| Abstract
| - Grapes and red wine prepared from Vitis vinifera L. contain a variety of polyphenols. Some informationis available about the polyphenols of the seeds and leaves of grapevine, but considerably less isknown about the polyphenols of woody stems. In this paper, we describe the results of a study ofpolyphenolic compounds in grapevine stems. We demonstrate how a combination of reversed phasehigh-performance liquid chromatography with ultraviolet−diode array detection and electrosprayionization−tandem mass spectrometry ion-trap detection enables characterization of a phytochemicalmixture of considerable complexity. As the polyphenol source, the stems of three frost-hardy grapevinevarieties [Hasaine (Hasansky) sladki, Zilga, and Yubilei Novgoroda] were used. The main group ofmethanol-extractable polyphenols of stems consists of trans-resveratrol and its derivatives includingoligomers and glucosides. As minor components of the extract, stilbenoid piceatannol as well as anumber of nonstilbenoid polyphenols, mostly flavan-3-ols and phenolic acids glucosides, weredetermined. The total polyphenol content of the grapevine stems depends on the variety, wherebythe stems of cultivar Yubilei Novgoroda with white grapes contain significantly less of both groups ofpolyphenols. Keywords: Polyphenols; resveratrols; flavan-3-ols; LC-MS/MS; DAD; grapevine stems
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