Low density lipoprotein oxidation is inhibited by extracts of Ilex paraguariensis

Some dietary polyphenolic substances have been shown to inhibit oxidation of LDL. "Mate" is a polyphenol-containing beverage, brewed from the dried and minced leaves of Ilex paraguariensis. In the present work we studied the effect of water and alcohol extracts of Ilex paraguariensis on the initiation and propagation of LDL copper or H2O2-induced autoxidation. Our data show that substances in water extracts of Ilex paraguariensis are capable of inhibiting the initiation and the propagation of LDL oxidation. They inhibit lipid peroxidation, monitored by diene conjugates and thiobarbituric acid-reactive substances, as well as protein modification as shown through direct measurement of free amino groups, electrophoretic mobility, and fluorescence. This inhibition is a concentration dependent effect that becomes already apparent at concentrations of extracts as low as 7.5 micrograms/ml. Inhibition is almost complete at 37.5 micrograms/ml. Alcohol extracts show similar effects though with less potency. The substances implicated in this antioxidant activity are largely nondializable. In terms of mass, water extracts of Ilex paraguariensis were more potent antioxidants than either ascorbic acid, or butylated hydroxytoluene.