Antifouling Brominated Diterpenoids from Japanese Marine Red Alga Laurencia venusta Yamada

Abstract

The marine red algal genus Laurencia has abundant halogenated secondary metabolites, which exhibit novel structural types and possess various unique biological potentials, including antifouling activity. In this study, we report the isolation, structure elucidation, and antifouling activities of two novel brominated diterpenoids, aplysin‐20 aldehyde (1), 13‐dehydroxyisoaplysin‐20 (2), and its congeners. We screened marine red alga Laurencia venusta Yamada for their antifouling activity against the mussel Mytilus galloprovincialis. Ethyl acetate extracts of L. venusta from Hiroshima and Chiba, Japan, were isolated and purified, and the compound structures were identified using 1D and 2D NMR, HR‐APCI‐MS, IR, and chemical synthesis. Seven secondary metabolites were identified, and their antifouling activities were evaluated. Compounds 1, 2, and aplysin‐20 (3) exhibited strong activities against M. galloprovincialis. Therefore, these compounds can be explored as natural antifouling drugs.

Halogenated Cyclic Monoterpenoids with Anti‐Biofouling Activity from the Okinawan Red Marine Algae Portieria Hornemannii

“…Compounds 1 – 4 , which showed activity (inhibition >50 %) at concentration 0.16 μmol/cm 2 , were terpenes containing halogen atoms such as bromine and chlorine. Some natural products with halogen atoms isolated from red algae have previously anti‐biofouling activity [12–14] . These results suggest that halogen atoms may contribute to the anti‐biofouling activity.…”

“…The anti‐biofouling assay for M. galloprovincialis was performed using a previously reported method [12] …”