Proanthocyanidins spectrometry

Knowledge of the identity of phenolic compounds in food facilitates the analysis and discussion of potential antioxidant effects. Thus studies of phenolic compounds as antioxidants in food should usually by accompanied by the identification and quantification of the phenols. Reversed-phase HPLC combined with UV-VIS or electrochemical detection is the most common method for quantification of individual flavonoids and phenolic acids in foods (Merken and Beecher, 2000 Mattila and Kumpulainen, 2002), whereas HPLC combined with mass spectrometry has been used for identification of phenolic compounds (Justesen et al, 1998). Normal-phase HPLC combined with mass spectrometry has been used to identify monomeric and dimeric proanthocyanidins (Lazarus et al, 1999). Flavonoids are usually quantified as aglycones by HPLC, and samples containing flavonoid glycosides are therefore hydrolysed before analysis (Nuutila et al, 2002). 

LAZARUS s E, ADAMSON G E, HAMMERSTONE J F and SCHMITZ H H (1999) High-performance liquid chromatography/Mass spectrometry analysis of proanthocyanidins in foods and beverages, JAgric Food Chem, 47, 3693-701. 

Jing H, Deinzer ML (2007) Tandem mass spectrometry for sequencing proanthocyanidins. Anal Chem 79 1739-1748... 

Vivas, N. et al.. Differentiation of proanthocyanidin tannins from seeds, skins and stems of grapes Vitis vinifera) and heartwood of Quebracho (Schinopsis balansae) by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and thioacidolysis/liquid chromatography/electro-spray ionization mass spectrometry. Anal Chim. Acta, 513, 247, 2004. 

Lazarus, S.A. et al.. High-performance liquid chromatography/mass spectrometry analysis of proanthocyanidins in food and beverages, Meth. EnzymoL, 335, 46, 2001. 

Friedrich, W., Eberhardt, A., and Galensa, R., Investigation of proanthocyanidins by HPLC with electrospray ionization mass spectrometry. Eur. Food Res. Technol. 211, 56, 2000. 

Hayasaka, Y. and Asenstorfer, R.E., Screening for potential pigments derived from anthocyanins in red wine using nanoelectrospray tandem mass spectrometry. J. Agric. Food Chem. 50, 756, 2002. Hayasaka, Y. et al., Characterization of proanthocyanidins in grape seeds using electrospray mass spectrometry. Rapid Commun. Mass Spectrom. 17, 9, 2003. 

Peak identification and interpretation of mass spectra Mobile phases for proanthocyanidins contain 2% (v/v) of acetic acid, and it suppresses electrospray ionization at negative mode. This can be overcome by adding ammonia acetate as an ionization enhancer. The ammonia acetate (lOmM in methanol, 0.1 mL/min flow rate) can be added into the flow via a three-way micro-splitter ( P-445, Upchurch Scientific, WA) just before the mass spectrometry. It can be delivered by a separate HPLC pump or by a syringe pump. 

Stringano, E. Cramer, R. Flayes, W. Smith, C. Gibson, T. Mueller-Harvey, I. 2011. Deciphering the complexity of sainfoin (Onobrychis viciifolia) proanthocyanidins by maldi-tof mass spectrometry with a judicious choice of isotope patterns and matrixes. Anal. Chem. 83 4147 153. 

Figure 3.6 ESI mass spectra of PAs with DP (a) 3 and (b) 9 obtained by signal accumulation of 20 consecutive scans, m/z values major singly charged ions of PAs. Doubly charged ions of PAs monogallates. Analytical conditions ESI needle, orifice and ring potentials —4500, —60 and —350 V, respectively curtain gas N2, nebulizer gas air. (Reprinted from Rapid Communications in Mass Spectrometry 17, Hayasaka et al., Characterization of proanthocyanidins in grape seeds using electrospray mass spectrometry, p. 11, Copyright 2003, with permission from John Wiley Sons Ltd)...

Currently, LC/MS and multiple mass spectrometry (MS/MS) have been used to study the grape polyphenols (anthocyanins, flavonols, tannins and proanthocyanidins, hydroxycinnamic, and hydroxycinnam-oyltartaric acids), which allow to structurally characterize and understand the mechanisms involved in stabilizing the color in wines (Flamini, 2003). 

Figure 6.15. Positive fragmentation pathways of the monomer catechin retro-Diels-Alder fission (RDA), heterocychc ring fission (HRF), benzofuran-forming fission (BFF), and loss of water molecule. (Reprinted from Li and Deinzer, 2007, Tandem Mass Spectrometry for Sequencing Proanthocyanidins, Analytical Chemistry, 79, p. 1740, with permission from American Chemical Society.)...

Gonzalez-Manzano, S., Santos-Buelga, C., Perez-Alonso, J.J., Rivas-Gonzalo, J.C., and Escribano-Bailon, M.T. (2006). Characterization of the mean degree of polymerization of proanthocyanidins in red wines using liquid chromatography-mass spectrometry (LC-MS), J. Agric. Food Chem., 54(12), 4326-4332. 

Evidence for the presence of covalent adducts involving proanthocyanidins and anthocyanidins was also observed by infusion mass spectrometry. These minor ions appeared in two series, one series starting at m/z 781 and one at m/z 783. Each of these series is observable up to m/z 2509/2511, with ions separated by a mass of 288 (Figure 4). Based upon previous studies and speculation, these ions were consistent with two types of anthocyanin-proanthocyanidin adducts. Specifically, these ions agree with the direct condensation products of... 

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