Medicine From Nature

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The bountiful diversity of life on Earth is slipping away at an alarming rate. By one estimate, 40 percent of all species are endangered. Why does it really matter how many species exist on Earth? Of all the arguments for why we need biodiversity, there is one selfish reason that should be most relevant to anyone who has ever been sick or in pain. It is that most of our medicines come from biodiversity. They are first “invented” by plants or animals over millions of years of evolution, and only then adapted by us. According to a recent study of more than 1,000 drugs approved over a 20-year period, not a single one was truly synthetic. All were derived from, or at least based on, a natural source. Plant toxins have long been a source of medicine for people. Now scientists are discovering that animal toxins, such as those in the venom of species from snakes to spiders to bees, may prove to be useful as well.

Venom is really modified saliva. A complex concoction, venom is made up of toxins and hundreds of other ingredients. Each venomous species’ concoction is unique, consisting of molecules modified to attack very specific targets. For example, some toxins target red blood cells, others the muscle cells of the heart, others nerve cells, and still others target fat cells. Because they are so targeted, drugs based on these toxins have the potential of causing very few side effects.

Such is the case with the first drug developed from snake venom. Scientists noticed that workers in banana plantations bit by the Brazilian pit viper would collapse suddenly from a drop in blood pressure. They developed a drug based on the viper’s venom to intentionally lower blood pressure—it was the first ACE inhibitor. Today ACE inhibitors are widely used to treat high blood pressure and cause fewer side effects than any other blood pressure medication.

Dozens of other toxin-based drugs have since been invented, with many more currently under development, to treat everything from diabetes to asthma. A toxin from the Chilean Rose tarantula may stop heart attacks. Cone snail and box jellyfish toxins may lead to non-addictive painkillers. Sea anemone toxins may treat paralysis and multiple sclerosis. And a drug based on a giant yellow Israeli scorpion toxin may deliver radioactive iodine to brain tumor cells, effectively removing tumor cells left behind after surgery.

Despite the great potential of toxins in medicine, our knowledge about them, even for known species, is minimal. Only now are scientists beginning to scour the Earth, collecting the genetic sequences of toxins for storage and possible use before they could be lost forever.

Questions:

1. In order to justify the allocation of resources to biodiversity preservation, some organizations are attempting to quantify the value of biodiversity. Using the 2006 data from the report in this link, or a more recent source, estimate the annual value of nature-based pharmaceuticals. Assume that 63 percent of the market is derived from natural sources.

2. Despite the potential for medical applications, only a small fraction of Earth’s species have been explored for this purpose. Speculate on the reasons for this.

3. The toxins of many marine invertebrates including cone snails, jellyfish, sea anemones, and sea stars may lead to new medicines. Research and describe one of these applications.

4. Use your research from Question 3 to write an argument persuading the public to value marine biodiversity.

More To Explore

Venoms as a Platform for Human Drugs: Translating Toxins into Therapeutics
The Venom Cure PBS Video

American Samoa

Fagaalu Bay

Fagaalu Bay in American Samoa, which is located in the South Pacific. (Photo courtesy of Cheryl Wendling)

Turquoise seas filled with exotic fish, moonlit beaches, mountainsides blanketed with tropical rain forests … typhoons, earthquakes, tsunamis … invasive species, contaminated water, soil erosion … these descriptions are all wildly different, except that they aren’t talking about different places. All of this imagery describes the same region deep in the South Pacific: the U.S. territory of American Samoa.

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