Determination of major anthocyanin pigments and flavonols in red grape skin of some table grape varieties (<em>Vitis vinifera sp.</em>) by high-performance liquid chromatography–photodiode array detection (HPLC-DAD)

Aim: The aim of this study was the investigation of the anthocyanin and flavonol content in grape skin extracts. Five prevalent anthocyanin-types and four flavonol-types were determined in the skin of three red table grape varieties widely cultivated in El-Tarf (Algeria). Methods and results: The identification of the compounds was performed by HPLC-DAD based on C-18 reversed phase column separation. Results from HPLC analysis showed that malvidin and petunidin-3-O-glucoside were the major anthocyanin glucoside, whereas quercetin-3-O-glucoside was the major flavonol among the four identified. Conclusion: The content of anthocyanins and flavonols in the grape skin of three grapevine (Vitis vinifera) varieties exhibits notable differences among the cultivars studied, confirming their importance in the varietal characterization. The highest concentrations of total anthocyanins and flavonols corresponded to the Gros noir variety. The results of the present study also indicate that the grape skin extracts of these Algerian cultivars can be used as easily accessible source of natural antioxidants. Significance and impact of the study: To the best of our knowledge, this is the first report on the identification of different anthocyanins and flavonols in berry skin from some red grape varieties largely cultivated in this region of Algeria