Chemical and biological aspects of sponge secondary metabolites

Sponge secondary metabolites have been investigated to find potential lead compounds for the development of commercially interesting products. During the Camellia project entitled ‘Environmentally compatible antifouling coatings for the protection of ships, water systems, fish cages and other immersed structures against aquatic growth,’ several analogues of terpenes containing isocyano, thioisocyano, thiocyano and formamide functionalities were synthesized and evaluated for their antifouling activity against the settlement of the barnacle Balanus amphitrite. The best activities were obtained with N-formylated alkylamines the length of the carbon chain of which is comprised between C-11 and C-14. In the aromatic series, the isocyano derivatives showed high antifouling activities. But they were too toxic against many microorganisms to be incorporated in paint formulations. During the Symbiosponge project entitled ‘Biology of sponge natural products’ the methanolic extract of about 230 sponges were submitted to bioassays guided fractionation to isolate bioactive compounds. Several cytostatic sesquiterpene quinones and tryptamine-derived alkaloids were isolated from 4 sponges of the genus Hyrtios. A new 4-sphingenine analogue and a novel polyacetylenic derivative were found to be responsible for the bioactivities of the methanolic extracts of Haliclona vansoesti and Callyspongia pseudoreticulata, respectively.