INHIBITION OF OXIDATIVE MODIFICATION OF PROTEINS BY RU486

Objectives: To elucidate further the antioxidant properties of RU486. We determined whether it can protect biologic molecules such as protei ns (albumin, low-density lipoprotein [LDL] and oxidized LDL) from dama ge by pre-existing lipid peroxides. Design: In vitro study. Interventi ons: We tested the effects of RU486 on the formation of fluorescent ox idatively modified proteins by pre-existing lipid peroxides. We used t wo model systems, the incubation of oxidized Linoleic acid with serum albumin and the incubation of human LDL with copper. Main Outcome Meas ures: The formation of modified protein was established by determining fluorescence at excitation wavelength of 330 nm and emission waveleng th between 390 and 500 nm. Modified protein has a characteristic emiss ion between 425 and 430 nm. Results: The addition of increasing amount s of RU486 inhibited the formation of fluorescent oxidatively modified protein products in both model systems. Conclusion: These results pro vide evidence that RU486 not only can prevent the formation of lipid p eroxide, but also can block the formation of fluorescent protein adduc ts in the presence of pre-existing lipid peroxides.