Phenolic composition and free radical scavenging activity of wine produced from the Serbian autochthonous grape variety Prokupac - A model approach

Phenolic compounds are very important quality parameters of wine because of their impact on colour, taste and health properties. The present study was aimed at evaluating the general phenolic composition and free radical scavenging activity of aqueous and organic fractions obtained using liquid liquid extraction of red wine produced from the Serbian autochthonous grape variety Prokupac. The total phenolic contents in the different fractions ranged from 48.22 to 289.12 mg GAE per g dry fraction. Phenolic acids (mainly hydroxycinnamic acids) and quercetin 3-O-glucuronide were the main components in the EtOAc fraction at pH 2.0; catechins, phenolic acids (mainly hydroxybenzoic acids) and quercetin were found in the EtOAc fraction at pH 7.0, while anthocyanins were identified in the aqueous residue after EtOAc extraction. The major anthocyanin extracted into the aqueous fraction was malvidin-3-glucoside, while the most abundant non-anthocyanin phenolic compounds in the organic fractions were ethyl gallate and trans-caftaric acid. The radical scavenging activities of the fraction differed significantly and the IC50 values were 138.58 mu g mL(-1) for the aqueous fraction, 17.83 and 3.47 ng mL(-1) for the EtOAc fractions at pH 2.0 and 7.0, respectively. As the EtOAc fractions were found to be more potent radical scavengers, it could be assumed that non-anthocyanin phenolic compounds were responsible for such activity in Prokupac wine.