Comparative Antioxidant Effectiveness of White and Red Wine and Their Phenolic Extracts Towards Low-Density Lipoprotein Oxidation

Abstract

The ability of six white and four red Greek wines to inhibit the Cu²⁺-induced oxidation of LDL was evaluated. All red wines exhibited much higher antioxidant activity and total phenolics than white wines. Moreover, all red wines exhibited lower concentration of total phenolics that induces a 50% prolongation of the lag time of LDL oxidation (IC₅₀value) than white ones. Two out of four red wines exhibited lower IC₅₀values than the others.

One white and one red wine—young and aged—were fractionated by extraction, and several fractions were sub-fractionated by column chromatography. All white and red wine fractions and sub-fractions appeared to be effective in inhibiting LDL oxidation indicating that many wine phenolics may be active.

Some young red wine sub-fractions exhibited IC₅₀ values different from the respective components of aged wine, indicating that the oxidative aging in barrels may have an effect on the antioxidant potency of wine phenolics towards LDL oxidation.

One white wine phenolic sub-fraction exhibited IC₅₀ values similar to the two most active red wine sub-fractions, indicating that, besides red, white wine may also be considered as a pool of very active phenolics in inhibiting LDL oxidation. These three most active sub-fractions were rich in phenolic acids and flavonols.

Some biotechnological strategies may serve to enrich wines with active phenolic components and improve their potency towards LDL oxidation.

Key Words:

• white wine
• red wine
• phenolics
• LDL oxidation

Acknowledgements

This work has been funded by the Greek General Secretariat of Research and Technology (EPET II, Project 97-DIATRO-25). Thanks are due to ‘Ktima Kir-Yianni’ and ‘Ampeloeniki’ companies for providing Xinomavro and Roditis wines respectively.