2003/05/19 by Julia Kubanek, Paul R. Jensen, Paul A. Keifer +3 · 249 citations
Biochemistry, Genetics and Molecular Biology · Earth and Planetary Sciences · Engineering · #Algae #Antimicrobial #Bacteria #Biochemistry #Biology #Chemical defense #Cyanobacteria #Defence mechanisms #Ecology #Herbivore #Marine Biology and Environmental Chemistry #Marine Sponges and Natural Products #Marine and coastal plant biology #Marine bacteriophage #Marine fungi #Microbiology #Microorganism
paper · open access · doi:10.1073/pnas.1131855100
published in Proceedings of the National Academy of Sciences 100(12), 6916-6921 (National Academy of Sciences)
openalex publication_date 2003/05/19 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
Pathogenic microbes can devastate populations of marine plants and animals. Yet, many sessile organisms such as seaweeds and sponges suffer remarkably low levels of microbial infection, despite lacking cell-based immune systems. Antimicrobial defenses of marine organisms are largely uncharacterized, although from a small number of studies it appears that chemical defenses may improve host resistance. In this study, we asked whether the common seaweed Lobophora variegata is chemically defended against potentially deleterious microorganisms. Using bioassay-guided fractionation, we isolated and characterized a 22-membered cyclic lactone, lobophorolide (1), of presumed polyketide origin, with sub-microM activity against pathogenic and saprophytic marine fungi. Deterrent concentrations of 1 were found in 46 of 51 samples collected from 10 locations in the Bahamas over a 4-year period. Lobophorolide (1) is structurally unprecedented, yet parts of the molecule are related to tolytoxin, the scytophycins, and the swinholides, macrolides previously isolated from terrestrial cyanobacteria and from marine sponges and gastropods. Until now, compounds of this structural class have not been associated with marine macrophytes. Our findings suggest that seaweeds use targeted antimicrobial chemical defense strategies and that secondary metabolites important in the ecological interactions between marine macroorganisms and microorganisms could be a promising source of novel bioactive compounds.