Aromatic Esters Research Articles

Insight into the Corrosion Inhibition Performance of Pistia stratiotes Leaf Extract as a Novel Eco-Friendly Corrosion Inhibitor for Mild Steel in 1 M HCl Solution

In this research, the Pistia stratiotes leaf (PSL) extract was evaluated as a green corrosion inhibitor for the corrosion of mild steel in 1 M HCl using electrochemical measurements and surface characterization. Electrochemical impedance spectroscopy (EIS) spectra showed that the inhibitory activity of the phytochemical compounds enhanced with increasing concentration up to 400 ppm, which was reflected in the increase in the charge transfer resistance and double-layer capacitance. Regarding the effect of immersion time, EIS results indicated that the persistence of the PSL extract was between 4 h and 8 h of exposure time. From polarization curve (PCC) results, the best performance of the corrosion inhibitor was achieved at 400 ppm with an inhibition efficiency of 93.7%. The PSL extract acted as a mixed-type corrosion inhibitor. The adsorption of the phytomolecules on the metal surface obeyed the Langmuir isotherm through a mixed mechanism (physical and chemical interactions) dominated by physisorption. Scanning electron microscopy (SEM) examinations and energy-dispersive X-ray spectroscopy (EDS) elemental analysis of the corroded samples confirmed the anticorrosive protection of the PSL extract. Chemical characterization of the PSL extract by GC-MS revealed the presence of phytol, steroids, and aromatic and long-chain unsaturated fatty acid esters, in order of abundance. Chemical quantum calculations by DFT allowed for determining that the phthalic acid, di(2-propylpentyl) ester compound has the most significant potential to act as the main active component in corrosion inhibition activity.

Pyrolysis behavior of sewage sludge coexisted with microplastics: Kinetics, mechanism, and product characteristics

Microplastics can accumulate in the excess sludge from wastewater treatment plants through domestic wastewater. This study investigated the co-pyrolysis behavior of sewage sludge coexisting with two types of microplastics (polyethylene (PE) and polylactic acid (PLA)) and found a superior comprehensive pyrolysis performance. By calculating the difference between theoretical and experimental weight loss during the pyrolysis process, it was found that the incorporation of microplastics PE and PLA created a synergistic effect at 270°C–450 °C, which was confirmed through the Malek method analysis from a pyrolysis mechanism perspective that it could increase the random nuclei on each particle, that is, enhance the heterogeneous diffusion of volatiles. The average activation energy was reduced by 84.99 kJ/mol, as determined using three isoconversional methods: Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS), and Starink. Regarding the products, the aforementioned synergistic effect led to a reduction in char retention and larger specific surface area of the biochar, while the quantities of gaseous products and bio-oil escalated. Through a thermogravimetric analyzer and Fourier transform infrared spectroscopy (TG-FTIR), an increase in aromatic hydrocarbons, alkanes, aldehydes, ethers, and esters in the gaseous products were detected. Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) revealed an increase in hydrocarbons, esters, and alcohols in the bio-oil, and acids and aldehydes decreased, overall enhancing the quality of the bio-oil. This study elucidated that pyrolysis completely transformed microplastics in sludge, thus eliminating environmental risks and provided a theoretical reference for understanding the pyrolysis behavior of sludge containing microplastics.

Scent-mediated bee pollination and myrmecochory in an enigmatic geophyte with pyrogenic flowering and subterranean development of fleshy fruits.

Volatile emissions from flowers and fruits play a key role in signalling to animals responsible for pollination and seed dispersal. Here, we investigated the pollination biology and chemical ecology of reproduction in Apodolirion buchananii, an African amaryllid that flowers in a leafless state soon after grassland vegetation is burnt in the dry late-winter season. Pollinators were identified through field collection and pollen loads were quantified. Floral traits including spectral reflectance and scent chemistry were documented. Bioassays using cup traps were used to test the function of floral volatiles. Fruiting biology was investigated using controlled hand-pollination experiments and chemical analysis of fruit scent. Seed germination was scored in greenhouse trials. Seed dispersal was monitored using observations and camera trapping. The sweetly scented white flowers of A. buchananii are pollen-rewarding and pollinated mainly by a diverse assemblage of bees. Cup-trap experiments demonstrated that pollinators are attracted to phenylacetaldehyde, the dominant volatile in the floral scent. Plants are shown to be self-incompatible, and the fleshy fruits were found to emerge from the soil six months after pollination during the peak of the summer rains. Fruits emit a diverse blend of aliphatic and aromatic esters and contain large fleshy recalcitrant seeds which germinate within days of fruits splitting open. Seed dispersal by ants was recorded. This first account of the reproductive biology of a species in the genus Apodolirion highlights an outcrossing mating system involving bees attracted to color and scent as well as the unusual fruiting biology and ant-mediated system of seed dispersal.

Metabolic engineering of Escherichia coli for high-level production of benzyl acetate from glucose

BackgroundBenzyl acetate is an aromatic ester with a jasmine scent. It was discovered in plants and has broad applications in food, cosmetic, and pharmaceutical industries. Its current production predominantly relies on chemical synthesis. In this study, Escherichia coli was engineered to produce benzyl acetate.ResultsTwo biosynthetic routes based on the CoA-dependent β-oxidation pathway were constructed in E. coli for benzyl acetate production. In route I, benzoic acid pathway was extended to produce benzyl alcohol by combining carboxylic acid reductase and endogenous dehydrogenases and/or aldo-keto reductases in E. coli. Benzyl alcohol was then condensed with acetyl-CoA by the alcohol acetyltransferase ATF1 from yeast to form benzyl acetate. In route II, a plant CoA-dependent β-oxidation pathway via benzoyl-CoA was assessed for benzyl alcohol and benzyl acetate production in E. coli. The overexpression of the phosphotransacetylase from Clostridium kluyveri (CkPta) further improved benzyl acetate production in E. coli. Two-phase extractive fermentation in situ was adopted and optimized for benzyl acetate production in a shake flask. The most optimal strain produced 3.0 ± 0.2 g/L benzyl acetate in 48 h by shake-flask fermentation.ConclusionsWe were able to establish the whole pathway for benzyl acetate based on the CoA-dependent β-oxidation in single strain for the first time. The highest titer for benzyl acetate produced from glucose by E. coli is reported. Moreover, cinnamyl acetate production as an unwanted by-product was very low. Results provided novel information regarding the engineering benzyl acetate production in microorganisms.Graphical abstract

Treatment of bio-treated coking wastewater in a 3DEF system with Fe-loaded needle coke particle electrodes

As one of the most representative hard-to-biodegrade industrial wastewater, coking wastewater is poor in biodegradability and has a high concentration of organic matter. Consequently, even after treatment using biochemical technology, the discharge standards cannot be reached. We used the self-developed Fe-loaded needle coke electrodes (Fe-NCPEs) as particle electrodes and established a three-dimensional electro-Fenton (3DEF) system for the treatment of bio-treated coking wastewater (BTCW) in this study. The 3DEF system's conditions for treating BTCW were optimized using Response Surface Method (RSM). When the initial pH was 4.69, the applied voltage was 11.1 V, the Fe-NCPE dosage was 11.63 g L−1, and the COD was reduced from 387 to 57.3 mg L−1 and the colour removal rate reached 99 % after 3 h of reaction, meeting local coking wastewater discharge standards. The power consumption is only 15 kWh per ton of BTCW, indicating that this system can treat the BTCW with high efficiency and low energy consumption. UV-Vis, FTIR, and GC-MS analysis illustrated that cyclic aromatic compounds, esters, and ethers can be efficiently degraded to alkanes and olefins by the 3DEF system. The ·OH quenching experiments showed that in the 3DEF system, the ·OH is the main reactive group, which can oxidize the large hard-to-degrade organic compounds in BTCW to small organic compounds, and even to CO2 and H2O. Dynamic experiments showed that the 3DEF system can successfully remove pollutants from BTCW under continuous flow conditions with an HRT of 3 h, allowing it to meet emission standards.

The Association of the Cholesterol Efflux Capacity with the Paraoxonase 1 Q192R Genotype and the Paraoxonase Activity.

Paraoxonase 1 (PON1) binds to high-density lipoprotein (HDL) and protects against atherosclerosis. However, the relationship between functional PON1 Q192R polymorphism, which is associated with the hydrolysis of paraoxon (POXase activity) and atherosclerotic cardiovascular disease (ASCVD), remains controversial. As the effect of PON1 Q192R polymorphism on the HDL function is unclear, we investigated the relationship between this polymorphism and the cholesterol efflux capacity (CEC), one of the biological functions of HDL, in association with the PON1 activity. The relationship between PON1 Q192R polymorphisms and CEC was investigated retrospectively in 150 subjects without ASCVD (50 with the PON1 Q/Q genotype, 50 with the Q/R genotype, and 50 with the R/R genotype) who participated in a health screening program. The POXase and arylesterase (AREase: hydrolysis of aromatic esters) activities were used as measures of the PON1 activity. The AREase activity was positively correlated with CEC independent of the HDL cholesterol levels. When stratified by the PON1 Q192R genotype, the POXase activity was also positively correlated with CEC independent of HDL cholesterol. PON1 Q192R R/R genotype carriers had a lower CEC than Q/Q or Q/R genotype carriers, despite having a higher POXase activity. Moreover, in a multiple regression analysis, the PON1 Q192R genotype was associated with the degree of CEC, independent of the HDL cholesterol and POXase activity. The PON1 Q192R R allele is associated with reduced CEC in Japanese people without ASCVD. Further studies on the impact of this association on the severity of atherosclerosis and ASCVD development are thus called for.

Metabolism of isodecyl diphenyl phosphate in rice and microbiome system: Differential metabolic pathways and underlying mechanisms

Isodecyl diphenyl phosphate (IDDP) is among the emerging aromatic organophosphate esters (aryl-OPEs) that pose risks to both human beings and other organisms. This study aims to investigate the translocation and biotransformation behavior of IDDP in rice and the rhizosphere microbiome through hydroponic exposure (the duration of hydroponic exposure was 10 days). The rhizosphere microbiome 9-FY was found to efficiently eliminate IDDP, thereby reducing its uptake in rice tissues and mitigating the negative impact of IDDP on rice growth. Furthermore, this study proposed the first-ever transformation pathways of IDDP, identifying hydrolysis, hydroxylation, methylation, methoxylation, carboxylation, and glucuronidation products. Notably, the methylation and glycosylation pathways were exclusively observed in rice, indicating that the transformation of IDDP in rice may be more complex than in microbiome 9-FY. Additionally, the presence of the product COOH-IDDP in rice suggested that there might be an exchange of degradation products between rice and rhizobacteria, implying their potential interaction. This finding highlights the significance of rhizobacteria's role which cannot be overlooked in the accumulation and transformation of organic pollutants in grain crops. The study revealed active members in 9-FY during IDDP degradation, and metagenomic analysis indicated that most of the active populations contained IDDP-degrading genes. Moreover, transcriptome sequencing showed that cytochrome P450, acid phosphatase, glucosyltransferase, and methyltransferases genes in rice were up-regulated, which was further confirmed by RT-qPCR. This provides insight into the intermediate products identified in rice, such as hydrolysis, hydroxylated, glycosylated, and methylated products. These results significantly contribute to our understanding of the translocation and transformation of organophosphate esters (OPEs) in plants and the rhizosphere microbiome, and reveal the fate of OPEs in rice and microbiome system to ensure the paddy yield and rice safety.

Unveiling the crystal structure of thermostable dienelactone hydrolase exhibiting activity on terephthalate esters

Dienelactone hydrolase (DLH) is one of numerous hydrolytic enzymes with an α/β-hydrolase fold, which catalyze the hydrolysis of dienelactone to maleylacetate. The DLHs share remarkably similar tertiary structures and a conserved arrangement of catalytic residues. This study presents the crystal structure and comprehensive functional characterization of a novel thermostable DLH from the bacterium Hydrogenobacter thermophilus (HtDLH). The crystal structure of the HtDLH, solved at a resolution of about 1.67 Å, exhibits a canonical α/β-hydrolase fold formed by eight β-sheet strands in the core, with one buried α-helix and six others exposed to the solvent. The structure also confirmed the conserved catalytic triad of DHLs formed by Cys121, Asp170, and His202 residues. The HtDLH forms stable homodimers in solution. Functional studies showed that HtDLH has the expected esterase activity over esters with short carbon chains, such as p-nitrophenyl acetate, reaching optimal activity at pH 7.5 and 70 °C. Furthermore, HtDLH maintains more than 50 % of its activity even after incubation at 90 °C for 16 h. Interestingly, HtDLH exhibits catalytic activity towards polyethylene terephthalate (PET) monomers, including bis-1,2-hydroxyethyl terephthalate (BHET) and 1-(2-hydroxyethyl) 4-methyl terephthalate, as well as other aliphatic and aromatic esters. These findings associated with the lack of activity on amorphous PET indicate that HtDLH has characteristic of a BHET-degrading enzyme. This work expands our understanding of enzyme families involved in PET degradation, providing novel insights for plastic biorecycling through protein engineering, which could lead to eco-friendly solutions to reduce the accumulation of plastic in landfills and natural environments.

Oenological suitability of Chinese indigenous Saccharomyces cerevisiae in Chardonnay wine: The observation of grape maturity and vintage

Emphasis of this study lies in oenological suitability and potential of three indigenous Saccharomyces cerevisiae as wine starters culture in Chardonnay wines at three harvest points. Results showed that the use of indigenous starters, particularly NX4 and NX16, had a greater impact on adjusting wine phenolic profiles compared to commercial TXL. Volatile profiles found that M1 wines presented lower total volatile content and aroma intensities, especially in TXL wines. Indigenous S. cerevisiae NX4 and NX16 reduced higher alcohol content and increased aromatic ethyl esters and terpenes in M3 wines. Additionally, they diminished bake flavor and enhanced floral characteristics of the wines. Differential volatiles between variant starters were identified based on maturity and vintage, possessed higher fruity ester levels of wines especially by indigenous S. cerevisiae NX16. This study underscores the potential of using indigenous S. cerevisiae as wine starters in China, offering the possibility of creating uniquely regional wines.

Mechanistic studies on an isothiourea-catalyzed reaction of an aromatic ester with an imine

Increasing attention is being paid to divergent chemical reactions as a strategy for synthesizing complex organic molecules simply by regulating and adjusting reaction conditions. However, the factors controlling this switchable transformation remain unclear. A systematic study was conducted using density functional theory (DFT) at the M06–2X level to determine the mechanism of an isothiourea-catalyzed divergent chemical reaction of an aryl acetic acid ester with an imine in different solvents (acetonitrile and ethanol). The origins of the stereoselectivity and chemoselectivity of the reaction were determined using noncovalent interaction (NCI) and electrostatic potential surface (EPS) analyses. Lactamization reaction occurs preferentially in acetonitrile, and esterification proceeds preferentially in ethanol. The reaction of an ammonium enolate intermediate with an alkynyl imine preferentially generates the SS-configured isomer. The results of this theoretical study provide insight into the general mechanism of isothiourea-catalyzed reactions in which the key intermediate is ammonium enolate.

Anticandidal Properties of Launaea sarmentosa among the Salt Marsh Plants Collected from Palk Bay and the Gulf of Mannar Coast, Southeastern India.

Tidal wetlands, commonly known as salt marshes, are highly productive ecosystems in temperate regions worldwide. These environments constitute a unique flora composed primarily of salt-tolerant herbs, grasses, and shrubs. This study investigated the therapeutic properties of ten salt marsh plants collected mainly from Palk Bay and Mannar Gulf against Candida disease. This study examined the changes in natural plant products associated with their anti-Candida growth activity during two distinct seasonal changes-monsoon and summer. The potential of the salt marshes to inhibit the growth of five different Candida strains was assessed using four solvents. In phytochemical analysis, the extracts obtained from a Launaea sarmentosa exhibited the highest results compared to the other plant extracts. Fourier transform infrared spectroscopy revealed 12 peaks with alkane, aldehyde, amine, aromatic ester, phenol, secondary alcohol, and 1,2,3,4-tetrasubstituted. Gas-chromatography-mass spectrometry detected 30 compounds. Cyclotetracosane, lupeol, β-amyrin, and 12-oleanen-3-yl acetate showed the highest peak range. In particular, plant samples collected during the monsoon season were more effective in preventing Canda growth than the summer plant samples. In the monsoon season, the salt marsh plant extracted with ethyl acetate showed a high anti-Candida growth activity, while in the summer, the acetone extract exhibited a higher anti-Candida growth activity than the other solvents. The hexane extract of L. sarmentosa showed the highest inhibition zone against all Candidal strains. Furthermore, compounds, such as β-amyrin, lupeol, and oxirane, from the hexane extract of L. sarmentosa play a vital role in anti-Candida activity. This paper reports the potential of tidal marsh plant extracts for developing new antifungal agents for Candida infections.

Ammonia-Borane Dependent Transfer Hydrogenation of Carboxylic Esters to Primary Alcohols.

Here, we present a user-friendly protocol that uses bench-stable NH3·BH3 (AB) as the hydrogen transfer agent for the reduction of both aromatic and aliphatic esters without an external catalyst and base, delivering a structurally diverse array of primary alcohols (80-98% yields). The broad functional-group tolerance (halogen, boronic ester, -NO2, -OH, etc.) under environmentally acceptable conditions implies high practical utility. Further, a tandem catalytic conversion of a plastic waste polyethylene terephthalate (PET) bottle to 1,4-benzenedimethanol including fatty esters into respective fatty alcohols was shown.

The Potential Significance of Microwave-Assisted Catalytic Pyrolysis for Valuable Bio-Products Driven from Albizia Tree

The objective of this study is to investigate the feasibility of Na2CO3 and ZSM-5 as catalysts in the microwave pyrolysis of Albizia branches. An evaluation was conducted to determine the influence of power applied, experimental time, particle size, and catalysis type and ratio on the quality and quantity of pyrolysis products. Established methods such as GC-MS, FTIR, HHV, SEM, EDX, and BET were used to characterize the properties of bio-oil and biochar produced. The results demonstrated that using both catalyst types led to a substantial enhancement in biogas production. The improvement ranged from 5% to 41% with Na2CO3 and reached 45% with ZSM-5. At a lower power level of 300 W, the bio-oil yield augmented from 28% to 40% and 53% when using ZSM-5 and Na2CO3, respectively. The GC-MS analysis revealed that the utilizing of catalysts enhanced the levels of aromatic compounds, esters, and alcohols in bio-oil, along with an increase in the higher heating value (HHV) from 19.5 MJ/kg to 22 MJ/kg and 24.2 MJ/kg using Na2CO3 and ZSM-5, respectively. Moreover, the biochar's surface area and pore volume experienced a considerable rise, going from 0.5512 m2/g and 0.00011 cm3/g to a higher value of 115.2073 m2/g and 0.0774 cm3/g when treated with Na2CO3. The data indicated that both catalyst types enhanced the generation of CH4, and CO2 was lower with ZSM-5. The utilization of catalysts improves the quality of the biofuel produced and promotes the efficiency of the process in terms of energy consumption and processing time.

Structural and sensory characteristics of ultrasonic assisted wet-heating Maillard reaction products of Giant salamander protein hydrolysates.

Chinese giant salamander protein hydrolysates (CGSPH) are beneficial to human health as a result of their high content of amino acids and peptides. However, the formation of bitter peptides in protein hydrolysates (PHs) would hinder their application in food industry. The ultrasound assisted wet-heating Maillard reaction (MR) is an effective way to improve the flavor of PHs. Thus, the effect of ultrasonic assisted wet-heating MR on the structure and flavor of CGSPH was investigated in the present study. The results indicated that the ultrasound assisted wet-heating MR products (MRPs) exhibited a higher degree of graft and more significant changes in the secondary and tertiary structures of CGSPH compared to traditional wet-heating MRPs. Moreover, ultrasound assisted wet-heating MR could significantly increase the content of small molecule peptides and reduce the content of free amino acids of CGSPH, which resulted in more significant changes in flavor characteristics. The changed in flavor properties after MR (especially ultrasound assisted wet-heating MRPs) were mainly manifested by a significant reduction in bitterness, as well as a significant increase in the content of aromatic aldehyde ester compounds such as furan-2-carbaldehyde, butanal, benzaldehyde, furfural, etc. CONCLUSIONS: Ultrasound assisted wet-heating MR between CGSPH and xylose could be a promising way to improve the sensory characteristics of CGSPH. © 2024 Society of Chemical Industry.

Comparative evaluation of sensory and instrumental flavor profiles of four edible microalgae: Spirulina platensis, Chlorella pyrenoidosa, Chlamydomonas reinhardtii, and Haematococcus pluvialis

Microalgae sensory features are an important parameter to consider in food applications. The current study comparatively evaluated the flavor profiles of four commercial edible microalgae species, i.e., Spirulina platensis, Chlorella proteinosa, Chlamydomonas reinhardtii, and Haematococcus pluvialis through sensory evaluation by a trained expert panel (n = 15) and chemical profiling of flavor compounds, with multivariate statistical methods used to correlate descriptive taste and odor analysis with non-volatile and volatile compounds. S. platensis displayed characteristic salty and umami tastes arising from inorganic ions and 5′-nucleotides, respectively, as well as “muddy” and “floral” odor attributes mainly associated with sulfur compounds and ketones. C. proteinosa and C. reinhardtii shared the taste attributes of sweetness and bitterness mainly contributed by free amino acids, as well as the odor attributes of “seaweed” and “mushroom” in association with aldehydes and alcohols. H. pluvialis had a typical sour taste owning to the presence of abundant organic acids, and smelled “fatty”, “phenolic”, “licorice”, and “fruity” due to aromatic ester and phenolic compounds. Overall, our results provide fundamental insights into the sensory features of common edible microalgae to guide future food applications.

Enzymatic acylation of cyanidin-3-O-glucoside with aromatic and aliphatic acid methyl ester: Structure–stability relationships of acylated derivatives

Anthocyanins are water-soluble pigments, but they tend to be unstable in aqueous solutions. Modification of their molecular structure offers a viable approach to alter their intrinsic properties and enhance stability. Aromatic and aliphatic acid methyl esters were used as acyl donors in the enzymatic acylation of cyanidin-3-O-glucoside (C3G), and their analysis was conducted using ultraperformance liquid chromatography–mass spectrometry (UPLC-MS). The highest conversion rate achieved was 96.41 % for cyanidin-3-O-(6″-feruloyl) glucoside. Comparative evaluations of stability revealed that aromatic acyl group–conjugated C3G exhibited superior stability enhancement compared with aliphatic acyl group derivatives. The stability of aliphatic C3G decreased with increasing carbon chain length. The molecular geometries of different anthocyanins were optimized, and energy level calculations using density functional theory (DFT) identified their sites with antioxidant activities. Computational calculations aligned with the in vitro antioxidant assay results. This study provided theoretical support for stabilizing anthocyanins and broadened the application of acylated anthocyanins as food colorants and nutrient supplements.

Hydrogen solubility in different chemicals: A modelling approach and review of literature data

Hydrogen (H2) solubility is a crucial parameter for industrial processes. This study utilises various Machine Learning (ML) techniques, including Decision Tree (DT), Multilayer Perceptron (MLP), Random Forest (RF), and Extremely Randomized Trees (ET), to predict H2 solubility across diverse chemical classes, encompassing n-alkanes, aliphatic and aromatic hydrocarbons, alcohols, aldehydes, diols, esters, ethers, ketones, and halides. An extensive database of 4337 samples of H2 solubility in 100 different chemicals was compiled from open literature. Problematic samples were identified through preprocessing. Three input sets were utilised for model development to determine the optimal combination of regressors. It was found that including dimensionless pressure and temperature significantly improved modelling accuracy. Higher accuracy was achieved by employing polynomial extracted features. 76 chemicals trained the model, and 20 tested it, with none overlapping. High accuracy on the test set shows applicability to a diverse chemical range beyond the study's dataset. The study's modelling results indicate RF and ET ensemble methods outperform DT and MLP in accuracy and stability, with ET being the most accurate. This study improves our understanding of H2 solubility in various chemicals, crucial for industrial processes like designing H2-based renewable energy plants. Our study advances ML in predicting chemical solubility by introducing advanced feature extraction and testing models with unseen chemicals. This not only validates our models' predictive capability but also yields deeper insights into H2 solubility. With standardized data preprocessing and a model adept at handling diverse chemicals, we demonstrate a substantial advancement in the field through a meticulous testing methodology.

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.

Novel ionic polymers encompassing di-cationic pyridinium hydrazones and aromatic ester as potent antimicrobial agents against resistant bacteria

In this work, readily achievable synthetic pathways including quaternization, metathesis and copolymerization reactions were utilized for the construction of a new di-pyridinium monomers and their respected ionic polymers scaffold with ester fragments. All synthesized material were well characterized by spectroscopic experiments. The surface morphology and thermal study of the produced polyesters were carried out using SEM, PXRD, and TGA analysis. The impact of the counter anions on the crystallinity and thermal analysis of the polymer network was confirmed by thermal analysis and surface investigation. The related polyesters' crystallinity was decreased, and their thermal stability was increased by the TFSI anion. Various significant consequences regarding the development of innovative antibacterial agents along with specific therapies. Subsequently, we evaluated the antimicrobial, antibiotic resistant strains, and anti-prophage properties of these novel class of ionic and poly-ionic materials. Throughout antibacterial studies, the M-Br monomer excelled all synthesized materials, although PPy-TFSI and its monomer outperformed antibiotic-resistant organisms. Both M-PF6 and PPy-PF6 decreased S. aureus bacteriophage proliferation. Understanding the bacterial species or strains that are vulnerable to polyesters encourages subsequent studies in this field to focus on creating targeted therapies for illnesses caused by these pathogens.

Visible light-driven selective cleavage of Cα-Cβ or Cβ-O bond in lignin β-O-4 model into high-value aromatic chemicals over surface modified 2D g-C3N4

Selective cleavage of C–C/C–O linkages in lignin is highly pursued to obtain aromatic monomers but remains challenging due to distinct dissociation energies and steric hindrance. Herein, two photocatalysts were reported to respectively scissor the Cα-Cβ and Cβ-O in lignin β-O-4 model (2-phenoxy-1-phenylethanol) based on the reactive oxygen species control. On one hand, 2D g-C3N4 promotes protons extraction from Cβ-H and ·O2– formation, which further scissored Cα-Cβ via six-membered ring transition state produced via the coupling of ·Cβ and ·HO2, providing aromatic aldehydes and esters. When single-atomic Cu+ species were coordinated with N atoms in 2D g-C3N4 during surface modification, however, the ·O2– formation was prohibited because of the improper redox potentials. Under the catalysis of Cu/2D g-C3N4, CαO-H would be preferentially activated, causing the selective Cβ-O cleavage via self-hydrogen transfer hydrogenolysis to provide phenolics and aromatic ketones. The access and inhibition mechanism for ·O2– formation as well as the different catalytic mechanisms for two reaction pathways were discussed. Current work shows a promising way to selectively supply aromatic chemicals using the renewable biomass and photoenergy.