Marine sponges; a potent source of bioactive compounds

Marine animals in general and marine invertebrates in particular are promising organisms for synthesis of novel bioactive compounds. This is an adaptation strategy to thrive in the extreme environmental conditions of the sea and as a defense strategy to escape from predators by the marine invertebrates especially soft bodied animals like sponges (Werner et al., 2004). Focusing on sponges, a conceptual progress occurred with the study of Thakur et al. (2003), who suggested that marine animals and their symbiotic microorganisms (bacteria and fungi) produce an array of bioactive compounds against foreign attackers. Pharmaceutical interest in sponges was aroused in the early 1950’s by the discovery of a number of unknown nucleosides: spongothymidine and spongouridine in the marine sponge Cryptotethia crypta (Bergmann and Feeney, 1950; 1951). These nucleosides were the basis for the synthesis of Ara-C, the first marine derived anticancer agent and the antiviral drug Ara-A (Proksch et al., 2002). Ara-C is currently used in the routine treatment of patients with leukaemia and lymphoma. More than 15.000 marine products have been described up to now (MarinLit, 1999; Faulkner, 2000; 2001; 2002). Sponges are champion producers, concerning the diversity of products that have been found. They are responsible for more than 5300 different products and every year hundreds of new compounds are being discovered (Faulkner 2000; 2001; 2002). Most bioactive compounds from sponges can be classified as antiinflammatory, antitumour, immuno- or neurosurpressive, antiviral, antimalarial, antibiotic or antifouling. The chemical diversity of sponge products is remarkable. In addition to the unusual nucleosides, bioactive terpenes, sterols, cyclic peptides, alkaloids, fatty acids, peroxides, and amino acid derivatives (which are frequently halogenated) have been described from sponges.