CYCS and endothelial dysfunction: Tsai et al. (2012) have demonstrated that CoQ10 ameliorates endothelial dysfunction by inhibiting the reduction in catalase activity induced by oxidized low-density lipoprotein (ox-LDL), thereby resulting in decreased ROS production in endothelial cells, increasing NO bioavailability, blocking cytochrome c release, and attenuating pro-apoptotic responses.