Salty Secrets New Drugs From The Sea

The discovery of penicillin in 1928 triggered a systematic search for other terrestrial micro-organisms that could be used in new antibiotics, leading to the discovery of drugs such as streptomycin, neomycin, chlorophenocol and chlorotetracyclin. For many years, research focused on terrestrial plants and micro-organisms, mainly because specimens are easy to obtain. But a growing proportion of today's promising pharmaceutical research focuses on the sea, where marine organisms have evolved biologically unique molecules.

Life began in the sea, and three-quarters of the Earth's surface is covered by water. Innumerable organisms, displaying rich biodiversity, populate the ocean depths. There are extremely diverse species of invertebrates - fixed or sessile - many in plant form and others capable of slow, primitive movement. These invertebrates possess no physical defenses such as protective shells or spines; instead, they have developed biologically active molecules - secondary metabolic substances - that they use to attack prey or defend their habitat. The fascinating variety of marine organisms hints at a myriad of new possibilities for drug discovery.

Exploration of the sea and its organisms is still at a relatively early stage. Although the oceans contain much greater biodiversity than is found on land, efforts to exploit this biodiversity by identifying new chemical compounds have hardly begun: at present, there are some 11,000 marine- derived natural products compared with more than 155,000 natural, terrestrial products.

Sponges became the focus of many studies after the discovery, in 1959, that some produced active antimicrobial substances. Research soon revealed that other invertebrates, such as tunicates, ascidians, echinoderms, bryozoans, corals and molluscs, produced similar substances. Biologists and chemists worldwide began searching for natural products of marine origin, leading to a boom in marine bio-prospecting - the search for aquatic organisms for the research and development of new therapeutic products. The discovery in the 1980s of various marine-derived compounds with the ability to inhibit cell culture growth stimulated the interest of the pharmaceutical industry.

There are several phases in marine product research: specimen collection; establishing taxonomy; extracting possible active molecules; using screening techniques to evaluate therapeutic...