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Morlock G.E.,Justus Liebig University | Meyer S.,Justus Liebig University | Zimmermann B.F.,University of Bonn | Zimmermann B.F.,Institute Prof. Dr. Georg Kurz GmbH | Roussel J.-M.,Analytical Methods Development and Validation Consulting
Journal of Chromatography A

A high-performance TLC (HPTLC) method was newly developed and validated for analysis of 7 steviol glycosides in 6 different types of food and Stevia formulations. After a minimized one-step sample preparation, 21 samples were developed in parallel, allowing an effective food screening. Depending on the sample application volume, the method was suited to analyze food sample concentrations in the mg/kg range. LOQs of stevioside in natural yoghurt matrix spiked at 0.02, 0.13 and 0.2% were determined by the calibration curve method to be 12. ng/band (peak height). ANOVA was successfully passed to prove data homogeneity in the working range (30-600. ng/band). The accuracy (recovery tolerance limit, 92-120%), repeatability (3.1-5.4%) and intermediate precision (4.0-8.4%) were determined for stevioside in milk-based matrix including sample preparation and recovery rates at 3 different concentration levels. For the first time, the recording of HPTLC-ESI-MS spectra via the TLC-MS Interface was demonstrated for rebaudioside A. HPTLC contents for rebaudioside A were compared with results of two (U)HPLC methods. The running costs and analysis time of the three different methods were discussed in detail with regard to screening of food products. © 2014 Elsevier B.V. Source

Chrubasik-Hausmann S.,Albert Ludwigs University of Freiburg | Vlachojannis C.,Albert Ludwigs University of Freiburg | Zimmermann B.F.,University of Bonn | Zimmermann B.F.,Institute Prof. Dr. Georg Kurz GmbH
Phytotherapy Research

The CE marking is a statutory marking for certain products sold within the European Economic Area. Medicinal products with a CE label are not regulated by the European Medicines Agency but are licensed according to the directives of the European Community. We have analysed the proanthocyanin (PAC) content of four cranberry CE products by both a photometric (DMAC method using 4-dimethylamino-cinnamic-aldehyde as colouring reagent) and a high-performance liquid chromatography assay and have compared the daily dosages recommended for the products by theirmanufacturers with benchmark doses obtained from the literature. For all CE products, the identified DMAC values for the PAC content per unit were below those declared. For two of the CE medicinal products, not even the manufacturers' maximum daily dosages have type A PAC contents that would have any chance of providing the health benefits promised on the product information sheets; the other two might have some chance, but only at maximum dosage (nine capsules per day for one of them). CE medicinal products should be better controlled by regulatory authorities to prevent consumers from buying and taking doses that are inadequate to provide the benefits claimed. Copyright © 2014 JohnWiley & Sons, Ltd. Source

Vlachojannis C.,Albert Ludwigs University of Freiburg | Zimmermann B.F.,University of Bonn | Zimmermann B.F.,Institute Prof. Dr. Georg Kurz GmbH | Chrubasik-Hausmann S.,Albert Ludwigs University of Freiburg
Evidence-based Complementary and Alternative Medicine

Preclinical in vitro and in vivo studies demonstrate potent effects of pomegranate preparations in cancer cell lines and animal models with chemically induced cancers. We have carried out one systematic review of the effectiveness of pomegranate products in the treatment of cancer and another on their safety. The PubMed search provided 162 references for pomegranate and cancer and 122 references for pomegranate and safety/toxicity. We identified 4 clinical studies investigating 3 pomegranate products, of which one was inappropriate because of the low polyphenol content. The evidence of clinical effectiveness was poor because the quality of the studies was poor. Although there is no concern over safety with the doses used in the clinical studies, pomegranate preparations may be harmful by inducing synthetic drug metabolism through activation of liver enzymes. We have analysed various pomegranate products for their content of anthocyanins, punicalagin, and ellagic acid in order to compare them with the benchmark doses from published data. If the amount of coactive constituents is not declared, patients risk not benefiting from the putative pomegranate effects. Moreover, pomegranate end products are affected by many determinants. Their declaration should be incorporated into the regulatory guidance and controlled before pomegranate products enter the market. © 2015 Christian Vlachojannis et al. Source

Mahler A.,Charite - Medical University of Berlin | Steiniger J.,Charite - Medical University of Berlin | Bock M.,Charite - Medical University of Berlin | Klug L.,Charite - Medical University of Berlin | And 8 more authors.
American Journal of Clinical Nutrition

Background: Muscle weakness and fatigue are common symptoms in multiple sclerosis (MS). Green tea catechins such as (-)epigallocatechin- 3-gallate (EGCG) are known to improve energy metabolism at rest and during exercise. Objective: We tested the hypothesis that EGCG improves energy metabolism and substrate utilization in patients with MS. Design: Eighteen patients (8 men) with relapsing-remitting MS (expanded disability status scale score <4.5, all receiving glatiramer acetate) participated in this randomized, double-blind, placebocontrolled, crossover trial at a clinical research center. All patients received EGCG (600 mg/d) and placebo over 12 wk (4-wk washout in between). After each intervention, fasting and postprandial energy expenditure (EE), as well as fat oxidation (FAOx) and carbohydrate oxidation (CHOx) rates, were measured either at rest or during 40 min of exercise (0.5 W/kg). At rest, blood samples and microdialysates from adipose tissue and skeletal muscle were also taken. Results: At rest, postprandial EE and CHOx, as well as adipose tissue perfusion and glucose supply, were significantly lower in men but higher in women receiving EGCG compared with placebo. During exercise, postprandial EE was lower after EGCG than after placebo, indicating an increased working efficiency (men > women). After placebo, exercise EE was mainly fueled by FAOx in both men and women. After EGCG, there was a shift to a higher and more stable CHOx during exercise in men but not in women. Conclusions: Our data indicate that EGCG given to patients with MS over 12 wk improves muscle metabolism during moderate exercise to a greater extent in men than in women, possibly because of sex-specific effects on autonomic and endocrine control. © 2015 American Society for Nutrition. Source

Nakae Y.,University of Geneva | Dorchies O.M.,University of Geneva | Stoward P.J.,University of Geneva | Zimmermann B.F.,University of Bonn | And 3 more authors.
Histochemistry and Cell Biology

In two separate previous studies, we reported that subcutaneous (sc) or oral administration of (-)-epigallocatechin- 3-gallate (EGCG) limited the development of muscle degeneration of mdx mice, a mild phenotype model for Duchenne muscular dystrophy (DMD). However, it was not possible to conclude which was the more efficient route of EGCG administration because different strains of mdx mice, periods of treatment and methods of assessment were used. In this study, we investigated which administration routes and dosages of EGCG are the most effective for limiting the onset of dystrophic lesions in the same strain of mdx mice and applying the same methods of assessment. Three-week-old mdx mice were injected sc for 5 weeks with either saline or a daily average of 3 or 6 mg/kg EGCG. For comparison, age-matched mdx mice were fed for 5 weeks with either a diet containing 0.1% EGCG or a control diet. The effects of EGCG were assessed quantitatively by determining the activities of serum muscle-derived creatine kinase, isometric contractions of triceps surae muscles, integrated spontaneous locomotor activities, and oxidative stress and fibrosis in selected muscles. Oral administration of 180 mg/kg/day EGCG in the diet was found the most effective for significantly improving several parameters associated with muscular dystrophy. However, the improvements were slightly less than those observed previously for sc injection started immediately after birth. The efficacy of EGCG for limiting the development of dystrophic muscle lesions in mice suggests that EGCG may be of benefit for DMD patients. © The Author(s) 2012. Source

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