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DNA‐based tension probes with precisely programmable force responses provide important insights into cellular mechanosensing. However, their degradability in cell culture limits their use for long‐term imaging, for instance, when cells migrate, divide, and differentiate. This is a critical limitation for providing insights into mechanobiology for these longer‐term processes. Here, we present DNA‐based tension probes that are entirely designed based on the stereoisomer of biological D‐DNA, i.e., L‐DNA. We demonstrate that L‐DNA tension probes are essentially indestructible by nucleases and provide days‐long imaging without significant loss in image quality. We also show their superiority already for short imaging times commonly used for classical D‐DNA tension probes. We showcase the potential of these resilient probes to image minute movements, and for generating long term force maps of single cells and of collectively migrating cell populations. [ABSTRACT FROM AUTHOR]

DNA is commonly known as the "molecule of life" because it holds the genetic instructions for all living organisms on Earth. The utilization of modified nucleosides holds the potential to transform the management of a wide range of human illnesses. Modified nucleosides and their role directly led to the 2023 Nobel prize. Acyclic nucleosides, due to their distinctive physiochemical and biological characteristics, rank among the most adaptable modified nucleosides in the field of medicinal chemistry. Acyclic nucleosides are more resistant to chemical and biological deterioration, and their adaptable acyclic structure makes it possible for them to interact with various enzymes. A phosphonate group, which is linked via an aliphatic functionality to a purine or a pyrimidine base, distinguishes acyclic nucleoside phosphonates (ANPs) from other nucleotide analogs. Acyclic nucleosides and their derivatives have demonstrated various biological activities such as anti-viral, anti-bacterial, anti-cancer, anti-microbial, etc. Ganciclovir, Famciclovir, and Penciclovir are the acyclic nucleoside-based drugs approved by FDA for the treatment of various diseases. Thus, acyclic nucleosides are extremely useful for generating a variety of unique bioactive chemicals. Their biological activities as well as selectivity is significantly influenced by the stereochemistry of the acyclic nucleosides because chiral acyclic nucleosides have drawn a lot of interest due to their intriguing biological functions and potential as medicines. For example, tenofovir's (R) enantiomer is roughly 50 times more potent against HIV than its (S) counterpart. We can confidently state, "The most promising developments are yet to come in the realm of acyclic nucleosides!" Herein, we have covered the most current developments in the field of chemical synthesis and therapeutic applications of acyclic nucleosides based upon our continued interest and activity in this field since mid-1990's. [ABSTRACT FROM AUTHOR]

Enantiomers of a chiral active pharmaceutical ingredient (API) often exhibit different physicochemical, pharmacokinetic, and biological properties. Therefore, enantioseparation becomes a critical aspect of pharmaceutical development. Sertraline, one of the most widely prescribed antidepressant medications, requires purification from its chiral impurities, and this is recommended and essential for its quality control. This perspective highlights the current established research on the separation and quantification of sertraline's chiral impurities, with a focus on instrumental and crystallization‐based techniques. [ABSTRACT FROM AUTHOR]

Potassium channels encoded by human Ether-à-go-go-Related Gene (hERG) are inhibited by diverse cardiac and non-cardiac drugs. Disopyramide is a chiral Class Ia antiarrhythmic that inhibits hERG at clinical concentrations. This study evaluated effects of disopyramide enantiomers on hERG current (IhERG) from hERG expressing HEK 293 cells at 37 °C. S(+) and R(−) disopyramide inhibited wild-type (WT) IhERG with IC50 values of 3.9 µM and 12.9 µM respectively. The attenuated-inactivation mutant N588K had little effect on the action of S(+) disopyramide but the IC50 for the R(−) enantiomer was ~ 15-fold that for S(+) disopyramide. The enhanced inactivation mutant N588E only slightly increased the potency of R(−) disopyramide. S6 mutation Y652A reduced S(+) disopyramide potency more than that of R(−) disopyramide (respective IC50 values ~ 49-fold and 11-fold their WT controls). The F656A mutation also exerted a stronger effect on S(+) than R(−) disopyramide, albeit with less IC50 elevation. A WT-Y652A tandem dimer exhibited a sensitivity to the enantiomers that was intermediate between that of WT and Y652A, suggesting Y652 groups on adjacent subunits contribute to the binding. Moving the Y (normally at site 652) one residue in the N- terminal (up) direction in N588K hERG markedly increased the blocking potency of R(−) disopyramide. Molecular dynamics simulations using a hERG pore model produced different binding modes for S(+) and R(−) disopyramide consistent with the experimental observations. In conclusion, S(+) disopyramide interacts more strongly with S6 aromatic binding residues on hERG than does R(−) disopyramide, whilst optimal binding of the latter is more reliant on intact inactivation. [ABSTRACT FROM AUTHOR]

[Display omitted] An original phenobarbital anticonvulsant Halonal, 5-ethyl-1-(2-fluorobenzoyl)-5-phenylpyrimidine-2,4,6(1 H ,3 H ,5 H)-trione, stimulated the cellular immune and the humoral response in long-term alcoholized male (CBAxC57Bl/6) F1 mice to the level of healthy animals. Voltammetry was found to be suitable for determination of Halonal R / S -enantiomeric ratio, which was exemplified on the authentic sample with the R / S -composition of 40:60. Molecular docking (Schrödinger program, Glide) showed that Halonal behaved as a benzonal derivative interacting with GABA A R via the BARB binding site, with S -Halonal having higher similarity score than its R -enantiomer because of a different orientation of the 2-fluorobenzoyl substituent. [ABSTRACT FROM AUTHOR]

Chiral compounds are abundantly distributed in both the natural world and biological systems. It is crucial to identify and detect chiral compounds in living systems or to separate and determine them in the natural environment. Many researchers have developed a range of chiral materials with different functionalizations to separate and detect chiral substances. Chiral metal–organic frameworks (CMOFs) have the potential to be used in enantioselective separation and detection due to their large surface areas, regulated framework topologies, particular substrate interactions, and accessible chiral sites. CMOFs contribute significantly to the development of enantiomer separation and detection in medicine, agriculture, food, environment, and other fields. This review focuses on four synthesis methods of CMOFs and their applications in chiral separation and chiral sensing in the past five years, mainly including chromatographic separation, membrane separation, optical sensing, electrochemical sensing, and other sensing methods. Finally, the challenges and potential growth direction of CMOFs in enantiomer separation and detection are discussed and prospected. [ABSTRACT FROM AUTHOR]

Tegoprazan is a novel potassium‐competitive acid blocker used for gastroesophageal reflux disease. It is administered as the (S)‐ and (R)‐enantiomers are considered impurities that should be controlled. The objective of this work was to establish a chiral analytical method for the determination of the enantiomeric impurity of tegoprazan in the drug substance by high‐performance liquid chromatography (HPLC). Enantioselective separation was performed on a Chiralpak alpha1‐acid glycoprotein (AGP) column (4.6 mm × 250 mm, 5.0 µm) at 30°C utilizing a mobile phase consisting of 5 mmol L−1 ammonium acetate buffer (pH 6.0) and 2‐propanol (93:7, v/v) at a flow rate of 0.7 mL min−1 with a detection wavelength of 220 nm. The effects of chromatographic conditions, including the type and concentration of organic modifiers, buffer pH, buffer concentration, flow rate, and column temperature, were thoroughly investigated. Under the optimized conditions, the resolution between (S)‐ and (R)‐tegoprazan was greater than 3.0. Moreover, the developed method was validated in terms of linearity, limits of detection (LOD) and quantitation (LOQ), accuracy, precision, and stability. Each enantiomer showed a good linear relationship over the concentration range of 1.0–100 µg mL−1, with the correlation coefficient of 0.9999. The LOD and LOQ were 0.1 and 0.3 µg mL−1, respectively. In addition, the recoveries ranged from 94.10% to 99.39% with a relative standard deviation (RSD) of 1.9%. Application of this proposed method to determine the enantiomeric impurity in tegoprazan drug substance proved satisfactory. The quantitative results were about 2.0%, demonstrating that enantiomeric impurity remained in the tegoprazan drug substance and should be controlled in the quality criteria. [ABSTRACT FROM AUTHOR]

Background: Despite the application of various tools for the control of vectors of Plasmodium falciparum, malaria remains the major killer disease in sub-Saharan Africa accounting for up to 90% of deaths due to the disease. Due to limitations of the useage of chemical insecticides such as resistance, negative impact on the environment and to nontarget organisms, the World Health Organization (WHO) requires that affected countries find alternative vector control tools. This study evaluated the effectiveness of (+)-usnic acid (UA) as an insecticide through oral administration to male and female Anopheles gambiae as an alternative or additional active ingredient to be used in toxic sugar bait. Methods: (+)-usnic acid was diluted using acetone at 5, 10, and 15 mg/ml concentrations in three replicates. A 5 ml mixture of 2% food dye and 10% sugar using chlorine-free water mixed with the dilutions of the (+)-usnic acid and negative control was made containing 2% food dye and 10% sugar solution. The preparations were soaked on a ball of cotton wool and placed over the net of a cup. 5 male and 5 non-blood-fed female newly hatched starved An. gambiae Kisumu strain were introduced together into a cup and monitored for knockdown and mortalities after 4, 24 48, and 72 h. The data were analysed using a multiple linear regression model using the lm function, a base R function and a posthoc test were conducted on the significant main effects and interaction terms using the emmeans function from the emmeans R package. All analyses were performed in RStudio using base R (version 4.3.3). Results: There was high mortality of both male and female An. gambiae after ingestion of the toxic sugar bait. 15 mg/ml usnic acid caused the highest mortality (50%) within the first 4 h compared to 5 and 10 mg/ml (+)-UA. There was a decline in the mortality rate with increased exposure time from 24 to 72 h, however, there was a significant difference in mortality at 5, 10 and 15 mg/ml. Acute toxicity was associated with ingestion of 15 mg/ml after 24 h. 72 h post-mortality was lower in all concentrations than in the control. High mortality was observed among females over the first 4 h (60%) compared to males (40%) due to higher feeding rate of the toxic agent. The proportion of dead males and females was equal after 24 h while after 48 h, the proportion of dead males was high.There was a significantly lower mortality rate after 72 h for both males and females (0 to 13.3%). Compared to all the treatments, high mortality of males was observed. Conclusions: The results of this study indicate that (+)-UA when administered as oral sugar bait to An. gambiae has insecticidal properties and is a suitable ingredient to be used as a toxic agent in the novel attractive toxic sugar bait for the control of malaria vectors. (+)-UA may be an alternative active ingredient as toxic bait in the effort to reduce and eliminate the transmission of Plasmodium falciparum in Africa. [ABSTRACT FROM AUTHOR]

The aim of this study was to establish a simple, fast, and sensitive method with liquid chromatography–tandem mass spectrometry (LC–MS/MS) for simultaneously determining ibuprofen enantiomers using mouse blood in very small volumes. LC–MS/MS equipped with an electrospray ionization (ESI) source was used in negative ion mode and multiple‐reaction monitoring mode. Enantiomer chromatographic separation was carried out on a Lux® 5 μm Cellulose‐3 (250 × 4.6 mm, 5 μm) column at a flow rate of 0.6 mL/min. Samples were pretreated by extracting only 5 μL of blood with 40 μL of acetonitrile (containing 1.3% formic acid) so that a concentration‐time profile could be completed using a single mouse. 2‐(4‐Propylphenyl) propanoic acid was used as an internal standard. Standard curves for each enantiomer were linear from 0.04 to 80.00 μg/mL, demonstrating a lower limit of quantitation (LLOQ) than all previously reported methods. This method was completely validated and successfully executed to investigate the pharmacokinetics of ibuprofen enantiomers after intravenous administration of racemic ibuprofen, (S)‐(+)‐ibuprofen, and (R)‐(−)‐ibuprofen in Kunming mice, respectively. The results showed that the pharmacokinetic profiles of the (R)‐(−)‐ibuprofen and (S)‐(+)‐ibuprofen were significantly different, indicating the unidirectional inversion of R‐(−)‐ibuprofen to (S)‐(+)‐ibuprofen. [ABSTRACT FROM AUTHOR]

1-(1-Chloroethyl)-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline was synthesized through the reaction of homoveratrylamine with racemic lactic acid. The formation of two enantiomers, RR and SS, was detected by performing X-ray diffraction analysis on their chloride salts. The asymmetric unit of the crystal consists of a C13H19ClNO2+ molecular cation and a Cl− anion. Two protonated enantiomers of the title compound, with RR and SS configurations of the chiral atoms, are connected into hydrogen-bonded dimers bridged by Cl− anions. Weak C—H...Cl interactions lead to the formation of a chain running along the a-axis direction of the unit cell, which corresponds to the longest dimension (the preferential growth direction) of the needle-shaped monocrystal. The crystal studied was refined as a two-component twin.

Abstract Background Despite the application of various tools for the control of vectors of Plasmodium falciparum, malaria remains the major killer disease in sub-Saharan Africa accounting for up to 90% of deaths due to the disease. Due to limitations of the useage of chemical insecticides such as resistance, negative impact on the environment and to nontarget organisms, the World Health Organization (WHO) requires that affected countries find alternative vector control tools. This study evaluated the effectiveness of ( +)-usnic acid (UA) as an insecticide through oral administration to male and female Anopheles gambiae as an alternative or additional active ingredient to be used in toxic sugar bait. Methods ( +)-usnic acid was diluted using acetone at 5, 10, and 15 mg/ml concentrations in three replicates. A 5 ml mixture of 2% food dye and 10% sugar using chlorine-free water mixed with the dilutions of the ( +)-usnic acid and negative control was made containing 2% food dye and 10% sugar solution. The preparations were soaked on a ball of cotton wool and placed over the net of a cup. 5 male and 5 non-blood-fed female newly hatched starved An. gambiae Kisumu strain were introduced together into a cup and monitored for knockdown and mortalities after 4, 24 48, and 72 h. The data were analysed using a multiple linear regression model using the lm function, a base R function and a posthoc test were conducted on the significant main effects and interaction terms using the emmeans function from the emmeans R package. All analyses were performed in RStudio using base R (version 4.3.3). Results There was high mortality of both male and female An. gambiae after ingestion of the toxic sugar bait. 15 mg/ml usnic acid caused the highest mortality (50%) within the first 4 h compared to 5 and 10 mg/ml ( +)-UA. There was a decline in the mortality rate with increased exposure time from 24 to 72 h, however, there was a significant difference in mortality at 5, 10 and 15 mg/ml. Acute toxicity was associated with ingestion of 15 mg/ml after 24 h. 72 h post-mortality was lower in all concentrations than in the control. High mortality was observed among females over the first 4 h (60%) compared to males (40%) due to higher feeding rate of the toxic agent. The proportion of dead males and females was equal after 24 h while after 48 h, the proportion of dead males was high.There was a significantly lower mortality rate after 72 h for both males and females (0 to 13.3%). Compared to all the treatments, high mortality of males was observed. Conclusions The results of this study indicate that ( +)-UA when administered as oral sugar bait to An. gambiae has insecticidal properties and is a suitable ingredient to be used as a toxic agent in the novel attractive toxic sugar bait for the control of malaria vectors. ( +)-UA may be an alternative active ingredient as toxic bait in the effort to reduce and eliminate the transmission of Plasmodium falciparum in Africa.

The significance and necessity of separating enantiomers in food, pharmaceuticals, pesticides, and other samples remains constant and unrelenting. The successful chiral separation usually includes the application of a chiral auxiliary compound, known also as a chiral selector (CS), that forms complexes with enantiomers of different physicochemical properties, enabling efficient separation. While both native and substituted cyclodextrins (CDs) are commonly used as CSs, β-CD is undoubtedly the most popular one among them. This review includes recent advancements in the application of β-CD as a CS. While the theoretical background behind the enantioseparation is also part of this work, the main emphasis is put on the factors that affect the efficacy of this process such as temperature, pH, solvent, and the choice of other additives. Also, the different analytical methods: Nuclear Magnetic Resonance (NMR) spectroscopy, Capillary Electrophoresis (CE), fluorescence spectroscopy (FS), High-Performance Liquid Chromatography (HPLC), Isothermal Titration Calorimetry (ITC), and UV–vis spectroscopy, used for enantioseparation with the aid of β-CD as CS, are thoroughly compared. Also, since some of the chiral compounds have been studied in the context of their enantioseparation more than once, those works are compared and critically analyzed. In conclusion, while β-CD can be in most cases used as CS, the choice of the experimental conditions and method of analysis is crucial to achieve the success. [ABSTRACT FROM AUTHOR]

Chiral pesticides account for about 40% of the total pesticides. In the process of using pesticides, it will inevitably flow into the surface water and even penetrate into the groundwater through surface runoff and other means, as a consequence, it affects the water environment. Although the enantiomers of chiral pesticides have the same physical and chemical properties, their distribution, ratio, metabolism, toxicity, etc. in the organism are often different, and sometimes even show completely opposite biological activities. In this article, the selective fate of different types of chiral pesticides such as organochlorine, organophosphorus, triazole, pyrethroid and other chiral pesticides in natural water bodies and sediments, acute toxicity to aquatic organisms, chronic toxicity and other aspects are summarized to further reflect the risks between the enantiomers of chiral pesticides to non-target organisms in the water environment. In this review, we hope to further explore its harm to human society through the study of the toxicity of chiral pesticide enantiomers, so as to provide data support and theoretical basis for the development and production of biochemical pesticides. [ABSTRACT FROM AUTHOR]

In order to improve and replace the enantiomer method outlined in the olodaterol hydrochloride draft monograph (From the European Pharmacopoeia forum), one new, simple, and fast enantioselective normal phase high‐performance liquid chromatography chiral method was developed on polysaccharide‐based Chiral MX (2) (4.6 × 250 mm, 5 μm) column. n‐Hexane, ethanol, and diethylamine in the ratio of 40:60:0.1 (V/V/V) were selected as mobile phase at a flow rate of 0.8 mL/min, and the detection was performed on a photodiode array detector at 225 nm with 5 μL injection volume. The column temperature was set at 40°C for better peak shape and sensitivity. The analysis time can be shortened to 15 min, whereas the resolution between enantiomer and olodaterol was found to be even more than 10.0, which was far better than that obtained with the reported method in this draft monograph. The developed chiral method was validated in accordance with ICH Q2 (R1), including specificity, LOD&LOQ, precision, linearity, accuracy, and robustness. Thereby, the proposed method was demonstrated to be suitable for the determination of enantiomer in olodaterol hydrochloride bulk drug and drug product. Besides, the thermodynamic parameters were evaluated on the basis of Van't Hoff plots that was used to explain correlative chiral recognition mechanisms with the chiral stationary phase. [ABSTRACT FROM AUTHOR]

2-Keto-3-deoxy-galactonate (KDGal) serves as a pivotal metabolic intermediate within both the fungal d-galacturonate pathway, which is integral to pectin catabolism, and the bacterial DeLey-Doudoroff pathway for d-galactose catabolism. The presence of KDGal enantiomers, l-KDGal and d-KDGal, varies across these pathways. Fungal pathways generate l-KDGal through the reduction and dehydration of d-galacturonate, whereas bacterial pathways produce d-KDGal through the oxidation and dehydration of d-galactose. Two distinct catabolic routes further metabolize KDGal: a nonphosphorolytic pathway that employs aldolase and a phosphorolytic pathway involving kinase and aldolase. Recent findings have revealed that l-KDGal, identified in the bacterial catabolism of 3,6-anhydro-l-galactose, a major component of red seaweeds, is also catabolized by Escherichia coli, which is traditionally known to be catabolized by specific fungal species, such as Trichoderma reesei. Furthermore, the potential industrial applications of KDGal and its derivatives, such as pyruvate and d- and l-glyceraldehyde, are underscored by their significant biological functions. This review comprehensively outlines the catabolism of l-KDGal and d-KDGal across different biological systems, highlights stereospecific methods for discriminating between enantiomers, and explores industrial application prospects for producing KDGal enantiomers. Key points: • KDGal is a metabolic intermediate in fungal and bacterial pathways • Stereospecific enzymes can be used to identify the enantiomeric nature of KDGal • KDGal can be used to induce pectin catabolism or produce functional materials [ABSTRACT FROM AUTHOR]

Chiral pollutants often pose significant differential environmental health risks. In this study, the biotransformation of chiral dinotefuran (DIN) and its enantioselective metabolic toxicity mechanisms have been systemically investigated. Firstly, reversed-phase chromatography-high resolution mass spectrometry was developed to quantify the content of DIN R/S chiral enantiomer with pg level sensitivity, revealing a lower elimination rate constant (Ke) of S-DIN (0.730 h−1) than R-DIN (0.746 h−1). Secondly, the interaction mechanism between DIN metabolism and important endogenous bioactive molecules, such as aldehyde oxidase (AOX) and neurotransmitters, was revealed. The DIN nitro-group was converted into a guanidine group by the reducing site of nearby flavin adenine dinucleotide (FAD) in AOX with the preferred higher affinity of S-configuration. Meanwhile, the endogenous tryptophan (Trp) aldehyde metabolic intermediate, 5-hydroxyindoleacetaldehyde (5-HIAL), provides a persistent electron donor for DIN reduction via the oxidation-catalyzed site in AOX, resulting in remarkable up-regulation of monoamine neurotransmitters such as serotonin and dopamine. Thirdly, the higher level of neurotransmitters further mediated dysregulation of oxylipin homeostasis via the serotonergic pathway, where S-DIN exhibited more pronounced liver lipid damage and environmental health risk with the accumulated lipid biomarkers, oxidized triglyceride (OxTG) and oxidized sphingomyelin (OxSM). This study elucidates the AOX-mediated enantioselectivity metabolic pathway of DIN, providing a new analytical method for chiral pollutants and paves the way for their health risk assessments. [ABSTRACT FROM AUTHOR]

The tobacco-specific nitrosamines N ʹ-nitrosonornicotine (NNN) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) are considered 'carcinogenic to humans' by the International Agency for Research on Cancer (IARC) and are believed to be important in the carcinogenic effects of both smokeless tobacco and combusted tobacco products. This short review focuses on the results of recent studies on the formation of NNN and NNK in tobacco, and their carcinogenicity and toxicity in laboratory animals. New mechanistic insights are presented regarding the role of dissimilatory nitrate reductases in certain microorganisms involved in the conversion of nitrate to nitrite that leads to the formation of NNN and NNK during curing and processing of tobacco. Carcinogenicity studies of the enantiomers of the major NNK metabolite 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) and the enantiomers of NNN are reviewed. Recent toxicity studies of inhaled NNK and co-administration studies of NNK with formaldehyde, acetaldehyde, acrolein and CO2, all of which occur in high concentrations in cigarette smoke, are discussed. [ABSTRACT FROM AUTHOR]

Chiral pesticides have one or more enantiomers, and their biological activity, toxicity, environmental behavior, degradation and metabolism may be different. Tea, as one of the three major beverages, has attracted much attention in terms of quality and safety. However, more attention is currently paid to the total amount of pesticide racemate residues. With the development of analytical techniques, it is particularly crucial to fully understand the stereoselective behavior of the chiral pesticide enantiomer in tea, as well as to examine residue degradation in tea and to set the maximum residue limits for enantiomers. This would help to improve the efficacies of chiral pesticides and reduce their residues and toxicities to non-target organisms. In this paper, the current status of chiral pesticide separation and residue detection technology in tea were reviewed, such as liquid chromatography, gas chromatography and supercritical fluid chromatography. In addition, it provided a summary of the residue degradation behaviors and risk assessment of chiral pesticide enantiomers in tea, which would be useful as a guide for further in-depth studies on chiral pesticide enantiomers in tea. [ABSTRACT FROM AUTHOR]

A pair of new quinolone alkaloid enantiomers, (Ra)-(-)-viridicatol (1) and (Sa)-(+)-viridicatol (4), and seven known compounds, namely, 2, 3 and 5–9, were isolated from Penicillium christenseniae SD.84. The structures of 1 and 4 were determined using NMR and HRESIMS data. Theoretical calculations through CD and ECD confirmed 1 and 4 as a pair of enantiomers. The MIC values of 4 against Staphylococcus aureus and methicillin-resistant S. aureus were 12.4 and 24.7 μM, respectively, compound 1 had no inhibitory activity. Antimicrobial assays of 2, 3, and 5–7 showed a moderate activity against S. aureus and methicillin-resistant S. aureus. This study demonstrated the remarkable potential of Penicillium sp. to produce new drug-resistant leading compounds, thereby advancing the mining for new sources of antimicrobial agents. [ABSTRACT FROM AUTHOR]

AbstractTwo pairs of cyclohexene amide alkaloid enantiomers were obtained from the root of Piper nigrum. Their plane structures were established by NMR and HRESIMS spectra. The absolute configurations of 1a/1b and 2a/2b were determined by the comparison between the experimental and calculated electronic circular dichroism (ECD) spectra. All identified compounds were tested for inhibitory effects on acetylcholinesterase (AChE) in vitro. Notably, compounds 1b and 2b showed strong inhibitory effects on AChE and the interaction between proteins and compounds was discussed by molecular docking studies. [ABSTRACT FROM AUTHOR]

Optical Activity, Or Chirality, Is an Important Characteristic of Many Chemical Compounds. Various Industries Use Organic Compounds with Stereo Genic Centers, Which Can Affect Their Properties. Investigating The Attributes of Each Drug Enantiomer Is Crucial, As Only One Typically Exhibits Activity. Enantioselective Chromatography Plays a Valuable Role in Producing Pure Compounds and Developing Chiral Drugs. Advancements In Chiral Methods Within the Pharmaceutical Industry, Traditionally Reliant on Liquid Chromatography, Should Be Assessed. [ABSTRACT FROM AUTHOR]

The pinyon pines, Pinus edulis (two-needle pinyon pine) and Pinus monophylla (single-leaf pinyon pine) are conspicuous trees in the pinyon-juniper woodlands of the Great Basin. The purpose of this study is to examine the volatile phytochemicals in the leaf essential oils of P. edulis and P. monophylla, including enantiomeric distribution of the chiral monoterpenoids. Leaves (needles) of P. edulis and P. monophylla were collected in Utah and the essential oils were obtained by hydrodistillation. Gas chromatographic analysis revealed the major components to be α-pinene (13.1-36.5% and 27.8-29.0%, respectively), β-pinene (6.2-34.8% and 11.2-23.4%), β-phellandrene (9.5-20.2% and 11.9-14.7%), and α-terpineol (3.8-6.8% and 6.2-9.2%). Enantioselective gas chromatography showed (–)-β-pinene (> 95%), (–)-β-phellandrene (> 98%), and (–)-α-terpineol (53.6-93.0%) to be the dominant enantiomers while α-pinene showed some variability (39.5-88.9% (+)-α-pinene). The enantiomeric distributions of chiral terpenoids are presented for these essential oils for the first time and adds to our understanding of Pinus essential oils. However, additional research is needed to investigate the enantiomeric distributions of chiral terpenoids of Pinus essential oils more fully. [ABSTRACT FROM AUTHOR]

Three pairs of enantiomers (1–3)—the new 12R-aloesol (1a) and two new fatty acids (2 and 3)—and one new natural product (4) together three known compounds (5–7) were isolated from a coral-reef-derived Streptomyces sp. SCSIO 66814. Their structures were determined through extensive spectroscopic analysis, chiral analysis, and single-crystal X-ray diffraction data. Compounds 2 and 3 were presumed to be intermediates for further generating homononactic acid (5) and nonactic acid, and the latter two molecules were able to act as precursors to form macrotetrolides with remarkable biological activity. The isolation of related precursors, compounds 2–5, provided more evidence to support the proposal of a plausible biosynthetic pathway for nonactic acid and its homologs. Additionally, (+)-1 exhibited a weak activity against DPPH radicals. [ABSTRACT FROM AUTHOR]

Tofacitinib citrate (RR-isomer) is a janus kinase (JAK) inhibitor approved for the treatment of rheumatoid arthritis (RA) in adults who have had an inadequate response or intolerance to methotrexate. The presence of the enantiomer of tofacitinib citrate (SS-isomer) is monitored for quality control as a possible impurity in the final product. In this study, a reversed-phase high-performance liquid chromatography (RP-HPLC) method based on a chiral recognition mechanism for the separation of tofacitinib citrate and its enantiomer was established based on the principles of green analytical chemistry. A CHIRALPAK IH column was used with a mobile phase of ammonium acetate buffer (pH 8.0) and acetonitrile in a gradient elution at a detection wavelength of 285 nm. The calibration curve exhibited excellent linearity over the range of 0.1002–20.04 μg/mL (r = 0.9999). The average recovery of the enantiomer was 98.6% with a relative standard deviation (RSD) of 0.7%. The limit of detection (LOD) and the limit of quantitation (LOQ) were 0.04 and 0.1 μg/mL, respectively. This RP-HPLC method was suitable for detecting the enantiomers of tofacitinib citrate in tablets. Furthermore, the method proved to be environmentally friendly based on the evaluation by Analytical Eco-Scale, Analytical GREEnness (AGREE) and Green Analytical Procedure Index (GAPI). [ABSTRACT FROM AUTHOR]

We herein present for the first time the phosphylated (*) tetrapeptide (TP)-adduct GlyGluSer198*Ala generated from butyrylcholinesterase (BChE) with proteinase K excellently suited for the verification of exposure to toxic organophosphorus nerve agents (OPNA). Verification requires bioanalytical methods mandatory for toxicological and legal reasons. OPNA react with BChE by phosphonylation of the active site serine residue (Ser198) forming one of the major target protein adducts for verification. After its enzymatic cleavage with pepsin, the nonapeptide (NP) PheGlyGluSer*AlaGlyAlaAlaSer is typically produced as biomarker. Usually OPNA occur as racemic mixtures of phosphonic acid derivatives with the stereocenter at the phosphorus atom, e.g. (±)-VX. Both enantiomers react with BChE, but the adducted NP does not allow their chromatographic distinction. In contrast, the herein introduced TP-adducts appeared as two peaks when using a stationary reversed phase (1.8 µm) in micro-liquid chromatography–electrospray ionisation tandem-mass spectrometry (µLC–ESI MS/MS) analysis. These two peaks represent diastereomers of the (+)- and (−)-OPNA adducted to the peptide that comprises chiral L-amino acids exclusively. Concentration- and time-dependent effects of adduct formation with (±)-VX and its pure enantiomers (+)- and (−)-VX as well as with (±)-cyclosarin (GF) were investigated in detail characterising enantioselective adduct formation, stability, ageing and spontaneous reactivation. The method was also successfully applied to samples from a real case of pesticide poisoning as well as to samples of biomedical proficiency tests provided by the Organisation for the Prohibition of Chemical Weapons. [ABSTRACT FROM AUTHOR]

Chiral pesticides have the special chiral structures, so enantioselective biological effects are usually observed in living organisms. Current study used paclobutrazol as a case study and explored the enantioselective degradation and oxidative stress effect on wheat. The results demonstrated that the degradation of R‐paclobutrazol was faster than S‐paclobutrazol significantly and improved the content of MDA and O2− in wheat plants, which proved that the R‐paclobutrazol induced oxidative damage in wheat, showing selective biological effects, and S‐paclobutrazol was friendly to wheat. This study provided a theoretical basis for the selective activity of chiral pesticides and the development of chiral pesticide monomers. [ABSTRACT FROM AUTHOR]

Enantiomerically enriched phosphorus‐containing α‐amino acids were synthesized by the method of asymmetric synthesis, using Ni(II) square planar complex of dehydroalanine as an initial complex. After acidic hydrolysis, α‐amino acids with high enantiomeric purity were isolated. At the next stage, Fmoc derivatives of the obtained α‐amino acids were synthesized (ee >99 %). Synthesized α‐amino acids and their Fmoc derivatives exhibited anticholinesterase activity, inhibiting AChE and BuChE. At the same time, the antiacetylcholinesterase activity ranged from 14 to 77 %, and (S)‐2‐((((9H‐fluoren‐9‐yl)methoxy)carbonyl)amino)‐3‐(diisopropoxyphosphoryl) propanoic acid showed relatively high activity (77.9 %). In the case of studying the antibutyrylcholinesterase properties, the activity ranged from 4 to 71 %, and (S)‐2‐amino‐3‐(diisopropoxyphosphoryl)propanoic acid showed high activity (71 %). [ABSTRACT FROM AUTHOR]

The chiral media is crucial to the chiral recognition and separation of enantiomers. In this study, we report the preparation of novel chiral carbon nanoparticles (CCNPs) via surface passivation using glucose as the carbon source and S‐(−)‐α‐methylbenzylamine as the chiral ligand. The structures of the obtained CCNPs are characterized via FT‐IR, Raman spectroscopy, DLS, XPS, XRD, TEM, and zeta potential analysis. These CCNPs could be employed as the chiral adsorbent and used for the enantioselective adsorption of the ibuprofen enantiomers. The results demonstrated that the CCNPs could selectively adsorb R‐enantiomer from ibuprofen racemate solution and give an enantiomeric excess (e.e.) of about 50% under an optimal adsorption condition. Moreover, the regeneration efficiency of the CCNPs remained above e.e. of 43% after the fifth cycle. The present work confirmed that the prepared CCNPs show great potential in the enantioselective separation of ibuprofen racemate. [ABSTRACT FROM AUTHOR]

Four new 2-pyrone derivatives, two pairs of enantiomers, (±)-egypyrone A [(±)-1] and (±)-egypyrone B [(±)-2], together with a new benzophenone analogue, orbiophenone B (3), were isolated from the endophytic fungus Penicillium egyptiacum. The enantiomeric mixtures (±)-1 and (±)-2 were separated through chiral HPLC, respectively. Their structures were elucidated by extensive analysis of spectroscopic data and the absolute configuration was determined by comparing the optical rotation of structurally similar molecule. Subsequently, the cytotoxic activities of (±)-1, (±)-2, and 3 against the U87 cell line were tested and no activity was observed at a concentration of 10 µM. [ABSTRACT FROM AUTHOR]

Three pairs of enantiomers (1–3)—the new 12R-aloesol (1a) and two new fatty acids (2 and 3)—and one new natural product (4) together three known compounds (5–7) were isolated from a coral-reef-derived Streptomyces sp. SCSIO 66814. Their structures were determined through extensive spectroscopic analysis, chiral analysis, and single-crystal X-ray diffraction data. Compounds 2 and 3 were presumed to be intermediates for further generating homononactic acid (5) and nonactic acid, and the latter two molecules were able to act as precursors to form macrotetrolides with remarkable biological activity. The isolation of related precursors, compounds 2–5, provided more evidence to support the proposal of a plausible biosynthetic pathway for nonactic acid and its homologs. Additionally, (+)-1 exhibited a weak activity against DPPH radicals.

Tofacitinib citrate (RR-isomer) is a janus kinase (JAK) inhibitor approved for the treatment of rheumatoid arthritis (RA) in adults who have had an inadequate response or intolerance to methotrexate. The presence of the enantiomer of tofacitinib citrate (SS-isomer) is monitored for quality control as a possible impurity in the final product. In this study, a reversed-phase high-performance liquid chromatography (RP-HPLC) method based on a chiral recognition mechanism for the separation of tofacitinib citrate and its enantiomer was established based on the principles of green analytical chemistry. A CHIRALPAK IH column was used with a mobile phase of ammonium acetate buffer (pH 8.0) and acetonitrile in a gradient elution at a detection wavelength of 285 nm. The calibration curve exhibited excellent linearity over the range of 0.1002–20.04 μg/mL (r = 0.9999). The average recovery of the enantiomer was 98.6% with a relative standard deviation (RSD) of 0.7%. The limit of detection (LOD) and the limit of quantitation (LOQ) were 0.04 and 0.1 μg/mL, respectively. This RP-HPLC method was suitable for detecting the enantiomers of tofacitinib citrate in tablets. Furthermore, the method proved to be environmentally friendly based on the evaluation by Analytical Eco-Scale, Analytical GREEnness (AGREE) and Green Analytical Procedure Index (GAPI).

In recent years, incidents of pesticide pollution and abuse of feed additives have occurred frequently, which pose a great threat to human health. Raman spectroscopy has become an important method in the field of food safety due to its rapidity, simplicity and sensitivity. It is important to obtain complex structure to promote surface-enhanced Raman scattering (SERS) effect. In this study, gold helical nanoparticles with rich surface structure were synthesized using cysteine as induce agent. Notably, the complex helical structure and tip led to an excellent electromagnetic enhancement property. The helical structure showed ultra-sensitive detection of hazardous molecular, such as thiram and ractopamine. Interestingly, the D/L-Au structure had significant chiral optical activity and could be used as an unlabeled SERS platform for enantiomer identification. This study provided an effective strategy for the detection of pesticides and feed additives, which could be applied in other aspects of food safety in the future. [Display omitted] • A convenient strategy for preparing Raman substrates was provided. • The gold helix was an excellent Raman substrate. • It could analyze harmful chemical residues in food. • It could recognize amino acid enantiomers and expanded the application range of SERS. [ABSTRACT FROM AUTHOR]

• Chiral materials applied in biosensor applications are reviewed and classified. • The recognition and separation techniques are summarized and discussed. • Various applications of chiral structures are reviewed and discussed. • Different chiral-based biosensor design and synthesis strategies are summarized. • Electrochemically-active chiral molecule biosensors are reviewed. Chirality is a phenomenon commonly observed in biomolecules, which supports various applications such as biosensing, bioimaging, and disease treatments. Chiral molecules and ions are building blocks of advanced materials and technologies enabling intermolecular communication between species competing in receiving, sending, or recognizing chemical scenarios. Therefore, chiral molecules nowadays are at the core of attention in developing sensing materials and devices. A sub-class of stereoisomers known as enantiomers or optical antipodes takes the privilege of chiral structures, supporting distinct optical and electrochemical responses required in sensing and identification applications. Therefore, it is critical to establish a reliable and fast method for chiral identification and separation. Big technological advances have been made in the field of bio-inspired and controlled self-assembly sensing, but there is still a great demand for improving the sensitivity and accuracy of chiral-based biosensors. This review seeks to collect, summarize, classify and discuss the latest advances in chiral-based optical biosensors. Starting from the identification of chiral molecules, photoluminescence, and electrochemical sensors, applications of chiral structures in biosensing molecules are reviewed. Then, biosensors working on the basis of chirality are classified, followed by summarizing the outcomes of research works on design, synthesis, and mechanisms of performances of chiral-based optical biosensors. Electrochemically active molecules are subsequently reviewed, emphasizing molecularly imprinted polymers (MIP), doped electrodeposited conducting polymers, enzymatic chiral sensors, and metal–organic framework (MOF) based chiral molecules applied in biosensing applications. [ABSTRACT FROM AUTHOR]

• Validated assay for arachidonic acid (AA)-underived chiral epoxy-metabolites. • A reliable and reproducible chiral analysis for epoxy-metabolites of AA. • Enantioselective analysis of epoxy-metabolites formed by human liver microsomes. • The assay showed acceptable linearity, precision, and accuracy. Epoxyeicosatrienoic acids (EETs) are increasingly recognized as key metabolites in the arachidonic acid (AA) metabolic pathway. EETs are epoxy derivatives of AA with two chiral centers formed by cytochrome P450 (CYP) enzymes. EETs have reported biological activities as racemates; however, knowledge on specific optical isomers of EET is lacking. A main reason is the absence of practical assay to quantify EETs isomers associated with specific pathological conditions and enzymes. The reported underivatized chiral LC-MS/MS assays utilize different mobile phases and flow rates or required long run times to achieve separation of EET stereoisomers. Others incorporated a derivatization step before the separation of EETs in their assays. Therefore, the objective of this study was to develop and validate a stereoselective assay for the simultaneous quantitation of underivatized EET enantiomers using Liquid Chromatography Mass Spectrometry (LC-MS/MS) with an optimum baseline separation using binary mobile phase and gradient elution. Herein, we report the development and validation of an LC-MS/MS assay, and its application to quantify the formation of EET enantiomers mediated by human liver microsomes. Assay linearity extends over 10–600 ng/mL with r2 > 0.99 for all EETs enantiomers. The inter-run accuracy was within ± 15 %, and precision was ≤ 15 %, and < 20 % for the LLOQ. The matrix effect for the current assay was within ≤ ±20 %, and the mean recovery for quantitative methods was 70–125 %. The assay proved to be reliable and practical for chiral analysis. [ABSTRACT FROM AUTHOR]

In our effort to establish a direct synthetic approach for bis(dihydridoborate) complexes of first-row transition metals, we have investigated the reactivity of [Cp*Fe(dppe)Cl] (dppe = 1,2-bis(diphenylphosphino)ethane) with Na[BH3L] (L = 2-mercaptopyridine (mp) and 2-mercaptobenzothiazole (mbz)) that led to the formation of iron(II) dihydridoborate complexes, [Cp*Fe{κ3-S,H,H-(H2BH(L))}] 1a-b (L = mp (1a) and L = mbz (1b)). Further, in an attempt to isolate the bis(dihydridoborate) complex of iron by the insertion of borane into the κ2-N,S-chelated iron complex, [(dppe)Fe{κ2-N,S-(mp)}2] (2), we have isolated and structurally characterized a rare example of dimeric iron bis(dihydridoborate) complex, [Fe{κ3-S,H,H-(H2BH(mp))}2]2, ΛΔ/ΔΛ-3 as pair of enantiomers. Interestingly, these enantiomers ΛΔ/ΔΛ-3 have two trans-[Fe{κ3-S,H,H-(H2BH(mp))}2] moieties bridged through sulfur atoms of 2-mercaptopyridinyl ligands, where the iron centres are hepta-coordinated. The natural bond-orbital (NBO) analyses of ΛΔ-3 and ΔΛ-3 show considerable electron donation from the filled σB-H bonding orbital to vacant dz2 orbital of iron with a substantial contribution from the hydrogen atoms. The localized orbital bonding analyses (LOBA) method suggests that all the iron centres are in +2 oxidation state., (© 2024 Wiley‐VCH GmbH.)

Understanding the function of a biomolecule hinges on its 3D conformation or secondary structure. Chirally sensitive, optically active techniques based on the differential absorption of UV-vis circularly polarized light excel at rapid characterisation of secondary structures. However, Raman spectroscopy, a powerful method for determining the structure of simple molecules, has limited capacity for structural analysis of biomolecules because of intrinsically weak optical activity, necessitating millimolar (mM) sample quantities. A breakthrough is presented for utilising Raman spectroscopy in ultrasensitive biomolecular conformation detection, surpassing conventional Raman optical activity by 15 orders of magnitude. This strategy combines chiral plasmonic metasurfaces with achiral molecular Raman reporters and enables the detection of different conformations (α-helix and random coil) of a model peptide (poly-L/D-lysine) at the ≤attomole level (monolayer). This exceptional sensitivity stems from the ability to detect local, molecular-scale changes in the electromagnetic (EM) environment of a chiral nanocavity induced by the presence of biomolecules using molecular Raman reporters. Further signal enhancement is achieved by incorporating achiral Au nanoparticles. The introduction of the nanoparticles creates highly localized regions of extreme optical chirality. This approach, which exploits Raman, a generic phenomenon, paves the way for next-generation technologies for the ultrasensitive detection of diverse biomolecular structures., (© 2024 The Author(s). Small published by Wiley‐VCH GmbH.)

Two new carbazole alkaloids clauemarazole H ( 1 ) and clauemarazole I ( 2 ) were isolated from the stems of Clausena emarginata C. C. Huang. Their structures were confirmed by comprehensive spectroscopic analyses, and the absolute configurations were determined based on ECD experiments. The two compounds were evaluated for their neuroprotective effects against rotenone-induced damage in PC12 cells but did not exhibit any significant activity.

• This review focuses on terpenoids extracted from essential oils. • Terpenoids have enantiomers with distinct physiological activities. • Predominant extraction methods are HD, SFME, HS-SPME and supercritical fluid. • 2D GC is found to have stronger chiral chromatography resolution ability. • Specific distribution and enantiomer excess results could be used as quality markers. Terpenoids possess significant physiological activities and are rich in essential oils. Some terpenoids have chiral centers and could form enantiomers with distinct physiological activities. Therefore, the extraction and separation of terpenoids enantiomers are very important and have attracted extensive attention in recent years. Meanwhile, the specific distribution and enantiomer excess results (the excess of one enantiomer over the other in a mixture of enantiomers) could be used as quality markers for illegitimate adulteration, origin identification, and exploring component variations and functional interrelations across different plant tissues. In this study, an overview of the progress in the extraction of terpenoids from essential oils and the separation of their enantiomers over the past two decades has been made. Extraction methods were retrieved by the resultant network visualization findings. The results showed that the predominant methods are hydrodistillation, solvent-free microwave extraction, headspace solid-phase microextraction and supercritical fluid extraction methods. GC–MS combined with chiral chromatography columns is commonly used for the separation of enantiomers, while 2D GC is found to have stronger resolution ability. Finally, some prospects for future research directions in the extraction and separation identification of essential oils are proposed. [ABSTRACT FROM AUTHOR]

With exercise, muscle and bone produce factors with beneficial effects on brain, fat, and other organs. Exercise in mice increased fibroblast growth factor 23 (FGF23), urine phosphate, and the muscle metabolite L-β-aminoisobutyric acid (L-BAIBA), suggesting that L-BAIBA may play a role in phosphate metabolism. Here, we show that L-BAIBA increases in serum with exercise and elevates Fgf23 in osteocytes. The D enantiomer, described to be elevated with exercise in humans, can also induce Fgf23 but through a delayed, indirect process via sclerostin. The two enantiomers both signal through the same receptor, Mas-related G-protein-coupled receptor type D, but activate distinct signaling pathways; L-BAIBA increases Fgf23 through Gαs/cAMP/PKA/CBP/β-catenin and Gαq/PKC/CREB, whereas D-BAIBA increases Fgf23 indirectly through sclerostin via Gαi/NF-κB. In vivo , both enantiomers increased Fgf23 in bone in parallel with elevated urinary phosphate excretion. Thus, exercise-induced increases in BAIBA and FGF23 work together to maintain phosphate homeostasis. [Display omitted] • Exercise-induced L-BAIBA correlates with intact FGF23 and urine phosphate in mice • Both L- and D-BAIBA induce Fgf23 in osteocytes in vitro and ex vivo • Both BAIBA enantiomers use the same receptor but activate distinct pathways • Both BAIBA enantiomers increase Fgf23 in bone and urine phosphate in mice Kitase, Bonewald et al. demonstrate that the exercise metabolite BAIBA induces Fgf23 expression in osteocytes through the same receptor but through distinct, enantiomer-specific signaling pathways and molecular mechanisms. [ABSTRACT FROM AUTHOR]

Seven pairs of undescribed monoterpenoid polyprenylated acylphloroglucinol enantiomers [(±)-hypermonanones A-G (1 – 7)], together with three known analogues, were identified from the whole plant of Hypericum monanthemum Hook. The structures of these compounds were determined by analyses of their UV, HRESIMS, 1D/2D NMR spectroscopic data, and NMR calculations. The absolute configurations of these compounds were assigned by ECD calculations after chiral HPLC separation. Diverse monoterpene moieties were fused at C-3/C-4 of the dearomatized acylphloroglucinol core, which led to 3,4-dihydro-2 H -pyran-integrated angular or linear type 6/6/6 tricyclic skeletons in 1 – 7. Compounds (−)- 2 and (+)- 2 exhibited significant NO inhibitory activity against LPS induced RAW264.7 cells with the IC 50 values of 7.07 ± 1.02 μM and 11.39 ± 0.24 μM, respectively. [Display omitted] [ABSTRACT FROM AUTHOR]

The present study investigates the use of dextrins (maltodextrin, β-cyclodextrin, and hydroxypropyl-β-cyclodextrin) to improve the efficiency of the agarose-based gel electromembrane extraction technique for extracting chiral basic drugs (citalopram, hydroxyzine, and cetirizine). Additionally, it examines the enantioselectivity of the extraction process for these drugs. To achieve these, dextrins were incorporated into either the sample solution, the membrane, or the acceptor solution, and then the extraction procedure was performed. Enantiomers were separated and analyzed using a capillary electrophoresis device equipped with a UV detector. The results obtained under the optimal extraction conditions (sample solution pH: 4.0, acceptor solution pH: 2.0, gel membrane pH: 3.0, agarose concentration: 3 % w/v, stirring rate: 1000 rpm, gel thickness: 4.4 mm, extraction voltage: 62.3 V, and extraction time: 32.1 min) indicated that incorporating dextrins into either the sample solution, membrane or the acceptor solution enhances extraction efficiency by 17.3–23.1 %. The most significant increase was observed when hydroxypropyl-β-cyclodextrin was added to the acceptor solution. The findings indicated that the inclusion of hydroxypropyl-β-cyclodextrin in the sample solution resulted in an enantioselective extraction, yielding an enantiomeric excess of 6.42–7.14 %. The proposed method showed a linear range of 5.0–2000 ng/mL for enantiomers of model drugs. The limit of detection and limit of quantification for all enantiomers were found to be < 4.5 ng/mL and <15.0 ng/mL, respectively. Intra- and inter-day RSDs (n = 4) were less than 10.8 %, and the relative errors were less than 3.2 % for all the enantiomers. Finally, the developed method was successfully applied to determine concentrations of enantiomers in a urine sample with relative recoveries of 96.8–99.2 %, indicating good reliability of the developed method. [Display omitted] • Dextrin-assisted gel electromembrane extraction was developed. • The effect of dextrins on enantioselective extraction was investigated. • Addition of maltodextrin to the sample solution increased the extraction efficiency. • Including HP-β-CD in the acceptor solution resulted in increased extraction efficiency. • Addition of HP-β-CD to the sample solution led to an enantioselective extraction. [ABSTRACT FROM AUTHOR]

Under normal experimental conditions in an achiral environment, NMR spectra of enantiomers have chemical shifts and J couplings which are not differentiable. In this work, the reproducibility of spectral intensities for pairs of amino acid enantiomers, as well as factors influencing these intensities, is assessed using 13C and 15N cross-polarization magic-angle spinning (CP/MAS) NMR spectroscopy. Prompted by a recent literature debate over a possible influence of the chirality-induced spin selectivity (CISS) effect on spectral intensities obtained in CP/MAS NMR experiments carried out on enantiomers, a number of control experiments were performed with recycle delays of at least 5 T 1. These included the analysis of proton-decoupled Bloch decay solid-state NMR spectra as well as solution NMR spectra where the cross polarization process is absent. Bloch decay and CP/MAS NMR spectra yield the same relative intensities for pairs of enantiomers while solution NMR spectra provide relative intensities closest to unity. Differences of plus-or-minus a few percent in the D/L spectral intensity ratios observed in all solid-state NMR experiments are due to sample preparation (i.e., grinding, particle size, partial amorphization) and limitations on sample purity. As previously described in the literature, more drastic intensity differences on the order of 50% are easily created by ball milling the samples. Finally, apodization is shown to invert the apparent D/L ratio in low signal-to-noise 15N CP/MAS NMR spectra of aspartic acid enantiomers. In summary, no spectral intensity differences attributable to enantiomerism are identified. [Display omitted] • Factors influencing reproducibility in solid-state NMR spectra are explored. • Intensities may differ by a few percent depending on crystallinity, purity, sample preparation. • Enantiomers provide identical NMR spectra within limits of reproducibility. • No evidence that chirality results in measurable differences in NMR spectra. [ABSTRACT FROM AUTHOR]

• A chiral ATPS was constructed using 4-arm PEG-DHAA as a phase-forming polymer and chiral selector. • Propranolol enantiomers were separated through liquid–liquid enantioselective extraction via the chiral ATPS. • The chiral ATPS can be reused, with potency in enantiomeric recognition and liquid–liquid enantioselective extraction. In this work, we successfully synthesized a chiral dehydroabietic acid-terminated tetra-arm PEG (4-arm PEG-DHAA) and utilized it to construct a chiral aqueous two-phase system (ATPS) alongside PEG2000 and (NH 4) 2 SO 4. The 4-arm PEG-DHAA served as both an assisted phase-forming polymer and a chiral selector. This ATPS can be employed for chiral recognition and liquid–liquid enantioselective extraction of the propranolol enantiomers. The effects of four primary factors, namely initial r ac-propranolol concentration, extraction temperature, system pH, and the concentration of 4-arm PEG-DHAA on enantioseparation, were thoroughly evaluated. Furthermore, the optimization of extraction conditions was conducted using the response surface methodology. The results indicated that the chiral ATPS has better and higher enantioselectivity, with a one-step chiral extraction achieving an e.e. up to 57% and a yield exceeding 73% for S-isomers under the optimized conditions. In addition, the chiral ATPS can be regenerated through simple back-extraction with diethyl ether and reused at least five times, achieving similar enantioselective extraction results. This research presents a valuable enantioseparation approach for propranolol enantiomers via liquid–liquid enantioselective extraction using the chiral ATPS. [ABSTRACT FROM AUTHOR]

Phenylalanine is an aromatic essential amino acid that exhibits the tendency to self-aggregate into fibrillar structures in its enantiomerically pure form. This observation was indicated as the underlying mechanism of phenylketonuria, which is a genetic condition associated with various neurological, physical, and developmental issues, characterized with phenylalanine buildup in the brain. The presence of D-phenylalanine was demonstrated previously to inhibit the formation of fibrils by L-phenlyalanine, indicating its potential use in phenylketonuria treatment. In this study, several combinations of D and L-phenylalanine were examined with the help of state-of-the-art deep learning methods for their fibril forming capacity, demonstrating the usefulness and accuracy of deep learning methods in distinguishing between different self-assembled structures. • This study addressed the classification of D- and L-phenylalanine images. • A total of 525 images for 7 different mixing ratios were collected with a Nikon ECLIPSE LV150N microscope at 500x. • An accuracy value of 99% was obtained by using deep learning models for classification. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel ELLME was established based on the principle of emulsification dilution. • ELLME is a non-toxic alternative to DLLME. • O/W emulsion prepared by pipette was added to samples to complete extraction in 1 s. • Rapid separation of extractant was achieved without using a centrifuge. • Chiral prothioconazole and its chiral metabolite were detected in food samples. Emulsive liquid–liquid microextraction (ELLME), a simple, rapid, and environmentally friendly technique, was established to identify chiral prothioconazole and its chiral metabolite in water, juice, tea, and vinegar using ultra-high-performance liquid chromatography (UPLC). Environmentally friendly extractant was mixed with pure water to prepare a high-concentration emulsion, which was added to samples to complete the emulsification and extraction in 1 s. Afterward, an electrolyte solution was added to complete the demulsification without centrifugation. ELLME did not use dispersants compared to the familiar dispersive liquid–liquid microextraction (DLLME), thus reducing the use of toxic solvents and avoiding the effect of dispersants on the partition coefficient. The linear range was from 0.01 to 1 mg/L. The limit of detection was 0.003 mg/L. The extraction recoveries ranged from 82.4 % to 101.6 %, with relative standard deviations of 0.7–5.2 %. The ELLME method developed has the potential to serve as an alternative to DLLME. [ABSTRACT FROM AUTHOR]

[Display omitted] • Innovative synthesis approach for the creation of molecularly imprinted GO/Fe 3 O 4 composites. • The synthesized MIP-GO/Fe 3 O 4 for advanced chiral amino acids separation. • The developed material demonstrates high selectivity with enantiomeric excess (%ee) of 97.86% • The materialshas a good stability and reusability. Enantiomeric compounds have been reported to exhibit different biological and pharmacological activities. MIP-GO/Fe 3 O 4 has been synthesized with L-glutamic acid (L-Glu) as template molecules and developed to separate amino acids enantiomeric compounds (AAs) especially for DL-glutamic acid (DL-Glu). The MIP-GO/Fe 3 O 4 adsorbent material was synthesized in several stages, namely electrochemically synthesizing GO, co-precipitation for GO/Fe 3 O 4 , and surface imprinting polymerization to obtain MIP-GO/Fe 3 O 4. The characterization results of MIP-GO/Fe 3 O 4 show that the composite system has been successfully created with saturation magnetization (Ms) values of 49.37 emu/g. Adsorption tests are carried out on the racemic mixture of DL-Glu and show that the material worked effectively and selectively to separate D- and L-Glu with a %ee value of 97.86 % and an adsorption capacity for L of 9.9 mg g−1 on optimum conditions. In addition, the adsorbent developed shows good reusability values with a decreasing performance of no more than 2.0 % after 10-time use cycles and is easily separated in less than 15 s. This research contributes to developing advanced materials with extraordinary selectivity and efficiency, paving the way for advances in enantiomer separation technology. [ABSTRACT FROM AUTHOR]

• An easy-to-use LC–MS method to quantify racemic MDMA and MDA was developed. • An enantioselective LC–MS method for MDMA and MDA was developed using a chiral column. • Both bioanalytical methods allow sensitive and rapid sample measurement. • Chiral pharmacokinetics were assessed in subjects dosed with MDMA or its enantiomer. 3,4-Methylenedioxymethamphetamine (MDMA) is an entactogen with therapeutic potential. The two enantiomers of MDMA differ regarding their pharmacokinetics and pharmacodynamics but the chiral pharmacology of MDMA needs further study in clinical trials. Here, an achiral and an enantioselective high performance liquid chromatography–tandem mass spectrometry method for the quantification of MDMA and its psychoactive phase I metabolite 3,4-methylenedioxyamphetamine (MDA) in human plasma were developed and validated. The analytes were detected by positive electrospray ionization followed by multiple reaction monitoring. The calibration range was 0.5–500 ng/mL for the achiral analysis of both analytes, 0.5–1,000 ng/mL for chiral MDMA analysis, and 1–1,000 ng/mL for chiral MDA analysis. Accuracy, precision, selectivity, and sensitivity of both bioanalytical methods were in accordance with regulatory guidelines. Furthermore, accuracy and precision of the enantioselective method were maintained when racemic calibrations were used to measure quality control samples containing only one of the enantiomers. Likewise, enantiomeric calibrations could be used to reliably quantify enantiomers in racemic samples. The achiral and enantioselective methods were employed to assess pharmacokinetic parameters in clinical study participants treated with racemic MDMA or one of its enantiomers. The pharmacokinetic parameters assessed with both bioanalytical methods were comparable. In conclusion, the enantioselective method is useful for the simultaneous quantification of both enantiomers in subjects treated with racemic MDMA. However, as MDMA and MDA do not undergo chiral inversion, enantioselective separation is not necessary in subjects treated with only one of the enantiomers. [ABSTRACT FROM AUTHOR]