized by nuclear magnetic resonance spectroscopy (hydrogen and carbon), and evaluated using toxicity tests. The optimum reaction conditions were as follows: n(lauric acid):n(camphene) = 2.5:1, m(titanium sulfate):m(camphene) = 0.25:1, reaction temperature of 80 °C, and reaction time of 25 h. Under these conditions, the content of isobornyl laurate in the product was 74.49%, and the content of purified product was 95.02%. The reaction kinetics for isobornyl laurate showed an apparent first-order reaction in the first 9 h with an activation energy of 31.01 kJ/mol. The reaction conditions of myristic acid, palmitic acid, and stearic acid were similar to those of lauric acid, but the reaction time had to be increased as the molecular weight of the fatty acid increased. Toxicity tests for four types of long-chain fatty acid isobornyl esters showed that the samples had low toxicity.

Assessing the usefulness of Raman spectroscopy and lipid analysis of decomposed human bones in forensic genetics and molecular taphonomy

Bones are among the structures most likely to be recovered after death. However, the low quantity of preserved DNA and complex processing from sample to DNA profile make forensic DNA analysis of bones a challenging task. Raman spectroscopy and gas chromatography-mass spectrometry (GC/MS), have the potential to be useful as screening tools for DNA analysis and in decomposition studies. The objective of this research was to assess the usefulness of such molecular investigations. Femur samples collected from 50 decomposing human bodies were subjected to Raman spectroscopy and GC/MS. Assessment of nuclear DNA quantity and short tandem repeat (STR) genotyping efficiency were also performed. Raman parameters (crystallinity, carbonate-to-phosphate ratio, mineral-to-matrix ratio) and detected lipids were recorded. Background fluorescence proved problematic for Raman analysis of forensic bones. Regardless, it was not associated with less preserved DNA or less detected STR alleles. Fatty acids, hydrocarbons, and five types of fatty acid methyl esters (FAMEs) were detected. The main phosphate peak position in Raman spectra was significantly correlated with preserved DNA (p = 0.03713), while significantly more STR alleles were detected in bones containing methyl hexadecenoate (p = 0.04236). Detection of FAMEs in the bone matrix suggests a reaction between methanol produced by bacteria and free fatty acids, which are not associated with the level of preservation of endogenous DNA. The techniques assessed have shown to be useful in molecular taphonomy studies and forensic genetics.

Investigating C3 and C4 esters and alcohols in a diesel engine: Combined influence of carbon chain length, oxyfuel type, and oxygen content

Diesel engines fueled by liquid fuels will continue to dominate the transportation and heavy machinery application market despite the advancement of other technologies. Studies have yet to be conducted to investigate the combined influence of carbon chain length, oxyfuel type, oxygen content, and blending ratio of esters and alcohols as additives in diesel fuel. The present study addresses this by preparing two sets of experiments using three-carbon (C3) and four-carbon (C4) additives, one at an equal blending ratio of 4% and the other at an equal oxygen mass content of 1.94%. Although the additives caused up to 24.84% rise in brake specific fuel consumption at low load, the value diminished to 7.86% at medium load and 11.63% at high load. The C4 fuels were found to have better NOx reduction potential than the C3 fuels. However, most additives significantly increased CO emissions, except for EE4.9 (4.9% ethyl ethanoate and 95.1% diesel), leading to 3.7% and 7.1% lower CO emissions than neat diesel at low and medium loads, respectively. Smoke emissions were also reduced by up to 32.84% when oxygenated additives were used. Although all blends tested are promising fuel alternatives in a diesel engine, EE4.9 provided the most suitable trade-off between engine performance and emissions.

Profiling apple volatile organic compounds in a New Zealand collection of germplasm as a resource for breeding cultivars with desirable flavors

Flavor is a major component of the apple eating experience, along with taste, texture and appearance. Apples produce a wide array of volatile organic compounds that impart particular flavors. Cultivars producing increased or novel flavors may have more desirability for consumers and help to differentiate the fruit. Efficiently breeding more flavorful apples requires understanding the volatiles present in apple germplasm and their potential sensory impact. As an initial step towards the development of more flavorful apple cultivars, a New Zealand collection of germplasm was surveyed, and seventy-three volatiles were identified as being present in at least half the accessions. Substantial differences in the presence and relative abundance of specific volatiles were uncovered across the accessions and could sometimes be linked to an apple’s flavor profile. The large number of volatiles analyzed allowed relationships between and among molecule classes to be established. Esters were found to be the main drivers of volatile differentiation across accessions. Apples tended to produce either ethyl or acetate esters, suggesting there is different genetic control for these two ester types. Additionally, esters generally had larger broad-sense heritabilities, indicating they could be easier targets for modifying apple flavor. This volatile dataset is a valuable resource for apple breeding, and increases the understanding of an important consumer trait.

Principles of the pharmacology of local anesthetics

The development of local anesthetics revolutionized the performance of painful interventions. Local anesthetics have an effect on voltage-gated sodium channels in nerve fibers and modulate the conduction of impulses. With respect to the chemical structure, local anesthetics can be divided into amide and ester types. The structural differences of local anesthetics have an influence on the duration of action, the degradation pathways and specific side effects. Severe adverse events include cardiotoxicity and neurotoxicity. In addition to basic measures, such as the monitoring and securing of vital parameters, lipid infusion represents a treatment option in cases of intoxication. The recent developments of local anesthetics are particularly concerned with the reduction of toxicity and prolonging the duration of action.