Additive or synergetic effects of phenolic compounds on low density lipoprotein oxidation

Polyphenols, a large group of plant metabolites found in a wide variety of fruits, vegetables and beverages, have shown significant benefits in chronic disease prevention. The in vitro assessment of the antioxidant capacity of four phenoilc compounds (catechin, hesperidin, ferulic acid, and quercetin) and a mix of all four compounds was evaluated by the examination of their ability to inhibit Cu2+-mediated LDL oxidation by using the thiobarbituric acid-reactive substances (TBARS) assay. The analysis of the individual compounds demonstrated antioxidant (catechin and hesperidin) and pro-oxidant (ferulic acid and quercetin) effect in this study. Combined compounds, however, showed significant antioxidant capacity at all enrichment levels (2 μM, 4.3 μM, 9.3 μM, and 20 μM), confirming that total effect seems to be greater than the sum of the individual effects. Our findings support previous suggestions that the daily ingestion of fruits and vegetables might be involved in disease prevention.