Oxidation of low-density lipoprotein (LDL) may be important in the pathogenesis of atherosclerosis. Recent studies have reported that specific polyphenols play a role as antioxidants inhibiting lipid peroxidation, LDL oxidation and scavenging oxygen radicals. To investigate the mechanism by which dietary antioxidants may reduce the risk of atherosclerosis by inhibiting oxidative damage of lipoproteins, low-density lipoprotein oxidizability indexes were studied to measure the antioxidant activity of dietary polyphenols and a modification in the CLT50 parameter was proposed. This parameter measure the concentration of antioxidant that increase the Lag time to 50% greater than that of the control, and the proposed modification eliminate the effects of the LDL status in the oxidation induced with Cu2+. The lower the CLT50, the higher antioxidant activity in the inhibition of LDL oxidation. Polyphenols with different structures such as condensed tannins (tannin acid), flavonols (catechin, quercetin, rutin), cinnamic acids (caffeic and ferulic acid), stilbenes (resveratrol), benzoic acids (gallic acid), anthocyanidins (malvidin); a synthetic phenol (3-tert-butyl-4-hydroxyanisole, BHA) and two vitamins (ascorbic acid - vitamin C- and DL-α-tocopherol -vitamin E-) were studied. All antioxidants tested showed dose-dependent inhibition of LDL oxidation. In general, it was suggested that dietary polyphenols are better antioxidants than other common antioxidants, such as vitamin C and E. An adequate study of the low-density lipoprotein oxidizability indexes could determine the serum antioxidant status within different subjects, and/or evaluate the antioxidant efficiency of different antioxidants in the inhibition of human LDL oxidation.

Authors would like to acknowledge to Spanish Comision Interministerial de Ciencia y Tecnologia (CICYT) the sponsor of the project ALI98-0830. C. Sanchez-Moreno wants to thank the Comunidad de Madrid for her scholarship.

13 páginas, 3 tablas.

Peer reviewed