N-[(2E)-3-(3,4-dihydroxyphenyl)-1-oxo-2-propenyl]-L-alanine, methyl ester, inhibits formation of fatty streak lesions of the thoracic aorta, which characterize early stage atherosclerosis, in high cholesterol-fed rabbits without significantly inhibiting ACAT-1 or ACAT-2 activity or affecting plasma lipid profiles. The percent area occupied by the atherosclerotic lesion in rabbits supplemented with 0.05% N-[(2E)-3-(3,4-dihydroxyphenyl)-1-oxo-2-propenyl]-L-alanine, methyl ester, in the diet was 16.1% compared to 53.5% in control rabbits. N-[(2E)-3-(3,4-dihydroxyphenyl)-1-oxo-2-propenyl]-L-alanine, methyl ester, also exhibits antioxidant activity, inhibiting copper-mediated oxidation of low-density lipoprotein by about 75% at a concentration of 2 µM.