Halogenated metabolites with antibacterial activity from the Okinawan Laurencia species

The chemical compositions of five species of the red algal genus Laurencia from coastal waters of Okinawa Prefecture, Japan, have been investigated. A halogenated C 15 acetogenin, (12 E)-lembyne-A, was isolated from L. mariannensis, and a halogenated sesquiterpene, (6 R,9 R,10 S)-10-bromo-9-hydroxy-chamigra-2,7(14)-diene, was first found from L. majuscula as a naturally occurring compound. Laurencia nidifica yielded previously known laurinterol and isolaurinterol. Samples of L. cartilaginea and L. concreta afforded no halogenated metabolites. The structures of these halogenated metabolites as well as their antibacterial activity against some marine bacteria are reported. Halogenated C 15 acetogenin, such as (12 E)-lembyne-A was isolated from the red alga Laurencia mariannensis, and other species, all were analysed for their antibacterial properties.