Antioxidant function of coenzyme Q.

Evidence for in vivo antioxidative activity of reduced CoQ homologs has been presented. This came from studies with experimental endotoxemia in mice, reoxygenation of rat liver following ischemia, and reoxygenation of canine heart following 24-hour cold preservation. In radical-induced injury of hepatocytes, it has been first shown that reduced CoQ9 acts as a potential antioxidant regardless of its cellular concentration, whereas reduced CoQ10 acts in cells containing CoQ10 as the predominant homolog. The antioxidant activity of reduced CoQ homologs appears to be independent of that of alpha-tocopherol under the conditions employed.