Anthocyanins characterization

Giusti, M.M. et al.. Electrospray and tandem mass spectroscopy as tools for anthocyanin characterization, J. Agric. Food Chem., Al, 4657, 1999. 

Purification of anthocyanin-containing extracts is often necessary for further structural identification. Since none of the solvents used for extraction is specific for anthocyanins, considerable amounts of other compounds may be also extracted and concentrated. The variety and concentration of other compounds will depend on the solvent and methodologies used. The presence of extraneous materials could affect the stability and/or analysis of anthocyanins. Therefore, the next step toward anthocyanin characterization is the purification of those extracts. 

Tandem mass spectrometry (MS-MS) uses more than one mass analyzer for structural and sequencing studies that have been found very useful for anthocyanin characterization. These mass analyzers may be of the same type (triple or quadru-poie)85,86 Qj. such as ion trap quadrupole, - and quadrupole-time-of-flight... 

Anthocyanin purification steps are important for anthocyanin characterization. Removal of interfering compounds allows for more reliable HPLC separation, spectral information, mass spectra, and NMR spectra during the identification of anthocyanins in plant extracts. 

The first step in anthocyanin characterization is the identification of the anthocyani-din moiety (aglycon) and the sugar(s). This can be accomplished by acid hydrolysis... 

WANG H, NAIR M G, lOZZONi A F, STRASBURG G M, BOOREN A M and GRAY JI (1997) Quantification and characterization of anthocyanins in Balaton tart cherries, JAgr Food Chem, 45, 2556-60. 

Hong, V. and Wrolstad, R.E., Use of HPLC separation/photodiode array detection for characterization of anthocyanins, J. Agric. Food Chem., 38, 708, 1990. Osmianski, J. and Lee, C.Y., Isolation and HPLC determination of phenolic compounds in red grapes. Am. J. Enol. Vitic., 41, 204, 1990. 

Wu, X. and Prior, R.L., Identification and characterization of anthocyanins hy high performance liquid chromatography-electrospray ionization-tandem mass spectrometry in common foods in the United States vegetables, nuts, and grains, J. Agric. Food Chem., 53, 3101, 2005. 

Giusti, M.M. and Wrolstad, R.E., Characterization and measurement of anthocyanins by UV-visible spectroscopy, in Handbook of Food Analytical Chemistry Pigments, Colorants, Flavors, Texture, and Bioactive Food Components, Wrolstad, R.E. et al., Eds., John Wiley Sons, New York, 2005, 19. 

Lee, H.S., Characterization of major anthocyanins and the color of red-fleshed budd blood orange (Citrus sinensis), J. Agric. Food Chem., 50, 1243, 2002. 

Mnllen, W., Lean, M.E.J., and Crozier, A., Rapid characterization of anthocyanins in red raspberry frnit hy high-performance liqnid chromatography coupled to single qnadrupole mass spectrometry, J. Chromatogr. A, 966, 63, 2002. 

Wang, H., Race, E.J., and Shrikhande, A.J., Characterization of anthocyanins in grape juices by ion trap liquid chromatography-mass spectrometry, J. Agric. Food Chem.,... 

The availability of HPLC systems coupled to photodiode array detectors allows for online spectral characterization of anthocyanins. 

The use of mass spectroscopic analyses for characterization of anthocyanins has increased dramatically over the past decade. Most reports cite the use of HPLC coupled to MS detectors or isolating individual pigments prior to the mass spectroscopic analysis. - - " ... 

ESI-MS has emerged as a powerful technique for the characterization of biomolecules, and is the most versatile ionization technique in existence today. This highly sensitive and soft ionization technique allows mass spectrometric analysis of thermolabile, non-volatile, and polar compounds and produces intact ions from large and complex species in solution. In addition, it has the ability to introduce liquid samples to a mass detector with minimum manipulation. Volatile acids (such as formic acid and acetic acid) are often added to the mobile phase as well to protonate anthocyanins. A chromatogram with only the base peak for every mass spectrum provides more readily interpretable data because of fewer interference peaks. Cleaner mass spectra are achieved if anthocyanins are isolated from other phenolics by the use of C18 solid phase purification. - ... 

NMR spectroscopy is the most powerful method for structural elucidation in solution and advances in NMR techniques have made significant impacts on anthocyanin studies. Complete structural characterization of anthocyanins is possible with one- and two-dimensional NMR techniques. However, relatively large quantities of... 

Many recent stndies of NMR spectroscopy have been reported for structure elucidation of anthocyanins from many plant materials such as carrot, tart berries, boysenberries, " flowers, black soybeans, and anthocyanin and flavonol derivatives in red wine. Ginsti et al. (1998) structurally elucidated two novel diacylated anthocyanins and two monoacylated anthocyanins from radish Raphanus sativus) by one- and two-dimensional NMR. Anderson et al. (2006) applied two-dimensional NMR to characterize carboxypyranoanthocyanins. Two 3-deoxyantho-cyanins, lnteolinidin-5-glncoside, and apigeninidin-5-glucoside were identified by Swinny et al. nsing H and C NMR. 

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