The LC–MS method for the simultaneous analysis of selected fat-soluble vitamins and their metabolites in serum samples obtained from pediatric patients with cystic fibrosis

The investigation of connection between anticoagulant therapy and vitamin K homologues in human determined by LC-MS/MS

Aim: Differences are existed in the bioactivity among various vitamin K (VK) forms. To investigate the correlation between clinical parameters of initial anticoagulation and plasma levels of VK1 and VK2 (MK-4 and MK-7), it was necessary to establish a quantitative method for simultaneous determination.Materials & methods: Plasma samples in cardiovascular patients were extracted by cyclohexane and analyzed using a C18 column. Baseline concentrations of VK1, MK-4 and MK-7 were 0.98 ± 0.52 ng/ml, 0.45 ± 0.13 ng/ml and 0.65 ± 0.31 ng/ml, respectively. The concentrations of MK-7 and total VKs were significantly relevant to INR0, respectively (p = 0.010 and p = 0.048, respectively).Conclusion: Thus, when adjusting anticoagulation dosage, concentrations of various VK homologues might be considered.

Vitamin K Status Based on K1, MK-4, MK-7, and Undercarboxylated Prothrombin Levels in Adolescent and Adult Patients with Cystic Fibrosis: A Cross-Sectional Study

The available evidence on vitamin K status in cystic fibrosis (CF) is scarce, lacking data on vitamin K2 (menaquinones-MK). Therefore, we assessed vitamin K1, MK-4 and MK-7 concentrations (LC-MS/MS) in 63 pancreatic insufficient and modulator naïve CF patients, and compared to 61 healthy subjects (HS). Vitamin K1 levels did not differ between studied groups. MK-4 concentrations were higher (median <1st-3rd quartile>: 0.778 <0.589-1.086> vs. 0.349 <0.256-0.469>, p < 0.0001) and MK-7 levels lower (0.150 <0.094-0.259> vs. 0.231 <0.191-0.315>, p = 0.0007) in CF patients than in HS. MK-7 concentrations were higher in CF patients receiving K1 and MK-7 supplementation than in those receiving vitamin K1 alone or no supplementation. Moreover, vitamin K1 concentrations depended on the supplementation regime. Based on multivariate logistic regression analysis, we have found that MK-7 supplementation dose has been the only predictive factor for MK-7 levels. In conclusion, vitamin K1 levels in CF are low if not currently supplemented. MK-4 concentrations in CF patients supplemented with large doses of vitamin K1 are higher than in HS. MK-7 levels in CF subjects not receiving MK-7 supplementation, with no regard to vitamin K1 supplementation, are low. There do not seem to be any good clinical predictive factors for vitamin K status.

Analysis of vitamin K1 and major K2 variants in rat/human serum and lipoprotein fractions by a rapid, simple, and sensitive UHPLC-MS/MS method

Determination of the various forms of vitamin K, which are involved in coagulation and other physiological processes in humans, is challenging and no standardized method is yet available. Therefore, a reliable and practical method was developed to quantify vitamin K levels in serum and additionally in lipoprotein fractions to clarify its distribution. The LC-MS/MS method for the determination of vitamin K1 and the three main isoforms of vitamin K2 (MK-4, MK-7, MK-9) was combined with a gradient ultracentrifugation technique to allow the separation of lipoprotein fractions. The chromatographic separation was carried out on a Kinetex™ C18 column using a mobile phase consisting mainly of methanol. The target analytes were detected by electrospray ionization mass spectrometry. The separation of all four substances was achieved after a simple sample preparation technique based on miniaturized liquid-liquid extraction. Our method of only 8.5 min revealed the levels of the major forms of vitamin K in 59 human and 12 rat sera and confirmed our hypothesis that vitamin K is primarily (about 50 %) found in the high-density lipoprotein fraction. The median concentrations of vitamin K1, MK-4, MK-7, and MK-9 were found to be 1.19, 2.98, 0.43, and < 0.71 nmol/L in human serum and 1.74, 6.75, less than 0.2, and less than 0.5 nmol/L in rat serum, respectively.

Rapid simultaneous determination of 7 fat-soluble vitamins in human serum by ultra high performance liquid chromatography tandem mass spectrometry

Accurate detection of vitamins is critically important for clinical diagnosis, metabolomics and epidemiological studies. However, the amounts of different vitamins vary dramatically in human serum. It is a challenge to achieve simultaneous detection of multiple vitamins rapidly. Herein, we developed and validated a sensitive and specific method using ultra high-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) for simultaneous quantification of 7 fat-soluble vitamins (FSVs) across their physiological concentrations in serum for the first time, which was subjected to protein precipitation, liquid-liquid extraction to an organic phase, evaporation to dryness and reconstitution with acetonitrile. In the present procedure, retinol (vitamin A), ergocalciferol (25-OH-D2), cholecalciferol (25-OH-D3), α-tocopherol (vitamin E), phylloquinone (vitamin K1), menatetrenone-4 (MK-4), and menaquinone-7 (MK-7) were detected in one analytical procedure for the first time within 5.0 min by triple quadrupole tandem mass spectrometry. The limit of quantification (LOQ) for vitamin A was 10.0 ng mL-1, LOQs for 25-OH-D2 and 25-OH-D3 were 1.0 ng mL-1, LOQ for vitamin E was 100.0 ng mL-1, and LOQs for vitamin K1, MK-4 and MK-7 were 0.10 ng mL-1, respectively, with a correlation (R2) of 0.995-0.999. Recoveries ranged from 80.5% to 118.5% and the intra-day and inter-day coefficients of variance (CVs) were 0.72-8.89% and 3.2-9.0% respectively. The method was validated according to the European Medicines Agency (EMA) and U.S. Food and Drug guidelines and C62-A on bioanalytical methods, and was used for clinical routine determination.

Processes and Interactions Impacting the Stability and Compatibility of Vitamin K and Gold Nanoparticles

This study provides evidence on the stability of vitamin K1 (VK) in the form of phytomenadione, in the absence and presence of a therapeutic preparation, as the gold nanoparticles (AuNPs), under the effect of sodium halide ions. The degradation susceptibility of the two compounds was assessed individually and in mixtures by cyclic voltammetry and electrolysis at a constant current density assisted by UV-Vis spectrophotometry. Their interactions with the halide ions differently impact on the electrochemical processes as follows: (i) the fluoride ions weakly affects the VK/AuNP stability and compatibility; (ii) the presence of chloride ions leads to VK/AuNP stability, for a short time and restrictive compatibility; (iii) bromide ions induce instability and incompatibility of the VK/AuNP system; (iv) spontaneous interactions between VK/AuNPs and iodide ions take place, consequently defining as an unstable and incompatible system.

A novel LC-MS/MS method for the simultaneous analysis of selected fat-soluble vitamins in serum obtained from pediatric patients with pneumonia

Several observational studies have reported associations between low levels of fat-soluble vitamins (A, D and E) and the incidence of pneumonia. Whether infection affects or negatively regulates serum vitamin levels remains controversial. Our aims were to develop and validate a simple-pretreatment and fast method to determine the serum levels of selected fat-soluble vitamins, namely vitamin A (retinol), vitamin D (25-OH-D₃, 25-OH-D₂, and 3-epi-25-OH-D₃), and vitamin E (α-tocopherol), in children suffering from pneumonia during the acute phase and after inflammatory marker recovery. The sample preparation procedure involving protein precipitation and filtration was finished in one step, and separation took 8 min per sample. The calibrations were linear, with R² > 0.99. Both the intra-run (n = 6) and inter-run (n = 3) precision (relative standard deviation, RSD%) values were below 14.61%. The spiked recoveries at 3 concentrations ranged from 80.97 to 111.91%. Accuracies were calibrated using both National Institute of Standards and Technology serum (NIST 968f) and external quality assurance (EQA) samples offered by the National Center of Clinical Laboratories of China, and the relative error (RE%) values ranged from -13.17% to 12.53%. Clinical sample analysis revealed that infection did alter the serum retinol concentration and it did not alter the 25-OH-D and α-tocopherol levels in young children with pneumonia.

Absolute quantification of eleven A, D, E and K vitamers in human plasma using automated extraction and UHPLC-Orbitrap MS

Fat-Soluble Vitamers [FSV] deficiencies and hypervitaminosis are associated with lifestyle diseases such as cardiovascular disease, diabetes, and cancer. Quantification of FSV and their metabolites in plasma has proved to be one of the most demanding analytical chemistry challenges. Current FSV quantification methods are compromises between breadth of coverage and sensitivity across the physiological range. Here, we developed and validated a sensitive, robust, semi-automated method using liquid-liquid extraction coupled with LC-ESI-MS/MS to quantify 11 FSV across their physiological concentrations in plasma. The addition of Phree® phospholipid removal plates as the last step in the extraction process reduced matrix effects, improving precision, recoveries, and the method's final sensitivity. This method can detect and quantify: retinol, retinoic acid, retinyl palmitate, 25 hydroxyvitamin D₃ [25-OH-D₃], 1-α-25-dihydroxy-D_3, α-tocopherol, γ-tocopherol, α-tocotrienol, phylloquinone [K1], Menatetrenone [MK-4], and menaquinone-7 [MK-7].The Instrument Quantitation Limit [IQL]s for retinol (64.1 ng/mL), 25-OH-D₃ (10.2 ng/mL), and α-tocopherol (3000 ng/mL) can detect clinical deficiencies. Our automated method will assist in the understanding of the complex interaction between these compounds and their possible role in health and disease.

Design, Synthesis and Structure-Activity Relationship Studies of Glycosylated Derivatives of Marine Natural Product Lamellarin D

Lamellarin D, a marine natural product, acts as a potent inhibitor of DNA topoisomerase I (Topo I). To modify its physicochemical property and biological activity, a series of mono- and di-glycosylated derivatives were designed and synthesized through 22-26 multi-steps. Their inhibition of human Topo I was evaluated, and most of the glycosylated derivatives exhibited high potency in inhibiting Topo I activity as well as lamellarin D. All the 15 target compounds were evaluated for their cytotoxic activities against five human cancer cell lines. The typical lamellarin derivative ZL-3 exhibited the best activity with IC₅₀ values of 3 nM, 10 nM, and 15 nM against human lung cancer A549 cells, human colon cancer HCT116 cells and human hepatocellular carcinoma HepG2 cells. Compound ZL-1 exhibited anti-cancer activity with IC₅₀ of 14 nM and 24 nM against human colon cancer HCT116 cells and human hepatocellular carcinoma HepG2 cells, respectively. Cell cycle analysis in MDA-MB-231 suggested ZL-3 inhibited cell growth through arresting cells at the G2/M phase of the cell cycle. Further tests showed a significant improvement in aqueous solubility of ZL-1 and ZL-7. This study suggested that glycosylation could be utilized as a useful strategy to optimize lamellarin D derivatives as Topo I inhibitors and anticancer agents.

LC-MS/MS quantification of fat soluble vitamers - A systematic review

Fat soluble vitamers (FSV) are several biochemically diverse micronutrients essential for healthy development, growth, metabolism, and cell regulation. We cannot synthesize FSV completely or at the required concentrations. Deficiency or excess of FSV can result in many health problems. Plasma is the most accessible sample matrix for the quantification of FSV. However, due to its complexity and other analytical challenges (e.g., FSV sensitivity to light, oxygen, heat, pH, chemical heterogeneity, standard availability), developing a method for the simultaneous quantification of multiple FSV at physiological concentrations has been challenging. In this systematic review, we examine the parameters and criteria used in existing Liquid Chromatography with tandem Mass Spectrometry (LC-MS/MS) methods for FSV quantification to the extraction method, chromatographic resolution, matrix effects, and method validation as critical to a sensitive and robust method. We conclude that the final FSV method sensitivity is predominantly based on aforementioned criteria and future method development using LC-MS/MS will benefit from the application of this systematic review.

Quantification of fat-soluble vitamins and their metabolites in biological matrices: an updated review

Fat-soluble vitamins (FSVs) are micronutrients essential in maintaining normal physiological function, metabolism and human growth. Ongoing increased awareness regarding FSV concentrations and their impact on human growth along with disease progression warrant the need of developing selective and sensitive analytical methods. LC–MS/MS is currently the method of choice for accurate quantitation of FSVs. However, there are multiple approaches for extraction, separation and calibration of FSVs in biological matrices. This review discusses recent LC–MS/MS methods for the simultaneous quantification of FSVs in biological matrices and summarizes sample pretreatment procedures, chromatographic conditions and calibration approaches. Current challenges and clinical applications in various disease states are also highlighted.

UPLC-MS/MS method for determination of retinol and α-tocopherol in serum using a simple sample pretreatment and UniSpray as ionization technique to reduce matrix effects

Background

Our goal was to develop a simple, rapid and precise ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method for the determination of retinol and α-tocopherol in serum. Currently published LC-MS/MS methods either require complex extraction procedures (liquid-liquid or solid-phase) or do not meet desirable specifications for imprecision in serum (coefficient of variation [CV] <6.8% and 6.9%, respectively).

Methods

Sample preparation consisted of a simple protein precipitation with ethanol and acetonitrile. Stable isotope-labeled internal standards (IS) and a homemade calibration curve were used for quantification. The analysis was performed using an Acquity I-class Xevo TQ XS LC-MS/MS. Chromatographic runtime was 6.0 min using a reversed phase gradient elution. UniSpray (US) as an ionization technique was compared to electrospray ionization (ESI). Analytical validation included matrix effect, recovery and trueness compared to National Institute of Standards and Technology (NIST) standards and United Kingdom National External Quality Assessment Service (UK NEQAS) samples.

Results

Intra- and inter-run CVs were <4.9% for retinol and <1.7% for α-tocopherol, both complying with desirable specifications for imprecision. Bias compared to NIST standards was <3.1% for both compounds. The method was linear over the entire tested range. The lower limit of quantification (LLOQ) with US was lower than with ESI for both retinol (0.022 vs. 0.043 mg/L) and α-tocopherol (0.22 vs. 0.87 mg/L). Matrix effects were not significant (<15%) for retinol. However, for α-tocopherol matrix effects of on average 54.0% were noted using ESI, but not with US.

Conclusions

We developed a fast, precise and accurate UPLC-MS/MS method for the determination of retinol and α-tocopherol in human serum using a single-step sample pretreatment. Ionization using US eliminated the matrix effects for α-tocopherol.

A concise review of quantification methods for determination of vitamin K in various biological matrices

Vitamin K is an essential nutrient in the body and involved in numerous physiological and pathophysiological functions. Both the lack and surplus of vitamin K can put human health at risk. Therefore, it becomes necessary to monitor vitamin K concentrations in different biomatrices through establishing sensitive and specific analytical methods. This review collectively describes an updated overview of the sample pretreatment methodologies and methods for quantitative determination of vitamin K that have been used in last two decades. High Performance Liquid Chromatography (HPLC) is commonly utilized as a standard for separation of vitamin K in combination with different detection including spectroscopic, spectrometric, fluorometric and mass spectroscopy. Recent progress in sample pretreatment technologies and quantitation methodologies have enhanced the ability to identify and quantitate vitamin K in biomatrices to further advance our understanding of the role of this vitamin in human health and disease.

Neuroprotective Natural Molecules, From Food to Brain

The prevalence of neurodegenerative disorders is increasing; however, an effective neuroprotective treatment is still remaining. Nutrition plays an important role in neuroprotection as recently shown by epidemiological and biochemical studies which identified food components as promising therapeutic agents. Neuroprotection includes mechanisms such as activation of specific receptors, changes in enzymatic neuronal activity, and synthesis and secretion of different bioactive molecules. All these mechanisms are focused on preventing neuronal damage and alleviating the consequences of massive cell loss. Some neuropathological disorders selectively affect to particular neuronal populations, thus is important to know their neurochemical and anatomical properties in order to design effective therapies. Although the design of such treatments would be specific to neuronal groups sensible to damage, the effect would have an impact in the whole nervous system. The difficult overcoming of the blood brain barrier has hampered the development of efficient therapies for prevention or protection. This structure is a physical, enzymatic, and influx barrier that efficiently protects the brain from exogenous molecules. Therefore, the development of new strategies, like nanocarriers, that help to promote the access of neuroprotective molecules to the brain, is needed for providing more effective therapies for the disorders of the central nervous system (CNS). In order both to trace the success of these nanoplatforms on the release of the bioactive cargo in the CNS and determinate the concentration at trace levels of targets biomolecules by analytical chemistry and concretely separation instrumental techniques, constitute an essential tool. Currently, these techniques are used for the determination and identification of natural neuroprotective molecules in complex matrixes at different concentration levels. Separation techniques such as chromatography and capillary electrophoresis (CE), using optical and/or mass spectrometry (MS) detectors, provide multiples combinations for the quantitative and qualitative analysis at basal levels or higher concentrations of bioactive analytes in biological samples. Bearing this in mind, the development of food neuroprotective molecules as brain therapeutic agents is a complex task that requires the intimate collaboration and engagement of different disciplines for a successful outcome. In this sense, this work reviews the new advances achieved in the area toward a better understanding of the current state of the art and highlights promising approaches for brain neuroprotection.

New LC-MS/MS method with single-step pretreatment analyzes fat-soluble vitamins in plasma and amniotic fluid

Fat-soluble vitamins (FSVs), A, D, and E, are components of prenatal vitamin care. Previously, limited evidence existed to explain on a molecular level how maternal FSV supplementation affects the fetus during pregnancy. We developed a simplified LC-MS/MS method to simultaneously detect FSVs in maternal plasma (MP) and amniotic fluid (AF); we used this approach to investigate the correlation between FSV levels in these two matrices. With this method, we circumvented frequently used liquid-liquid extraction or solid-phase extraction methods and, instead, used simple protein precipitation with acetonitrile for sample preparation. This method displayed satisfactory linearity, intra- and inter-day imprecision, and accuracy. We validated the consistency with standard reference material 972a and 968f certification. In analysis of MP and AF samples from 50 pregnant women in the second trimester, concentrations of retinol, 25-hydroxyvitamin D3 [25(OH)D3], and α-tocopherol (reflecting vitamins A, D, and E, respectively) were lower in AF than in MP. Significant positive correlations existed between MP and AF for 25(OH)D3 (r = 0.667; P < 0.001) and retinol (r = 0.393; P = 0.005), but not for α-tocopherol (r = 0.145, P > 0.05). This novel LC-MS/MS method shows prominent applicability for FSV detection and the observed correlations contribute to research on fetal development.

Ultrafast determination of vitamin E using LC–ESI–MS/MS for preclinical development of new nutraceutical formulations

Aim: We proposed a rapid and high quality method to determine α-tocopherol (α-T) in different biopharmaceutical samples using liquid chromatography-diode array detector on-line ESI–MS/MS. Materials & methods: A working standard solution of α-T and internal standard, phenyl-5,7-dimethyl-d6-α-tocopherol, were used for optimization and validation of the method. Levels of α-T in nanoemulsions, serum and plasma samples were evaluated. Results & conclusion: Precision (1% for retention time, 5% for peak area and 3% for relative peak area), linearity range (among 0.625–20.0 μg ml-1), LOD and LOQ, accuracy and matrix effect were studied. The validated chromatographic method is presented as valuable analytical tool for the determination of α-tocopherol in loaded drug delivery systems and in biodistribution levels in blood samples.