Two new brominated C 15 -acetogenins from the red alga Laurencia japonensis .

We report on the chemical characteristics of the red alga Laurencia japonensis , collected off the coast of Yoshio, Katsuura, Boso Peninsula, Japan. We isolated two new brominated C ₁₅ -acetogenins in this species, which we name katsuurenyne A ( 1 ) and katsuurenyne B ( 2 ), along with two already known halogenated terpenes [2,10-dibromo-3-chloro-α-chamigrene ( 7 ) and aplysiadiol ( 8 )]. We extensively analysed spectral data (from IR, ESI-MS, 1D-NMR and 2D-NMR) to confirm the structure of these compounds.