engleski

Screening of 21 Vitis vinifera L. leaf and grape skin extracts for antioxidant capacity and phenolic content

The aim of the present study was to determine and compare polyphenolic profile and related antioxidative properties of Vitis vinifera L. leaf extracts and grape berry skin extracts. The research includes 21 grape varieties (White: Bogdanuša, Debit, Grk, Kuč, Malvasija, Maraština, Medna, Prč, Pošip, Trebbiano toscano, Vugava and Žlahtina ; Red: Babica, Babić, Cabernet sauvignon, Dobričić, Glavinuša, Ninčuša, Plavac mali, Plavina and Vranac). Plant material was collected at the stage of grape technological maturity. Phenolic profile of plant extracts (total phenols, flavonoids, catechins and flavanols) was determined using spectrophotometric methods. Antioxidant capacity of plant extracts was estimated by Ferric Reducing/Antioxidant Power assay. The research of polyphenolic profile of berry skin extracts and grapevine leaf extracts has shown difference in the mass amounts of total phenols among selected grape cultivars, as expected. The high antioxidant capacity of tested extracts has been observed and related to the presence of a mixture of polyphenolic compounds with good antioxidant properties. Significant linear correlation between total phenol content or main phenolic subgroups and ferric reducing/antioxidant power was confirmed. To make practical comparison of relative antioxidant potential of phenolic mixtures extracted from berry skins and grapevine leaves, the phenol antioxidant coefficient was calculated for each extract. The values of phenol antioxidant coefficient ranged from 4.54-13.05 for grape skin extracts, and from 8.42 -12.13 for grape leaves extracts. It can be concluded that grape skin extracts, as well as grapevine leaf extracts, can be relevant sources of phenolics with good antioxidant properties.

grape skin extracts ; vine leaf extracts ; polyphenols ; antioxidant activity

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