Physiological and pharmacological properties of 5-methoxytryptophol

5-methoxytryptophol (5-ML) is a pineal indoleamine derived from serotonin shown to be biologically active in a number of species. This indolamine exhibits a circadian pattern synchronized with the day-night cycle with significant increases during daylight, already recognized in vertebrates. The multiplicity of physiological and endocrine functions of 5-ML is remarkable; it is involved in circadian rhythms, reproduction and sexual processes. Furthermore, a number of pharmacological benefits of 5-ML have been reported, including immunomodulatory, antitumor and antioxidative activities. However, the molecular mechanisms of these pharmacological effects remain unclear. The purpose of this article is to provide an overview on the general properties and physiological functions of 5-ML. An attempt has been made to fully document all studies performed using 5-ML. In addition, this article aims to gain insight into the current state of knowledge regarding pharmacological and therapeutic effects of this indoleamine.