Occurrence and potential risks of organophosphate esters in agricultural soils: A case study of Fuzhou City, Southeast China.

Fifty agricultural soil samples collected from Fuzhou, southeast China, were first investigated for the occurrence, distribution, and potential risks of twelve organophosphate esters (OPEs). The total concentration of OPEs (ΣOPEs) in soil ranged from 1.33 to 96.5 ng/g dry weight (dw), with an average value of 17.1 ng/g dw. Especially, halogenated-OPEs were the predominant group with a mean level of 9.75 ng/g dw, and tris(1-chloro-2-propyl) phosphate (TCIPP) was the most abundant OPEs, accounting for 51.1% of ΣOPEs. The concentrations of TCIPP and ∑OPEs were found to be significantly higher (P < 0.05) in soils of urban areas than those in suburban areas. In addition, the use of agricultural plastic films and total organic carbon had a positive effect on the occurrence of OPE in this study. The positive matrix factorization model suggested complex sources of OPEs in agricultural soils from Fuzhou. The ecological risk assessment demonstrated that tricresyl phosphate presented a medium risk to land-based organisms (0.1 ≤ risk quotient < 1.0). Nevertheless, the carcinogenic and non-carcinogenic risks for human exposure to OPEs through soil ingestion and dermal absorption were negligible. These findings would facilitate further investigations into the pollution management and risk control of OPEs.

Distinguishing Artifactual Fatty Acid Dimers from Fatty Acid Esters of Hydroxy Fatty Acids in Untargeted LC-MS Pipelines.

Untargeted metabolomics is a powerful profiling tool for the discovery of possible biomarkers of disease onset and progression. Analytical pipelines applying liquid chromatography (LC) and mass spectrometry (MS)-based methods are widely used to survey a broad range of metabolites within various metabolic pathways, including organic acids, amino acids, nucleosides, and lipids. Accurate and complete identification of putative metabolites is an ongoing challenge in untargeted metabolomics studies. Highly sensitive instrumentation can result in the detection of adduct and fragment ions that form reproducibly and contain identifiable ions that are difficult to distinguish from metabolic pathway intermediates, which may result in false-positive identification. At concentrations as low as 10 µM, free fatty acids have been found to form homo- and heterodimers in untargeted metabolomics pipelines that resemble the lipid class fatty acid esters of hydroxy fatty acids (FAHFAs), resulting in misidentification. This chapter details a protocol for LC-MS-based untargeted metabolomics using hydrophilic interaction chromatography (HILIC) that specifically aids in distinguishing artifactual fatty acid dimers from endogenous FAHFAs.

Colloid, interface, and foam properties of water-soluble polyglycerol esters solutions.

HYPOTHESIS: Polyglycerol esters of fatty acids are generated via the esterification of a polydisperse mixture of polyglycerol with naturally derived fatty acids. The polymerization process of polyglycerol results in the production of various oligomers, ranging from di-, tri-, and higher-order forms, which contribute to the complexity of final products. The combination of complementary experimental techniques and adequate theoretical interpretations can reveal the wide variety of their physicochemical properties. EXPERIMENTS: The colloid and interface properties of polyglyceryl mono-laurate, mono-stearate, mono-oleate, and a mixture of mono-caprylate and mono-caprate esters solutions were characterized by measurements of the electrolytic conductivity, static and dynamic surface tension, aggregate and micelle sizes and distributions, thin liquid film stability and stratification, and solubility in aqueous and in oil phases. The formation, stability, and bubble size distribution of foams generated from polyglycerol esters aqueous solutions were systematically investigated. FINDINGS: The low concentrations of double-tail molecules and fatty acids in polyglycerol esters affect considerably their micellar, aggregation, and vesicle formations in aqueous solutions. The theoretical data interpretation of polyglycerol esters isotherms and thin liquid films data provide information on the adsorption energies, excluded areas per molecule, interaction parameters of molecules at interfaces, surface electrostatic potential, and the size of micelles. Polyglyceryl mono-oleate exhibits spontaneous emulsification properties. Short chain length polyglycerol esters have excellent foaming ability but relatively low foam stability. The optimal weight fractions of the short-chain polyglyceryl esters and polyglyceryl mono-stearate mixtures with respect to good foaminess and foam stability upon Ostwald ripening are obtained. The reported physicochemical characterization of the water-soluble polyglycerol esters could be of interest to increase the range of their applicability in practice.

Accumulation characteristics and fate modeling of phthalic acid esters in surface water from the Three Gorges Reservoir area, China.

Phthalic acid esters (PAEs) are a group of compounds widespread in the environment. To investigate the occurrence and accumulation characteristics of PAEs, surface water samples were collected from the Three Gorges Reservoir area, China. The total concentrations of 11 analyzed PAEs (∑11PAEs) in the collected water samples ranging from 197.7 to 1,409.3 ng/L (mean ± IQR: 583.1 ± 308.4 ng/L). While DEHP was the most frequently detected PAE, DnBP and DnNP were the most predominant PAEs in the analyzed water samples with a mean contribution of 63.3% of the ∑11PAEs. The concentrations of the ∑11PAEs in the water samples from the upper reaches of the Yangtze River were significantly higher than those from the middle reaches. To better understand the transport and fate of the PAEs, seven detected PAEs were modeled by Quantitative Water Air Sediment Interaction (QWASI). The simulated and measured values were close for most PAEs, and differences are within one order of magnitude even for the worst one. For all simulated PAEs, water and particle inflow were main sources in the reservoir, whereas water outflow and degradation in water were important removal pathways. The contribution ratios of different sources/losses varied from PAEs, depending on their properties. The calculated risk quotients of DnNP in the Three Gorges Reservoir area whether based on monitoring or simulating results were all far exceeded the safety threshold value, implying the occurrence of this PAE compound may cause potential adverse effects for the aquatic ecology of the Three Gorges Reservoir area.

Colonization of phthalate-degrading endophytic bacterial consortium altered bacterial community and enzyme activity in plants.

Phthalates (PAEs) are widely distributed hazardous organic compounds that pose threats to ecosystems and human health. Endophytic bacteria can effectively eliminate PAEs contamination risk. However, limited information is available regarding the impact of endophytic bacterial colonization on bacterial communities within plants. In this study, the endophytic bacterial consortium EN was colonized in lettuce by seed soaking, root irrigation, leaf spraying, and combined spraying-irrigation, resulting in a marked improvement in plant growth. The findings revealed that consortium EN colonization through combined spraying-irrigation exhibited superior degradation capability with 40.54% PAEs removal from soil. Meanwhile, the residual PAEs in lettuce decreased by 94.05% compared with the uninoculated treatment. High-throughput sequencing analysis indicated that colonization of consortium EN altered the bacterial community in lettuce. Specifically, the relative abundance of the dominant genus Pseudomonas was significantly higher than that in the uninoculated control (P < 0.01). Additionally, colonization enhanced the activities of peroxidase and catalase in lettuce, thereby improving plant resistance. This work offers a theoretical foundation for comprehending the mechanism underlying the bioremediation of PAEs contamination by endophytic bacteria in soil-plant system.

Mechanochemical Synthesis of ß-Sulfenylated Ketones and Esters.

For the first time, ball milling has been employed in the solvent-free synthesis of sulfur-functionalized materials from thiols and α,ß-unsaturated ketones and esters, using potassium carbonate as a transition metal-free catalyst. This environmentally friendly protocol makes use of easily accessible reagents to prepare ß-sulfenylated carbonyl compounds with yields exceeding 91% under ambient air and solvent-free conditions. Additionally, this innovative synthetic strategy enables the modification of  chalcones, compounds with significant medicinal and synthetic potential. The reactions are efficient and easily scalable to gram quantities, offering substantial benefits for practical applications.

Fast determination of organophosphate esters and their metabolites in human matrices by a straightforward cold-induced strategy coupled with HPLC-MS/MS.

Organophosphate esters (OPEs) are commonly used chemicals and are also regarded as emerging environmental pollutants. Recently, it has been proved that metabolites of OPEs (mOPEs) could also cause health concerns. However, analytical methods for the concurrent measurement of OPEs and mOPEs in human matrices are still complicated. In this study, a convenient and efficient analytical method combining a cold-induced strategy and HPLC-MS/MS was developed to simultaneously determine 18 OPEs and 10 mOPEs in human serum, urine, and human milk. In brief, after the sample was extracted with acetonitrile, a "one-step" treatment combining purification and enrichment was accomplished by cold-induced liquid-liquid extraction (CI-LLE), and analytes were then quantified by HPLC-ESI-MS/MS. The ratio of acetonitrile/water, and the temperature and time set in the CI-LLE procedure were optimized for achieving the highest enrichment factors. Under the best conditions, linearity, limits of detection (LODs), recovery, precision, and matrix effects of OPEs/mOPEs were verified. LODs of OPEs/mOPEs in serum, urine, and human milk were 0.1-113 pg/mL, 0.1-22 pg/mL, and 0.2-22 pg/mL, respectively. Average recoveries ranged from 80 to 123%, with relative standard deviations lower than 15% for most analytes. The matrix effect test showed slight signal enhancement or inhibition, and the use of isotopically labeled internal standards (ISs) could compensate for the effects. In real sample analysis, both OPEs and mOPEs showed high detecting frequency, which indicated their ubiquity in humans.

Inhibiting the Cholesterol Storage Enzyme ACAT1/SOAT1 in Myelin Debris-Treated Microglial Cell Lines Activates the Gene Expression of Cholesterol Efflux Transporter ABCA1.

Aging is the major risk factor for Alzheimer's disease (AD). In the aged brain, myelin debris accumulates and is cleared by microglia. Phagocytosed myelin debris increases neutral lipid droplet content in microglia. Neutral lipids include cholesteryl esters (CE) and triacylglycerol (TAG). To examine the effects of myelin debris on neutral lipid content in microglia, we added myelin debris to human HMC3 and mouse N9 cells. The results obtained when using 3H-oleate as a precursor in intact cells reveal that myelin debris significantly increases the biosynthesis of CE but not TAG. Mass analyses have shown that myelin debris increases both CE and TAG. The increase in CE biosynthesis was abolished using inhibitors of the cholesterol storage enzyme acyl-CoA:cholesterol acyltransferase 1 (ACAT1/SOAT1). ACAT1 inhibitors are promising drug candidates for AD treatment. In myelin debris-loaded microglia, treatment with two different ACAT1 inhibitors, K604 and F12511, increased the mRNA and protein content of ATP-binding cassette subfamily A1 (ABCA1), a protein that is located at the plasma membrane and which controls cellular cholesterol disposal. The effect of the ACAT1 inhibitor on ABCA1 was abolished by preincubating cells with the liver X receptor (LXR) antagonist GSK2033. We conclude that ACAT1 inhibitors prevent the accumulation of cholesterol and CE in myelin debris-treated microglia by activating ABCA1 gene expression via the LXR pathway.

Revealing protein aggregation behaviour and dispersion properties induced by molecular interactions between sucrose esters and myofibrillar protein in an aqueous phase system.

The effects of sucrose esters (SE) with varying hydrophilic-lipophilic balance (HLB) values (SE 11, 13, 15) and different concentrations (0.01, 0.1, 1.0 mM) on the dispersion properties and structure of myofibrillar proteins (MPs) in the aqueous phase were investigated. The results demonstrated that the SE 11 and SE 13 reduced the particle size and enhanced the distribution uniformity of the MPs. All of the SE exhibited a slight reduction in the ζ-potential absolute values of the MPs. Meanwhile, the SE 11 significantly reduced the turbidity of the MPs, especially in the 0.1 mM group. Macroscopic and microscopic images showed that the optimum dispersion state was in the SE 11-0.1 group. Furthermore, the interactions between SE and MPs exerted a significant impact on the proteins structure. The SE 13 and SE 15 caused significant changes, which presented concentration correlation, in the tertiary and secondary spatial structures of the MPs. Nevertheless, slight structural changes were observed in MPs with different SE11 concentrations. The SE did not alter the molecular weight of the MPs, i.e. it did not induce irreversible aggregation, nor degradation of the proteins. These results were verified by the surface hydrophobicity, UV-Vis spectroscopy, intrinsic fluorescence, circular dichroism, and SDS-PAGE. Molecular docking simulation showed that hydrophobic interactions and hydrogen bonds were the main interaction force between SE 11 and MPs. Therefore, our findings provided meaningful insights into the dispersion state of the MPs aqueous containing SEs and contributed to the practical application of non-ionic surfactants in meat protein processing.

Current advances in phytosterol free forms and esters: Classification, biosynthesis, chemistry, and detection.

Phytosterols are plant sterols that are important secondary plant metabolites with significant pharmacological properties. Their presence in the plant kingdom concerns many unrelated botanical families such as oleageneous plants and cereals. The structures of phytosterols evoke those of cholesterol. These molecules are composed of a sterane ring, also known as perhydrocyclopentanophenanthrene, along with a methyl or ethyl group at C-24 in their side chains, a hydroxyl group at C-3 on ring A, and one or two double bonds in the B ring. Phytosterols display different oxidation degrees at the sterane ring and at the side chain as well as varying numbers of carbons with complex stereochemistries. Fats and water solubilities of phytosterols have been achieved by physical, chemical and enzymatic esterifications to favor their bioavailability and to improve the sensory quality of food, and the efficiency of pharmaceutic and cosmetic products. This review aims to provide comprehensive information starting from the definition and structural classification of phytosterols, and exposes an update of their biogenic relationships. Next, the synthesis of phytosterol esters and their applications as well as their effective roles as hormone precursors are discussed. Finally, a concise exploration of the latest advancements in phytosterol / oxyphytosterols analysis techniques is provided, with a particular focus on modern hyphenated techniques.

Occurrence of legacy and emerging organophosphate flame retardants (OPFRs) on silicone wristbands: Comparison within couples.

Novel organophosphate flame retardants (OPFRs) are recently identified and highly detected in indoor dusts, but their personal exposure was not clear. Here, wristband was used to estimate non-dietary exposure to emerging OPFRs in comparison with legacy OPFRs in 93 adults in Beijing, China. Comparison of studies in wristband monitoring data showed a clear difference in profiles of legacy OPFRs between China and United States, where tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) was usually the dominant OPFR in the United States, but triphenyl phosphate has the highest contribution to total OPFRs in China. Five emerging OPFRs, including diethylene glycol bis(bis(2-chloroisopropyl) phosphate) (DEGBBCPP) and bis(2-ethylhexyl) phenyl phosphate (BEHPP), were detected in above 45 % of wristbands. The median concentration of DEGBBCPP (2.2 ng/g) was about three times higher than TDCIPP (0.76 ng/g), a legacy chloro-OPFR. Both emerging and legacy OPFRs were significantly correlated within 40 pairs of couples, suggesting major exposure in their homes. Wristbands from husbands had significantly higher tris(2-butoxyethyl) phosphate (TBOEP) and DEGBBCPP, while 2-ethylhexyl diphenyl phosphate (EHDPP) was significantly higher in wives' bands, suggesting gender-related exposure sources for these OPFRs.

A green approach coupled with molecular dynamics simulations and toxicity assays to infer the mode of action for organophosphate esters.

Organophosphate esters (OPEs) have attracted extensive attention due to their toxic effects on human health and biological systems as plasticizers and flame retardants. This study focused on exploring a green approach to get toxicity mechanisms that used less solvents or organisms. The toxicity values of selected organophosphate esters including tri (2-chloroethyl) phosphate (TCEP), tri (1, 3-dichloro-2-propyl) phosphate (TDCP), tripropyl phosphate (TPrP), tri-n-butyl phosphate (TnBP), and tritolyl Phosphate (TCrP) to Photobacterium phosphoreum were determined. Their EC50 range was between 7.27 × 10-8-5.12 × 10-6 mol/L. Based on molecular dynamics simulation the data of binding affinity between OPEs and n-octanol / phospholipid bilayer were calculated respectively. Coupling with binding affinity energies and toxicity values, the mode of action (MOA) of OPEs including types of reactive or anesthetic mechanism could be fast deduced. The proposed hypothesis of n-octanol (C8H18O) as a virtual biofilm to replace phospholipid bilayer was verified. The alternative green approach could simplify toxicity assay and realize fast predicting MOA for different chemicals and model organisms.

An Enabling Peptide Ligation Induced by Thiol-Salicylaldehyde Ester for Chemical Protein Synthesis.

Chemical protein synthesis by amide-forming ligation of two unprotected peptide segments offers an effective strategy for the preparation of protein derivatives that are not accessible through bioengineering approaches. Herein, an unprecedented chemical ligation between peptides with C-terminal 2-mercaptobenzaldehyde (thiol-salicylaldehyde, TSAL) esters and peptides bearing N-terminal cysteine/penicillamine is reported. Reactive peptide TSAL esters can be obtained from peptide hydrazides in an operationally simple and highly effective manner. This chemoselective peptide ligation enables the rapid production of N,S-benzylidene acetal intermediates, which can readily be converted into native amide bonds even at sterically hindered junctions. In addition, the current method can be applied compatibly in concert with other types of ligations and subsequent desulfurization chemistry, thereby facilitating convergent protein synthesis. The effectiveness of this new method is also showcased by the total synthesis of proteins ubiquitin and hyalomin-3 (Hyal-3), the efficient synthesis of protein ubiquitin-fold modifier 1 (UFM1) via a C-to-N sequential TSAL ester-induced ligation strategy, and the chemical synthesis of protein Mtb CM through a combined strategy of Ser/Thr ligation and TSAL ester-induced ligations.

Phthalate Esters in Different Types of Cosmetic Products: A Five-Year Quality Control Survey.

Phthalate esters are commonly included in the formulations of cosmetics and related products in order to retain fragrance, enhance flexibility (i.e., by acting as plasticizers), facilitate the dissolution and dispersion of other ingredients, and improve the overall texture and sensory experience of the products. This study aimed to assess the presence and concentrations of phthalates in cosmetics by analyzing a comprehensive set of samples collected over a period of five years (2016-2020). The concentrations of nine different phthalate esters (BBP, DEHP, DNOP, DPP, DBP, DIPP, DMEP, DMP and PIPP) in 1110 cosmetics samples from France and Spain were determined by gas chromatography-mass spectrometry. The samples were included in five categories: soaps and shampoos; hand and body creams; lip gloss and lipsticks; nail polish; and facial makeup and skincare products. Some of the samples (4.86%) contained at least one phthalate at concentrations above the threshold limit (1 µg mL-1). Variable concentrations of different phthalates were determined in the 54 positive samples identified. DEHP was the most frequently detected phthalate, followed by DBP. The findings revealed different profiles according to the different categories of cosmetics and the phthalates detected in each. The results were critically compared with those obtained in various previous studies.

Cholesteryl Phenolipids as Potential Biomembrane Antioxidants.

The lipophilization of polyphenols (phenolipids) may increase their affinity for membranes, leading to better antioxidant protection. Cholesteryl esters of caffeic, dihydrocaffeic, homoprotocatechuic and protocatechuic acids were synthetized in a one-step procedure with good to excellent yields of ~50-95%. After evaluation of their radical scavenging capacity by the DPPH method and establishing the anodic peak potential by cyclic voltammetry, their antioxidant capacity against AAPH-induced oxidative stress in soybean PC liposomes was determined. Their interaction with the liposomal membrane was studied with the aid of three fluorescence probes located at different depths in the membrane. The cholesteryl esters showed a better or similar radical scavenging capacity to that of α-tocopherol and a lower anodic peak potential than the corresponding parental phenolic acids. Cholesteryl esters were able to protect liposomes to a similar or greater extent than α-tocopherol. However, despite their antiradical capacity and being able to penetrate and orientate in the membrane in a parallel position to phospholipids, the antioxidant efficiency of cholesteryl esters was deeply dependent on the phenolipid polyphenolic moiety structure. When incorporated during liposome preparation, cholesteryl protocatechuate and caffeate showed more than double the activity of α-tocopherol. Thus, cholesteryl phenolipids may protect biomembranes against oxidative stress to a greater extent than α-tocopherol.

Gestational organophosphate esters (OPEs) and executive function in adolescence: The HOME Study.

BACKGROUND: Evidence from toxicological studies indicate organophosphate esters (OPEs) are neurotoxic, but few epidemiological studies investigated associations between gestational OPEs and executive function. OBJECTIVE: To examine the associations between gestational concentrations of OPE urinary metabolites and executive function at 12 years METHODS: We used data from 223 mother-adolescent dyads from the Health Outcomes of Measures of the Environment (HOME) Study. Women provided spot urine samples at 16 weeks gestation, 26 weeks gestation, and at delivery for quantification of bis(1,3-dichloro-2-propyl) phosphate, bis-2-chloroethyl phosphate (BCEP), diphenyl phosphate (DPHP), and di-n-butyl phosphate (DNBP). Executive function was assessed at age 12 years using the parent- and self-report Behavior Rating Inventory of Executive Function (BRIEF2). Covariate-adjusted associations between specific gravity-corrected OPEs and BRIEF2 scores were estimated using multiple informant models. Bayesian Kernel Machine Regression (BKMR) was used to assess the impact of all OPEs simultaneously. RESULTS: Parent- and self-report BRIEF2 indices and composite scores were weakly to moderately correlated (rs=0.32-0.41). A natural-log unit increase in BCEP at 26 weeks was associated with approximately a 1-point increase on the self-report Cognitive Regulation Index [CRI] (95% CI 0.4, 2.3), the Emotion Regulation Index [ERI] (95% CI 0.3, 2.2), and the Global Executive Composite [GEC] (95% CI 0.4, 2.2), indicating poorer performance. Higher DPHP at 16 weeks was associated with lower parent-report GEC score (ß=-1.1, 95% CI -2.3, -0.003). BKMR identified BCEP and DNBP at 26 weeks as important contributors to CRI and ERI, respectively. CONCLUSION: OPE metabolites during gestational development, particularly BCEP, may influence adolescent executive function. However, since the FDR p-values failed to reach statistical significance, additional studies would benefit from using larger cohorts.

Legacy and emerging flame retardants in sediments and wastewater treatment plant-derived biosolids.

A baseline assessment of legacy and emerging flame retardant chemicals was performed in inland and transitional sediments as well as biosolids emanating from a selection of wastewater treatment plants (WWTPs) in Ireland. A selection of 24 polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and chlorinated organophosphate esters (Cl-OPEs) were quantified in: 81 inland and transitional sediment samples collected during 2023; 39 transitional sediments collected between 2018 and 2022; and 21 biosolid samples collected from 7 WWTPs over 4-month intervals in January, May, and September 2023. Highest concentrations of BDE-209 and several Cl-OPEs were detected in both sediment and biosolid samples, while most PCBs and penta-/octa-BDEs were comparatively low. Moderate levels of PBDEs and Cl-OPEs were detected in Irish sediments compared to similar studies conducted internationally. In biosolid samples, levels of BDE-209 were on the higher end of figured reported worldwide while levels of Σ8Cl-OPEs were the highest relative to comparable international studies. PCBs meanwhile are on the lower end of international levels for both biosolids and sediments. Based on available predicted no-effect concentrations (PNECs), the majority of compounds assessed were found to be of low-risk based on their levels in sediments with the exception of TCIPP (Risk Quotient - RQ = 1.354 = high risk) as well as EHDPP, TEHP, PCB-118, and PCB-52 (RQ = 0.948, 0.576, 0.446, and 0.257 respectively = moderate risk). Similar risk assessment could not be performed on contaminants in biosolids, though levels of BDE-209 were on the higher end of figured reported worldwide (avg = 3155 ng/g) while levels of Σ8Cl-OPEs were the highest relative to comparable international studies (avg8 = 3290 ng/g). As the legacy PBDEs and PCBs have been listed as persistent organic pollutants (POPs) and replacement flame retardants such as Cl-OPEs have been flagged by programmes such as human biomonitoring for EU (HBM4EU) and the NORMAN Network as chemicals of emerging concern, continued monitoring of these moderate and high-risk contaminants in sediments, as well as an investigation of potential contamination of the food chain through land-spreading of biosolids on agricultural lands, would be warranted.

Bioproduction of Geranyl Esters by Integrating Microbial Biosynthesis and Enzymatic Conversion.

Geranyl esters (GEs) are valuable monoterpene esters derived from the esterification of geraniol and various carboxylic acids with a range of unique aromas and properties, making them valuable in perfumery, pharmaceutical, and cosmetic applications. Lipase-mediated esterification is considered to be a sustainable process but is challenged by the lack of a compatible catalytic method in conjunction with a customized microbial biosynthesis of geraniol. In this study, we developed an integrated process to convert glycerol and various carboxylates into GEs. The process includes microbial biosynthesis of geraniol using metabolically engineered Escherichia coli and enzymatic conversion of geraniol into GEs in a fermentation medium-organic biphasic system using an immobilized lipase. The enzymatic step for esterifying the target carboxylates with geraniol achieved >90% conversion under the optimized condition. Coupled with the geraniol from microbial fermentation, 0.59 g/L geranyl butyrate and 1.04 g/L geranyl hexanoate were produced subsequently, demonstrating the feasibility of converting renewable source into monoterpene esters through this integrated process, which bypassed feeding extra geraniol in the conventional lipase-mediated GE synthesis.

Lipase Substrate Anchoring Dynamics Guided the Rational Design of Novel Deep Eutectic Solvents for Glucose Ester Synthesis.

Glucose esters, heralded for their emulsifying and solubilizing properties, have found increasing application in food, pharmaceutical, and cosmetic sectors. However, the environmental impact of chemical synthesis and the problem of enzyme inactivation in enzymatic synthesis have hindered their application. To this end, deep eutectic solvents (DESs) with stabilized enzyme activity and better solubility properties are considered a promising solution. In the study, 12 kinds of hydrophilic DESs and 22 kinds of hydrophobic DESs were screened, and we examined their efficiency in the synthesis of glucose esters. The results indicated that d,l-menthol-based DESs have excellent performance, with the highest yield of 92.85%. The molecular dynamics simulations suggested that it can be attributed to DESs changing the size of substrate binding pocket, which in turn affects the substrate anchoring ability and the catalytic efficiency of lipase. To further evaluate the effects of the solvent on the substrate anchoring ability of enzymes, a novel strategy, namely, substrate anchoring index, which is based on the stability of the tetrahedral intermediate, was proposed and used for the designing of more efficient DESs. Fortunately, novel DESs based on cyclohexanone (menthol analogues) were successfully developed with a yield of 98.85%.

Facile preparation of fluorine-containing 2,3-epoxypropanoates and their epoxy ring-opening reactions with various nucleophiles.

We describe herein a facile method to access 2,3-epoxyesters with fluorine-containing substituents at their 3-position starting from the corresponding enoates by utilization of the low-costed and easy-to-handle reagent, NaOCl·5H2O. Because very little has been disclosed about the reactivity of such 2,3-epoxyesters, their epoxy ring opening by a variety of nucleophiles was carried out and we succeeded in clarifying these chemo- as well as regioselective processes proceeding via the SN2 mechanism to mainly afford 2-substituted 3-hydroxyesters usually in a highly anti selective manner.