The Marine Bromotyrosine Derivatives

Publisher Summary This chapter discusses the isolation, structure, physicochemical and spectral data of all bromotyrosine derivatives isolated from marine organisms. The biosynthesis, total synthesis, and bioactivity of the bromotyrosine derivatives are also discussed followed by cyclopeptides containing halogenated tyrosine units. The bromotyrosine derivatives are divided into six categories: simple bromotyrosine derivatives, spirocyclohexadienylisoxazolines, spirooxepinisoxazolines, oximes, bastadins, and other structural classes. The simple bromotyrosine derivatives are products of one bromotyrosine undergoing degradation, reduction, hydroxylation, alkylation, or esterification with simple functional groups. In spirocyclohexadienylisoxazoline bromotyrosine derivatives, one or two bromotyrosine units are transformed into a spirocyclohexadienylisoxazoline undergoing an arene oxide biosynthetic pathway. This class of alkaloids generally consists of one to three bromotyrosinederived units, as well as other functional groups, such as histamine. Bromotyrosine alkaloids provide a unique diversity in chemical structure and in bioactivity. As the first bromotyrosine derivative, the dienone, was isolated as an antibiotic, a large number of bromotyrosine derivatives have been found to have diverse activities, which include antibacterial, antifungal, anticancer, antiviral, antifouling, etc. The majority of the dibromotyrosine-derived natural products from Verongida have been reported to possess significant antimicrobial and cytotoxic activity. The presence of antibacterial compounds in marine sponges has been reported as a general phenomenon, and has been suggested to reflect a defensive strategy of these sedentary, filter-feeding animals.