Natural sources of drugs
Modern drug discovery tends to favor automated approaches involving the creation of novel compounds within the laboratory setting. Although they are in the minority, a few companies in the industry still believe that the natural world holds clues that will result in breakthrough medical treatments. They may not receive much in the way of objective, mainstream scientific coverage, but natural products have been used for thousands of years to treat a host of medical conditions. According to one published scientific review, 23 new medicines launched onto the global market during 2000–2005 were derived from natural sources (1).
In recent times, the World Health Organization (WHO) has become increasingly interested in traditional medicines and has been looking at medical systems developed in a range of countries. It has recognized that traditional medicines are being used by much of the world’s population and may offer a convenient and affordable means to tackle major disease threats. WHO has been developing a comprehensive traditional medicine strategy to enable all countries to benefit in a manner that can be scientifically monitored and safely regulated. As part of these moves it has helped set up training workshops on the use of traditional medicines for selected diseases and disorders in a number of countries. Oceanic innovation
Strange though it may sound, the oceans represent a huge, but untapped source of natural products that could be developed into medical treatments. Given that the oceans cover 70.8% of the planet (2), it is not surprising that knowledge of the natural life inhabiting them is far from complete. The task of sampling and evaluating each oceanic region for marine life is an immense project, which is limited by the availability of appropriate technology. The Census of Marine Life project is an ambitious ten-year international initiative, involving 70 nations, which aims to categorize as many species as possible, ranging from “large ocean predators to the tiniest microbes in ocean realms ranging from shallow coastal waters to the deepest darkest seas” (3). Their current databases hold information on over 78,000 species (3).
Investigating ocean life has already resulted in some novel medical discoveries, although this has been more due to chance than a systematic scientific approach. For example, the anticancer drug, cytosine arabinoside has its origins in a compound from the Caribbean sponge (Cryptotheca crypta) (1). The same organism also possessed a compound that was isolated and developed into the anti-viral drug adenine arabinoside (1).
There has been a noticeable increase in academic research to isolate additional compounds from marine life, with a particular emphasis on those exhibiting anti-cancer properties (1). This renewed activity has resulted in a number of compounds entering clinical trials and a greater interest in such research by commercial organizations (1). A recent success has been the launch of ziconotide, which is used for the treatment of severe chronic pain (1, 4, 5). Ziconotide is a synthetic equivalent of a naturally occurring conopeptide from the marine snail, Conus magus (4).
Unfortunately, increasing damage to the environment stands in the way of investigating marine life as a source of new medicines. Fishing, climate change and pollution have altered the food chains in the ocean thereby reducing biodiversity (6). A particular worry is the rising acidity of oceans, due to due to pollution from carbon dioxide (7). This has been linked to the burning of fossil fuels and is predicted to have a dramatic impact on marine life. The Intergovernmental Oceanographic Commission has estimated that between 20-25 million tonnes of carbon dioxide are being added to the oceans each day and that this outranks changes that have occurred during the past 20 million years of Earth’s history (7). Acidification of the oceans will affect the reproduction rates of fish, as well as having an impact on the plankton on which they survive. Acidification will also reduce the availability of calcium carbonate, which is important for many sea creatures to produce their hard protective skeletons (7). Outlook
The scale of the challenge in evaluating the environment for new product leads is immense. The Earth is rich in biodiversity, but the planet’s complex geography has meant that many plant and animal species have barely characterized due to the difficulties in accessing their habitats. Unfortunately, environmental pollution and human activity threaten to render many species extinct and this may happen before their potential as sources of new medicines can be scientifically demonstrated. References
- Chin Y-W et al. (2006). AAPS Journal. 8(2): E239-E253. DOI:10.
- Pidwirny, M (2006). "Oceans." Encyclopedia of Earth. Eds. Cutler J. Cleveland and J Emmett Duffy. (Washington, D.C.: Environmental Information Coalition, National Council for Science and the Environment).
- Anon (2006). Extreme Life, Marine Style, Highlights 2006 Ocean Census.Census of Marine Life Press Release. 10 December 2006.
- Anon (2006). PRIALT (ziconotide intrathecal infusion).
- Staats PS et al. (2004). Intrathecal Ziconotide in the Treatment of Refractory Pain in Patients With Cancer or AIDS. JAMA. 2004;291:63-70.
- Fry C (2004). Ocean medicines could be lost. BBC News. 13 May, 2004.
- Anon (2004). Probe into rising ocean acidity. BBC News. 17 August, 2004.
Dr Faiz Kermani has several years experience in both academia and the pharmaceutical industry. He has worked in pharmaceutical R&D, pricing and reimbursement, marketing and medical communications. He holds a PhD in Immunopharmacology from St. Thomas’ Hospital, London and a First Class Honours degree in Pharmacology with Toxicology from King’s College, London. He has written extensively on international healthcare issues, and is on the editorial board of a number of publications. In March 2006, he was a delegate on the UK Government’s Trade and Investment Biotech Scoping Mission to China and was a speaker at the subsequent presentation.
You can contact Dr Kermani via firstname.lastname@example.org