New meroterpenoids from Sargassum macrocarpum as inhibitors of amyloid β aggregation

Three new meroterpenoids, macrocarquinoids J(1)–L(3) were isolated from brown alga, Sargassum macrocarpum, along with sargahydroquinoic acid. The structures of 1–3 were elucidated with 2D NMR spectral data. The inhibitory activities of these compounds against Aβ42 aggregation were evaluated using thioflavin T assay and transmission electron microscopy. All three new meroterpenoids were found to be active, and macrocarquinoid L was the strongest among the three compounds. Furthermore, sargahydroquinoic acid significantly delayed the onset of paralysis in transgenic Caenorhabditis elegans, suggesting its potential inhibitory effect on amyloid aggregation.