Inhibitory effect of lipid hydroperoxide on cholesteryl esterases.

The oral supplement of air-oxidized linoleate hydroperoxide (LHPO) given in a small quantity to rats resulted in an increase in lipid peroxides (LPO) in the plasma and liver, together with the formation of an oxidatively modified low-density lipoprotein (LDL) with a high content of conjugated diene. Both acid and neutral cholesteryl esterases (CEases) were significantly suppressed in mononuclear leukocytes (MNL), liver, and aorta of the LHPO fed-rats. Significant inverse correlation coefficients were observed between two CEases activities and plasma LPO levels. The LDL isolated from the LHPO fed-rats inhibited in vitro both acid and neutral activities most efficiently among LDL derived from the experimental groups and confirmed in vivo oxidative inactivation of the intracellular CEases, possibly by lipid hydroperoxides in LDL through its increased uptake by the cells.