## 3 Results and Discussion  
### Identification of Major Polyphenols  
The mass spectrometric profiling of polyphenols was based on the method previously developed by [PERSON] [27]. Briefly, compounds separated by HPLC were passed through an on-line coupled diode array detector (DAD) before entering the ESI-MS system. The Q-TOF mass spectrometer was used in TOF mode and in-source fragmentation was utilized in order to provide structural information on the compounds. This approach offers an advantage compared to real tandem MS experiments, where precursor ion is selected and then subjected to fragmentation. In this 'pseudo MS/MS' approach, fragmentation information is obtained simultaneously on unlimited numbers of compounds without requiring any preliminary selection and isolation of the suspected ions. Tentative identification of major polyphenol compounds was based on combined UV and MS data. Background corrected MS peak spectra of the UV peaks obtained at 280 and 330 nm were investigated on first attempt. Tentative identification of compounds was primarily based on the evaluation of stacked extracted ion chromatograms (EICs) (with \(\pm\)5 mDa mass window selection) of selected predefined diagnostic ions. In addition, the UV spectra of indicated compounds, which are indicative of classes of compounds, were also applied as an additional piece of information for tentative identification. As a result of profiling, 16 putative polyphenol compounds could be detected in the studied Goher leaf samples (Table A1). Eight of these 16 compounds, which provided remarkable peaks in most samples also with UV detection and therefore were considered as major compounds, were subjected to further confirmation using reference standards. As a result, 8 polyphenols namely, _trans_-caflaric acid (\(\mathrm{t_{R}}=6.3\) min), quercetin-3-\(O\)-retinoside (\(\mathrm{t_{R}}=19.2\) min), quercetin-3-\(O\)-galactosidase (\(\mathrm{t_{R}}=19.7\) min), quercetin-3-\(O\)-glucuronide (\(\mathrm{t_{R}}=19.8\) min), quercetin-3-\(O\)-glucose (\(\mathrm{t_{R}}=20.0\) min.), kaempfer-3-\(O\)-retinoside (\(\mathrm{t_{R}}=21.1\) min), kaempfer-3-\(O\)-glucose (\(\mathrm{t_{R}}=21.2\) min) and kaempfer-3-\(O\)-glucuronide (\(\mathrm{t_{R}}=22.0\) min) could be identified. The remaining eight tentatively identified compounds were considered as minor compounds, thus they were not subjected to any further investigation. The eight identified polyphenols are among the principal nonanthocyanin polyphenols of grape [28]. The priority of quercetin- and kaempfer-derivatives of grapevine leaves (_Vitis vinifera_ L.) has been found in the variety Silveraner, where the only flavonoids resulted by acidic hydrolysis were these aglycones analyzed by HPLC [18]. Quercetin- and kaempfer-glycoses proved to also be the main leaf flavonoids in Pinot noir leaves [8]. Quercetin and kaempfer content in leaf extracts of _Vitis vinifera_[4] and _Vitis labrusca_[2] were measured in order to study their health protecting properties. However, the major flavonoids in muscadine leaves were myricetin-derivatives [29]. Regarding phenolic acid content in grapevine leaves, [PERSON] [4] identified _trans_-cafaric acid as the only hydroxycinnamic acid derivative in leaf extracts, whereas the presence of caffeic and chlorogenic acids and their derivatives were detected in grapevine leaves by [PERSON] [3]. Some papers analyzed secondary metabolites from both leaves and berries. [PERSON] and coworkers' [30] results indicated that there was a positive correlation between healthy leaf and berry phenolic content of three grape varieties. Studies on total amount of phenolics in different grapevine parts showed that leaves contained significantly higher amount of these metabolites than berries [31,32], while detailed phenolic profiling proved the same main components in leaves and berries [29]. Therefore our study in leaves will be important from the point of berry phenolics and wine quality.