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This review draws attention to the use of chiral monolithic silica HPLC columns for the enantiomeric separation and determination of chiral compounds. Properties and advantages of monolithic silica HPLC columns are also highlighted in comparison to conventional particle-packed, fused-core, and sub-2-µm HPLC columns. Nano-LC capillary monolithic silica columns as well as polymeric-based and hybrid-based monolithic columns are also demonstrated to show good enantioresolution abilities. Methods for introducing the chiral selector into the monolithic silica column in the form of mobile phase additive, by encapsulation and surface coating, or by covalent functionalization are described. The application of molecular modeling methods to elucidate the selector-selectand interaction is discussed. An application for enantiomeric impurity determination is also considered.

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This work reviews the literature of chiral capillary electrokinetic chromatography from January 2016 to March 2021. This is done to explore the state-of-the-art approach and recent developments carried out in this field. The separation principle of the technique is described and supported with simple graphical illustrations, showing migration under normal and reversed polarity modes of the separation voltage. The most relevant applications of the technique for enantioseparation of drugs and other enantiomeric molecules in different fields using chiral selectors in single, dual, or multiple systems are highlighted. Measures to improve the detection sensitivity of chiral capillary electrokinetic chromatography with UV detector are discussed, and the alternative aspects are explored, besides special emphases to hyphenation compatibility to mass spectrometry. Partial filling and counter migration techniques are described. Indirect identification of the separated enantiomers and the determination of enantiomeric migration order are mentioned. The application of Quality by Design principles to facilitate method development, optimization, and validation is presented. The elucidation and explanation of chiral recognition in molecular bases are discussed with special focus on the role of molecular modeling.

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Moringa oleifera (MO) is a highly nutritious plant, whose leaves and seed pods are consumed in Africa, Asia, sub-Himalayan regions and South America. A novel ultra-high performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method for the standardization of the bioactive thiocarbamate compound from MO, niazimicin (NZ) in seeds and leaves, is developed, optimized and validated according to the International Conference on Harmonization (ICH) guidelines, using desipramine as the internal standard. Multiple reaction monitoring detection of transitions 358.05>106.86 and 266.38 > 193.04 with collision energy of 25V and 40V, respectively were used. A gradient was optimized at 35-55%B in 7 min, where mobile phase A is aqueous 0.1% formic acid and B is 0.1% formic acid in acetonitrile. The method proved to be linear in the range of 0.05-100 µg/mL, precise, robust and accurate, with LOD and LOQ of 0.02 and 0.05 µg/mL, respectively. MO seeds were found to contain double NZ content (620 mg% ±3.2%) compared to leaves, and the methylene chloride fraction of seeds comprised triple the amount in ethyl acetate fraction (450 mg% ± 2.4%). Results emphasize that seeds of MO are a much richer source for NZ than the most commonly edible and marketed leaves extracts. The reported method can be used for standardization and quality control of the seeds and leaves NZ content.

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Cardiovascular diseases remain a major public health burden worldwide. It was reported that vitamin D protects the cardiovascular system through several mechanisms mainly by hindering atherosclerosis development. Genetic variations in vitamin D metabolic pathway were found to affect vitamin D levels. This study aimed at investigating the association between single nucleotide polymorphisms in genes involved in vitamin D metabolism, CYP27B and CYP24A1; 25-hydroxyvitamin D (25(OH)D) levels; and susceptibility to acute coronary syndrome (ACS). One hundred and eighty-five patients and 138 healthy controls were recruited. CYP24A1 rs2762939 was genotyped using fast real-time PCR, while CYP24A1 rs4809960 and CYP27B1 rs703842 were genotyped using polymerase chain reaction followed by restriction fragment length polymorphism (PCR-RFLP). 25(OH)D3 and 25(OH)D2 levels were measured using ultra-performance liquid chromatography tandem mass spectrum. Vitamin D level was significantly lower in patients than controls (p < 0.05). The GG genotype of rs2762939 was significantly associated with the risk of ACS development, but not correlated to the vitamin D level. rs4809960 and rs703842 genetic variations were not associated with ACS nor with 25(OH)D level. The genetic variant rs2762939 of CYP24A1 is remarkably associated with ACS. Meanwhile, the variants rs4809960 and rs703842 are not associated with ACS incidence.

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Quality-by-Design approach for enantioselective HPLC method development surpasses Quality-by-Testing in offering the optimal separation conditions with the least number of experiments and in its ability to describe the method's Design Space visually which helps to determine enantiorecognition to a significant extent. Although some schemes exist for enantiomeric separations on Cinchona-based zwitterionic stationary phases, the exact design space and the weights by which each of the chromatographic parameters influences the separation have not yet been statistically studied. In the current work, a screening design followed by a Response Surface Methodology optimization design were adopted for enantioseparation optimization of 3 model drugs namely the acidic Fmoc leucine, the amphoteric tryptophan and the basic salbutamol. The screening design proved that the acid/base additives are of utmost importance for the 3 chiral drugs, and that among 3 different pairs of acids and bases, acetic acid and diethylamine is the couple able to provide acceptable resolution at variable conditions. Visualization of the response surface of the retention factor, separation factor and resolution helped describe accurately the magnitude by which each chromatographic factor (% MeOH, concentration and ratio of acid base modifiers) affects the separation while interacting with other parameters. The global optima compromising highest enantioresolution with the least run time for the 3 chiral model drugs varied extremely, where it was best to set low % methanol with equal ratio of acid-base modifiers for the acidic drug, very high % methanol and 10-fold higher concentration of the acid for the amphoteric drug while 20 folds of the base modifier with moderate %methanol were needed for the basic drug. Considering the selected drugs as models for many series of structurally related compounds, the design space defined and the optimum conditions computed are the key for method development on cinchona-based chiral stationary phases.

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Aims: To examine the regulation of SREBP-1c and CAV1 by microRNA-29a (miR-29a) in cells infected with hepatitis C virus (HCV) in an attempt to control HCV-induced non-alcoholic fatty liver disease. Methods: In order to examine the manipulation of SREBP-1c and CAV1 by miR-29a, oleic acid (OA)-treated JFH-I-infected Huh-7 cells were used. OA was added 24 h post-transfection and gene expression was investigated by qRT-PCR at 48 h post treatment. The functional impact of the observed alteration in SREBP-1c and CAV1 expression was analyzed by examining lipid droplet (LD) and triglyceride (TG) content at 72 h post-OA treatment using light microscopy and spectrophotometry, respectively. Viral load was quantified by qRT-PCR at 72 h post-transfection. Results: OA treatment induced the expression of miR-29a and SREBP-1c, as compared to untreated cells. Forced miR-29a expression led to a significant up-regulation of SREBP-1c as well as CAV1 compared to mock untransfected cells. Ectopic expression of miR-29a resulted in a marked increase in LDs and their respective TGs, while miR-29a antagomirs decreased both the LD and TG content compared to mock untransfected cells. Moreover, forcing the expression of miR-29a in JFH-1 HCV-infected Huh-7 cells resulted in 53% reduction in viral titers compared to mock untransfected Huh-7 cells. Conclusion: Inducing miR-29a expression significantly induces SREBP-1c and CAV1 expression, thereby increasing LDs as well as their respective TGs. Nonetheless, forcing the expression of miR-29a resulted in reduction of HCV RNA levels in Huh-7 cells.

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Although high-performance liquid chromatography-mass spectrometry (HPLC-MS) is adopted as the method of choice for the determination of vitamin D and its metabolites in plasma, yet the unavailability of this expensive detection technique in many clinical laboratories makes ultraviolet (UV) detection the alternative of choice in many places worldwide. In this regard, determination of parameters affecting HPLC separation of vitamins D2, D3 and their hydroxyl metabolites in plasma in a systematic way would put an end to irrelevant trials for more optimization. A new robust HPLC-UV was developed, optimized using DryLab(®)2000 and validated for the determination of vitamins D2 and D3 and their 25-hydroxyl metabolites in plasma to achieve best resolution and least runtime where the metabolites elute in <10 min, where vitamin D2 is considered a feasible internal standard. Chromatographic parameters affecting resolution of the four peaks were specifically defined by a two-dimensional resolution map. Forty-six plasma samples were analyzed by the optimized method as well as by an ELISA kit to compare results and to judge validity of ELISA as a technique of clinical importance. Statistical analyses proved that the investigated assays were incomparable. Variation among subjects was detected by HPLC but not ELISA, concluding that HPLC-UV is the better tool in determining vitamin D status than ELISA.

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