Biological activities of natural halogen compounds

Abstract Algae, bacteria, fungi, lichens, sponges, plants, and mammals produce a wide variety of halogen-containing secondary metabolites. Biological activities also cover a wide range. Many natural halogen compounds exhibit antibiotic activity, for example the alternatamides, the pyralomycms, the longamides, clathramides, celen-amide, axinellamides, and the macrolide flurithromycin. Cytotoxicity is displayed by the polychlorinated phenolethers russuphelins, the macrolide phorboxazoles, the cyclopropane derivatives grenadadiene and callipeltosides, the aurantosides, the aurisides, the rubrosides, the didemnolines, the spiro isoxazole derivates purealidins, and the cyclic peptides geodiamolides. The chloropyrrol-containing hexapeptide cyclocinamide A, and the nostocyclophanes, natural cyclophanes, also belong to this category. Spongistatins are among the most cancer cell growth inhibitory compounds yet discovered. Some natural halogen compounds display a gallery of activities, like the cytotoxic cyclodepsipeptide jaspamide which is also antifungal and insecticidal. The mycorrhizin-related chloroepoxide lachnumone combines antifungal, nematicidal and antimicrobial activities. The chlorosteroid glycoside blatellastanoside is a pheromone of cockroaches. Polyhalogenated monoterpens are insecticides, some deter the settlement of larvae. The volutamides, barbamide, and parguerol show antifeedant properties. Kalihinol A inhibits the settlement of barnacle larvae. Some natural halogen compounds have emerged as potent lead structuRes. for the development of new synthetic drugs, like the analgesic chloropyridine epibatidine, or pyrrolnitrin and dioxapyrrolomycin which have lead to powerful fungicides and insecticides. Even polychlorinated dibenzodioxins have been found in nature. In some cases, the halogen is essential for activity like the antifungal chloroorcinols, ichthyotoxic malyngamides, and cytotoxic makaluvamines. The biological activities of these and related compounds are reviewed, and 173 references are given.