Elucidation of the enantioselective recognition mechanism of a penicillin G acylase-based chiral stationary phase towards a series of 2-aryloxy-2-arylacetic acids. | LitMetric
A series of structurally related 2-aryloxy-2-arylacetic acids (1-3, 5-16) together with a thioisostere derivative (4) have been synthesized and characterized by GC-MS and 1H NMR. The designed compounds were analyzed on a Penicillin G Acylase chiral stationary phase (PGA-CSP) and the influence of the structure variations on retention and enantioselectivity was investigated. The chromatographic study includes the direct separation of the enantiomers of the synthesized compounds and the determination of the elution order of selected racemic mixtures. 10 out of 16 racemates were separated; high chromatographic enantioseparation factors (alpha > 2) were achieved for some compounds. For the enantiomers of four compounds whose absolute configuration was known (1, 3, 12, 16), the elution order was R:S with the exception of 2-(4-chloro-phenoxy)phenylacetic acid (1), for which the elution order was reversed. Preliminary molecular modeling studies suggest that both polar and charge-transfer interactions as well as steric effects play an important role in determining the retention factors and the enantioselectivities observed.
State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China;3. University of Chinese Academy of Sciences, Beijing 100049, China.
Post-transcriptional ribonucleic acid (RNA) modifications play crucial roles in regulating gene expression, with both eukaryotic and prokaryotic RNA exhibiting more than 170 distinct and ubiquitous modifications. RNA turnover generates numerous free nucleosides, including unmodified nucleosides and a variety of modified ones. Unlike unmodified nucleosides, modified nucleosides are not further degraded or used in the salvage-synthesis pathway owing to a lack of specific enzymes, which leads to the cytosolic accumulation or cellular efflux of modified nucleosides.
State Key Laboratory for Quality Ensurance and Sustainable Use of Dao-di Herbs, National Resource Center for Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing 100700, China; Institute of Collaborative Innovation in Great Health, College of Biotechnology and Food Science, Tianjin Key Laboratory of Food Biotechnology, Tianjin University of Commerce, Tianjin 300134, China. Electronic address:
Huo-Xiang-Zheng-Qi Mixture is a renowned traditional Chinese medicine formula used to treat ailments associated with dampness pathogens. This study employed ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry to perform a comprehensive qualitative and quantitative analysis of the chemical compounds in Huo-Xiang-Zheng-Qi Mixture. A total of 155 compounds were identified, including 61 flavonoids and their glycosides, 36 phenylethanoid glycosides, 23 saponins, 14 coumarins, 9 organic acids, 1 amino acid, 2 nucleosides and purines, and 9 additional compounds.
Mixture analysis is crucial in many areas of chemistry, and a wide variety of separation methods are in use. A common method for physical separation is high-performance liquid chromatography (HPLC), but resolution is a problem: chemically similar species coelute. An alternative approach is diffusion-ordered NMR spectroscopy (DOSY), in which the signals of mixture components are separated according to the diffusion coefficient.
Lysergic acid diethylamide (LSD) analogs, often referred to as new psychoactive substances, are synthesized to mimic controlled substances while evading drug regulations. This study emphasizes the challenges of identifying these compounds, particularly their isomeric forms. Gas chromatography-mass spectrometry (GC-MS) and UV spectroscopy were employed to analyze 13 LSD analogs.
Safe, effective pain management remains one of the biggest challenges following surgical procedures. Despite widespread recognition of this problem and advances in the mechanistic understanding of pain signaling, post-surgical pain is often undermanaged, with opioid use remaining the clinical standard. As an alternative to current oral, systemic treatments, a degradable bupivacaine-loaded poly(ester urea) (PEU) thin film has been developed to deliver bupivacaine directly to the site of injury over an extended duration.
