ASCORBIC-ACID PREVENTS LIPID-PEROXIDATION AND OXIDATIVE DAMAGE OF PROTEINS IN GUINEA-PIG EXTRAHEPATIC TISSUE MICROSOMES

It has recently been indicated that in the absence of free iron, NADPH initiates oxidative damage of proteins in guinea pig liver microsomes and also lipid peroxidation and protein damage in cardiac microsomes and that ascorbic acid specifically inhibits both the lipid peroxidati on and protein damage [Mukhopadhyay CK, Chatterjee IB: J Biol Chem 269 : 13390-13397, 1994; Mukhopadhyay M et al.: Mol Cell Biochem 126: 69-7 5, 1993]. In this paper we demonstrate that Fe(III)-independent NADPH- initiated lipid peroxidation and oxidative damage of proteins occur in the microsomes of all the extrahepatic tissues including lung, kidney , adrenal gland and brain and that both the lipid peroxidation and pro tein damage are specifically prevented by ascorbic acid. We further de monstrate that when NADPH is replaced by O-2(radical anion) as the ele ctron donor, the O-2(radical anion)-initiated lipid peroxidation and p rotein damage are also inhibited by ascorbic acid.