Bromophycolides C-I from the Fijian red alga Callophycus serratus

Bromophycolides C-I ( 1-7) were isolated from extracts of the Fijian red alga Callophycus serratus and identified by NMR and mass spectral techniques. These novel natural products share a carbon skeleton and biosynthetic origin with previously identified bromophycolides A ( 8) and B ( 9), which form a rare group of diterpene-benzoate macrolides. Bromophycolides C-I ( 1-7) displayed modest antineoplastic activity against a range of human tumor cell lines.