Correlations between polyphenolic composition and antioxidant activity of Venetian propolis

Four propolis samples have been picked up in the Venetian region, from different orography and habitative density areas with the purpose to: (i) evaluate propolis' antioxidant activity, measured by inhibition of lipid peroxidation; (ii) determine the polyphenolic components - flavonoids and caffeic acid derivatives - which give antioxidant activity to propolis; (iii) verify the potential correlations between antioxidant activity, polyphenolic content, that has been determined by Folin-Ciocalteu, enzymatic, DPPH quenching, TEAC-like assays, and spectroscopic characteristics of propolis and (iv) correlate chemical Structure and antioxidant efficacy of each of the major components. The possible localization of the lipophylic components of propolis into the phospholipidic bilayer by thermal analysis (DSC) and spin label EPR techniques has also been investigated. (C) 2009 Elsevier Ltd. All rights reserved.