Statins and modulation of oxidative stress.
Statins inhibit the activity of a rate-limiting enzyme in cholesterol biosynthesis, converting 3-hydroxy 3-methylglutaryl coenzyme A to mevalonate, and are widely used in the treatment of cardiovascular diseases. Statins decrease the synthesis of cholesterol and other nonsteroid isoprenoids originating from mevalonate, such as farnesyl- and geranylgeranylpyrophosphate, dolichol, and ubiquinone. Recent studies indicate that the beneficial effect of statins on cardiovascular risk also occurs in persons with normal plasma cholesterol because of the pleiotropic cholesterol-independent activities of statins. Among these effects, modulation of oxidative stress is one of the most important. Statins reduce the generation of reactive oxygen species by vascular NAD(P)H oxidase, inhibit the respiratory burst of phagocytes, antagonize the prooxidant effect of angiotensin II and endothelin-1, and increase the synthesis of vascular nitric oxide. Some statins and their metabolites posses direct free radical scavenging activity. The antioxidant effect of statins contributes to inhibition of atherogenesis, stabilization of atherosclerotic plaque, inhibition of myocardial hypertrophy and remodeling, and modulation of vascular tone. However, the prooxidant effect of statins resulting from the inhibition of ubiquinone synthesis has also been reported in some experimental models. This effect may contribute to side effects of statins, such as myopathy and hepatotoxicity.