Ovothiol: A Potent Natural Antioxidant from Marine Organisms

Ovothiols are histidine-derived thiols found in many marine invertebrates (Paracentrotus lividus, Strongylocentrotus purpuratus, Arbacia lixula, Marthasterias glacialis, Astropecten aurantiacus, Octopus vulgaris, Loligo vulgaris, and Platynereis dumerilii), as well as in algae and protozoa. Different aspects related to ovothiols are examined in this chapter, including their isolation, structural characterization, and detection.Asurvey of protocols for the chemical synthesis of ovothiols is summarized from the initial studies in the 1980s to more recently developed synthetic routes. A careful examination of the chemical properties of ovothiols and their reactivity toward biological oxidants is reported. The enzyme 5-histidylcysteine sulfoxide synthase (OvoA), which catalyzes the first step of ovothiols biosynthesis, has been recently characterized, providing some insights into the mechanism of ovothiol formation. The involvement of ovothiols in different biological functions, ranging from fertilization and reproductive behavior to redox state regulation and protection from oxidative stress, is reviewed. The synthesis of a variety of thiol derivatives is reported, together with the analysis of their antioxidant properties. Moreover, the studies reported in the literature on the biological activities of ovothiols and ovothiol derivatives with promising pharmacological applications are discussed.