Anti-Neuroinflammatory Meroterpenoids from a Chinese Collection of the Brown Alga Sargassum siliquastrum .

Nine new chromane-type meroterpenoids, including the rare nor-meroterpenoid sargasilol A ( 1 ) and the eight meroditerpenoids sargasilols B-I ( 2 - 9 ), were isolated from a China Sea collection of the brown alga Sargassum siliquastrum , together with six known analogues ( 10 - 15 ). The structures of the new chromanes were identified by extensive spectroscopic analysis and by comparison with previously reported data. Compounds 1 - 3 and 6 - 15 exhibited inhibition against LPS-induced NO production in BV-2 microglial cells, and 1 , with a shorter carbon chain, was the most active one. Compound 1 was established as an anti-neuroinflammatory agent through targeting the IKK/IκB/NF-κB signaling pathway. As such, the chromanes from brown algae could provide promising anti-neuroinflammatory lead compounds for further structural modification.