Recent trends in multidimensional countercurrent chromatography.

Countercurrent chromatography (CCC) is a potent separation approach known for its remarkable efficiency and capacity in preparation. It's applied as a substitute or combined with different chromatographic techniques, resulting in its rebranding as multidimensional CCC (MDCCC). Numerous essential mixtures from natural products contain hundreds or thousands of distinct components of importance. These mix types are too complicated to separate in any reasonable time using a single CCC dimension. However, if a multidimensional technique is utilized, where a complex mixture is separated by an initial dimension, smaller fractions of that separation are gathered. Each fraction is studied individually; complex mixes can be resolved relatively quickly. Thus, several MDCCC separation features have been studied to demonstrate their advantages, limitations, and prospective capacity to separate exceedingly complex mixtures. In this review, MDCCC aspects, including principles, multiple columns system, multilayer coil J-type, on-line monitoring system, and applications, have been thoroughly_explored.

Continuous chiral separation process for high-speed countercurrent chromatography established and scaled up: A case of Voriconazole enantioseparation.

An efficient method for the continuous separation of Voriconazole enantiomers was developed using sulfobutyl ether-ß-cyclodextrin (SBE-ß-CD) as a chiral selector in high-speed countercurrent chromatography (HSCCC) with different types. The separation was performed using a two-phase solvent system consisting of n-hexane/ethyl acetate/100 mmol/L phosphate buffer solution (pH = 3.0, containing 50 mmol/L SBE-ß-CD) (1.5:0.5:2, v/v/v). A fast and predictable scale-up process was achieved using an analytical DE HSCCC instrument. The optimized parameters were subsequently applied to a preparative Tauto HSCCC instrument, resulting in consistent separation time and enantiomeric purity, with throughput boosted by a remarkable 11-fold. Preparative HSCCC successfully separated 506 mg of the racemate, delivering enantiomers exceeding 99% purity as confirmed by high-performance liquid chromatography analysis. This investigation presents an effective methodology for forecasting the HSCCC scale-up process and attaining continuous separation of chiral drugs.

Prediction model for retention volumes of the three-phase solvent system in high-speed countercurrent chromatography.

Owing to its ability to separate substances with a broad scope of polarities, exploring the three-phase solvent systems (TPSSs) with high-speed countercurrent chromatography is a topic of interest in separation science, and their retention volumes should be more concerned. This study primarily investigates the behavior of retention volumes while examining the isolation abilities of the TPSS in the technique above. We took standard compounds, including sophoricoside, Sudan red 7B, and rotenone, which have a broad range of polarity, for investigation in this study and separated them using different four-liquid TPSSs made up of water, acetonitrile, methyl acetate, and n-hexane (WAMH). Our findings show that the retention volumes gradually alter in response to changes in phase polarity within the proposed solvent systems. With TPSSs, we preliminarily studied compound isolation and the promising formula of their retention volumes. The proposed solvent systems WAMH in different ratios showed high correlations and adjusted correlation coefficients above 0.9978 and 0.9913 for the actual and calculated retention volumes. This study will be particularly beneficial for researchers focusing on countercurrent chromatography with TPSSs, as it offers valuable time-saving insights.

Synthesis and Antimicrobial Activity Evaluation of Pyridine Derivatives Containing Imidazo[2,1-b][1,3,4]Thiadiazole Moiety.

Four series of novel pyridine derivatives (17 a-i, 18 a-i, 19 a-e, and 20 a-e) were synthesized and their antimicrobial activities were evaluated. Of all the target compounds, almost half target compounds showed moderate or high antibacterial activity. The 4-F substituted compound 17 d (MIC=0.5 µg/mL) showed the highest antibacterial activity, its activity was twice the positive control compound gatifloxacin (MIC=1.0 µg/mL). For fungus ATCC 9763, the activities of compounds 17 a and 17 d are equivalent to the positive control compound fluconazole (MIC=8 µg/mL). Furthermore, compounds 17 a and 17 d showed little cytotoxicity to human LO2 cells, and did not show hemolysis even at ultra-high concentration (200 µM). The results indicate that these compounds are valuable for further development as antibacterial and antifungal agents.

Separation of astragaloside IV from Astragalus membranaceus based on high-speed countercurrent chromatography in continuous injection mode.

INTRODUCTION: Astragaloside IV (AS-IV) is an index for the quality evaluation of the traditional Chinese medicine Astragalus and an important material basis for Astragalus to exert its medicinal effects, and it is difficult to obtain a single AS-IV by ordinary separation methods. OBJECTIVE: To find a new isolation method that can prepare AS-IV quickly and efficiently. METHODOLOGY: AS-IV was isolated from Astragalus membranaceus extract by high-speed countercurrent chromatography using a two-phase solvent system consisting of ethyl acetate/n-butanol/water (4.2:0.8:5, v/v) at a speed of 950 rpm at a flow rate of 2 mL/min using one of the high-speed countercurrent chromatographic sequential injection models developed during the previous study. RESULTS: Compared with the common countercurrent chromatographic separation, this separation method increased the injection volume and yield by 4-fold and 4.47-fold, respectively, with only about 1.2-fold increase in solvent consumption and separation time, and the purity was basically not reduced, and 55.9 mg of AS-IV, with a purity of 96.95%, was finally prepared from 400 mg of the crude extract in 240 min. CONCLUSION: The continuous injection mode of high-speed countercurrent chromatography was able to successfully prepare a large amount of AS-IV with high purity at one time.

Parental Autonomy Granting, Peer Attachment and Problematic Internet Use Among Chinese Adolescents: The Moderating Effect of School Climate.

While the correlation between parental autonomy granting and adolescents' problematic Internet use (PIU) has been confirmed, the processes underlying this connection have not been thoroughly investigated. Drawing on the ecological systems theory, this study sought to investigate the mediating mechanism of peer attachment and the moderating mechanism of school climate that link parental autonomy granting to PIU. A two-wave longitudinal design was employed with a time interval of six months. The participants were 852 adolescents who attended three middle schools located in Guangdong Province, China. Self-report questionnaires were used to obtain data on demographics, parental autonomy granting, peer attachment, school climate, and PIU. The findings indicated that peer attachment significantly mediated the link between parental autonomy granting and adolescent PIU. A positive school climate significantly moderated the influence of parental autonomy granting on peer attachment and the influence of peer attachment on PIU. Specifically, the association between parental autonomy granting and peer attachment and the association between peer attachment and PIU were more pronounced when the school climate was perceived to be positive. This research underscores the possible significance of peer attachment in the association between parental autonomy granting and PIU and offers valuable insights for mitigating the negative outcomes of PIU.

A Nomogram Based on Nutrition-Related Indicators and Computed Tomography Imaging Features for Predicting Preoperative Lymph Node Metastasis in Curatively Resected Esophagogastric Junction Adenocarcinoma.

BACKGROUNDS: Preoperative noninvasive tools to predict pretreatment lymph node metastasis (PLNM) status accurately for esophagogastric junction adenocarcinoma (EJA) are few. Thus, the authors aimed to construct a nomogram for predicting PLNM in curatively resected EJA. METHODS: This study enrolled 638 EJA patients who received curative surgery resection and divided them randomly (7:3) into training and validation groups. For nomogram construction, 26 candidate parameters involving 21 preoperative clinical laboratory blood nutrition-related indicators, computed tomography (CT)-reported tumor size, CT-reported PLNM, gender, age, and body mass index were screened. RESULTS: In the training group, Lasso regression included nine nutrition-related blood indicators in the PLNM-prediction nomogram. The PLNM prediction nomogram yielded an area under the receiver operating characteristic (ROC) curve of 0.741 (95 % confidence interval [CI], 0.697-0.781), which was better than that of the CT-reported PLNM (0.635; 95% CI 0.588-0.680; p < 0.0001). Application of the nomogram in the validation cohort still gave good discrimination (0.725 [95% CI 0.658-0.785] vs 0.634 [95% CI 0.563-0.700]; p = 0.0042). Good calibration and a net benefit were observed in both groups. CONCLUSIONS: This study presented a nomogram incorporating preoperative nutrition-related blood indicators and CT imaging features that might be used as a convenient tool to facilitate the preoperative individualized prediction of PLNM for patients with curatively resected EJA.

Design, synthesis, and evaluation of 2,2'-bipyridyl derivatives as bifunctional agents against Alzheimer's disease.

Alzheimer's disease (AD) is a complex multifactorial neurodegenerative disease. Metal ion dyshomeostasis and Aß aggregation have been proposed to contribute to AD progression. Metal ions can bind to Aß and promote Aß aggregation, and ultimately lead to neuronal death. Bifunctional (metal chelation and Aß interaction) compounds are showing promise against AD. In this work, eleven new 3,3'-diamino-2,2'-bipyridine derivatives 4a-4k were synthesized, and evaluated as bifunctional agents for AD treatment. In vitro Aß aggregation inhibition assay confirmed that most of the synthesized compounds exhibited significant self-induced Aß1-42 aggregation inhibition. Among them, compound 4d displayed the best inhibitory potency of self-induced Aß1-42 aggregation with IC50 value of 9.4 µM, and it could selectively chelate with Cu2+ and exhibited 66.2% inhibition of Cu2+-induced Aß1-42 aggregation. Meanwhile, compound 4d showed strong neuroprotective activity against Aß1-42 and Cu2+-treated Aß1-42 induced cell damage. Moreover, compound 4d in high dose significantly reversed Aß-induced memory impairment in mice.

An overview of recent progress in multiple dual-mode counter-current chromatography.

Counter-current chromatography is a chromatographic separation and purification technique being developed. The development of different elution modes has significantly contributed to this field. Multiple dual-mode elution is a method developed based on dual-mode elution, which consists of a series of changing cycles of the phase role and the direction by switching between normal and reverse elution modes of counter-current chromatography. This dual-mode elution method takes full advantage of the liquid nature of stationary and mobile phases of counter-current chromatography and effectively improves the separation efficiency. So, this unique elution mode has gained extensive attention for separating complex samples. This review mainly describes and summarizes in detail its development, applications, and characteristics in recent years. Meanwhile, its advantages, limitations, and future outlook also have been discussed in this paper.

[Advantages, development opportunities, and practice paths of traditional Chinese medicine in prevention and treatment of elderly comorbidities].

This article focused on the significant public health issue of comorbidities in the elderly population and highlighted the important role of traditional Chinese medicine(TCM) in the prevention and treatment of comorbidities in the elderly. It suggested that TCM should fully utilize its advantages in holistic perspective, syndrome differentiation and treatment, and preventive medicine in the process of preventing and treating comorbidities in the elderly. At the same time, in response to the significant shift in the disease spectrum of the elderly, the increasingly innovative concepts in diagnosis and treatment, the growing demand for proactive health by the el-derly population, and the current emphasis on patient-centered evaluation standards, it is necessary to further conduct basic theoretical and experimental research on comorbidities in the elderly using TCM, emphasize clinical research on comorbidities in the elderly, explore appropriate efficacy evaluation systems, improve TCM prevention and treatment strategies and comprehensive intervention programs for comorbidities in the elderly, and leverage the unique role of TCM in the rehabilitation of elderly comorbidity patients. By analyzing the potential of TCM in the field of comorbidities in the elderly, this article is expected to provide new insights for future clinical practice and scientific research.