Novel antineoplastic diterpene-benzoates from the Fijian red alga Callophycus serratus

Red macroalgae are well-known for the production of brominated metabolites, including terpenoids and phenols, yet some taxa within the Rhodophyta remain relatively unstudied. Herein, we report the discovery of unusual diterpene-benzoate natural products representing three novel carbon skeletons, from the red alga Callophycus serratus collected in Fiji. Included among the new compounds were 15- and 16-membered macrolides as well as non-macrocyclic diterpene-benzoic acid structural motifs, all apparently sharing the same 27-carbon biosynthetic precursor. Biological activities of these compounds included moderate antibacterial, antiviral, and antineoplastic effects via specific apoptotic cell death