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Drugs from the Sea
Many coral reef invertebrate animals contain biologically-active chemicals that can be used to develop drugs for human use. Some invertebrates, such as sponges, have chemicals that have evolved as defence mechanisms to make the animal unpalatable to predators. Others, such as cone shells, have complex toxins that are used to catch and immobilise prey. Several on-going research projects at Lizard Island are investigating potential drugs from coral reef invertebrates. Cone shells, highly prized by collectors for their beautiful shell patterns, have recently attracted the attention of researchers because their venoms provide chemical templates for the design of new drugs of value in several medical conditions. Of the 500 species of Conus worldwide, over 80 are found on the Great Barrier Reef and about 50 of these occur in the waters of Lizard Island. While the venoms of several species have caused human fatalities, toxins of some other species show potential as novel drugs for use in pain management, epilepsy and the prevention of stroke. A group from the Department of Biochemistry and Molecular Biology at the University of Melbourne is studying the venoms of cone shells found at Lizard Island. Led by Associate Professor Bruce Livett and Dr John Down, the group collects specimens of Conus for isolation of toxins and screening of biological activity. Interesting new toxins are purified, characterised and synthesised in collaboration with others at the Centre for Drug Design and Development at the University of Queensland. The synthetic toxins provide workable quantities for subsequent research, obviating the need for further collections of cone shells. Research is presently focusing on the alpha conotoxins which target the nicotinic receptors responsible for muscle movement and brain functions. Results show that the alpha-toxins from different species of Conus show selectivity towards either muscle or brain receptors. These toxins are useful tools for examining the molecular nature of diseases in which the function of nicotinic receptors in the brain is impaired, such as Alzheimer's disease, Parkinsons's disease and epilepsy. So far, only a few species of Conus have been analysed for their novel toxins. With over twenty different toxins in each species, the fifty species of Conus on the reefs around Lizard Island provide a treasure trove of potential novel compounds. Relevant links
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