Inhibition of oxidative modification of proteins by RU486

To elucidate further the antioxidant properties of RU486. We determined whether it can protect biologic molecules such as proteins (albumin, low-density lipoprotein [LDL] and oxidized LDL) from damage by pre-existing lipid peroxides.

In vitro study.

We tested the effects of RU486 on the formation of fluorescent oxidatively modified proteins by pre-existing lipid peroxides. We used two model systems, the incubation of oxidized linoleic acid with serum albumin and the incubation of human LDL with copper.

The formation of modified protein was established by determining fluorescence at excitation wavelength of 330 nm and emission wavelength between 390 and 500 nm. Modified protein has a characteristic emission between 425 and 430 nm.

The addition of increasing amounts of RU486 inhibited the formation of fluorescent oxidatively modified protein products in both model systems.

These results provide evidence that RU486 not only can prevent the formation of lipid peroxide, but also can block the formation of fluorescent protein adducts in the presence of pre-existing lipid peroxides.