Ester Formation Research Articles

Transcription factors PuNAC37/PuWRKY74 and E3 ubiquitin ligase PuRDUF2 inhibit volatile ester synthesis in 'Nanguo' pear.

As major contributors to flavor in many fruit species, volatile esters are useful for investigating the regulation of the biosynthesis pathways of volatile aroma compounds in plants. Ethylene promotes the biosynthesis of volatile esters during fruit storage while accelerating fruit ripening; thus, the ethylene perception inhibitor 1-Methylcyclopropene (1-MCP) is employed to prolong the shelf life of fruits. However, the mechanisms by which 1-MCP regulates volatiles synthesis remain unclear. In this study, we analyzed the pathway of 1-MCP-mediated volatile ester synthesis in 'Nanguo' pear (Pyrus ussuriensis). 1-MCP significantly decreased volatile ester synthesis during storage. Comparative transcriptome analysis showed that the genes encoding two transcription factors (PuNAC37, PuWRKY74) and a RING-type E3 ubiquitin ligase which have a domain of unknown function (PuRDUF2) were expressed at high levels, whereas ALCOHOL ACYLTRANSFERASE 1 (PuAAT1), encoding an enzyme responsible for volatile ester synthesis, was expressed at low levels in 1-MCP-treated fruit. Moreover, PuNAC37 inhibited the expression of PuWRKY74 via transcriptional regulation, whereas PuNAC37 and PuWRKY74, after directly binding to the promoter of PuAAT1, synergistically inhibited its expression in 1-MCP-treated fruit. In addition, in vitro and in vivo ubiquitination experiments revealed that PuRDUF2 functions as an E3 ubiquitin ligase that ubiquitinates PuAAT1, causing its degradation via the 26S proteasome pathway following 1-MCP treatment. Subsequent PuAAT1 degradation resulted in a reduction of volatile esters during fruit storage. Our findings provide insights into the complex transcriptional regulation of volatile ester formation in 'Nanguo' pears and contribute to future research on AAT protein ubiquitination in other species.

Diastereoselective Synthesis of N-Heterocycle Substituted Cyclobutanes via Michael Addition onto Cyclobutenes.

Herein, we present a method for the diastereoselective synthesis of N-heterocycle-substituted cyclobutanes from commercially available bromocyclobutanes. This method enables the efficient formation of various heterocyclic aminocyclobutane esters and amides using simple reagents. Notably, N-nucleophiles such as imidazoles, azoles, and nucleobase derivatives were successfully incorporated, enhancing the chemical diversity of small ring building blocks for medicinal chemistry applications.

A 11B-NMR Method for the In Situ Monitoring of the Formation of Dynamic Covalent Boronate Esters in Dendrimers

The in situ monitoring of dynamic covalent macromolecular boronate esters represents a difficult task. In this report, we present an in situ method using fluoride coordination and 11B NMR spectroscopy to determine the amount of boronate esters in a mixture of boronic acids and cis-diols. With fluoride coordination, the boronic acid and boronate esters afforded trifluoroborate and fluoroboronate esters, giving identical resonances at 3 and 9 ppm in the 11B NMR spectra. The same titration did not alter the resonance of amine-coordinated boronate esters, which gave resonances of 14 ppm in the 11B NMR spectra. Therefore, boronic acids, boronate esters, and amine-coordinated boronate esters gave three identical resonances, and the ratio of each component was obtained by deconvolution for a further equilibrium analysis. This method monitored the conversion among three species in various conditions, including separation. Accordingly, boronate esters were more stable after precipitation than chromatography, in which 29% and 20% of boronate esters were lost after purification. This method was applied to study the reaction between the boronic acid-decorated defect lysine dendron (16) and dopamine. No boronic acid signal was observed after adding 1 equivalent of dopamine; no boronic acid signal was observed in the NMR spectrum. According to the spectrum, the product contains 65% boronate ester and 35% N–B-coordinated derivatives. This method helps identify the presence of the three intermediates and provides more insights into this reaction.

Fecal fatty acid-linked bile acid profiles in pediatric patients with ulcerative colitis

ObjectiveEffect of gut dysbiosis on fatty acid (FA) linked 3β-hydroxy-bile acid esters (FA-isoBAs) formation is currently unknown. This study aimed to investigate the profile of FA-isoBAs in fecal samples from pediatric patients with ulcerative colitis (UC). MethodsFecal samples were collected from seven pediatric patients diagnosed with UC and seven age-matched healthy controls. Liquid chromatography-tandem mass spectrometry (LC/MS) method was set up for quantifications of thirteen different FA-isoBAs, including three new FA-isoBAs which had never been characterized. Method validation tests were performed with optimization of sample preparation. Statistical analyses were conducted to compare FA-isoBA concentrations between UC patients and healthy controls. ResultsThe LC/MS method had sufficient linearity (r > 0.998), with the low detection limit (0.03–2.82 nmol/g stool), and limits of quantification (0.10–9.40 nmol/g stool) for all FA-isoBAs. The total FA-isoBAs concentration in UC patients was significantly lower than healthy controls, regardless of the degree of the disease severity. The UC subjects had markedly increased primary bile acid (BA) levels with decreased secondary BAs. Propionic acid-linked isoBA and stearic acid-linked 12-oxo-isolithocholic acid were newly identified from healthy subjects but they were not present in UC subjects. In agreement with the previous report, composition of long-chain (C16-C18) FA-linked BAs dominated over short-chain FA-linked BAs both in healthy and disease subjects. ConclusionThe present study reported the fecal FA-isoBA profiles in pediatric UC patients for the first time. The results open the door to the new field that investigates the role of these microbial-driven BAs in gastrointestinal health.

Room-Temperature Formate Ester Transfer Hydrogenation Enables an Electrochemical/Thermal Organometallic Cascade for Methanol Synthesis from CO2.

The reduction of CO2 to synthetic fuels is a valuable strategy for energy storage. However, the formation of energy-dense liquid fuels such as methanol remains rare, particularly under low-temperature and -pressure conditions that can be coupled to renewable electricity sources via electrochemistry. Here, a multicatalyst system pairing an electrocatalyst with a thermal organometallic catalyst is introduced, which enables the reduction of CO2 to methanol at ambient temperature and pressure. The cascade methanol synthesis proceeds via CO2 reduction to formate by electrocatalyst [Cp*Ir(bpy)Cl]+ (Cp* = pentamethylcyclopentadienyl, bpy = 2,2'-bipyridine), Fischer esterification of formate to isopropyl formate catalyzed by trifluoromethanesulfonic acid (HOTf), and thermal transfer hydrogenation of isopropyl formate to methanol facilitated by the organometallic catalyst (H-PNP)Ir(H)3 (H-PNP = HN(C2H4PiPr2)2). The isopropanol solvent plays several crucial roles: activating formate ion as isopropyl formate, donating hydrogen for the reduction of formate ester to methanol via transfer hydrogenation, and lowering the barrier for transfer hydrogenation through hydrogen bonding interactions. In addition to reporting a method for room-temperature reduction of challenging ester substrates, this work provides a prototype for pairing electrochemical and thermal organometallic reactions that will guide the design and development of multicatalyst cascades.

Diloxanide in amoebiasis management: Unravelling the mechanism of action and effectiveness.

Although diloxanide is a drug of choice for treating asymptomatic amoebiasis, its mechanism of action (MOA) remains unclear. This review aims to shed light on the current understanding of the effectiveness and MOA of diloxanide in treating amoebiasis . It involves analysis of articles, retrieved from PubMed, Google Scholar and EBSCOhost, on diloxanide and the treatment of Entamoeba histolytica infection. Diloxanide is used in an ester form, which allows its high luminal concentration and greater efficacy than metronidazole in the management of asymptomatic amoebiasis. The current understanding of the action of diloxanide is based on its structural similarity to chloramphenicol at dichloroacetamide group. It acts against protein synthesis in E. histolytica trophozoites, blocking their conversion to more virulent and invasive cyst forms. Furthermore, it has a parasite clearance rate of 81-96% and treats amoebic abscesses when combined with metronidazole and chloroquine. Nevertheless, it is associated with adverse events such as flatulence, anorexia, headache and urticaria. Diloxanide is efficacious against amoebiasis but there is a need to explore its structure-activity relationship.The study suggests future directions, including novel drug formulations, diagnostic improvements, and combination regimens to enhance treatment outcomes and mitigate relapse associated with the use of diloxanide.

Gelation and Cryogelation of Chitosan: Origin of Low Efficiency of Diglycidyl Ethers as Cross-Linkers in Acetic Acid Solutions

Although diglycidyl ethers of glycols (DEs)—FDA-approved reagents for biomedical applications—were considered unsuitable for the fabrication of chitosan (CH) hydrogels and cryogels, we have recently shown that CH cross-linking with DEs is possible, but its efficiency depends on the nature of the acid used to dissolve chitosan and pH. To elucidate the origin of the low efficiency of chitosan interactions with DEs in acetic acid solutions, we have put forward two hypotheses: (i) DEs are consumed in a side reaction with acetic acid; (ii) DE chain length strongly affects the probability of cross-linking. We then verified them using FT-IR spectroscopy, rheological measurements, and uniaxial compression tests. The formation of esters in acetic acid solutions was confirmed for ethylene glycol diglycidyl ether (EGDE) and poly(ethylene glycol) diglycidyl ether (PEGDE). By the 7th day of gelation at pH 5.5, the G’HCl/G’HAc ratio was 5.1 and 1.5 for EGDE and PEGDE, respectively, indicating that the loss of cross-linking efficiency in acetic acid solution was less pronounced for the long-chain cross-linker. Under conditions of cryotropic gelation, only weak cryogels were obtained from acetic acid solutions at a DE:CH molar ratio of 1:1, while stable cryogels were fabricated at a molar ratio of 1:20 from HCl solutions.

Medium-chain fatty acid triglycerides improve feed intake and oxidative stress of finishing bulls by regulating ghrelin concentration and gastrointestinal tract microorganisms and rumen metabolites

BackgroundAs a feed additive, medium-chain fatty acids (MCFAs)/medium-chain fatty acid triglycerides (MCTs) have been used in ruminant production, but mostly added in the form of mixed esters. Studies have shown that MCTs may have a positive effect on feed intake or oxidative stress in animals, but it is unclear which MCT could play a role, and the mechanism has not been elucidated. In this study, the effects of individual MCT on growth performance, serum intake-related hormones, and oxidative stress indices in finishing bulls were investigated and further studied the effects of MCT supplementation on gastrointestinal tract bacteria and rumen fluid metabolomics.ResultsFour ruminally fistulated Yanbian cattle (bulls) were selected in 4 × 4 Latin square designs and allocated to four treatment groups: a control group (CON) fed a basal diet (total mixed ration, TMR), three groups fed a basal diet supplemented with 60 g/bull/day glycerol monocaprylin (GMC, C8), glycerol monodecanoate (GMD, C10), and glycerol monolaurate (GML, C12), respectively. Compared with the CON group, GMD tended to increase the dry matter intake (DMI) of finishing bulls (P = 0.069). Compared with the CON group, GMD significantly increased the concentration of ghrelin O-acyl transferase (GOAT), total ghrelin (TG), acylated ghrelin (AG), and orexins (P < 0.05) and significantly decreased the concentrations of hydrogen peroxide (H2O2), malondialdehyde, reactive oxygen species (ROS), and lipopolysaccharides (LPS) in the serum of finishing bulls (P < 0.05). Compared with the CON group, GMD and GML significantly increased the concentrations of total antioxidant capacity (T-AOC), catalase, glutathione peroxidase (GSH-PX), glutathione reductase (GR), and nitric oxide (NO) in the serum of finishing bulls (P < 0.05). Compared with the CON group, there were 5, 14, and 6 significantly different bacteria in the rumen digesta in the C8, C10, and C12 groups, respectively; there were 3, 10, and 5 significantly different bacteria in the rumen fluid in the C8, C10, and C12 groups, respectively; and only one differential bacteria (genus level) in the feces among the four treatment groups. Compared with the CON group, there were 3, 14, and 15 significantly differential metabolites identified under positive ionization mode in the C8, C10, and C12 groups, respectively, while under negative ionization mode were 3, 11 and 14, respectively. Correlation analysis showed that there was a significant correlation between DMI, GOAT, AG, GSH-PX, LPS, gastrointestinal tract bacteria, and rumen fluid metabolites.ConclusionsOur findings revealed that different types of MCTs have different application effects in ruminants. Among them, GMD may improve the feed intake of finishing bulls by stimulating the secretion of AG. GMD and GML may change gastrointestinal tract microorganisms and produce specific rumen metabolites to improve the oxidative stress of finishing bulls, and ghrelin may also be involved. This study enlightens the potential mechanisms by which MCT improves feed intake and oxidative stress in finishing bulls.5d9kULzJFQsQ3ajLfa--XDVideo

Copper‐Catalyzed Simultaneous Dehydrogenation and Enantioselective Allylic Oxidation of Alkanes Using Chiral Heterogeneous Ligands to Produce Allylic Esters and Theoretical Investigation of the Mechanism

ABSTRACTA new asymmetric method for preparing chiral allylic esters from various unactivated alkanes through simultaneous dehydrogenation and enantioselective allylic oxidation in the presence of chiral heterogeneous oxazoline–based ligands is reported for the first time. For this purpose, chiral amino oxazoline ligands, synthesized from chiral amino alcohols and cyanogen bromide, were immobilized on modified MCM‐41 mesoporous silica. These chiral heterogeneous ligands were then characterized using Fourier‐transform infrared spectroscopy, thermogravimetric analysis, X‐ray diffraction, scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, and Brunauer–Emmett–Teller and Barrett–Joyner–Halenda techniques. Finally, copper complexes of these ligands were employed in the synthesis of chiral allylic esters, achieving the best result with a 90% yield and 77% enantiomeric excess. Evaluation of the recyclability of the chiral heterogeneous catalysts revealed that they can be reused three times without a noticeable reduction in the results. In addition, the mechanism of formation of the chiral allylic esters was investigated using a density functional theory method.

Systematic study on the hydrogen abstraction reactions from oxygenated compounds by H and HO2

AbstractTo extend the rule‐based approach for hydrogen abstraction reactions from oxygenated compounds, a systematic investigation was performed to examine the reactivity of gas‐phase hydrogen abstraction reactions from alkyl groups (methyl and ethyl groups) bound to oxygen atoms in five types of oxygenated compounds (alcohols, ethers, formate esters, acetate esters, and carbonate esters) by H atoms and HO2 radicals comprehensively considering rotational conformers. Quantum chemical calculations were conducted at the CBS‐QB3 level for stationary points. Rate constants were determined employing conventional transition state theory (TST). For hydrogen abstraction reactions by H, the rotational conformer distribution partition function was employed to approximate partition functions, owing to the similarity in vibrational energy‐level structures among conformers. In hydrogen abstraction reactions by HO2, the vibrational structures of transition‐state (TS) conformers varied significantly due to the hydrogen bonding, leading to an inappropriate evaluation of rate constants when using the lowest‐energy conformer as a representative. Therefore, the rate constants were calculated by the multi‐structural TST. It was revealed that the differences in functional groups containing O atoms mainly affect the bond dissociation energies of the C–H bonds and the activation energies of hydrogen abstraction reactions only when the C atoms are adjacent to the O atoms. Additionally, it was found that hydrogen bonds formed in the TSs show minor effect on rate parameters for the overall rate constants, apart from the reduction of the pre‐exponential factors for the H‐abstraction reactions from the methylene position of ethyl groups. The comparison with the rate constants from previous studies showed reasonable results, indicating that the rate constants in this study, which thoroughly consider rotational conformers, can be the current best estimates.

Synthesis and Binding Properties of High-Affinity Histidine-Bearing Polymers for Wood Lignin.

The pursuit of molecules capable of binding to wood lignin is pivotal for advancing lignin degradation technology, particularly when combined with lignin degradation catalysts. In this study, synthetic polymers bearing histidine moieties, demonstrating remarkable affinity for wood lignin are reported. These polymers, featuring varying degrees of histidine substitution in the form of histidine methyl esters, are synthesized through controlled radical polymerization of an activated ester-bearing monomer, employing a fluorescein-labeled chain transfer agent and subsequent postpolymerization amidation with histidine methyl ester. The binding properties of these histidine-bearing polymers with milled wood lignin under aqueous conditions are investigated. Qualitative assessment of lignin-binding capabilities involve spectroscopic analysis of changes in absorbance of visible light and fluorescence intensity. Furthermore, quantitative evaluation is conducted through surface plasmon resonance measurements to determine the binding parameters of the polymers with wood lignin. Notably, polymers with higher histidine substitution exhibit enhanced binding affinity compared to those with lower histidine substitution levels.

Scale-up of Sodium Persulfate Mediated, Nitroxide Catalyzed Oxidative Functionalization Reactions.

Oxidation is a valuable tool in preparative organic chemistry. Oxoammonium salts and nitroxides have proven valuable as reagents and catalysts in this endeavor. The objective of this study is to scale up the oxidative amidation, ester formation, and nitrile formation using nitroxide as an organocatalyst. Oxidative functionalization reactions were scaled from the 1 mmol to the 1 mole level. Sodium persulfate was used as the primary oxidant, and a nitroxide was employed as a catalyst. The products of the reactions were isolated in analytically pure form by extraction with no need for column chromatography. The oxidative amidation and esterification of aldehydes can be scaled up from 1 mmol to 1 mole effectively, with comparable product yields being obtained at each increment. This work shows that conditions developed on a small scale can be transferred to a larger scale without reoptimization. The oxidative functionalization of aldehydes to prepare nitriles is not amenable to direct scale-up due to the concomitant formation of significant quantities of the corresponding carboxylic acid, thereby compromising the product yield. Two of the three oxidative transformations studied here can be scaled up successfully from the 1 mmol to the 1 mole level.

Two-Dimensional Covalent Organic Frameworks: Structural Insights across Different Length Scales and Their Impact on Photocatalytic Efficiency.

ConspectusCovalent organic frameworks (COFs) are a rapidly emerging class of crystalline porous polymers, characterized by their highly defined, predictable, and tunable structure, porosity, and properties. COFs can form both two-dimensional (2D) and three-dimensional (3D) architectures, each with unique characteristics and potential applications. 2D COFs have attracted particular interest due to their favorable structural and optoelectronic properties. They can be equipped with a range of different functional moieties in their backbone, ranging from acidic to basic, from hydrophilic to hydrophobic, and from metal-coordinating to redox-active functions. In addition, their crystallinity, high specific surface area, and remarkable thermal and chemical stability make them attractive for a variety of applications, including gas separation, catalysis, energy storage, and optoelectronics.This Account provides a detailed overview of our recent efforts to synthesize and apply 2D COFs. First, various synthesis routes are discussed, focusing on methods that involve reversible and irreversible linkage reactions. Reversible reactions, such as imine or boronate ester formation, are advantageous for producing highly crystalline COFs because they allow for error correction during synthesis. In contrast, irreversible reactions, such as carbon-carbon or carbon-nitrogen bond formation, yield COFs with greater chemical stability, although controlling crystallinity can be more challenging. Our group has contributed significantly to refining these methods to balance crystallinity and stability, enhancing the performance of the resulting 2D COFs.In addition to different binding patterns, we have also developed strategies to control the micro- and macromorphologies of COFs, which is crucial for optimizing their properties for specific applications. For example, we have explored the synthesis of hierarchical porous COFs by using templating techniques or by forming composites with other functional materials. These strategies enable us to fine-tune the porosity and surface properties of COFs, thereby improving their performance in applications like catalysis. Hierarchical structures in particular enhance photocatalytic efficiency by providing a larger surface area for light absorption and facilitating the transport of photogenerated charge carriers.We further examine the practical applications of 2D COFs, with a primary focus on photocatalysis. Photocatalysis uses light to enable or accelerate chemical reactions, and 2D COFs are ideal for this purpose due to their tunable band gaps and large surface areas. Our research has shown that 2D COFs are highly versatile photocatalysts that can effectively catalyze reactions such as water splitting, carbon dioxide reduction, hydrogen peroxide formation, and cross-coupling reactions. By exploiting the unique properties of 2D COFs, we have achieved significant improvement in many photocatalytic reactions.With this comprehensive overview, we aim to contribute to the further development and understanding of 2D COFs and encourage further research and innovation in this promising field.

Contribution of polyvinylpolypyrrolidone (PVPP) treatment to the distribution of polyphenols and the evolution of esters and higher alcohols in Rosa roxburghii Tratt wine

Polyvinylpolypyrrolidone (PVPP) is commonly employed for fining in fruit wine brewing. This study aimed to investigate the impact of PVPP pretreatment on the formation of fermentation aroma and polyphenol distribution in Rosa roxburghii Tratt (RRT) wine. A significant effect of PVPP on polyphenol adsorption was observed, and polyphenol families or subfamilies such as flavanols and flavonols showed specific affinity for PVPP, decreasing by over 19 % and 30 %, respectively. Furthermore, it was the first time to demonstrate a significant enhancement in the ester content of the corresponding RRT wine after PVPP treatment, particularly in imparting sweet and fruity esters (increased by over 40 %). In contrast, the RRT wine treated with PVPP exhibited a significant reduction of over 20 % in the concentration of higher alcohols, particularly reflected in the green and chemical aromas. This indicates that PVPP treatment could promote the transformation of RRT wine aroma from green and chemical to sweet and fruity. Correlation analysis revealed a positive relationship between the concentration of higher alcohols and most phenolic compounds in RRT wine, while quercetin 3-glucoside, rutin, and polydatin were negatively correlated with esters that can impart fruit flavor and floral aroma to fruit wine. As a practical insight into fruit wine fermentation, PVPP fining before fermentation is more likely to alter the phenolic compositions of RRT wine, thereby influencing its aroma characteristics. Specifically, polyphenols associated with energy metabolism of yeast could have stimulated the formed fluxes of esters. The association between the formation of esters and higher alcohols with phenolic compounds will provide new information on the impact of clarification treatments on yeast-derived volatile metabolites in RRT wine and hold promise in improving the aroma of RRT wine by modulating polyphenol composition through pre-clarification.

Ether and ester formation from peroxy radical recombination: a qualitative reaction channel analysis

Abstract. The least volatile organic compounds participating in atmospheric new-particle formation are very likely accretion products from self- and cross-reactions of peroxy radicals (RO2). It has long been assumed that the only possible accretion product channel in this reaction is that forming a peroxide (RO2+RO2→ROOR+O2), but it has recently been discovered that a rapid alkoxy radical (RO) decomposition may precede the accretion step of the mechanism, forming slightly fragmented but more stable ether (ROR) or ester (RC′(O)OR) accretion products. In this work, the atmospheric implications of this new reaction channel have been explored further by using a modified version of the Generator for Explicit Chemistry and Kinetics of Organics in the Atmosphere (GECKO-A) software to generate a large amount of representative RO2 + RO2 reactive pairs formed from the oxidation of typical primary hydrocarbons and by applying structure–activity relationships (SARs) to predict the potential accretion products. These data are analysed in terms of the formation of low-volatility products, and new discoveries are presented on what types of RO2 are especially efficient (and which are surprisingly inefficient) at forming accretion products. These findings are discussed in terms of the atmospheric relevance of these new RO2 + RO2 reaction channels. As the generation of these data rests on several simplifications and assumptions, many open questions worthy of later studies are also raised.

One-Pot Microwave-Assisted Intramolecular Rearrangement of Pyranone Amide to Pyridone Ester

AbstractThis investigation presents a novel, cost-effective approach for creating a 2-pyridone core substituted with an ester group through intramolecular rearrangement. This one-step transformation involves an amide-mediated intramolecular transformation of a pyranone to pyridone scaffold, followed by alcoholic-mediated ester formation, in 75–85% yield. Deuterated alcohol was used to confirm the esterification under alcoholic conditions. The reaction requires a nucleophile source from the solvent, which was observed by performing the reaction of three derivatives in CD3OD to obtain the desired carboxylate compounds, replacing -OR with -OCD3. All synthesized compounds were characterized by spectroscopic analysis, and six selected compounds were further confirmed by single-crystal X-ray diffraction studies.

Transesterification of Azadirachta indica seed oil into biodiesel using MgO-supported tri-metallic catalyst– synthesis and characteristic evaluation

Environmentally sustainable biodiesel from non-edible waste Azadirachta indica (neem) seed oil provides an economical alternative to combat issues caused by fossil fuel combustion. The current study reports specifically a bi-functional trimetallic (Ca-Sr-Mo) catalyst delineated across MgO support synthesized via wet impregnation and green synthesis route using Cassia fistula extract. In FTIR analysis, peaks appeared at 992, 1390, 1424 cm−1 represent the C–O stretching, C–H deforming and M–O–M bending deformation vibrations, respectively. The diffraction peaks of all CaO, SrO, MoO2, and MgO in the XRD pattern represent the formation of catalysts. The prepared catalyst is employed in the transesterification reaction to convert A. indica oil into fatty acid methyl ester. The study used the response surface methodology to examine factors that could affect the conversion rate, including oil-methanol molar ratio, reaction time, and catalyst loading. The results were analyzed to determine the best combination of factors that yields the optimal catalytic transesterification process. The highest yield of 89.92 % was achieved under optimum conditions of methanol-to-oil (18:1), catalyst loading (5 wt%), and time (6 h). In FTIR analysis, the new peak appeared at 1160 cm−1, indicating the formation of methyl esters, while 1H NMR analysis confirmed the successful conversion of A.indica oil into FAMEs by the appearance of strong singlet at 3.66 ppm for methoxy proton.1H NMR also indicated a high yield (90.09 %) which is comparable to RSM obtained yield. Additionally, a reaction mechanism has been proposed. Specifically, GC-MS FAME profiles and physicochemical testing confirmed that biodiesel meets ASTMD6751 and EN14214 standards with key fatty acid methyl esters and desirable properties.

Sustainable bioenergy potential of peat-moss derived hydrothermal aqueous phase: Insights into methane production and organic transformation

Achieving Sustainable Development Goal 7 (SDG-7) by exploring bioenergy production from peat-moss derived hydrothermal aqueous phase (HAPs) through anaerobic digestion (AD). This study investigated six combinations of hydrothermal conversion temperature (HCT) and residence time (HCRT). Methane yields varied significantly, with the highest (256 mL/g COD) achieved at 200 °C:4h, while the lowest (97 mL/g COD) was at 320 °C:4h due to formation of toxic and refractory organics. Microtox analysis showed acute toxicity > 98 % for all HAPs. Notably, higher HCT and HCRT led to more complex and diverse organic patterns, promoting the formation of humus-like substances, ester, alkane alcohols, and aromatics. GC–MS analysis revealed a 23 % increase in aldehyde and ketone compounds at 320 °C:4h. Continuous experiments confirmed 29 % COD removal efficiency at 320 °C:4h and identified 13 refractory organics, highlighting challenges in biodegradability. These findings provided valuable insights for optimizing AD processes, enhancing bioenergy production, and advancing sustainable energy solutions in alignment with SDG-7.

Zein and 3-Aminophenyl Boronic Acid Conjugated Polyvinylpyrrolidone Polymer Blend: Electrospinning, Characterization, and Mucoadhesive Drug Delivery.

The era of mucoadhesive polymers has advanced to the next generation, focusing on targeted adhesion of chemical functional groups with mucosa. This work aims to develop boronic acid functionalized polymers, which could facilitate reversible binding with the mucin in the mucosa. Pendant groups of boronic acid were conjugated on the chains of polyvinylpyrrolidone (PVP) via C═N bonding. The evidence from FTIR spectroscopy, XPS analysis, and UV spectroscopy has been used for the confirmation of the chemical conjugation of 3-aminophenyl boronic acid (APBA) to PVP. Boronate ester formation is a pH-dependent process. High pKa values of APBA preferably cause the binding of trigonal-shaped boronic acid with sialic acid groups of mucin. Boronic acid moieties additionally benefited in mucoadhesion in comparison to PVP alone, which is a result of the formation of a five-membered boronate ester complex. The presence of boronic acid moieties enhanced the force of adhesion on porcine buccal mucosal tissue from 13.12 ± 1.52 to 19.04 ± 1.97 g force. Specific binding of the polymer to the mucosal surface caused prolonged adhesion of the polymer to the mucosal surface. A polymer blend of boronic acid functionalized PVP and zein has been explored for its potential for mucoadhesive delivery of propranolol hydrochloride.

Stability of Cholinium Chloride-Based Deep Eutectic Solvents with Carboxylic Acids: A Study on Ester Formation

Stability of Cholinium Chloride-Based Deep Eutectic Solvents with Carboxylic Acids: A Study on Ester Formation