SOAE inhibits oxidation of lipoproteins. LDL and HDL were isolated from human plasma and oxidation was carried out using copper (A, D); MPO (B, E) and MPO with tyrosine (C, F) in the presence or absence of SOAE. In all cases, SOAE effectively delayed or inhibited oxidation of lipoproteins in a concentration-dependent manner. HDL, high density lipoprotein; MPO, myeloperoxidase.