Melatonin: circadian rhythm regulator, chronobiotic, antioxidant and beyond

For many years, melatonin has been known to interact with circadian rhythms. New evidence indicates that melatonin acts as a free radical scavenger and antioxidant. Moreover, melatonin prevents apoptosis in different types of cells, because it induces mRNA levels of several antioxidant enzymes. It is evident that melatonin is involved in the cellular bioenergetic system as a mechanism that counteracts the progression of Alzheimer's disease. (c) 2009 Elsevier Inc. All rights reserved.