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Gleichenhagen M.,University of Bonn | Zimmermann B.F.,University of Bonn | Zimmermann B.F.,Institute Prof. Dr. Kurz GmbH | Herzig B.,University of Bonn | And 5 more authors.
Food Chemistry | Year: 2013

The intrinsic isotopic labelling of plants with 13CO2 is an effective method to generate highly labelled compounds using photosynthesis and avoiding labour-intensive complex organic syntheses. In this study, the intrinsic isotopic labelling of polyphenols in parsley, spinach and peppermint is shown for the first time. The plants were grown in an atmosphere where 12CO2 was replaced by 13CO2, in order to generate highly labelled compounds. The total content of 13C as well as the individual polyphenols were analysed by Isotopic Ratio-MS and HPLC-Iontrap-MSn. After 34 days of plant growth under 13CO2, degree of labelling was found to be higher than 90 atom% 13C for most polyphenols, predominantly consisting of highly and fully labelled isotopomers; the total plant material contained more than 88 atom% 13C. Such highly labelled compounds can be used in future studies to dissect both metabolism and bioavailability of polyphenols in humans. © 2013 Elsevier Ltd. All rights reserved.


Zimmermann B.F.,University of Bonn | Zimmermann B.F.,Institute Prof. Dr. Kurz GmbH | Woelwer-Rieck U.,University of Bonn | Papagiannopoulos M.,University of Bonn | Papagiannopoulos M.,Weleda AG
Food Analytical Methods | Year: 2012

Stevia rebaudiana Bertoni contains several steviol glycosides with sweet flavour. They all are sweeter than sucrose (up to factor 450). The various steviol glycosides are difficult to separate by reversed-phase chromatography. In this paper, five different hydrophilic liquid interaction chromatography columns are characterized using isocratic elution (5-20% water in acetonitrile with buffer or formic acid). Separation of the steviol glycosides is possible with all but one of the tested columns, but the robustness of the separation against changes of buffer concentration and percentage of water differ. Aqueous percentage and ion strength of the eluent are the main factors to be optimized in method development. © 2011 Springer Science+Business Media, LLC.


Chrubasik-Hausmann S.,Albert Ludwigs University of Freiburg | Vlachojannis C.,Albert Ludwigs University of Freiburg | Zimmermann B.,University of Bonn | Zimmermann B.,Institute Prof. Dr. Kurz GmbH
Phytotherapy Research | Year: 2014

Two exploratory clinical studies investigating proprietary pomegranate products showed a trend of effectiveness in increasing prostate-specific antigen doubling time in patients with prostate cancer. A recent clinical study did not support these results. We therefore analysed a lot of the marketed pomegranate blend for co-active pomegranate compounds. The high-performance liquid chromatography method was used to detect punicalagin, ellagic acid and anthocyanins. Total polyphenoles were determined by the Folin-Ciocalteu method using gallic acid as reference. The results show that the co-active compounds in the daily dose of the pomegranate blend were far below those previously tested and that the photometric assessment is not reliable for the standardisation of study medications. Not pomegranate but the low amount of co-active compounds in the proprietary pomegranate blend was responsible for its clinical ineffectiveness. Copyright © 2014 John Wiley & Sons, Ltd.


Zimmermann B.F.,Institute Prof. Dr. Kurz GmbH | Zimmermann B.F.,University of Bonn | Walch S.G.,Zentrales Institute des Sanitatsdienstes der Bundeswehr Koblenz andernacher Strasse 100 | Walch S.G.,UMIT University for Health Sciences, Medical Informatics and Technology | And 3 more authors.
Journal of Chromatography B: Analytical Technologies in the Biomedical and Life Sciences | Year: 2011

Sage tea, the aqueous infusion of dried sage leaves (Salvia officinalis L.), is used as a form of food as well as a form of traditional herbal medicine. Several in vivo and in vitro studies point to sage polyphenols as active principles that may inhibit lipid peroxidation and improve antioxidant defences. This study describes an UHPLC methodology with MS/MS and UV detection, which allows the separation, identification and quantification of the major phenolic constituents in sage tea within 34 min, and was used to characterize 16 commercial brands of sage tea. The quantitatively dominating compounds were either rosmarinic acid (12.2-296 mg/L) or luteolin-7-O-glucoside (37.9-166 mg/L). In general, considerable differences in polyphenolic composition between the brands were detected, leading to the demand for quality standardization and control, especially if these sage teas are to be used for therapeutic purposes. © 2011 Elsevier B.V.


Walch S.G.,University of Medical Sciences and Technology | Walch S.G.,University of Federal Defense Munich | Tinzoh L.N.,Institute Prof. Dr. Kurz GmbH | Zimmermann B.F.,Institute Prof. Dr. Kurz GmbH | And 3 more authors.
Frontiers in Pharmacology | Year: 2011

Sage (Salvia officinalis L.) is used as an herbal medicinal product, with the most typical form of application as infusion with boiling water (sage tea). The well-established traditional uses include symptomatic treatment of mild dyspeptic complaints, the treatment of inflammations in the mouth and the throat, and relief of excessive sweating and relief of minor skin inflammations. In this study, sage teas prepared from commercially available products were chemically analyzed for polyphenolic content using liquid chromatography, for antioxidant potential using the oxygen radical absorbance capacity method, and for the Folin-Ciocalteu (FC) index. The sage teas showed a high variation for all parameters studied (up to 20-fold differences for rosmarinic acid). Univariate and multivariate analyses showed that the antioxidant potential, which varied between 0.4 and 1.8 mmol trolox equivalents/100 mL, was highly dependent on rosmarinic acid and its derivatives. The FC index also showed a high correlation to these polyphenols, and could therefore be used as a screening parameter for sage tea quality. The considerable differences in polyphenolic composition and antioxidant capacity between the brands lead to a demand for quality standardization, especially if these sage teas are to be used for therapeutic purposes. Further research also appears to be necessary to characterize the dose-benefit relationship, as sage may also contain a constituent (thujone) with potentially adverse effects. © 2011 Walch, Tinzoh, Zimmermann, Stühlinger and Lachenmeier.


Zimmermann B.F.,University of Bonn | Zimmermann B.F.,Institute Prof. Dr. Kurz GmbH | Gleichenhagen M.,University of Bonn
Food Chemistry | Year: 2011

Green tea seems to have a positive impact on health due to the therein-found flavanols. The amounts of these substances depend on tea preparation. In this paper, the influence of steeping time (3-7 min) and temperature (70-100°C) on the content of the main flavanols in green tea (epicatechin EC, epicatechin gallate ECg, epigallocatechin EGC, and epigallocatechin gallate EGCg) is presented. Furthermore, additives (phosphate buffers, ascorbic acid in different amounts, and citric acid) are used to investigate the influence of pH, antioxidative, and chelating agents, simulating the addition of lemon juice or pure vitamin C.The concentrations of flavanols in tea without additives are highest after 7 min of steeping at a constant 100°C; the respective lowest and highest concentrations of the flavanols differ widely: 2.1-, 2.2-, 3.1-, and 3.6-fold for EC, EGC, EGCg, and ECg, respectively. The additives increase the flavanol concentrations up to 20%. pH emerges as the decisive factor for increasing concentrations, rather than the chemistry of the used additive. © 2010 Elsevier Ltd.


Ritter C.,University of Bonn | Zimmermann B.F.,University of Bonn | Zimmermann B.F.,Institute Prof. Dr. Kurz GmbH | Galensa R.,University of Bonn
Analytical and Bioanalytical Chemistry | Year: 2010

Cocoa is well-known to be rich in flavan-3-ols. Previous analyses have established that alkaline treatment of cocoa beans results in epimerization of (-)-epicatechin to (-)-catechin and (+)-catechin to (+)-epicatechin. Now, the question is whether both epimers can be absorbed by the human organism. This paper describes sample preparation and an HPLC method for chiral determination of (+)/(-)-catechin from sulfated and glucuronidated metabolites in human plasma. The sample preparation includes enzymatic hydrolysis of the catechin metabolites, and solid-phase extraction (SPE). A PM-γ-cyclodextrin column is used with a coulometric electrode-array detection (CEAD) system. The recovery of catechin ranges from 89.9 to 96.8%. The limit of detection is 5.9 ng mL -1 for (-)-catechin and 6.8 ng mL-1 for (+)-catechin, and the limit of quantification is 12.8 ng mL-1 for (-)-catechin and 16.9 ng mL-1 for (+)-catechin. The relative standard deviation of the method ranges from 0.9 to 1.5%. This method was successfully applied to human plasma after consumption of a cocoa drink. In one human self-experiment, (+)-catechin and (-)-catechin were found in human plasma, but metabolism of the two enantiomers differed. © 2010 Springer-Verlag.


Zimmermann B.F.,University of Bonn | Zimmermann B.F.,Institute Prof. Dr. Kurz GmbH
Rapid Communications in Mass Spectrometry | Year: 2011

Stevia rebaudiana contains several steviol glycosides that have a sweet flavor. They are up to 450 times sweeter than sucrose, but some have an undesirable aftertaste. Up to 2010, ten different steviol glycosides have been described from the leaves or purified extracts of S. rebaudiana. In this paper, the tandem mass spectrometric fragmentation patterns of these ten compounds are compiled, along with a scheme for structural elucidation. This scheme is then applied to 12 steviol glycosides that have not yet been described. The proposed structures of five steviol glycosides have been confirmed by other authors. © 2011 John Wiley & Sons, Ltd.


Ellinger S.,University of Bonn | Gordon A.,University of Bonn | Kurten M.,University of Bonn | Jungfer E.,University of Bonn | And 6 more authors.
Journal of Agricultural and Food Chemistry | Year: 2012

Exotic fruits such as açai, camu-camu, and blackberries rich in natural antioxidants (ascorbic acid, anthocyanins) are marketed as "functional" foods supporting a pro-/antioxidant balance. Confirming data from human studies are lacking. Within a randomized controlled crossover trial, 12 healthy nonsmokers ingested 400 mL of a blended juice of these fruits or a sugar solution (control). Blood was drawn before and afterward to determine antioxidants in plasma, markers of antioxidant capacity [trolox equivalent antioxidant capacity, Folin-Ciocalteu reducing capacity, total oxidant scavenging capacity (TOSC)] and oxidative stress [isoprostane, DNA strand breaks in leukocytes in vivo], and their resistance versus H2O 2-induced strand breaks. Compared with sugar solution, juice consumption increased plasma ascorbic acid and maintained TOSC and partly Folin-Ciocalteu reducing capacity (both P values < 0.05). Strand breaks in vivo increased after ingestion of both beverages (P < 0.001), probably due to postprandial and/or circadian effects. This anthocyanin-rich fruit juice may stabilize the pro-/antioxidant balance in healthy nonsmokers without affecting markers of oxidative stress. © 2012 American Chemical Society.


PubMed | Institute Prof. Dr. Kurz GmbH
Type: Evaluation Studies | Journal: Journal of chromatography. B, Analytical technologies in the biomedical and life sciences | Year: 2011

Sage tea, the aqueous infusion of dried sage leaves (Salvia officinalis L.), is used as a form of food as well as a form of traditional herbal medicine. Several in vivo and in vitro studies point to sage polyphenols as active principles that may inhibit lipid peroxidation and improve antioxidant defences. This study describes an UHPLC methodology with MS/MS and UV detection, which allows the separation, identification and quantification of the major phenolic constituents in sage tea within 34 min, and was used to characterize 16 commercial brands of sage tea.The quantitatively dominating compounds were either rosmarinic acid (12.2296 mg/l) or luteolin-7-o-glucuronide (37.9166 mg/l) [corrected].In general, considerable differences in polyphenolic composition between the brands were detected, leading to the demand for quality standardization and control, especially if these sage teas are to be used for therapeutic purposes.

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