ANTIOXIDANT AND PROOXIDANT ACTIVITIES OF ELDERBERRY (SAMBUCUS-NIGRA) EXTRACT IN LOW-DENSITY-LIPOPROTEIN OXIDATION

Spray-dried elderberry juice, containing high amounts of anthocyanin g lucosides, was investigated for its antioxidant and prooxidant potenti als and mechanisms. A strong, concentration-dependent prolongation of the lag phase of copper-induced oxidation of human low-density lipopro tein (LDL) was found, but the maximum oxidation rate was unchanged. Pe roxyl-radical-driven LDL oxidation showed both prolongation of lag tim e and reduction of maximum oxidation rate. In the case of copper-media ted oxidation, the anthocyanins were able to reduce alpha-tocopheroxyl radical to alpha-tocopherol. Clear prooxidant activity in copper-medi ated oxidation was observed, depending on the time of addition of extr act: whenever the extract was present from the beginning or added with in the first 10 min; the antioxidant effect prevailed. Addition at lat er times led to a considerable reduction of lag phase and increase of maximum oxidation rate. No such effect was found in peroxyl-radical-me diated LDL oxidation; on the contrary, the extract was even able to-re duce the propagation rate considerably.