ABSTRACT
I. INTRODUCTION Although redox properties of indoles and derivatives have long been known (1-6), studies on the chemical reactivity and redox properties of melatonin are relatively recent. These studies, which developed on finding that melatonin has the ability to neutralize hydroxyl radicals (7), demonstrate that the indoleamine is capable of scavenging a number of free radicals, and led to a postulate that it may behave as an antioxidant. A remarkable amount of experimental work in vivo and in vitro has indeed shown that melatonin can protect cell and tissues from damage initiated by free radicals. These findings opened new perspectives on the biological aspects of this hormone, for which the physiological role in humans has remained elusive, as well as on its therapeutical potential in human pathophysiology.
