Simultaneous Determination of Various Isothiocyanates by RP-LC Following Precolumn Derivatization with Mercaptoethanol

Numerous isothiocyanates (ITCs) are poorly soluble in water which causes their precipitation in aqueous mobile phases used in reversed phase liquid chromatography (RP-LC), thus impacting the accuracy of the quantification. By comparing the amounts of ITCs injected and released from the column, losses could be estimated at 5–32% depending on polarities and concentrations. Results could be dramatically improved in terms of separation and quantification using RP-LC with a mercaptoethanol precolumn derivatization aimed at avoiding ITCs precipitation. The cancer chemoprotective allyl-ITC and sulforaphane were found in cabbage extracts at 1.2 and 2.7 μg g−1 fresh weight, respectively

La vitamine B12 (intérêt thérapeutique et optimisation d'une méthode de dosage par CLPH et détection fluorimétrique)

STRASBOURG ILLKIRCH-Pharmacie (672182101) / SudocSudocFranceF

Development and validation of an ultra-high performance liquid chromatography-high resolution mass spectrometry method for simultaneous quantification of cyanogenic glycosides and secoisolariciresinol diglucoside in flaxseed (Linum usitatissimum L.)

International audienc

Online acetylcholinesterase inhibition evaluation by high-performance liquid chromatography–mass spectrometry hyphenated with an immobilized enzyme reactor

International audienceA high-performance liquid chromatography-mass spectrometry technique hyphenated on-line with an immobilized enzyme reactor (IMER) was developed by the use of 3 known acetylcholinesterase (AChE) inhibitors (galanthamine, huperzine A and tacrine). This bioanalytical device allows qualitative comparison of the inhibitory strengths of AChE inhibitors. The AChE inhibitory strengths were evaluated and compared by the corresponding acetylcholine peak areas (mass signal) obtained after a chromatographic separation and the elution through the IMER. Only one injection of the analytes is needed to get this comparative analysis. This bioanalytical device was then applied to the extract of a natural plant, Lycoris radiata, which is known to contain AChE inhibitors such as galanthamine and lycoramine. Aside from the demonstration of the inhibitory activity of the two known AChE inhibitors, the AChE inhibitory activity of another compound (dihydro-latifaliumin C) was revealed. This is the first report describing the AChE inhibitory activity of this compound. (C) 2019 Elsevier B.V. All rights reserved

Effects of Processing Steps on the Phenolic Content and Antioxidant Activity of Beer

International audienceA new analytical method (liquid chromatography-antioxidant, LC-AOx) was used that is intended to separate beer polyphenols and to determine the potential antioxidant activity of these constituents after they were allowed to react online with a. buffered solution of the radical cation 2,2 '-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS(center dot+)). Using the LC-AOx method, it was possible to demonstrate that the extent of the antioxidant activity was very much dependent on the phenolic compound considered. The method was also applied to the analysis of beer extracts and allowed the evaluation of their antioxidant activity at different steps of beer processing: brewing, boiling, and fermentation. This study showed that the total antioxidant activity remained unchanged throughout beer processing, as opposed to the polyphenolic content, which showed a 3-fold increase. Hopping and fermentation steps were the main causes of this increase. However, the increase measured after fermentation was attributed to a better extraction of polyphenols due to the presence of ethanol, rather than to a real increase in their content. Moreover, this method allowed the detection of three unknown antioxidant compounds, which accounted for 64 +/- 4% of the total antioxidant activity of beer and were individually more efficient than caffeic acid and epicatechin

Validation of a major modification of the mobile phase in the European Pharmacopoeia LC-UV human insulin assay

International audienceTo prevent the buildup of salt crystals inside the chromatograph tubing and pump that occurs with the high mobile phase sodium sulfate concentration (148 mM) used in the European Pharmacopoeia method for the quantification of human insulin, the use of a lower concentration was proposed. A minimal concentration of 37 mM sodium sulfate maintained the chromatographic performance while avoiding instrumental damage. This buffer concentration modification is considered as a major change by the European Pharmacopoeia and this improved method therefore had to be validated. Using a single-point calibration (600 µg.mL−1) yielded adequate precision (the highest relative standard deviations for repeatability and intermediate precision were <5% and <8%, respectively) and accuracy (bias values between −8% and +7%) for the quantification of human insulin in solutions of known concentration and in commercial insulin preparations. The limits of detection and quantification (1.6 and 4.5 µg.mL−1, respectively) were largely sufficient for the purpose of the metho

Blood Cell Palmitoleate-Palmitate Ratio Is an Independent Prognostic Factor for Amyotrophic Lateral Sclerosis.

Growing evidence supports a link between fatty acid metabolism and amyotrophic lateral sclerosis (ALS). Here we determined the fatty acid composition of blood lipids to identify markers of disease progression and survival. We enrolled 117 patients from two clinical centers and 48 of these were age and gender matched with healthy volunteers. We extracted total lipids from serum and blood cells, and separated fatty acid methyl esters by gas chromatography. We measured circulating biochemical parameters indicative of the metabolic status. Association between fatty acid composition and clinical readouts was studied, including ALS functional rating scale-revised (ALSFRS-R), survival, disease duration, site of onset and body mass index. Palmitoleate (16:1) and oleate (18:1) levels, and stearoyl-CoA desaturase indices (16:1/16:0 and 18:1/18:0) significantly increased in blood cells from ALS patients compared to healthy controls. Palmitoleate levels and 16:1/16:0 ratio in blood cells, but not body mass index or leptin concentrations, negatively correlated with ALSFRS-R decline over a six-month period (p<0.05). Multivariate Cox analysis, with age, body mass index, site of onset and ALSFRS-R as covariables, showed that blood cell 16:1/16:0 ratio was an independent prognostic factor for survival (hazard ratio=0.1 per unit of ratio, 95% confidence interval=0.01-0.57, p=0.009). In patients with high 16:1/16:0 ratio, survival at blood collection was extended by 10 months, as compared to patients with low ratio. The 16:1/16:0 index is an easy-to-handle parameter that predicts survival of ALS patients independently of body mass index. It therefore deserves further validation in larger cohorts for being used to assess disease outcome and effects of disease-modifying drugs

Blood cell 16:1/16:0 ratio correlates with disease progression and affects survival of ALS patients.

<p>Correlation between 16:1/16:0 and 18:0/18:1 ratios and disease duration (A, E) at blood collection or ALSFRS-R slope (B, F), determined as the decline of the score over a period of six months starting at the point of blood collection. Correlation coefficients (r) and <i>p</i>-values are indicated. n.s., non-significant <i>p</i>-value (Spearman test, n = 111). Based on the median ratio of the population, ALSFRS-R decline is shown in patients with low or high 16:1/16:0 ratio (C), and in patients with low or high 18:1/18:0 ratio (G). *<i>p</i><0.05 (Mann-Withney test). (D, H) Kaplan-Meier curves of survival in the subgroups of patients as above. Survival was the interval between the point of blood collection and death. <i>P</i>-values are indicated (Gehan-Breslow-Wilcoxon test, n = 117).</p