INFLUENCE OF BILE-ACIDS ON STIMULATED LIPID-PEROXIDATION AND HYDROGEN-PEROXIDE PRODUCTION IN RAT-LIVER MICROSOMES

Bile acids were found to be effective antioxidants in bile and intestine. The influence of different bile acids on the NADPH-Fe++-stimulated lipid peroxidation (LPO) and cytochrome P-450 dependent hydrogen peroxide production (H2O2) in rat liver microsomes was investigated in vitro. LPO was determined as production of thiobarbituric acid reactants (TBAR). Different tri-, di- and monohydroxylated bile acids and cholesterol were given to the incubation mixture in concentrations ranging from 10(-5) to 10(-3) M. Sodium salts of cholic, tauroglycocholic and deoxycholic acids as well as cheno-deoxycholic, ursodeoxycholic, lithocholic acids and cholesterol did not alter the microsomal production of TBAR. H2O2 formation was significantly decreased by sodium deoxycholate whereas cholesterol increased H2O2 production up to 4 times. These results show that bile acids were not able to protect microsomal membrane lipids against peroxidative damage. Cholesterol mediated H2O2 formation as a source of hydroxyl radicals had no toxic effect concerning LPO, TBAR were not enhanced significantly.