Isocratic rapid liquid chromatographic method for simultaneous determination of carotenoids, retinol, and tocopherols in human serum

Fast and Easy Simultaneous Determination of Riboflavin, Folic Acid, All-Trans-Retinol and α-Tocopherol in Human Serum by LC/MS/MS for Bariatric Patients

The aim of this study was to develop and validate methods for the determination of vitamins B2, B9, E and A in serum using liquid chromatography with mass spectrometry (MS) detection. Vitamin analysis was performed using an ultra performance liquid chromatography combined with tandem MS. The compounds were separated on a BEH C18 RP column (2.1 × 100 mm, 1.7 μm) using a gradient elution with an analysis time of 10 min. Sample preparation included protein precipitation with ethanol. The concentration range in human serum was as follows: riboflavin 5-1000 nmol/L, folic acid 2.5-250 nmol/L, α-tocopherol 0.5-100 μmol/L and all-trans-retinol 25-2500 nmol/L. Accuracy and precision were validated according to Food and Drug Administration guidelines, with coefficients of variation ranging from 3.1-11.7% and recoveries from 94.4-107.5%. Routine monitoring of the complex range of vitamins in bariatric medicine is still not common. This is despite the fact that patients are at risk for glitch deficits, especially of a neurological nature. An analytical method that allows for the complex measurement of both water-soluble and fat-soluble vitamins is important and necessary for the clinical monitoring of bariatric patients. The method we have described could benefit both clinical practice and nutritional research.

Inherited causes of exocrine pancreatic insufficiency in pediatric patients: clinical presentation and laboratory testing

Pediatric patients with exocrine pancreatic insufficiency (EPI) have symptoms that include abdominal pain, weight loss or poor weight gain, malnutrition, and steatorrhea. This condition can be present at birth or develop during childhood for certain genetic disorders. Cystic fibrosis (CF) is the most prevalent disorder in which patients are screened for EPI; other disorders also are associated with pancreatic dysfunction, such as hereditary pancreatitis, Pearson syndrome, and Shwachman-Diamond syndrome. Understanding the clinical presentation and proposed pathophysiology of the pancreatic dysfunction of these disorders aids in diagnosis and treatment. Testing pancreatic function is challenging. Directly testing aspirates produced from the pancreas after stimulation is considered the gold standard, but the procedures are not standardized or widely available. Instead, indirect tests are often used in diagnosis and monitoring. Although indirect tests are more widely available and easier to perform, they have inherent limitations due to a lack of sensitivity and/or specificity for EPI.

Vitamin A Update: Forms, Sources, Kinetics, Detection, Function, Deficiency, Therapeutic Use and Toxicity

Vitamin A is a group of vital micronutrients widely present in the human diet. Animal-based products are a rich source of the retinyl ester form of the vitamin, while vegetables and fruits contain carotenoids, most of which are provitamin A. Vitamin A plays a key role in the correct functioning of multiple physiological functions. The human organism can metabolize natural forms of vitamin A and provitamin A into biologically active forms (retinol, retinal, retinoic acid), which interact with multiple molecular targets, including nuclear receptors, opsin in the retina and, according to the latest research, also some enzymes. In this review, we aim to provide a complex view on the present knowledge about vitamin A ranging from its sources through its physiological functions to consequences of its deficiency and metabolic fate up to possible pharmacological administration and potential toxicity. Current analytical methods used for its detection in real samples are included as well.

Simple and sensitive dilute-and-shoot analysis of carotenoids in human plasma

Carotenoids in human plasma are used as biomarkers of vegetable and fruit intake. Large sample volumes and intensive sample processing make measurement of these species cumbersome. We developed a dilute-and-shoot method for the quantitation of α-carotene, β-carotene, β-cryptoxanthin, lycopene and lutein/zeaxanthin using 10 μL of plasma. Plasma was injected into methanol containing internal standard and deproteinized by centrifugation. The carotenoids in the supernatant were separated using a YMC C-30 column and quantified by tandem mass spectrometry. The linearity for carotenoids ranged from sub-fmol to approximately 300 fmol on-column. Spike recovery experiments were used to correct for matrix effects. The method was validated using the human plasma standard NIST SRM 968e. Over 400 sample analyses were performed using the same guard and analytical columns. This method represents an improvement over current techniques because of the small sample size needed, ease of sample preparation, and improvement in the determination of carotenoid content.

Effects of Multivitamin, Multimineral and Phytonutrient Supplementation on Nutrient Status and Biomarkers of Heart Health Risk in a Russian Population: A Randomized, Double Blind, Placebo Controlled Study

The primary objective of this clinical study was to evaluate the effect of a dietary multivitamin, multimineral and phytonutrient (VMP) supplement on blood nutrient status and biomarkers of heart health risk in a Russian population. One hundred twenty healthy adults (40-70 years) were recruited for a 56-day (eight-week) randomized, double blind, placebo controlled study with parallel design. Subjects were divided into two groups and received either a VMP or a placebo (PLA) supplement. Blood nutrient levels of β-carotene, α-tocopherol, vitamin C, B6, B12, red blood cell (RBC) folate, Zinc and Selenium were measured at baseline and on Days 28 and 56, and quercetin was measured at baseline and on Day 56. Blood biomarkers of heart health, i.e. homocysteine (Hcy), high-sensitivity C-reactive protein (hs-CRP), oxidized LDL (ox-LDL), gamma-glutamyl transferase (GGT), uric acid and blood lipid profile, were measured at baseline and Day 56. Dietary VMP supplementation for 56 days significantly increased circulating levels of quercetin, vitamin C, RBC folate and partially prevented the decline in vitamin B6 and B12 status. Both serum Hcy and GGT were significantly reduced (-3.97 ± 10.09 µmol/L; -1.68 ± 14.53 U/L, respectively) after VMP supplementation compared to baseline. Dietary VMP supplementation improved the nutrient status and reduced biomarkers of heart health risk in a Russian population.

An improved method for fast and selective separation of carotenoids by LC-MS

Carotenoids are a large class of compounds that are biosynthesized by condensation of isoprene units in plants, fungi, bacteria, and some animals. They are characteristically highly conjugated through double bonds, which lead to many isomers as well susceptibility to oxidation and other chemical modifications. Carotenoids are important because of their potent antioxidant activity and are the pigments responsible for color in a wide variety of foods. Human consumption is correlated to many health benefits including prevention of cancer, cardiovascular disease, and age-related disease. Extreme hydrophobicity, poor stability, and low concentration in biological samples make these compounds difficult to analyze and difficult to develop analytical methods for aimed towards identification and quantification. Examples in the literature frequently report the use of exotic stationary phases, solvents, and additives, such as ethyl acetate, dichloromethane, and methyl tert-butyl ether that are incompatible with liquid chromatography mass spectrometry (LC-MS). In order to address these issues, we implemented the use of LC-MS friendly conditions using a low-hydrophobicity cyano-propyl column (Agilent Zorbax SB-CN). We successfully differentiated between isomeric carotenoids by optimizing two gradient methods and using a mixture of 11 standards and LC-MS in positive ionization mode. Three complex biological samples from strawberry leaf, chicken feed supplement, and the photosynthetic bacterium Chloroflexus aurantiacus were analyzed and several carotenoids were resolved in these diverse backgrounds. Our results show this methodology is a significant improvement over other alternatives for analyzing carotenoids because of its ease of use, rapid analysis time, high selectivity, and, most importantly, its compatibility with typical LC-MS conditions.

Tolerability and Safety of Combined Glatiramer Acetate and N-Acetylcysteine in Relapsing-Remitting Multiple Sclerosis

INTRODUCTION

Multiple sclerosis (MS) is an autoimmune disorder of the central nervous system where inflammation and neurodegeneration play key roles. Mounting evidence implicates oxidative stress in the development of irreversible neuronal and glial injury in this condition. N-acetylcysteine (NAC) is a sulfhydryl amino acid derivative with antioxidant and antiapoptotic properties. Administration of NAC to mice attenuated the induction of or improved experimental autoimmune encephalomyelitis (an MS model).

METHODS

We performed an open-label study to explore the tolerability and safety of the combination of glatiramer acetate (GA) and NAC in patients with relapsing-remitting multiple sclerosis at the outpatient MS clinics of the Jewish General Hospital and Hôpital Charles Lemoyne, Montreal, Canada. Seven patients with relapsing-remitting multiple sclerosis with at least one T1 gadolinium-enhancing lesion on screening magnetic resonance imaging were recruited. Treatment consisted of a 10-week run-in period followed by 36-week treatment with a combination of GA 20 mg subcutaneously once daily plus NAC 2.5 g orally twice daily. Outcome measures included safety and tolerability, redox biochemistry, and magnetic resonance imaging effect.

RESULTS

Treatment with the combination of GA and NAC was safe and well tolerated.

CONCLUSIONS

In light of the favorable safety profile, an efficacy-demonstrating study may be considered.

A New Method to Simultaneously Quantify the Antioxidants: Carotenes, Xanthophylls, and Vitamin A in Human Plasma

A simple and accurate reversed phase high-performance liquid chromatography coupled with diode array detector (HPLC-DAD) method for simultaneously determining and quantifying the antioxidants carotenes, xanthophylls, and retinol in human plasma is presented in this paper. Compounds were extracted with hexane, a C30 column, and a mobile phase of methanol, methyl tert-butyl ether, and water were used for the separation of the compounds. A total of 8 carotenoids, 3 Z-β-carotene isomers, and 1 fat-soluble vitamin (retinol) were resolved within 72 min at a flow rate of 0.6 mL/min. Detection was achieved at 450 nm for carotenoids and 330 nm for retinol. To evaluate the effectiveness of themethod, it has been applied to an intervention study conducted on eight volunteers. Results. Limits of detection were between 0.1 μg/mL for lycopene and astaxanthin and 1.3 μg/mL for 15-Z-β-carotene. Recoveries were ranged between 89% and 113% for α-carotene and astaxanthin, respectively. Accuracy was between 90.7% and 112.2% and precision was between 1% and 15% RSD. In human plasma samples compounds studied were identified besides three lycopene isomers, demonstrated to be suitable for application in dietary intervention studies. Conclusions. Due to its accuracy, precision, selectivity, and reproducibility, this method is suitable to dietary habits and/or antioxidants status studies.

High serum level of retinol and α-tocopherol affords protection against oral cancer in a multiethnic population

BACKGROUND

A comparative cross-sectional study involving oral cancer patients and healthy individuals was designed to investigate associations between retinol, α-tocopherol and β-carotene with the risk of oral cancer.

MATERIALS AND METHODS

This study included a total of 240 matched cases and controls where subjects were selected from the Malaysian Oral Cancer Database and Tissue Bank System (MOCDTBS). Retinol, α-tocopherol and β-carotene levels and intake were examined by high-performance liquid chromatography (HPLC) and food frequency questionnaire (FFQ) respectively.

RESULTS

It was found that results from the two methods applied did not correlate, so that further analysis was done using the HPLC method utilising blood serum. Serum levels of retinol and α-tocopherol among cases (0.177±0.081, 1.649±1.670μg/ml) were significantly lower than in controls (0.264±0.137, 3.225±2.054μg/ml) (p<0.005). Although serum level of β-carotene among cases (0.106±0.159 μg/ml) were lower compared to controls (0.134±0.131μg/ml), statistical significance was not observed. Logistic regression analysis showed that high serum level of retinol (OR=0.501, 95% CI=0.254-0.992, p<0.05) and α-tocopherol (OR=0.184, 95% CI=0.091-0.370, p<0.05) was significantly related to lower risk of oral cancer, whereas no relationship was observed between β-carotene and oral cancer risk.

CONCLUSIONS

High serum levels of retinol and α-tocopherol confer protection against oral cancer risk.

Analytical tools for the analysis of β-carotene and its degradation products

β-Carotene, the precursor of vitamin A, possesses pronounced radical scavenging properties. This has centered the attention on β-carotene dietary supplementation in healthcare as well as in the therapy of degenerative disorders and several cancer types. However, two intervention trials with β-carotene have revealed adverse effects on two proband groups, that is, cigarette smokers and asbestos-exposed workers. Beside other causative reasons, the detrimental effects observed have been related to the oxidation products of β-carotene. Their generation originates in the polyene structure of β-carotene that is beneficial for radical scavenging, but is also prone to oxidation. Depending on the dominant degradation mechanism, bond cleavage might occur either randomly or at defined positions of the conjugated electron system, resulting in a diversity of cleavage products (CPs). Due to their instability and hydrophobicity, the handling of standards and real samples containing β-carotene and related CPs requires preventive measures during specimen preparation, analyte extraction, and final analysis, to avoid artificial degradation and to preserve the initial analyte portfolio. This review critically discusses different preparation strategies of standards and treatment solutions, and also addresses their protection from oxidation. Additionally, in vitro oxidation strategies for the generation of oxidative model compounds are surveyed. Extraction methods are discussed for volatile and non-volatile CPs individually. Gas chromatography (GC), (ultra)high performance liquid chromatography (U)HPLC, and capillary electrochromatography (CEC) are reviewed as analytical tools for final analyte analysis. For identity confirmation of analytes, mass spectrometry (MS) is indispensable, and the appropriate ionization principles are comprehensively discussed. The final sections cover analysis of real samples and aspects of quality assurance, namely matrix effects and method validation.

Green extraction methods and environmental applications of carotenoids-a review

This review covers and discusses various aspects of carotenoids including their chemistry, classification, biosynthesis, extraction methods (conventional and non-conventional), analytical techniques and biological roles in living beings.

Supplemental β-carotene I: effect on plasma vitamin A, growth, performance, and carcass characteristics of feedlot cattle

To evaluate the effects of β-carotene (βC) on performance and carcass characteristics, 112 crossbred calves were allotted to 4 treatments consisting of retinyl palmitate (RP) supplemented at 2200IU/kg, and synthetic β-carotene supplemented at 1 (SβC1X), 5 (SβC5X), or 10 (SβC10X) times RP. Compared to RP, SβC1X did not impact performance (P≥0.25) or plasma concentrations of retinoids or carotenoids (P≥0.26). Increasing dietary βC increased (P≤0.04) plasma concentrations of RP and all of the isomers of βC, but did not affect weight, gain, or gain:feed (P≥0.24). Marbling and fat thickness did not differ between RP and SβC1X or because of amount of βC (P≥0.35). Lightness (L*) of LM decreased with increasing concentration of SβC (linear; P=0.01). Yellowness (b*) increased (P=0.04) and redness (a*) tended to increase (P=0.09) in subcutaneous fat as SβC amount increased (quadratic).

Validation and application of sub-2 μm core-shell UHPLC-UV-ESI-Orbitrap MS for identification and quantification of β-carotene and selected cleavage products with preceding solid-phase extraction

A validated ultrahigh-performance liquid chromatography method using 1.7 μm core–shell particles is presented for the identification and quantification of β-carotene (BC) and related cleavage products (CPs) in primary cell culture media. Besides BC, apo-4′-, apo-8′-, apo-10′-, and apo-12′-carotenals, as well as 5,6-epoxy-β-carotene, were selected as target analytes. Detection was performed via an 80-Hz diode array detector and an electrospray ionization–linear quadrupole ion trap–Orbitrap XL mass spectrometer, both hyphenated in series. Total analysis time was below 6 min with peak widths <12 s. Addition of trifluoroacetic acid and tetrahydrofuran to the mobile phase allowed for the mass spectrometric detection of BC and related CPs and reduced peak tailing due to improved solubility of hydrophobic analytes. Intra-day and inter-day precision for UV and mass spectrometric detection were ≤1.5 % for retention times and ≤5.1 % for peak areas. Instrumental linearity was confirmed by Mandel’s fitting test between 0.25 (or 1.00 μg/mL) and 5.00 μg/mL for UV detection. The higher sensitivity of mass spectrometric detection allowed for the coverage of three concentration domains between 0.025 and 5.00 μg/mL in linearity testing. Homoscedasticity was confirmed between 0.10 and 5.00 μg/mL for Orbitrap XL MS. The limits of quantification were between 52.6 and 889.4 ng/mL for UV detection and between 19.3 and 102.4 ng/L for mass spectrometric detection. Offline solid-phase extraction from culture media fortified with BC and CPs provided intra- and inter-day recoveries between 65.8 and 102.4 % with coefficients of variation ≤6.2 %. Primary rat hepatocyte cultures treated with BC and subjected to different oxidative stress conditions contained 5,6-epoxy-BC and apo-4′-carotenal besides residual BC. Apparently, 5,6-epoxy-BC was formed in the medium via autoxidation of BC by ambient oxygen.

Ultra-performance liquid chromatographic determination of tocopherols and retinol in human plasma

A rapid, selective and sensitive ultra-performance liquid chromatography method has been developed for the detection and quantification of tocopherols and retinol in human plasma. Alpha-tocopherol, gamma-tocopherol and retinol are assayed using fluorescence detection. Excitation/emission wavelengths are 295/330 nm and 325/470 nm for the analysis of both tocopherols and retinol, respectively. Retinol acetate is employed as the internal standard. The reversed-phase method incorporates gradient elution with a mobile phase consisting of methanol and acetonitrile. Separation of vitamin compounds is achieved using a bridged ethyl hybrid C18 column. The retention times for retinol, retinol acetate, gamma-tocopherol and alpha-tocopherol are 1.6, 1.8, 3.9 and 4.3 min, respectively. The limits of quantification for retinol, gamma-tocopherol and alpha-tocopherol were 0.02, 0.02 and 0.1 µg/mL, respectively. The assay method is suitable for the analysis of tocopherols and retinol in human plasma. The method may be applied following the ingestion of foods fortified with these fat-soluble vitamins.

Simultaneous analysis of circulating 25-hydroxy-vitamin D3, 25-hydroxy-vitamin D2, retinol, tocopherols, carotenoids, and oxidized and reduced coenzyme Q10 by high performance liquid chromatography with photo diode-array detection using C18 and C30 columns alone or in combination

Circulating lipid-phase micronutrients (LPM) such as 25-hydroxylated D vitamers, retinol, tocopherols, carotenoids including their isomers, and coenzyme Q10 play important roles in health maintenance and disease prevention and can serve as useful biomarkers. We developed fast, affordable, and accurate HPLC assays that simultaneously measured all above LPM in a single run using UV/VIS detection at 265nm, 295nm, and 480nm with (1) a C18 column alone; (2) a C30 column alone; or (3) each of these columns connected in series. The C18 column alone could separate all major LPM of interest in less than 17min but insufficiently resolved the lycopene isomers, the 25-hydroxylated D vitamers, lutein from zeaxanthin and β- from γ-tocopherol. The C30 column alone separated all LPM of interest including many isomeric analytes but failed to resolve the Q10 compounds, which co-eluted with carotenoids. Connecting the C18 and C30 columns in series with a detector after the C30 column and a pressure resistant detector between the columns resulted in ideal resolution and accurate quantitation of all LPM of interest but required software capable of processing the acquired data from both detectors. Connecting the C18 and C30 columns in series with exclusively one detector after the C30 column resulted in carotenoid-Q10 interferences, however, this was remedied by heart-cutting 2D-LC with a 6-port valve between the columns, which resolved all analytes in 42min. Faster run times led to some analytes not being resolved. Many variations of these methods are possible to meet the needs of individual requirements while minimizing sample material and turn-around-times.

Analysis of circulating lipid-phase micronutrients in humans by HPLC: review and overview of new developments

Retinol, tocopherols, coenzyme Q10, carotenoids, and vitamin D are lipophilic compounds shown to function as important health-protective agents by mitigating the damaging effects of oxidative and other injury. Scientific interest in evaluating these compounds has resurfaced in recent years, particularly in the nutritional, clinical and epidemiologic fields, and has precipitated the development of a multitude of new analytical techniques. This review considers recent developments in HPLC-based assays since 2007 for the simultaneous determination of these lipid-phase compounds utilizing exclusively serum or plasma as these matrices are mostly used in clinical and epidemiological investigations. We also provide an overview of blood measurements for selected carotenoids, tocopherols, coenzyme Q10 and retinol from the last 15years of healthy umbilical cord blood, children, and adults.

Determination of Retinol,α-Tocopherol, Lycopene, andβ-Carotene in Human Plasma Using HPLC with UV-Vis Detection: Application to a Clinical Study

A method is described here for the simultaneous determination of retinol,α-tocopherol, lycopene, andβ-carotene in human plasma. The effectiveness of various protein precipitants and extraction solvents was tested. After adequate sample preparation, the samples were injected directly into the HPLC system. The separation was realized on an analytical reversed-phase column with a UV-Vis detection. The analytical performance of this method was satisfactory. The intraassay and interassay coefficients of variation were below 10%. The recoveries were as follows: 97.0% (CV 2.4%) for retinol, 94.6% (CV 1.7%) forα-tocopherol, 91.9% (CV 3.6%) for lycopene, and 93.9% (CV 4.2%) forβ-carotene. The levels of selected fat-soluble vitamins in plasma of patients with cardiovascular disease were measured and discussed.

An excellent delivery system for improving the oral bioavailability of natural vitamin E in rats

This study set out to develop a novel and stable nanoemulsion formulation of natural vitamin E with increased oral bioavailability. The natural vitamin E nanoemulsion was prepared by a modified emulsification technique. The physicochemical characteristics of natural vitamin E nanoemulsion were characterized and its pharmacokinetics study was performed as well. The experimental results showed droplet diameters ranging from 20 to 400 nm (average, 87.7 nm) with a negative electrostatic potential (-23.5 ± 1.5 mv). The pharmacokinetics study of this nanoemulsion and corresponding soft capsule was carried out using noncompartment model method. Compared with the marketed soft capsule, the C (max) of the natural vitamin E nanoemulsion was higher, while the T (max) was shorter. Thus, plasma concentration-time profiles in rats dosed with nanoemulsion showed a 1.6-fold enhancement in the area under the curve of natural vitamin E compared with the marketed soft capsule. The antioxidative effects of the natural vitamin E nanoemulsion and the marketed soft capsule were also evaluated by the levels of superoxide dismutase (SOD) activity and malondialdehyde (MDA) concentration in serum and liver tissue. According to the SOD activity and the MDA concentration determined, the nanoemulsion was superior to the marketed soft as an antioxidative agent. The overall results demonstrated that the nanoemulsion drug delivery system could be a promising strategy for the delivery of natural vitamin E, which showed great potential for clinical application.

Optimization and validation of the reversed-phase high-performance liquid chromatography with fluorescence detection method for the separation of tocopherol and tocotrienol isomers in cereals, employing a novel sorbent material

The separation and determination of tocopherols (Ts) and tocotrienols (T3s) by reversed-phase high-performance liquid chromatography with fluorescence detection has been developed and validated after optimization of various chromatographic conditions and other experimental parameters. Analytes were separated on a PerfectSil Target ODS-3 (250 × 4.6 mm, 3 μm) column filled with a novel sorbent material of ultrapure silica gel. The separation of Ts and T3s was optimized in terms of mobile-phase composition and column temperature on the basis of the best compromise among efficiency, resolution, and analysis time. Using a gradient elution of mobile phase composed of isopropanol/water and 7 °C column temperature, a satisfactory resolution was achieved within 62 min. For the quantitative determination, α-T acetate (50 μg/mL) was used as the internal standard. Detection limits ranged from 0.27 μg/mL (γ-T) to 0.76 μg/mL (γ-T3). The validation of the method was examined performing intraday (n = 5) and interday (n = 3) assays and was found to be satisfactory, with high accuracy and precision results. Solid-phase extraction provided high relative extraction recoveries from cereal samples: 87.0% for γ-T3 and 115.5% for δ-T. The method was successfully applied to cereals, such as durum wheat, bread wheat, rice, barley, oat, rye, and corn.