Antioxidant and Anti-inflammatory Meroterpenoids from the Brown Alga Cystoseira usneoides

A chemical study of the alga Cystoseira usneoides has led to the isolation of six new meroterpenoids, cystodiones A–F (1–6), together with six known related compounds (7–12). The structures of the new metabolites have been established by spectroscopic techniques. In antioxidant assays all of the tested meroterpenes, and in particular cystodiones A (1) and B (2), 6-cis-amentadione-1′-methyl ether (7), and amentadione-1′-methyl ether (8), exhibited strong radical-scavenging activity. In anti-inflammatory assays, usneoidone Z (11) and its corresponding 6E isomer (12) showed significant activity as inhibitors of the production of the proinflammatory cytokine TNF-α in LPS-stimulated THP-1 human macrophages.