Antioxidant activity of Argentine propolis extracts

Propolis is used in Argentine folk medicine. We have examined its possible protective action against oxidative modification of lipid in unfractionated serum. The kinetics of copper-induced oxidation was continuously monitored by measuring the formation of conjugated dienes, as the increase in the ab sorbance at 234 nm. According to the kinetics of oxidation, the propolis we re classified in three different groups. Group I (CE, CO, BO, MO, BE) inhib ited lipid oxidation during the initiation and propagation phases even at l ow concentrations. Group II (SP, CA, AM) increased the lag-phase for conjug ated diene formation. All propolis in groups I and II diminished the maxima l rate of diene production and the maximal amount of dienes produced. Group III (PA, RA, FE, VR, TV) had no effect on the lipid oxidation. The extent of lipoprotein oxidation was measured by the thiobarbituric acid reactive s ubstance assay. Generation of malondialdehyde-like substances was inhibited and delayed by the presence of propolis extracts from group I and II. Our results justify the use of propolis (groups I and II) as a source of natura l antioxidants. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.