Chirality最新文献

L-3,4-dihydroxyphenylalanine (L-DOPA or Levodopa) is widely used to treat Parkinson's disease, but its large-scale chemical synthesis is costly and environmentally challenging. This study investigates the enzymatic conversion of L-tyrosine to L-Dopa to enhance efficiency and yield without any potential racemization. Tyrosinase, extracted from button mushrooms, was immobilized as cross-linked enzyme aggregates (TY CLEAs), achieving an activity of 31.32 units/g. Commercially available skim milk served as a protein feeder and demonstrated antioxidant properties, helping prevent the formation of L-dopachrome as a byproduct by inhibiting the sequential oxidation of L-dopaquinone, along with ascorbic acid as a reducing agent. We evaluated the stability of TY CLEAs under varying temperatures, pH levels, and organic solvents. High productivity of 1210.95 mgL⁻¹ h⁻¹ was achieved using 10 units of enzyme at a substrate concentration of 15 mM with the use of a surfactant.

³¹P is a very attractive nucleus for nuclear magnetic resonance (NMR) analysis because of the large chemical dispersion and the simplicity of the spectra when compared with other nuclei (other than ¹⁹F). The ability to rapidly and quantitatively assay for enantiomeric excess (ee) measurements of alcohols, amines, thiols, and other chiral species using ³¹P-NMR is essential. Analysis of ee is particularly important in the pharmaceutical industry because a majority of medicinal compounds contain chiral centers, and enantiomers may possess different pharmacological activities. Although high-performance liquid chromatography (HPLC) with chiral stationary phase has become the standard method for ee determination, it can often be expensive and time consuming and requires purified samples. ³¹P-NMR offers advantages over many other nuclei as the interpretation is rapid and can have large chemical shift differences (Δδ) when comparing diastereomers. Proton decoupling avoids overlapping signals by preventing proton coupling, which could result in overlapping signals. With the rapid growth of asymmetric organocatalysis and asymmetric synthesis, the ability to quickly determine ee via phosphorus containing chiral derivatizing agents (CDAs) and chiral solvating agents (CSAs) is of utmost utility. It might be especially useful if used to determine ee directly in a reaction mixture, thereby alleviating any need for purification. This review focuses on ee determination by ³¹P-NMR.

This study has been carried out to extend the validation of an amino alcohol catalyst in the asymmetric transfer hydrogenation (ATH) of ketones. Previously, the catalyst was tested in asymmetric addition to several aromatic aldehydes with good to excellent results. After having optimized the reaction conditions and tested different amino residues, the best catalyst was tested in ATH of various aromatic ketones, leading to generally high yields (up to > 95%) and moderate to good enantioselectivities (ee 24%–69%). Moreover, considering the lack of examples of recoverable and reusable amino alcohol–based nanostructured catalysts for the ATH, the catalyst of choice was immobilized on proper functionalized superparamagnetic core–shell magnetite–silica nanoparticles and employed in an ATH reaction in semi-homogeneous phase. The obtained nanocatalyst exhibited a moderate catalytic efficiency in the ATH, that remains unchanged in the three catalytic cycles performed, even if noticeably worse than in the homogeneous counterpart.

By utilizing β-cyclodextrin (β-CD) and bovine serum albumin (BSA) as chiral selectors, a simple method was employed to fabricate an electrochemical sensor that modified with aminoized multiwall carbon nanotubes (NH2-MWCNT) and silver nanoparticles (AgNPs). The appearance and structure of the chiral sensor were characterized through X-ray powder diffraction, scanning electron microscopy, transmission electron microscope, Fourier transform infrared spectroscopy, ultraviolet–visible spectrophotometer, and X-ray photoelectron spectroscopy. The electrochemical chiral recognition behavior of the phenylalanine (Phe) enantiomer was achieved by differential pulse voltammetry. The working chiral recognition is based on the “three-point action principle.” The hydrogen bond between chiral selectors and Phe is the key to chiral recognition. Under the optimal experimental conditions, the oxidation peak current ratio of D-Phe to L-Phe (ID/IL) was 1.71. In the linear range of 3–15 mM, the detection limits of D-Phe and L-Phe are 4.62 and 5.23 μM (S/N = 3), respectively. It is noteworthy that the sensor possessed good stability and reproducibility.

Molecular docking analysis of linalool interaction with mitogen-activated protein kinase 1 (MAPK1) provides valuable insights into the potential binding mechanisms and affinity of this interaction. Linalool, a naturally occurring terpene alcohol, has been the subject of increasing interest due to its diverse pharmacological properties, including anti-inflammatory, antioxidant, and anticancer activities. MAPK1 is a crucial signaling protein involved in various cellular processes, including cell proliferation, differentiation, and survival. Using MOE software, we conducted a stereoisomer analysis of (R)- and (S)-linalool in our study. After docking, the ligand was ranked according to their binding energy and the best lead compound was selected based on the highest binding energy. The results showed that the S-linalool isomer showed superior anticancer activity, while the R-linalool molecule showed less activity. This interaction could provide insights into linalool's potential therapeutic applications, highlighting its diverse pharmacological properties.

Dibenzoyl-L-tartaric acid (L-DBTA) is a crucial compound in the synthesis of chiral molecules, particularly within the pharmaceutical industry. Ensuring the enantiomeric purity of L-DBTA is essential for regulatory compliance, quality control, and process optimization. To achieve this, a high-performance liquid chromatography (HPLC) method was developed and validated for determining the D-DBTA content in L-DBTA. The method validation adhered to ICH Q2(R2) guidelines, covering parameters such as system suitability, solution stability, robustness, linearity, range, limit of detection (LOD), limit of quantification (LOQ), accuracy, and precision. HPLC separation was performed using a Chiral PAK IA column (250 × 4.6 mm, 5.0 μm) with an isocratic mobile phase consisting of n-heptane, isopropanol (IPA), and trifluoroacetic acid (900:100:1 v/v/v). The column temperature was maintained at 40°C, and the sample cooler was kept at ambient conditions. Detection was carried out at 230 nm, achieving a resolution greater than 1.5 between L-DBTA and D-DBTA. The method demonstrated excellent linearity over a range of 30%–200% of the specification limit, with accuracy and range established from the LOQ level to 200%. Solution stability was confirmed for 1 day at room temperature, and precision was validated at both the LOQ and 100% levels. All validation parameters met the acceptance criteria, confirming the method's suitability for routine testing and batch release at quality control sites. This HPLC method is both sensitive and selective, ensuring the reliable determination of chiral purity in L-DBTA and its impurities.

This article reports the synthesis of a molecularly imprinted phenolic formaldehyde resin for the selective recognition of the cationic S-enantiomer of venlafaxine. The resin was developed through the condensation polymerization of p-hydroxybenzoic acid (4-HBA) and 4-nitrophenol (4-NP) with formaldehyde in an acidic medium. The resultant polymer was reduced to introduce amino groups into the polymer to obtain a dual-functional resin with amino and carboxylic groups (CA-P). After the uptake of S-VF, glutaraldehyde cross-linking stabilized the resin and formed its enantioselective cavities. Adsorption studies showed that optimum conditions occurred at pH 7, whereas the maximum adsorption capacity was 420 mg/g according to the Langmuir isotherm. The selectivity coefficient of S-VF-IP was 13 times that of NIP, confirming that the imprinting process indeed occurred. Chiral separation experiments using the SV-imprinted polymer (S-VF-IP) column resulted in 98% enantiomeric excess for R-VF, whereas the respective NIP did not provide any enantioselectivity. These results show a great possibility of the developed resin in efficient enantioselective separation and offer a promising method for the purification of chiral drugs from racemic mixtures in pharmaceutical applications.

The simultaneous presence of natural and magnetic optical activity in chiral samples is a very interesting occurrence, but it may lead to incorrect data interpretation if appropriate care is not taken. Moving from simple but general principles, here we show which effects are possible and which are not in such cases.