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Dolichol, a long-chain polyisoprenoid broadly distributed in all tissues and cellular membranes with unknown function(s), might have a role in free radical metabolism [it accumulates in older tissues and decreases after CCl4 (in liver) or phenylhydrazine (in spleen and liver) administration]. The effects of the NADPH-ADP-Fe system on Dolichol levels in isolated hepatocytes were explored and the time-course of changes was compared with the release of MDA in the incubation medium and the decrease in CoQ 9 and 10 and Vitamin E levels. Results showed that the system increased lipid peroxidation and decreased Dolichol and CoQ levels in_parallel fashions and lowered Vitamin E levels with shorter latency. Meanwhile, no increase in dead cells and no Dolichol release in the medium were detected. In conclusion, an increase in oxidative stress possibly caused a rapid degradation of dolichol by the same (unknown) mechanism responsible for the breakdown of_Ubiquinone isoprenoid chains. [ABSTRACT FROM AUTHOR]