Bioactive brominated diterpenes from the marine red alga Jania rubens (L.) lamx.

Seven brominated diterpenes of the parguerene and isoparguerene series were isolated for the first time from the red alga Jania rubens (L.) Lamx., collected from the Red Sea coast at Hurghada, Egypt. The diterpenes were identified as isoparguerol (1), isoparguerol-16-acetate (2), isoparguerol-7,16-diacetate (3), parguerol-16-acetate (4), parguerol-7,16-diacetate (5), deoxyparguerol (6) and deoxyparguerol-7-acetate (7). The isolated diterpenes had a marked antitumour activity. Isoparguerol derivatives were slightly more effective than parguerol derivatives. Moreover, the data implied that the cytotoxicity of these compounds were dependent on the number of acetoxy groups. Also, anthelmintic activities of the isolated compounds on earthworms (Allolobophora caliginosa) were studied. Copyright (C) 2004 John Wiley Sons, Ltd.