A NEW PRENYLATED GUAIANE FROM THE BROWN SEAWEED Dictyota mertensii

A chemical investigation of the brown seaweed Dictyota mertensii (Hoyt) Schnetter, Hörning & Weber-Peukert, a member of the Dictyotaceae, was carried out. The ethyl acetate extract led to the isolation of two prenylated guaiane, including a new one (1) and the known dictyol H (2). In addition, the dolabellane diterpene 10,18-dihydroxy-dolabella-2,7-diene (3) and two benzalkonium chlorides (4-5) were also isolated. The structures of all compounds were elucidated by an extensive analysis of their one- and twodimensional nuclear magnetic resonance data (1D and 2D NMR), and high-resolution electrospray ionization mass spectrometry (HRESIMS). The cell viability and the anti-inflammatory activity of diterpenes 1 and 2 were evaluated against lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages.