Mar.Drugs 2003,1 6 "endosymbionts",a more advanced strategy is to focus on cloning and expression of the respective key biosynthetic gene clusters.This molecular biological approach will open up new avenues for biotechnological production of drugs or drug candidates from the sea. Keywords:drugs from the sea,mariculture,endosymbionts,biotechnology Introduction Among the various sources for the development of new drugs,compounds from living organisms,so called natural products,are of particular significance [1].Approximately one third of today's best selling drugs are either natural products or have been developed based on lead structures provided by nature. Traditionally higher plants used to be the most prolific sources of drugs from nature.Recent examples of plant-derived anti-cancer drugs include paclitaxel (taxol)from Taxus brevifolia,etoposide (vepesid) derived by partial synthesis from the lignan podophyllotoxin isolated from Podophyllum peltatum and irinotecan(camptosar)obtained based on the lead structure of camptothecin isolated from Camptotheca acuminata.Use of medicinal plants is well documented throughout human history but is by no means restricted to humans as apes such a chimpanzees have been shown to use plants for the treatment of wounds or to fight intestinal parasites. Looking at drugs from nature it is surprising that up to now almost all medicinally used natural products or derivatives thereof were obtained from terrestrial organisms rather than from those inhabiting the sea.The oceans cover more than 70%of the earth'surface and are an indispensable source of protein for human nutrition.With regard to drug discovery and development,however,the oceans started to attract interest from pharmaceutical companies and research institutions only approximately 50 years ago with the discovery of the sponge-derived nucleosides spongothymidine and spongouridine [2](Fig.1). Since then Figure 1.Antiviral nucleosides from sponges spongothymidine spongouridine from the sponge Cryptotethia cryptaMar. Drugs 2003, 1 6 “endosymbionts”, a more advanced strategy is to focus on cloning and expression of the respective key biosynthetic gene clusters. This molecular biological approach will open up new avenues for biotechnological production of drugs or drug candidates from the sea. Keywords: drugs from the sea, mariculture, endosymbionts, biotechnology. Introduction Among the various sources for the development of new drugs, compounds from living organisms, so called natural products, are of particular significance [1]. Approximately one third of today´s best selling drugs are either natural products or have been developed based on lead structures provided by nature. Traditionally higher plants used to be the most prolific sources of drugs from nature. Recent examples of plant-derived anti-cancer drugs include paclitaxel (taxol) from Taxus brevifolia, etoposide (vepesid) derived by partial synthesis from the lignan podophyllotoxin isolated from Podophyllum peltatum and irinotecan (camptosar) obtained based on the lead structure of camptothecin isolated from Camptotheca acuminata. Use of medicinal plants is well documented throughout human history but is by no means restricted to humans as apes such a chimpanzees have been shown to use plants for the treatment of wounds or to fight intestinal parasites. Looking at drugs from nature it is surprising that up to now almost all medicinally used natural products or derivatives thereof were obtained from terrestrial organisms rather than from those inhabiting the sea. The oceans cover more than 70% of the earth’surface and are an indispensable source of protein for human nutrition. With regard to drug discovery and development, however, the oceans started to attract interest from pharmaceutical companies and research institutions only approximately 50 years ago with the discovery of the sponge-derived nucleosides spongothymidine and spongouridine [2] (Fig. 1). Since then Figure 1. Antiviral nucleosides from sponges HN N HOH2C OH O OH O O CH3 HN N HOH2C OH O OH O O spongothymidine spongouridine from the sponge Cryptotethia crypta