Protein-lipid interactions during oxidation of liposomes

Oxidation of bovine serum albumin and its interaction with phenolic red raspberry and bilberry extracts (4.2 and 8.4 μg/ml) was investigated in a liposome system. Samples were incubated in the dark at 37°C with copper, and the extent of oxidation was measured by determing the loss of tryptophan fluorescence and the formation of protein carbonyls, conjugated diene hydroperoxides and hexanal. Both red raspberry and bilberry extracts inhibited lipid and protein oxidation. Red raspberry extract in 4.2 μg/ml concentration was the best inhibitor against both lipid and protein oxidation. In conclusion, oxidative deterioration due to protein-lipid oxidation is inhibited by phenolic compounds in berries.