Monoterpene biosynthesis in marine algae

AbstractMarine algae produce a variety of secondary metabolites, including monoterpenes, which present several highly unusual characteristics. The algal monoterpenes are nearly always halogenated and they possess ring structures quite unlike those in monoterpenes originating from terrestrial plants, suggesting novel biosynthetic pathways and mechanisms. Although limited in scope and number, field studies suggest that these compounds play a role in the defence of marine algae, similar to the role played by the more extensively studied terrestrial monoterpenes. This review examines the biogenetic pathways proposed for marine algal halogenated monoterpenes and compares them with the more thoroughly defined biosynthetic mechanisms of monoterpenes in terrestrial plants. A detailed characterization of monoterpene biosynthesis in cultured Ochtodes secundiramea (Rhodophyta) is also presented as a model for studying the biosynthesis of these unusual metabolites and evaluating their ecological functions.