Structural annotation and elucidation of conjugated phenolic compounds in black, green, and white tea extracts
Hooft, J.J.J. van der; Akermi, M. ; Yelda Ünlü, F. ; Mihaleva, V. ; Gomez Roldan, V. ; Bino, R.J. ; Vos, R.C.H. de; Vervoort, J.J.M. - \ 2012
Journal of Agricultural and Food Chemistry 60 (2012)36. - ISSN 0021-8561 - p. 8841 - 8850.
pu-erh tea - mass-spectrometry - oolong tea - hplc-dad - lc-msn - liquid-chromatography - chlorogenic acids - camellia-sinensis - purine alkaloids - ellagic acid
Advanced analytical approaches consisting of both LC-LTQ-Orbitrap Fourier transformed (FT)-MS and LC-time-of-flight-(TOF)-MS coupled to solid-phase extraction (SPE) NMR were used to obtain more insight into the complex phenolic composition of tea. On the basis of the combined structural information from (i) accurate mass fragmentation spectra, derived by using LC-Orbitrap FTMS(n), and (ii) proton NMR spectra, derived after LC-TOFMS triggered SPE trapping of selected compounds, 177 phenolic compounds were annotated. Most of these phenolics were glycosylated and acetylated derivatives of flavan-3-ols and flavonols. Principal component analysis based on the relative abundance of the annotated phenolic compounds in 17 commercially available black, green, and white tea products separated the black teas from the green and white teas, with epicatechin-3,5-di-O-gallate and prodelphinidin-O-gallate being among the main discriminators. The results indicate that the combined use of LC-LTQ-Orbitrap FTMS and LC-TOFMS-SPE-NMR leads to a more comprehensive metabolite description and comparison of tea and other plant samples
Structural elucidation and quantification of phenolic conjugates present in human urine after tea intake
Hooft, J.J.J. van der; Vos, R.C.H. de; Mihaleva, V. ; Bino, R.J. ; Ridder, L.O. ; Roo, N. de; Jacobs, D.M. ; Duynhoven, J.P.M. van; Vervoort, J.J.M. - \ 2012
Analytical Chemistry 84 (2012)16. - ISSN 0003-2700 - p. 7263 - 7271.
tandem mass-spectrometry - green tea - black tea - metabolite identification - ellagic acid - metabolomics - polyphenols - nmr - ingestion - phytochemicals
In dietary polyphenol exposure studies, annotation and identification of urinary metabolites present at low (micromolar) concentrations are major obstacles. In order to determine the biological activity of specific components, it is necessary to have the correct structures and the quantification of the polyphenol-derived conjugates present in the human body. We present a procedure for identification and quantification of metabolites and conjugates excreted in human urine after single bolus intake of black or green tea. A combination of a solid phase extraction (SPE) preparation step and two high pressure liquid chromatography (HPLC)-based analytical platforms was used; namely, accurate mass fragmentation (HPLC-FTMSn) and mass-guided SPE-trapping of selected compounds for nuclear magnetic resonance spectroscopy (NMR) measurements (HPLC-TOFMS-SPE-NMR). HPLC-FTMSn analysis led to the annotation of 138 urinary metabolites, including 48 valerolactone and valeric acid conjugates. By combining the results from MSn fragmentation with the one dimensional (1D)-1H-NMR spectra of HPLC-TOFMS-SPE trapped compounds, we elucidated the structures of 36 phenolic conjugates, including the glucuronides of 3’,4’-di, and 3’,4’,5’-trihydroxyphenyl-¿-valerolactone, three urolithin glucuronides, and indole-3-acetic acid glucuronide. We also obtained 26 hours of quantitative excretion profiles for specific valerolactone conjugates. The combination of the HPLC-FTMSn and HPLC-TOFMS-SPE-NMR platforms results in the efficient identification and quantification of low abundant phenolic conjugates down to nanomoles of trapped amounts of metabolite corresponding to micromolar metabolite concentrations in urine
Inhibition of Listeria monocytogenes by pomegranate (Punica granatum) peel extract in meat paté at different temperatures
Hayrapetyan, H. ; Hazeleger, W.C. ; Beumer, R.R. - \ 2012
Food Control 23 (2012)1. - ISSN 0956-7135 - p. 66 - 72.
vitro antibacterial activity - phenolic-compounds - antioxidant activity - ellagic acid - staphylococcus-aureus - escherichia-coli - herb extracts - juice - growth - turkey
Natural antimicrobials are being more and more considered as alternative approach for controlling growth of microorganisms in food. The objective of this study was to evaluate the pomegranate extract’s (PE) potential to be used as a natural preservative in ready to eat meats. Listeria monocytogenes was the main target. In a preliminary assessment with the disk diffusion method PE showed inhibitory effect against all five tested species, in the following order of increasing sensitivity: L. monocytogenes, Bacillus subtilis, Bacillus cereus, Escherichia coli and Staphylococcus aureus. No viable cells of L. monocytogenes were detected after incubation in BHI broth in presence of 7.5% v/v of the liquid PE (or 24.7 mg dry PE/ml). This concentration was considered as the Minimal Bactericidal Concentration (MBC) of the tested PE. Two pure components commonly found in PE, namely gallic and ellagic acids were also tested in BHI broth, however they did not show considerable inhibition of L. monocytogenes. PE in a concentration equal to the measured MBC was tested against L. monocytogenes in meat paté at different temperatures. At 4 °C during 46 days the extract inhibited the growth in meat paté by 4.1 log CFU/g compared to the control, which had reached log 9.2 CFU/g already on the 18th day. Inhibition was less pronounced at higher temperatures. The results indicate that the PE has a potential to be used as a natural preservative in meat products. --------------------------------------------------------------------------------
Structural identification of the main ellagitannins of a boysenberry (Rubus loganbaccus × baileyanus Britt.) extract by LC–ESI-MS/MS, MALDI-TOF-MS and NMR spectroscopy
Kool, M.M. ; Comeskey, D.J. ; Cooney, J.M. ; McGhie, T.K. - \ 2010
Food Chemistry 119 (2010)4. - ISSN 0308-8146 - p. 1535 - 1543.
antioxidant activity - ellagic acid - raspberries - chemoprevention - metabolism - phenolics - fruit - risk
Four ellagitannins from boysenberry, a cross between Rubus loganbaccus and Rubus baileyanus Britt., were isolated by preparative HPLC and the exact structures determined by a combination of LC–ESI-MS/MS, MALDI-TOF-MS and NMR spectroscopy. The two most abundant ellagitannins were identified as sanguiin H-6, which is known to be abundant in Rubus species, and the other was identified as an isomer of sanguiin H-10, which has not previously been reported in Rubus. The two less abundant ellagitannins were identified as sanguiin H-2 and [galloyl–bis-HHDP–glucose]2-gallate. Sanguiin H-2 has been previously reported in Rubus, whereas both sanguiin H-2 and [galloyl–bis-HHDP–glucose]2-gallate have been previously reported as hot-water degradation products of lambertianin C. Even though lambertianin C is reported to be a major ellagitannin in other Rubus species, it was not found in any of the fractions, suggesting that both sanguiin H-2 and [galloyl–bis-HHDP–glucose]2-gallate are present naturally in boysenberry.
Identification and dietary relevance of antioxidants from raspberry
Beekwilder, M.J. ; Hall, R.D. ; Vos, C.H. de - \ 2005
BioFactors 23 (2005)4. - ISSN 0951-6433 - p. 197 - 205.
ellagic acid - vitamin-c - red raspberries - capacity - anthocyanins - phenolics - ellagitannins - storage - fruits - flavonoids
In this paper we review the current literature on antioxidants from fruit of red raspberry (Rubus idaeus) and place these in context concerning what is known from other food species. The review concentrates on the methods of antioxidant testing, the diversity of antioxidants in raspberry, effects of ripeness, cultivar, storage and processing techniques, and the bioavailability of raspberry antioxidants in humans after eating the fruit. It is clear that raspberry, like several other fruits and vegetables such as tomato, strawberry, kiwi and broccoli, represents a valuable contrasting source of potentially healthy compounds and can represent an important component of a balanced diet