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Investigations have shown that storage bugs seriously harm grains during storage. In the interim, essential oils (EOs) have been proven to be a good botanical pesticide. The anti-Lasioderma serricorne properties of Elsholtzia ciliata essential oil, which was obtained by steam distillation, were evaluated using DL-limonene, carvone, and their two optical isomer components using contact, repelling, and fumigation techniques. Simultaneously, the fumigation, contact, and repellent activities of carvone and its two optical isomers mixed with DL-limonene against L. serruricorne were evaluated. The results showed that E. ciliata, its main components (R-carvone, DL-limonene), and S-carvone exhibited both fumigations (LC50 = 14.47, 4.42, 20.9 and 3.78 mg/L) and contact (LD50 = 7.31, 4.03, 28.62 and 5.63 µg/adult) activity against L.serricorne. A binary mixture (1:1) of R-carvone and DL-limonene displayed an obvious synergistic effect. A binary mixture (1:1) of carvone and its two optical isomers exhibited an obvious synergistic effect, too. Furthermore, the repellent activity of the EO, carvone, and its two optical isomers, DL-limonene, and a combination of them varied. To stop insect damage during storage, E. ciliata and its components can be utilized as bio-insecticides. [ABSTRACT FROM AUTHOR]

[Display omitted] Understanding the structure-function relationships encoded on chiral catalysts is important for investigating the fundamental principles of catalytic enantioselectivity. Herein, the synthesis and self-assembly of naphthalene substituted bis - l / d -histidine amphiphiles (bis - l / d - NapHis) in DMF/water solution mixture is reported. The resulting supramolecular assemblies featuring well-defined P/M nanoribbons (NRs). With combination of the (P/M)-NR and metal ion catalytic centers (M n+ = Co2+, Cu2+, Fe3+), the (P)-NR-M n+ as chiral supramolecular catalysts show catalytic preference to 3,4-dihydroxy- S -phenylalanine (S -DOPA) oxidation while the (M)-NR-M n+ show enantioselective bias to R -DOPA oxidation. In contrast, their monomeric counterparts bis - l / d - NapHis-M n+ display an inverse and dramatically lower catalytic selectivity in the R/S -DOPA oxidation. Among them, the Co2+-coordinated supramolecular nanostructures show the highest catalytic efficiency and enantioselectivity (select factor up to 2.70), while the Fe3+-coordinated monomeric ones show nearly racemic products. Analysis of the kinetic results suggests that the synergistic effect between metal ions and the chiral supramolecular NRs can significantly regulate the enantioselective catalytic activity, while the metal ion-mediated monomeric bis - l / d - NapHis were less active. The studies on association constants and activation energies reveal the difference in catalytic efficiency and enantioselectivity resulting from the different energy barriers and binding affinities existed between the chiral molecular/supramolecular structures and R/S -DOPA enantiomers. This work clarifies the correlation between chiral molecular/supramolecular structures and enantioselective catalytic activity, shedding new light on the rational design of chiral catalysts with outstanding enantioselectivity. [ABSTRACT FROM AUTHOR]

The Nebulizer produces droplets of size 5-8microns, only 37-60% of the drug will be deposited in the oropharynx. Hence, significant side effects are not observed. It is a water-soluble molecule structurally related to Phencyclidine. It contains an asymmetric carbon atom hence has two optical isomers: the S (+) isomer and R (-) isomer. Benzethonium chloride is added as a preservative. The present study was conducted after receiving approval from Ethical committee of our institution. Following detailed preanaesthetic checkup, informed written consent was obtained from all patients fulfilling the required inclusion and exclusion criteria. On the day of surgery, after arrival to the operation theatre, the patients were shifted to anesthesia preparation room. Post extubation, 16 patients had cough in test group as compared to 18 patients in control group (p=0.068). At the end of 2 hours only 1 patient had cough as compared to 14 patients in control group(p<0.001). At 4 hours post extubation, no patient had cough in test group as compared to 9 patients in the control group (p=0.002). At the end of 6 hours, no patient had cough as compared to 2 patients in control group (p=0.153). At the end of 24hrs no patient in the test and control group had the cough. [ABSTRACT FROM AUTHOR]

A small and flexible molecule, ribocil A (non-binder) or B (binder), binds to the deep pocket of the aptamer domain of the FMN riboswitch, which is an RNA molecule. This binding was studied by mD-VcMD, which is a generalized-ensemble simulation method. Ribocil A and B are structurally similar because they are optical isomers to each other. In the initial conformation of simulation, the ligands and the aptamer were completely dissociated in explicit solvent. The aptamer-ribocil B binding was stronger than the aptamer-ribocil A binding, which agrees with experiments. The computed free-energy landscape for the aptamer-ribocil B binding was funnel-like, whereas that for the aptamer-ribocil A binding was rugged. When passing through the gate (named "front gate") of the binding pocket, each ligand interacted with bases of the riboswitch by non-native 𝝅𝝅-𝝅𝝅 stackings, and the stackings restrained the ligand's orientation to be advantageous to reach the binding site smoothly. When the ligands reached the binding site in the pocket, the non-native stackings were replaced by the native stackings. The ligand's orientation restriction is discussed referring to a selection mechanism reported in an earlier work on a drug-GPCR interaction. The present simulation showed another pathway leading the ligands to the binding site. The gate ("rear gate") for this pathway was located completely opposite to the front gate on the aptamer's surface. However, the approach from the rear gate required overcoming a free-energy barrier regarding ligand's rotation before reaching the binding site. [ABSTRACT FROM AUTHOR]

An ideal life detection instrument would have high sensitivity but be insensitive to abiotic processes and would be capable of detecting life with alternate molecular structures. In this study, we propose that catalytic activity can be the basis of a nearly ideal life detection instrument. There are several advantages to catalysis as an agnostic life detection method. Demonstrating catalysis does not necessarily require culturing/growing the alien life and in fact may persist even in dead biomass for some time, and the amplification by catalysis is large even by minute amounts of catalysts and, hence, can be readily detected against abiotic background rates. In specific, we propose a hydrolytic catalysis detection instrument that could detect activity in samples of extraterrestrial organic material from unknown life. The instrument uses chromogenic assay-based detection of various hydrolytic catalytic activities, which are matched to corresponding artificial substrates having the same, chromogenic (preferably fluorescent) upon release, group; D- and L-enantiomers of these substrates can be used to also answer the question whether unknown life is chiral. Since catalysis is a time-proportional product-concentration amplification process, hydrolytic catalytic activity can be measured on a sample of even a minute size, and with instruments based on, for example, optofluidic chip technology. [ABSTRACT FROM AUTHOR]

3-Hydroxybutanone (Acetoin, AC) and 2,3-butanediol (BD) are two essential four-carbon platform compounds with numerous pharmaceutical and chemical synthesis applications. AC and BD have two and three stereoisomers, respectively, while the application of the single isomer product in chemical synthesis is superior. AC and BD are glucose overflow metabolites produced by biological fermentation from a variety of microorganisms. However, the AC or BD produced by microorganisms using glucose is typically a mixture of various stereoisomers. This was discovered to be due to the simultaneous presence of multiple butanediol dehydrogenases (BDHs) in microorganisms, and AC and BD can be interconverted under BDH catalysis. In this paper, beginning with the synthesis pathways of microbial AC and BD, we review in detail the studies on the formation mechanisms of different stereoisomers of AC and BD, summarize the properties of different types of BDH that have been tabulated, and analyze the structural characteristics and affinities of different types of BDH by comparing them using literature and biological database data. Using microorganisms, recent research on the production of optically pure AC or BD was also reviewed. Limiting factors and possible solutions for chiral AC and BD production are discussed. [ABSTRACT FROM AUTHOR]

Microreaction and membrane technologies offer optimal conditions for controlling enantiomer synthesis and purification processes in continuous production, with numerous advantages over batch manufacturing. One of the many forces driving the development of such technologies for the production of single optical isomers is the need for enantiomerically pure pharmaceutical drugs because enantiomers may display opposite therapeutic effects or different treatment efficacies and side effects. Yet, despite advances in asymmetric synthesis and separation techniques, preparing enantiomerically pure compounds remains a challenging task. Here, we review the progress in microfluidics and membrane chiral separation over the last two decades. In addition to describing and critically assessing the state of the art in both disciplines, we provide an overview of their beneficial properties and characteristics for developing technologies toward producing enantiomerically pure compounds. Concomitantly, we evaluate efforts to integrate synthesis and membrane separation into a microfluidic platform and pinpoint the limiting factors that must be overcome before these platforms can be fully deployed in the industry. [ABSTRACT FROM AUTHOR]

The sorption of vapors from the gas phase of a number of compounds on the surface of a wide-pore adsorbent Chromaton N-AW modified with a mixture of 4-(2-hydroxyethoxy)-4′-formylazobenzene–µ‑oxodimer 2,8,12,18-tetramethyl-3,7,13,17-tetra-n-amylporphine has been studied by the method of inverted gas chromatography. Electrodonor isomers of methylpyridines and dimethylpyridines, isomers of weakly polar xylenes, and a number of enantiomers have been selected as sorbates. The specific retention volumes of sorbates have been calculated, enthalpy and entropy contributions to the sorption process has been shown, and the analytical properties of the resulting stationary phase have been studied. The effect of temperature and the chemical nature of sorbates on the thermodynamic characteristics of sorption has been discussed. The separation factors of both structural and optical isomers and low-boiling hydrocarbons of various structures have been calculated. The influence of both components of the mixture on the sorption process has been considered: the formation of supramolecular ensembles with specific interactions and possible complex formation with iron µ-oxodimer 2,8,12,18-tetramethyl-3,7,13,17-tetra-n-amylporphine. It has been experimentally established that the sorbent based on the proposed mixture of mesogenic 4-(2-hydroxyethoxy)-4′-formylazobenzene and the iron µ-oxodimer 2,8,12,18-tetramethyl-3,7,13,17-tetra-n-amylporphine exhibits high selectivity with respect to low-boiling compounds of various nature, which is unattainable for an unmodified adsorbent. It has been concluded that the use of the presented modifiers in gas chromatography makes it possible to study new stationary phases based on similar mixtures using macrocycles of various structures and nature, promising from the point of view of both structural and chiral gas chromatography. [ABSTRACT FROM AUTHOR]

An X-ray diffraction study of a transesterification product of N-methyl-N-(trimethoxysilylmethyl)acetamide by 4,5-dibromobenzene-1,2-diol was carried out. It was established that the coordination polyhedron of the silicon atom in an anionic complex is a distorted octahedron disordered due to the superposition of the Δ and Λ optical isomers. The presence of various hydrogen donor groups in bis(cyclohexyl)ammonium cations, solvent ethanol molecules, and non-coordinated 4,5-dibromobenzene-1,2-diol caused the formation of H-bonded chains, while dibromobenzenediol also took part in stacking interactions. [ABSTRACT FROM AUTHOR]

Optical isomers of short peptide Lysine-Tryptophan-Lysine (Lys-{L/D-Trp}-Lys) and Lys-Trp-Lys with an acetate counter-ion were used to study photoinduced intramolecular and intermolecular processes of interest in photobiology. A comparison of L- and D-amino acid reactivity is also the focus of scientists' attention in various specialties because today, the presence of amyloid proteins with D-amino acids in the human brain is considered one of the leading causes of Alzheimer's disease. Since aggregated amyloids, mainly Aβ42, are highly disordered peptides that cannot be studied with traditional NMR and X-ray techniques, it is trending to explore the reasons for differences between L- and D-amino acids using short peptides, as in our article. Using NMR, chemically induced dynamic nuclear polarization (CIDNP) and fluorescence techniques allowed us to detect the influence of tryptophan (Trp) optical configuration on the peptides fluorescence quantum yields, bimolecular quenching rates of Trp excited state, and the photocleavage products formation. Thus, compared with the D-analog, the L-isomer shows a greater Trp excited state quenching efficiency with the electron transfer (ET) mechanism. There are experimental confirmations of the hypothesis about photoinduced ET between Trp and the CONH peptide bond, as well as between Trp and another amide group. [ABSTRACT FROM AUTHOR]

(S)-ketamine-induced rapid-acting antidepressant effects have revolutionized the pharmacotherapy of major depression; however, this medication also produces psychotomimetic effects such as timing distortion. While (R)-ketamine produces fewer dissociative effects, its antidepressant actions are less studied. Depression is associated with time overestimation (i.e., subjectively, time passes slowly). Our recent report suggests that while (S)-ketamine induces an opposite effect, i.e., time underestimation, the (R)-isomer does not affect timing. It has been suggested that opioid receptors are involved in the antidepressant effect of ketamine. In the present study we tested (R)- and (S)-ketamine, and fluoxetine as a positive control in the differential-reinforcement-of-low-rate (DRL) 72-s schedule of reinforcement in male rats following naloxone pretreatment. DRL classic metrics as well as peak deviation analyses served to determine antidepressant-like actions and those associated with timing. We report antidepressant-like effects of (S)-ketamine (30-60 mg/kg) that resemble fluoxetine's (2.5-10 mg/kg), as both compounds increased reinforcement rate and peak location (suggesting increased performance), reduced premature responses (suggesting time underestimation) and decreased Weber's fraction (suggesting increased timing precision). (R)-ketamine (30, but not 60 mg/kg) increased only the reinforcement rate and peak location but did not affect timing. Only fluoxetine decreased burst responses, suggesting decreased impulsivity. Naloxone pretreatment did not block ketamine enantiomers' actions, but unexpectedly, increased fluoxetine' performance. Thus, while all three medications produced antidepressant-like effects in DRL 72-s, fluoxetine- and (S)- but not (R)- ketamine-induced time underestimation (the subject experiences the time as passing quickly). The potentiation of DRL performance of fluoxetine by naloxone was unexpected and warrants clinical studies. [ABSTRACT FROM AUTHOR]

A short and efficient synthesis of three stereoisomeric and three process impurities of Alalevonadifloxacin mesylate (WCK 2349), a novel anti-methicillin-resistant Staphylococcus aureus (MRSA) antibiotic, has been disclosed. The synthesis and characterization of these impurities are discussed in detail to provide access to the reference standards for the impurity profile of the drug substance as well as the drug product. Moreover, systematic analytical method development for stereospecific separation between alalevonadifloxacin mesylate (1) and an enantiomer, WCK 6577 (2) in the presence of other process impurities for accurate quantification using liquid chromatography is also discussed. [ABSTRACT FROM AUTHOR]

2,3-Butanediol (BD) and acetoin (AC) are products of the non-oxidative metabolism of microorganisms, presenting industrial importance due to their wide range of applications and high market value. Their optical isomers have particular applications, justifying the efforts on the selective bioproduction. Each microorganism produces different isomer mixtures, as a consequence of having different butanediol dehydrogenase (BDH) enzymes. However, the whole scene of the isomer bioproduction, considering the several enzymes and conditions, has not been completely elucidated. Here we show the BDH classification as R, S or meso by bioinformatics analysis uncovering the details of the isomers production. The BDH was compared to diacetyl reductases (DAR) and the new enoyl reductases (ER). We observed that R-BDH is the most singular BDH, while meso and S-BDHs are similar and may be better distinguished through their stereo-selective triad. DAR and ER showed distinct stereo-triads from those described for BDHs, agreeing with kinetic data from the literature and our phylogenetic analysis. The ER family probably has meso-BDH like activity as already demonstrated for a single sequence from this group. These results are of great relevance, as they organize BD producing enzymes, to our known, never shown before in the literature. This review also brings attention to nontraditional enzymes/pathways that can be involved with BD/AC synthesis, as well as oxygen conditions that may lead to the differential production of their isomers. Together, this information can provide helpful orientation for future studies in the field of BD/AC biological production, thus contributing to achieve their production on an industrial scale. [ABSTRACT FROM AUTHOR]

Esketamine, the right-handed optical isomer of racemic ketamine, has recently become widely used for anesthesia and analgesia as a replacement for racemic ketamine. However, there are limited studies comparing the anesthetic and analgesic effects of esketamine and racemic ketamine in mice. This research was conducted to analyze the dose-dependent anesthetic and analgesic efficacy of esketamine in mice and to compare its potency with that of the racemate. We tested the anesthetic effects of different doses of esketamine and compared its potency with that of the racemate using righting reflex tests. Then, the acetic acid-induced pain model and formalin-induced pain model were used to investigate the analgesic effect. Compared with racemic ketamine, an equivalent dose of esketamine at 100 mg/kg was required to induce stable anesthesia. In contrast, 5 mg/kg esketamine was sufficient to provide analgesic effects similar to those of 10 mg/kg ketamine. Together, esketamine had a similar potency to racemic ketamine for anesthesia and a stronger potency for analgesia in mice. [ABSTRACT FROM AUTHOR]

Macrocyclic glycopeptide antibiotics immobilized on silica are one of the effective classes of stationary phases for chiral recognition and HPLC separation of a wide range of optically active compounds. Enantioselectivity primarily depends on the chemical structure of the chiral ligand, immobilization chemistry, and separation conditions. In the present work, three new chiral stationary phases (CSPs) based on macrocyclic antibiotic eremomycin were prepared and investigated for enantioseparation of amino acids. Two eremomycin derivatives, including simple non-substituted amide and bulky adamantyl amide, provided important information on the role of the carboxylic group in the eremomycin structure in the chiral recognition mechanism concerning amino acid optical isomers. One more CSP having a chlorine atom in the same position elucidates the role of the first aromatic ring in the eremomycin structure as a crucial point for chiral recognition. CSP with immobilized chloreremomycin was the most successful among the phases prepared in this work. It was additionally investigated under various separation conditions, including the type and content of the organic solvent in the eluent, the effects of different additives, and the concentration and pH of the buffer. Importantly, an efficient enantioselective separation of amino acids was achieved with pure water as the eluent. [ABSTRACT FROM AUTHOR]

Jules-Marie-Augustin Chautard (1826-1901), a French multifaceted scientist who started as a pharmacist and then turned physicist and coin collector. His main activities were related to phenomenon of light polarization, particularly in camphor and lavender, and the spectral study of chlorophyll. He showed that camphor appeared as dextro, levo, and racemic isomers, the same as tartaric acid, and demonstrated that these isomers could be obtained by chemical means. He postulated that a compound appearing in one isomeric form should also be present in the two other forms. He showed that the spectrum of chlorophyll possessed some typical lines, which allowed its detection down to one part in ten thousand, and also when mixed with other substances, fact that provided an important physiological and forensic tool. Together with Dessaignes they separated physalin, the active bitter component of the plant Chinese lantern (Physalis alkekengi). [ABSTRACT FROM AUTHOR]

We present a critical review of experimental studies of the efficiency of the separation of various groups of chemical compounds under the conditions of high-performance liquid chromatography using metal-organic framework polymers (metal-organic frameworks (MOFs)) or composite materials with MOFs as a stationary phase. MOFs demonstrated many advantages in high-performance liquid chromatography and a possibility of competing successfully with conventional phases, especially in the determination of low-molecular-weight compounds and optical isomers. Among the promising options for using this class of materials are the development of monolithic separation columns and hybrid adsorbents that eliminate the disadvantages of adsorbents based on pure MOFs. [ABSTRACT FROM AUTHOR]

The relationships between molecular structures and their properties are subtle and complex, and the properties of odor are no exception. Molecules with similar structures, such as a molecule and its optical isomer, may have completely different odors, whereas molecules with completely distinct structures may have similar odors. Many works have attempted to explain the molecular structure-odor relationship from chemical and data-driven perspectives. The Transformer model is widely used in natural language processing and computer vision, and the attention mechanism included in the Transformer model can identify relationships between inputs and outputs. In this paper, we describe the construction of a Transformer model for predicting molecular properties and interpreting the prediction results. The SMILES data of 100,000 molecules are collected and used to predict the existence of molecular substructures, and our proposed model achieves an F1 value of 0.98. The attention matrix is visualized to investigate the substructure annotation performance of the attention mechanism, and we find that certain atoms in the target substructures are accurately annotated. Finally, we collect 4462 molecules and their odor descriptors and use the proposed model to infer 98 odor descriptors, obtaining an average F1 value of 0.33. For the 19 odor descriptors that achieved F1 values greater than 0.45, we also attempt to summarize the relationship between the molecular substructures and odor quality through the attention matrix. [ABSTRACT FROM AUTHOR]

This work is a mini-review highlighting the relevance of the θ metallabis(dicarbollide) [3,3′-Co(1,2-C2B9H11)2]− with its peculiar and differentiating characteristics, among them the capacity to generate hydrogen and dihydrogen bonds, to generate micelles and vesicles, to be able to be dissolved in water or benzene, to have a wide range of redox reversible couples and many more, and to use these properties, in this case, for producing potentiometric membrane sensors to monitor amine-containing drugs or other nitrogen-containing molecules. Sensors have been produced with this monoanionic cluster [3,3′-Co(1,2-C2B9H11)2]−. Other monoanionic boron clusters are also discussed, but they are much fewer. It is noteworthy that most of the electrochemical sensor species incorporate an ammonium cation and that this cation is the species to be detected. Alternatively, the detection of the borate anion itself has also been studied, but with significantly fewer examples. The functions of the borate anion in the membrane are different, even as a doping agent for polypyrrole which was the conductive ground on which the PVC membrane was deposited. Apart from these cases related to closo borates, the bulk of the work has been devoted to sensors in which the θ metallabis (dicarbollide) [3,3′-Co(1,2-C2B9H11)2]− is the key element. The metallabis (dicarbollide) anion, [3,3′-Co(1,2-C2B9H11)2]−, has many applications; one of these is as new material used to prepare an ion-pair complex with bioactive protonable nitrogen containing compounds, [YH]x[3,3′-Co(1,2-C2B9H11)2]y as an active part of PVC membrane potentiometric sensors. The developed electrodes have Nernstian responses for target analytes, i.e., antibiotics, amino acids, neurotransmitters, analgesics, for some decades of concentrations, with a short response time, around 5 s, a good stability of membrane over 45 days, and an optimal selectivity, even for optical isomers, to be used also for real sample analysis and environmental, clinical, pharmaceutical and food analysis. [ABSTRACT FROM AUTHOR]

A gas chromatographic study of the adsorption of vapors of organic compounds with different polarities on a carbon adsorbent with a bilayer based on a liquid crystal of the "double dovetail" type and unsubstituted β-cyclodextrin is performed. The thermodynamic characteristics of adsorption are determined from the temperature dependences of the Henry constants of adsorption. Comparison of the obtained thermodynamic characteristics of adsorption on an adsorbent with a monolayer of a liquid crystal and a liquid crystal–cyclodextrin bilayer is performed. It is shown that the modified with a bilayer adsorbent possesses moderate selectivity to weakly polar optical isomers under the conditions of gas adsorption chromatography. [ABSTRACT FROM AUTHOR]

To develop potent and safer analgesics, we designed and synthesized a novel enantiomerically enriched ethereal analog of (R)-iso-moramide, namely 2-[(2R)-2-(morpholin-4-yl)propoxy]-2,2-diphenyl-1-(pyrrolidin-1-yl)ethan-1-one. The titled active agent can potentially serve as a powerful synthetic opiate with an improved affinity and selectivity toward opioid receptors (ORs). This hypothesis was postulated based on docking studies regarding the respective complexes between the designed ligand and µ-OR, δ-OR, and κ-OR. The key step of the elaborated asymmetric synthesis of novel analog involves lipase-catalyzed kinetic resolution of racemic 1-(morpholin-4-yl)propan-2-ol, which was accomplished on a 10 g scale via an enantioselective transesterification employing vinyl acetate as an irreversible acyl donor in tert-butyl methyl ether (MTBE) as the co-solvent. Next, the obtained homochiral (S)-(+)-morpholino-alcohol (>99% ee) was functionalized into corresponding chloro-derivative using thionyl chloride (SOCl2) or the Appel reaction conditions. Further transformation with N-diphenylacetyl-1-pyrrolidine under phase-transfer catalysis (PTC) conditions using O2-saturated DMSO/NaOH mixture as an oxidant furnished the desired levorotatory isomer of the title product isolated in 26% total yield after three steps, and with 89% ee. The absolute configuration of the key-intermediate of (R)-(–)-iso-moramide was determined using a modified form of Mosher's methodology. The preparation of the optically active dextrorotatory isomer of the titled product (87% ee) was carried out essentially by the same route, utilizing (R)-(–)-1-(morpholin-4-yl)propan-2-ol (98% ee) as a key intermediate. The spectroscopic characterization of the ethereal analog of iso-moramide and the enantioselective retention relationship of its enantiomers using HPLC on the cellulose-based chiral stationary phase were performed. Moreover, as a proof-of-principle, single-crystal X-ray diffraction (XRD) analysis of the synthesized 2-[(2R)-2-(morpholin-4-yl)propoxy]-2,2-diphenyl-1-(pyrrolidin-1-yl)ethan-1-one is reported. [ABSTRACT FROM AUTHOR]

Cell-penetrating peptides (CPPs) have been discovered to deliver chemical drugs, nucleic acids, and macromolecules to permeate cell membranes, creating a novel route for exogenous substances to enter cells. Up until now, various sequence structures and fundamental action mechanisms of CPPs have been established. Among them, arginine-rich peptides with unique cell penetration properties have attracted substantial scientific attention. Due to the positively charged essential amino acids of the arginine-rich peptides, they can interact with negatively charged drug molecules and cell membranes through non-covalent interaction, including electrostatic interactions. Significantly, the sequence design and the penetrating mechanisms are critical. In this brief synopsis, we summarize the transmembrane processes and mechanisms of arginine-rich peptides; and outline the relationship between the function of arginine-rich peptides and the number of arginine residues, arginine optical isomers, primary sequence, secondary and ternary structures, etc. Taking advantage of the penetration ability, biomedical applications of arginine-rich peptides have been refreshed, including drug/RNA delivery systems, biosensors, and blood-brain barrier (BBB) penetration. Understanding the membrane internalization mechanisms and design strategies of CPPs will expand their potential applications in clinical trials. [ABSTRACT FROM AUTHOR]

Fentanyl remains the primary cause of fatal overdoses, and its co-use with methamphetamine (METH) is a growing concern. We previously demonstrated that racemic METH can either enhance or mitigate opioid-induced respiratory depression (OIRD) dependent upon whether a low or high dose is administered. The optical isomers of METH, dextromethamphetamine (d- METH) and levomethamphetamine (l- METH), differ substantially in their selectivity and potency to activate various monoamine (MA) receptors, and these pharmacological differences may underlie the bidirectional effects of the racemate. Since it is unknown which of METH's MA receptor mechanisms mediate these respiratory effects, examination of METH's pharmacologically distinct enantiomers may provide insight into treatment targets for OIRD. The two optical isomers of METH, d- METH and l- METH, were tested in adult male mice to determine their effects on basal and fentanyl-depressed respiratory frequency, tidal volume, and minute ventilation (MVb; i.e., respiratory frequency x tidal volume) using whole-body plethysmography. When tested at dose ranges of 1.0–10 mg/kg, d- METH elevated MVb and l- METH decreased basal MVb. A dose of 30 mg/kg l- METH increased basal MVb. Under fentanyl-depressed conditions, the bidirectional effects of racemic METH were observed with d- METH treatment while l- METH significantly exacerbated OIRD at 1.0 and 3.0 mg/kg. d- METH and l- METH differentially contribute to the bidirectional respiratory modulation observed by the racemate, with d- METH exhibiting predominantly stimulatory effects and l- METH exhibiting primarily depressant effects depending on dose. • METH's isomers, d- and l-METH, differentially contribute to the racemate's bidirectional effects on respiration • d-METH dose-dependently stimulates basal respiration but has bidirectional effects under fentanyl-depressed conditions • l-METH depresses respiration at equimolar doses but exhibits stimulant effects as dose increases further • Both isomers' respiratory stimulant effects were frequency mediated while depression was mediated by tidal volume [ABSTRACT FROM AUTHOR]

In our study, enantiomers of bergamot essence components were investigated. Afterwards, the flavoring effects of each of its optical isomers were investigated. Our aim is to find and develop the product with the strongest aroma effect. The effects of components that determine the quality of bergamot oil on values such as odor, taste and colour were investigated by gas chromatography-mass spectrometry (GC-MS) and sensory analysis evaluation. Moreover, application studies taken place in which shelf life studies be monitored depending on the use of antioxidants. Application and GC results were examined. In line with these results, it was determined that butylated hydroxy anisole (BHA), caffeic acid and gallic acid kept the product stable until the end of the 18th month. [ABSTRACT FROM AUTHOR]

Organic compounds have been employed in developing new green energy solutions with good cost-efficiency compromise, such as photovoltaics. The light-harvesting process in these applications is a crucial feature that still needs improvements. Here, we studied natural dyes to propose an alternative for enhancing the light-harvesting capability of photovoltaics. We performed density functional theory calculations to investigate the electronic and optical properties of the four natural dyes found in achiote seeds (Bixa orellana L.). Different DFT functionals, and basis sets, were used to calculate the electronic and optical properties of the bixin, norbixin, and their trans-isomers (molecules present in Bixa orellana L.). We observed that the planarity of the molecules and their similar extension for the conjugation pathways provide substantially delocalized wavefunctions of the frontier orbitals and similar values for their energies. Our findings also revealed a strong absorption peak in the blue region and an absorption band over the visible spectrum. These results indicate that Bixa orellana L. molecules can be good candidates for improving light-harvesting in photovoltaics. [ABSTRACT FROM AUTHOR]

• Esketamine injection 0 h but not 6 h after reactivation facilitates NOR memory performance. • Esketamine injection 24 h after sampling without reactivation did not facilitate NOR memory performance. • NBQX block the improving effect of esketamine on memory reconsolidation. Esketamine, the right-handed optical isomer of racemic ketamine, is a rapidly acting antidepressant approved by the FDA for treatment-resistant depression in 2019. However, few studies have investigated esketamine's role in learning and memory, particularly in the context of memory reconsolidation. Herein, we evaluated esketamine's role in memory reconsolidation in 7-week-old male Institute of Cancer Research mice subjected to the novel object recognition (NOR) memory task. The NOR reconsolidation procedure comprised three phases: sampling, reactivation, and testing. Esketamine-enhanced NOR memory performance when injected into mice 0 h after reactivation rather than following a 6 h delay. Conversely, administering esketamine 24 h after sampling without reactivation did not enhance NOR memory performance. Notably, esketamine exhibited no discernible effects on nonspecific responses, such as locomotor activity and exploratory behavior. Furthermore, the α -amino-3‑hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-type receptor antagonist NBQX effectively blocked the esketamine-induced enhancement of memory reconsolidation. In conclusion, esketamine treatment markedly improves memory reconsolidation in NOR tasks, and this effect is linked to AMPA receptor activity. [ABSTRACT FROM AUTHOR]

A series of 3-oxygenated α-ionone analogs have been developed as highly specific male lures for the solanaceous fruit fly Bactrocera latifrons, a pest of solanaceous fruits. We compared the attractant and phagostimulant activities of analogs with or without (i) unsaturations at the 4,5-and/or 7,8-positions and (ii) oxygen moieties at the 3- and/or 9-positions of the ionone molecule. Since naturally occurring vomifoliol (V2) was found to induce a highly potent phagostimulant activity in B. latifrons males, related analogs including dehydrovomifoliol (V1), 6-hydroxy-α-ionone (U1), and 6-hydroxy-α-ionol (U2) were synthesized to evaluate their attractant and phagostimulant activities. Synthetic V1, V2, U1, and U2 exhibited low attractant activity, but their phagostimulant activity was relatively high. Optical isomers of 3-oxo-7,8-dihydro-α-ionone (P3) and V1 were prepared to examine the stereochemical specificity of attractants. (+)-(6R)-P3 and (+)-(6S)-V1 exhibited the corresponding activities, while their respective antipodal enantiomers were found entirely inactive. [ABSTRACT FROM AUTHOR]

The development of efficient and straightforward methods for obtaining all optically active isomers of structurally rigid spirocycles from readily available starting materials is of great value in drug discovery and chiral ligand development. However, the stereodivergent synthesis of spirocycles bearing multiple stereocenters remains an unsolved challenge owing to steric hindrance and ring strain. Herein, we report an enantio‐ and diastereodivergent synthesis of rigid spirocycles through dual‐metal‐catalyzed [3+2] annulation of oxy π‐allyl metallic dipoles with less commonly employed nucleophilic dipoles (imino esters). A series of spiro compounds bearing a pyrroline and an olefin were easily synthesized in an enantio‐ and diastereodivergent manner (up to 19:1 dr, >99 % ee), which showed great promise as a new type of N‐olefin ligand. Preliminary mechanistic studies were also carried out to understand the process of this bimetallic catalysis. [ABSTRACT FROM AUTHOR]

The development of efficient and straightforward methods for obtaining all optically active isomers of structurally rigid spirocycles from readily available starting materials is of great value in drug discovery and chiral ligand development. However, the stereodivergent synthesis of spirocycles bearing multiple stereocenters remains an unsolved challenge owing to steric hindrance and ring strain. Herein, we report an enantio‐ and diastereodivergent synthesis of rigid spirocycles through dual‐metal‐catalyzed [3+2] annulation of oxy π‐allyl metallic dipoles with less commonly employed nucleophilic dipoles (imino esters). A series of spiro compounds bearing a pyrroline and an olefin were easily synthesized in an enantio‐ and diastereodivergent manner (up to 19:1 dr, >99 % ee), which showed great promise as a new type of N‐olefin ligand. Preliminary mechanistic studies were also carried out to understand the process of this bimetallic catalysis. [ABSTRACT FROM AUTHOR]

In this work, an N4-donor Schiff base ligand, N,N'-(propane-1,2-diyl)bis(1-phenyl-1-(pyridin-2-yl)methanimine) (PPPM) and its Mn(II) complex, [Mn(PPPM)(OAc)2]·3H2O (1), were prepared and identified by elemental analysis, FT-IR, 1H NMR spectroscopy as well single-crystal X-ray diffraction. X-ray structure analysis of 1 revealed a distorted square-face bicapped trigonal prism geometry around manganese atom with MnN4O4 environment containing an N4-donor PPPM and two O2-donor acetato ligands. The ligand has a chiral center on carbon atom which leads to the formation of a racemic mixture of complex 1. In the crystal structure of complex, intermolecular hydrogen bonds form R44(8) hydrogen bond motifs. The ability of two optical isomers of PPPM ligand and manganese complex to interact with 10 selected biomacromolecules (BRAF kinase, CatB, DNA gyrase, HDAC7, rHA, RNR, TrxR, TS, Top II, B-DNA) was investigated by docking studies. These studies revealed that PPPMR,S and 1R,S isomers can bind to these molecules better than doxorubicin (except B-DNA). [ABSTRACT FROM AUTHOR]

We synthesized the optically active epineoclausenamide by utilizing chiral reagents, such as R‐α‐methylbenzylamine and S‐α‐methylbenzylamine, for the resolution of the intermediate (trans‐3‐phenyl‐oxiranecarboxylic acid 12), followed by amide exchange, cyclization, and reduction, unlike previously reported methods. The Meerwein–Ponndorf–Verley reduction was used to asymmetrically reduce neoclausenamidone. A plausible reduction mechanism of this method was elucidated. Thereafter, high‐performance liquid chromatography (HPLC) was investigated for the resolution of the epineoclausenamide enantiomers. HPLC was also used to determine the optical purity of these isomers. Two chiral stationary phases (CSPs) for separating the enantiomers were compared. Different mobile phase compositions were tested at 298.15 K. The results showed that the best separation was obtained when the mobile phase was composed of n‐hexane and isopropanol (IPA) (75/25, v/v), the racemate was separated on a Chiralcel OJ‐H column, and the flow rate was 1.0 mL/min at a wavelength of 210 nm and a temperature of 25°C. The enantiomeric ratio (e.r.) values of both the synthetic (−)‐epineoclausenamide and (+)‐epineoclausenamide were 1.3(+):98.7(−) and 99.3(+):0.7(−), respectively. In this study, a new synthetic route was designed with a yield of 12.3–14.1%, and a quick (8 min) effective separation method was obtained. This provides basis for pharmacological research and quality control of clausenamide analogues. [ABSTRACT FROM AUTHOR]

The N3P3 ring of hexachlorocyclotriphosphazene, N3P3Cl6 (1) (HCCP; trimer), was used significantly as a scaffold for the syntheses of inorganic–organic-based hybrid cyclotriphosphazenes, as it is a highly robust skeleton among inorganic phosphorus–nitrogen ring systems. However, hybrid cyclotriphosphazenes with pendant arm(s) have been quite less explored. In the present study, the unsymmetrical bulky 4-methoxybenzyldiamines, CH3OPhCH2NH(CH2)nNHR (n = 0, R=CH32; n = 0, R = C2H53 and n = 1, R = CH34), were obtained after the reduction of the corresponding Schiff bases formed as a result of condensation reactions of aliphatic diamines with 4-methoxybenzaldehyde. Reactions of the diamines (2–4) with HCCP (1) gave the new monospiro-(5–7), cis-dispiro (8–10) and trans-dispiro (11–13) cyclotriphosphazenes with 4-methoxybenzyl (p-anisyl) pendant arm(s). The fully substituted monospiro derivatives; 5a–7a, 5b–7b and 5c–7c, were prepared from the reactions of 5, 6 and 7 with pyrrolidine, tetra-1,4-dioxa-8-azaspiro[4.5]decane and piperidine, respectively. FTIR, ESI–MS and 1H, 13C, 31P NMR spectral data of all cyclotriphosphazenes were presented. The cis-dispiro (8–10) and trans-dispiro (11–13) cyclotriphosphazenes have two-equal stereogenic P-centers, and they can form cis (meso; RS/SR) and trans (racemic; RR/SS) optical isomers. The molecular and crystal structures of 7 and 11 were revealed by X-ray crystallography. The space group of compound 11 was found to be P − 1, and the absolute configurations of the centers P1 and P2 were determined as S and S, respectively. In addition, the antibacterial and antifungal activities of fourteen cyclotriphosphazenes against G(−) and G(+) bacteria and fungi were determined. The interactions of cyclotriphosphazenes with plasmid DNA were investigated using agarose gel electrophoresis. [ABSTRACT FROM AUTHOR]

As a naturally occurring small‐molecule, various optical isomers of chiral pyrrolo[2,1‐a]isoquinoline alkaloid crispine A represent a potential class of chiral molecules in contemporary organic chemistry, and possess diverse biological activities. The range of pharmacological activities include antidepressant, antiplatelet, antileukemic, and anticancer activities. This review provides an overview of the literature on the strategies, employed in the synthesis of crispine A in their racemic and enantiopure forms via Bischler‐Napieralski cyclization, Pictet‐Spengler cyclization, N‐Alkylation/Acylation‐cyclization, Oxidative cyclization, and Asymmetric hydrogenation in the period of 1931–2021. This study accentuates the need for the developing more effective synthesis, and search for involved biological applications for the pyrroloisoquinoline class of natural product. Attention has been drawn towards the use of relatively less documented but easily accessible naturally occurring diastereomeric scaffolds namely, garcinia and hibiscus acids. These lactones obtained from (+)‐ and (−)‐2‐hydroxycitric acids bearing chemically amenable functional groups are investigated as an ideal choice for the enantiopure synthesis of the (−)‐(R)‐ and (+)‐(S)‐Crispine A structural frame work. [ABSTRACT FROM AUTHOR]

Interest in studying the pheromone systems of animals has been growing from year to year. The Zygaenidae family (Insecta, Lepidoptera) taken as a model group for our studies includes more than 1000 species, but the structure of sex pheromones and sex attractants were only identified for a small number of species in two of the five subfamilies. The analysis of the published data on the chemical composition and structure of the known Zygaenidae sex pheromones and sex attractants allowed us to reveal specific features of their molecular structure potentially affecting attractive properties. The targeted synthesis of potential sex attractants with the given structural features was carried out from dodecanoic acid and stereoisomers of the chiral 2-butanol. Attractive properties of the compounds, R- and S-enantiomers of 2-butyl dodec-2-enoate, as well as the optically inactive racemic mixture of these esters, were studied for seven years in 14 countries worldwide. R- and S-enantiomers of 2-butyl dodec-2-enoate were shown to be sex attractants for males of 22 Zygaenidae species from six genera: Theresimima Strand, 1917 (1 species), Illiberis Walker, 1854 (1 species), Goazrea Mollet, 2016 (1 species), Rhagades Wallengren, 1863 (3 species), Adscita Retzius, 1783 (9 species), and Jordanita Verity, 1946 (7 species). In addition, attractive properties of 2-butyl dodec-2-enoate were found for three species of other Insecta families: Argyresthia semifusca (Haworth, 1828) (Lepidoptera, Yponomeutidae), Dolicharthria stigmosalis (Herrich-Schäffer, 1848) (Lepidoptera, Crambidae), and Tilloidea unifasciata (Fabricius, 1787) (Coleoptera, Cleridae). Male olfactory receptors, which perceive chemical signals, can differentiate optical isomers. Some species were attracted mainly by the R-enantiomer of 2-butyl dodec-2-enoate; some, by the S-enantiomer, and for others, the racemic mixture was biologically active. Ecological and faunistic studies of new synthetic sex attractants supported the discovery of two new species and one genus of Procridinae (Zygaenidae). They also allowed clarification of distribution boundaries of rare species and studies of their biology. The use of the synthesized compounds for the detection and monitoring of seasonal dynamics of pest species counts (Theresimima ampellophaga (Bayle-Barelle, 1808), Rhagades (Rhagades) pruni ([Denis & Schiffermüller], 1775), Illiberis (Primilliberis) pruni Dyar, 1905) seems promising for optimization of pest control with consideration of modern environmental protection requirements. In addition, the data on the functioning and structures of Procridinae attractants in combination with traditional morphological and cytogenetic approaches can be used for the analysis of phylogenetic relationships and support biosystematics in Zygaenidae. [ABSTRACT FROM AUTHOR]

• P. acidilactici TY112 consumed mannose and glucose for pure L -lactic acid production. • P. acidilactici ZP26 consumed mannose and glucose for pure D -lactic acid production. • Both strains consumed mannose in diluted spruce hydrolysate. Softwood is of interest as a renewable carbon source for production of lactic acid. Softwood hydrolysate contains a high content of mannose. Lactic acid production from mannose by two modified strains, L -lactic acid producing Pediococcus acidilactici TY112 and D -lactic acid producing ZP26, was investigated in the current work. The two strains efficiently converted mannose to L - and D -lactate isomers with an optical purity exceeding 99 %, although the mannose utilization rates were lower than the glucose utilization rates. The mannose conversion to L - and D -lactic acids by P. acidilactici was also confirmed in dilute spruce hemicellulose hydrolysate. The present study provides important knowledge on utilization of the spectrum of fermentable sugars in softwood for future production of chiral lactic acid from lignocellulose feedstocks. [ABSTRACT FROM AUTHOR]

Enantiomers differ greatly in their pharmacological and toxicological activities, and chirality is closely correlated with many significant biological processes; the separation of racemates is of great importance. Compared with traditional chiral separation methods such as crystallization, chromatographic separation and kinetic enzyme resolution, use of solid-state enantioselective membranes has the advantages of low energy consumption, simple equipment, and sustainable operation. Therefore, they are more suitable for the needs of large-scale industrial production. Herein, we discuss the theoretical and experimental developments in the emerging field of solid-state chiral separation membranes, focusing on the fundamental mechanisms of chiral molecule transport. Moreover, we highlight the advantages and disadvantages of different types of chiral separation membranes and their potential functional characteristics. Finally, the future trends of solid-state enantioselective membranes are proposed in this review, and we hope to provide some helpful ideas for researchers in the area. [ABSTRACT FROM AUTHOR]

Hydroxychloroquine (2-[[4-[(7-Chloroquinolin-4-yl) amino]pentyl](ethyl) amino]-ethanol, HCQ), an effective anti-malarial drug, has been tested in the clinics for potential treatment of severe coronavirus disease 2019 (COVID-19). Despite the controversy around the clinical benefits of HCQ, the existence of a chiral center in the molecule to possess two optical isomers suggests that there might be an enantiomeric difference on the treatment of COVID-19. Due to their poor resolution and the inability of quantification by previously reported methods for the analysis of HCQ enantiomers, it is necessary to develop an analytical method to achieve baseline separation for quantitative and accurate determination of the enantiomeric purity in order to compare the efficacy and toxicity profiles of different enantiomers. In this study, we developed and validated an accurate and reproducible normal phase chiral high-performance liquid chromatography (HPLC) method for the analysis of two enantiomers of HCQ, and the method was further evaluated with biological samples. With this newly developed method, the relative standard deviations of all analytes were lower than 5%, and the limits of quantification were 0.27 μg/ml, 0.34 μg/ml and 0.20 μg/ml for racemate, R- and S-enantiomer, respectively. The present method provides an essential analytical tool for preclinical and clinical evaluation of HCQ enantiomers for potential treatment of COVID-19. [ABSTRACT FROM AUTHOR]

In this work, the enantioselective toxicity and oxidative stress of hexaconazole on MCF-7 cells were investigated.. The activities of MCF-7 cells were tested after the exposure of hexaconazole enantiomers by CCK-8 kit. The changes of LDH release, ROS production, SOD and CAT enzyme activities were measured by oxidative damage kits. Results showed that cell activities decreased from 85.24%, 87.11% and 103.87% to 4.07%, 5.11% and 5.24%, respectively, after the treatment of (−)-, (+)- and rac-hexaconazole in the range of 10-160 mg/L. (−)-Hexaconazole exhibited the highest inhibitory rate on MCF-7 cell activity, followed by (+)- and rac-hexaconazole. Oxidative damage results showed that after hexaconazole exposure at the concentrations of 20, 40 and 80 mg/L, the intracellular LDH release and CAT enzyme activity were gradually increased with the increase of the concentration, while ROS production and SOD activity were increased first and then decreased with the increase of the concentration. Similar to cytotoxicity results, (−)-hexaconazole induced the highest cell oxidative damage. In conclusion, the toxicity order to MCF-7 cells was (−)-hexaconazole > (+)-hexaconazole > rac-hexaconazole. The results of this study provided a basis for further exploring the cytotoxicity mechanism of hexaconazole and the food safety risk assessment. [ABSTRACT FROM AUTHOR]

Chirality is ubiquitous in nature. Enantiomers have highly similar physicochemical proper ties, however. enantiomers especially chiral drugs behave rather differently in physiological activity. Therefore. it is of significant importance in analytical chemistry and life sciences for the chiral recognition of enantiomers. Although more and more attention has been paid to the development of chiral recognition techniques in recent years, it is still an important and challenging task to develop novel chiral recognition technologies which is rapid. sensitive and simple to operate. In this paper. we first re viewed the widely accepted three mechanisms of chiral recognition. and then summarized some common chiral recognition techniques including those reported by our group and outlined the advantages and limits of these known chiral recognition techniques. which is important for further development of high-efficient chiral recognition techniques. [ABSTRACT FROM AUTHOR]

• Ketamine has recently been used as an antidepressant drug. • (R)-Ketamine might exert "protective effects" against some psychotomimetic features. • Ketamine compositions used for treating depression might require inclusion of (R)-ketamine. • An ideal (R / S)-ketamine-ratio might range from 2:1 to 4:1 (R)-ketamine:(S)-ketamine. Ketamine and its (S)-enantiomer show distinct psychological effects that are investigated in psychiatric research. Its antidepressant activity may depend on the extent and quality of these psychological effects which may greatly differ between the enantiomers. Previous data indicate that the (S)-ketamine isomer is a more potent anesthetic than (R)-ketamine. In contrast, in subanesthetic doses (R)-ketamine seems to elicit fewer dissociative and psychotomimetic effects compared to (S)-ketamine. In this randomized double-blind placebo-controlled trial the effects of (R / S)-ketamine and (S)-ketamine on standardized neuropsychological and psychopathological measures were compared. After an initial bolus equipotent subanesthetic doses of (R / S)- and (S)-ketamine or placebo were given by continuous intravenous infusion to three groups of 10 healthy male volunteers each (n = 30). (R / S)-Ketamine and (S)-ketamine produced significant psychopathology and neurocognitive impairment compared to placebo. No significant differences were found between (R / S)-ketamine and (S)-ketamine. (S)-Ketamine administration did not result in reduced psychopathological symptomatology compared to (R / S)-ketamine as suggested by previous studies. However, this study revealed a somewhat more "negatively experienced" psychopathology with (S)-ketamine, which opens questions about potential "protective effects" associated with the (R)-enantiomer against some psychotomimetic effects induced by the (S)-enantiomer. As the antidepressant effect of ketamine might depend on a pleasant experience of altered consciousness and perceptions and avoidance of anxiety, the ideal ketamine composition to treat depression should include (R)-ketamine. Moreover, since preclinical data indicate that (R)-ketamine is a more potent and longer acting antidepressant compared to (S)-ketamine and (R/S)-ketamine, randomized controlled trials on (R)-ketamine and comparative studies with (S)-ketamine and (R/S)-ketamine are eagerly awaited. [ABSTRACT FROM AUTHOR]

[Display omitted] β 2 -Adrenergic receptor (β 2 AR) agonists have been reported to stimulate glucose uptake (GU) by skeletal muscle cells and are therefore highly interesting as a possible treatment for type 2 diabetes (T2D). The chirality of compounds often has a great impact on the activity of β 2 AR agonists, although this has thus far not been investigated for GU. Here we report the GU for a selection of synthesized acyclic and cyclic β-hydroxy-3-fluorophenethylamines. For the N -butyl and the N -(2-pentyl) compounds, the (R) and (R,R) (3d and 7e) stereoisomers induced the highest GU. When the compounds contained a saturated nitrogen containing 4- to 7-membered heterocycle, the (R,R,R) enantiomer of the azetidine (8a) and the pyrrolidine (9a) had the highest activity. Altogether, these results provide pivotal information for designing novel β 2 AR agonist for the treatment of T2D. [ABSTRACT FROM AUTHOR]

In recent years, there have been numerous incidents of serious accidents related to impurities of optical isomers, particularly in pharmaceutical treatment, environmental problems, and pesticide application. Among these impurities, chiral epichlorohydrin (ECH) is an important C3 synthon and a potentially genotoxic impurity. The enantiopure forms of S-ECH and R-ECH are key raw materials for synthesizing many drugs, which make it important to accurately quantify the specific conformation of chiral epichlorohydrin in pharmaceuticals. In this paper, we achieved the separation of chiral ECH by gas chromatography (GC) and based on the combination of vibrational circular dichroism (VCD) experiments and theoretical calculations, the qualitative method of chiral ECH was achieved without relying on a single enantiomeric standard. [Display omitted] • By comparing the theoretical VCD spectra of the single ECH enantiomer with the experimental VCD spectra of the R/S-ECH mixture, the configuration of the dominant enantiomer in the nonracemic mixture was determined. • Combined theoretical and experimental VCD spectra with GC, the peak of R/S-ECH in GC was successfully identified. A GC method for the determination of chiral ECH independent of a single enantiomer standard is first proposed. • The concentration of the single ECH enantiomer in the mixture can be accurately quantified. [ABSTRACT FROM AUTHOR]

In order to devise more effective penetration enhancers, 4-O-acylterpineol derivatives which were expected to be hydrolyzed into nontoxic metabolites by esterase in the living epidermis, were synthesized from 4-terpineol (4-TER) enantiomers and straight chain fatty acids. Their promoting activities on the SR-flurbiprofen and its enantiomers were tested across full-thickness rabbit skin, as well as to correlate under in vitro and in vivo conditions. The permeation studies indicated that both d-4-O-acylterpineol and l-4-O-acylterpineol had significant enhancing effects, interestingly, d-4-O-aclyterpineol had higher enhancing effects than l-4-O-aclyterpineol with the exception of d-4-methyl-1-(1-methylethyl)-3-cyclohexen-1-yl octadec-9-enoate (d-4-T-dC18). The mechanism of 4-O-acylterpineol facilitating the drug penetration across the skin was confirmed by Attenuated total reflection-Fourier transformed infrared spectroscopy (ATR-FTIR) and molecular simulation. The mechanism of penetration enhancers promoting drug release was explored by the in vitro release experiment. Finally, a relative safety skin irritation of enhancers was also investigated by in vivo histological evaluation. The present research suggested that d-4-O-aclyterpineol and l-4-O-aclyterpineol could significantly promote the penetration of SR-flurbiprofen and its enantiomers both in vitro and in vivo, with the superiorities of high flux and low dermal toxicity. [ABSTRACT FROM AUTHOR]

Tetrahydroisoquinoline (THIQ) scaffolds are important structural units that widely exist in a variety of natural alkaloids and synthetic analogues. Asymmetric synthesis of C1-chiral THIQ is of particular importance due to its significant pharmaceutical, agrochemical, and other biological activities, and the usually distinct bioactivities exhibited by the two enantiomers. In this review, we highlight the significant advances achieved in this field, present recent asymmetric synthesis with imines in isoquinoline rings ordered according to the sequence of various substrate types. New strategies could be inspired and more types of substrates need further development. 1 Introduction 2 Catalytic Asymmetric Reaction of Dihydroisoquinolines 2.1 Asymmetric Reactions of 3,4-Dihydroisoquinolines 2.2 Asymmetric Reactions of Dihydroisoquinolinium Salts 2.3 Asymmetric Reactions of C , N -Cyclic N ′-Acyl Azomethine Imines 2.3.1 NED [3+2] Cycloaddition of C , N -Cyclic N ′-Acyl Azomethine Imines 2.3.2 IED [3+2] Cycloaddition of C , N -Cyclic N ′-Acyl Azomethine Imines 2.3.3 [3+3] Cycloaddition of C , N -Cyclic N ′-Acyl Azomethine Imines 2.3.4 [4+3] Cycloaddition of C , N -Cyclic N ′-Acyl Azomethine Imines 2.3.5 Asymmetric Addition Reactions to C , N -Cyclic N ′-Acyl Azomethine Imines 2.4 Asymmetric Reactions of C , N -Cyclic Nitrones 3 Catalytic Asymmetric Mannich Reactions of Isoquinolines 4 Conclusions and Perspectives [ABSTRACT FROM AUTHOR]

Dufulin is a new type of chiral antiplant virus agent independently developed in China. The present study was conducted to determine the effects of different concentrations of rac‐dufulin and dufulin enantiomers (1, 5, and 10 mg/L) on oxidative stress in Tubifex after exposure for 3, 7, and 14 d. Results showed that rac‐dufulin and individual enantiomers had no significant effects on total protein content and glutathione reductase activities. Increased superoxide dismutase demonstrated the generation of superoxide anion radical. The increase in glutathione S‐transferase may be due to detoxification mechanisms. The different changes in catalase activities could be due to oxidative stress. The increase in malondialdehyde may be due to the accumulation and toxicity of contaminations. The degradation behavior of dufulin enantiomers was studied through spiked‐water and spiked‐soil tests. The degradation rate of S‐(+)‐dufulin was faster than that of R‐(−)‐dufulin. The present study demonstrated the occurrence of enantioselectivity in the degradation and oxidative stress of dufulin to Tubifex. In spiked soil, the concentrations of dufulin enantiomers in underlying soil were significantly higher than those in overlying water; but after 5 d of degradation, the bioturbation of Tubifex could facilitate part of dufulin diffusing from the underlying soil into the overlying water and altered the partitioning of dufulin. The present study provided a basis for conducting environmental safety risk assessments and rationally using dufulin as a chiral pesticide. Environ Toxicol Chem 2020;39:2136–2146. © 2020 SETAC [ABSTRACT FROM AUTHOR]

Short ranged potentials and their anisotropy produce spontaneous chiral resolution in a two dimensional model of patchy particles introduced in this paper. This model could represent an equimolar binary mixture (racemic mixture) of two kinds of chiral molecules (enantiomers) adsorbed to a bidimensional domain where only lateral short ranged interactions are present. Most racemic mixtures undergo chiral resolution due to their spatial anisotropy, the combined effect of long range forces and the thermodynamic conditions. The patchy particles are modeled as a hard disk and four different bonding sites located to produce chirality. Phase behavior and structural properties are analysed using Discontinuous Molecular Dynamics in the canonical ensemble. When the four patchy particles are separated by the angles {60°, 120°, 60°, 120°}, spontaneous chiral resolution is produced, given by the formation of homochiral clusters, if started from the corresponding racemic mixture. Gel behavior is also obtained in all the systems for low temperatures and low densities. [ABSTRACT FROM AUTHOR]

The R,R and S,S enantiomers of N,N'‐bis(1‐phenylpropyl)‐2,6‐pyridinedicarboxamide, L(Et), react with Ln3+ ions (Ln = La, Eu, Gd, and Tb) to give stable [Ln((R,R)‐ and (S,S)‐L(Et))3]3+ in anhydrous acetonitrile solution, as evidenced by various spectroscopic measurements, including NMR and luminescence titrations. In addition to the characteristic Eu3+ and Tb3+ luminescence bands, the steady‐state and time‐resolved luminescence spectra of the aforementioned complexes show the residual ligand‐centered emission of the 1ππ* to 3ππ* states, indicating an incomplete intersystem crossing (ISC) transfer from the 1ππ* to 3ππ* and ligand‐to‐Ln3+ energy transfer, respectively. The high circularly polarized luminescence (CPL) activity of [Eu(L(Et))3]3+ confirms that using a single enantiomer of L(Et) induces the preferential formation of one chiral [Eu(L(Et))3]3+ complex, consistent with the [EuL3]3+ complexes formed with other ligands derived from a 2,6‐pyridine dicarboxamide moiety. Furthermore, the CPL sign patterns of complexes with (R,R) or (S,S) enantiomer of L(Et) are consistent with the CPL sign pattern of related [LnL3]3+ complexes with the (R,R) or (S,S) enantiomer of the respective ligands in this family. [ABSTRACT FROM AUTHOR]

Methods for the synthesis of optical isomers of monoamine complexones derived from dicarboxylic amino acids and their complexes with 3d-metals are considered. The physicochemical properties of the compounds in question were studied and a number of specific properties of the complexes were revealed. An approach was proposed to the study of quantitative relationships between the chemical composition, structure, and properties of chemical substances. [ABSTRACT FROM AUTHOR]

The contribution of Russian experts to the development of HPLC is significant; they have proposed and developed new chromatography methods, adsorbents, and instruments. New applications of HPLC are proposed, in particular, for the separation of viruses, nanoparticles, optical isomers, peptides, and other compounds. HPLC has become widely used in Russia for the control of contamination of food products, medicines, and environmental samples, for the early diagnosis of dangerous diseases, for solving the problems of forensic chemistry and criminalistics. [ABSTRACT FROM AUTHOR]