OXIDATION PROCESSES IN EGG PHOSPHATIDYLCH OLINE LIPOSOMES ENTRAPPED WITH L-3,4-DIHYDROXYPHENYLALANINE OR DOPAMINE - RECIPROCAL INFLUENCE OFTHE COMPONENTS

Oxidation of egg phosphatidylcholine and catechols (L-3,4-dihydroxyphe nylalanine or dopamine) in liposome dispersions was studied. These cat echols, encapsulated in liposomes, were shown to decrease the rate of phosphatidylcholine oxidation by factors of 4.9 and 2.6, respectively, at storage in darkness at 4 degrees C. After 40 min of Fe(II)-ascorba te-induced oxidation, the level of malonaldehyde in such liposomes rem ained constant, while in the empty liposomes, it increased 3.4-fold. E gg phosphatidylcholine protected catechols encapsulated into liposomes from oxidation, and the rate of this oxidation was shown to be substa ntially lower than that in micellar solutions under the same condition s. Evidently, this can be due to the barrier function of a lipid bilay er.