Arsenobetaine: the ongoing mystery

Abstract Arsenobetaine (AsB) is a non-toxic organoarsenical identified as a major arsenic species in marine animals and a number of terrestrial mushrooms. Since its first identification nearly 40 years ago, numerous studies investigating the biosynthesis and function of AsB have been carried out, although molecular mechanisms have not been fully elucidated. Where and how is AsB formed? Why do marine animals acquire high concentrations of AsB? This review briefly summarizes the current progress of AsB research toward understanding its origin, function and the putative pathways for its biosynthesis. This paper also suggests potential future studies in the attempt to solve the AsB mystery.