National Geographic : 2013 Feb
venom 83 against Alzheimer’s and Parkinson’s diseases, depression, and even nicotine addiction. So far, five compounds from the snails have made it to human trials, and one morphine-like pain drug, ziconotide, has resulted. Ziconotide is chemically identical to the component the snail makes. Another sea creature, the sun anemone, has toxic tentacles that stun its prey before wrapping the victim—often a small fish or a shrimp—into its maw for dinner. But the anemone’s stinging cells, called nematocysts, fire off venom that con- tains peptides useful in treating human auto- immune diseases. In the 1990s a team led by physiologist George Chandy of the University of California, Irvine revealed that one of the peptides blocks the activity of a protein that promotes inflammation. The researchers recon- figured the peptide into one they called ShK-186. Now Kineta, a biotechnology company based in Seattle, is developing this against autoimmune diseases. What makes it so promising, says Shawn Iadonato, Kineta’s chief scientific officer, is how specifically it binds to diseased cells. “Our drug is very specialized to target the cells at work in these diseases. Other meds are problematic because they have many side effects and leave patients vulnerable to infection and cancer.” The sun anemone holds promise for treating diseases such as multiple sclerosis, rheumatoid arthritis, psoriasis, and lupus. “It will let patients experience a more normal life,” Iadonato says. “It just takes a long time, even when you have a breakthrough discovery. There are so many side avenues to take to make sure there are no unintended effects. There’s a lot of unraveling and putting back together to get it just right.” Advances in fields such as molecular biology continue to give scientists better ways to un- derstand venoms and their targets. While drug companies once relied on luck, screening thou- sands of compounds for a particular effect, today’s higher tech options, such as Designer Toxins, give sharper detail, making it easier to shape medicinal keys to fit specific molecular locks. This means that a spray to stop bleeding derived from the venom of the brown snake will likely soon be saving lives at accident scenes, and a peptide from mambas will someday be treating heart failure. The medical potential of venom, Zoltan Takacs never tires of saying, is “mind-blowing.” But we’re at risk of losing the sources of that potential fast- er than we can identify their toxin gifts. Snakes, in adapting to fill varied niches all over the globe, have evolved a stunning range of venomous com- pounds. But snakes are in decline, as are so many other animals. The oceans too are under pres- sure; their changing chemistry could wipe out promising sources of venom, from cone snails to octopuses. “In conserving biodiversity worldwide,” Takacs says, “we should better appreciate mo- lecular biodiversity.” That would put the mol- ecules in nature’s deadliest potions high on the agenda when conservation decisions are made. And that would be a lifesaver. j The element of surprise gives this rhino viper in Cameroon an edge over prey. Quick-kill venom finishes the job. Vipers provide valuable toxins, including those used in drugs for hyperten- sion and heart disease and to control bleeding during surgery. You can’t just put venom in a pill. The useful component must be modified at the molecular level.