Achieving firsthand experience with snake venom is probably not high on anyone’s list of things to accomplish in life. Even the most harmless snakes aren’t exactly cuddly or loveable, so it’s no wonder that people aren’t rushing to extol the virtues of the many species whose bite can kill a human within a matter of hours.
Like sharks and spiders, snakes occupy a special place in the animal kingdom that humans often consider “fascinating but terrifying.” As much as we’re scared of them, we know that their venom has healing powers that many of us don’t fully understand. And just like spiders and sharks, snakes occupy a very special place in the environment and the food chain. For humans, they hold a special promise, because their venom, the very thing that makes them so fearsome, might hold the key to curing some of our worst diseases.
Picking the Right Poison
Snake venom is an astoundingly precise and effective product of evolution. Of the approximately 3,000 species of snakes in the world, only about 650 are venomous, and most of the deadliest kinds live in Australia, Asia, Africa, and Central and South America. There are roughly twenty-four known kinds of snake toxins, which vary between species and even subtly between members of the same species. Venoms mainly work in one of two ways, either by interfering with the circulatory system or by disrupting the nervous system.
No matter what part of the body the venom targets, all snake venom is incredibly effective. In the 1960s, doctors began looking at its effects on prey and realizing that venoms affected the same systems as many human diseases, but had the opposite effects. Researchers began wondering if they could find a way to use the venom itself, in smaller, more controlled doses, to cure those diseases.
The hunch was right and venom has proven extremely helpful in the treatment of heart disease, especially congestive heart failure and high blood pressure. Until the past few decades, there was no reliable treatment for high blood pressure until a Brazilian researcher began investigating the venom of the Brazilian pit viper (in the same family as rattlesnakes), when he realized that people bitten by the snake experienced a sudden and severe drop in blood pressure. Scientists discovered that the venom contains a protein that blocks the enzyme in the body responsible for regulating blood pressure. In a snake’s lethal dose, it causes the circulatory system to shut down, but when doctors created a less potent synthetic form, the result was the first ACE inhibitor, the most common class of drugs to treat the chronic condition.
Many snake venoms also inhibit clotting. The venoms cause their prey to hemorrhage and bleed to death, but once scientists isolated the proper toxins, they were able to turn them into drugs that can prevent clotting in people prone to heart attacks and strokes.
A Killer Cure for Cancer?
Some snake venoms work by causing the cells that line blood vessels to separate from each other, killing them. Researchers in Australia discovered that the toxin that caused this effect only worked on specific kinds of blood vessels, like the blood vessels that feed cancerous tumors. One new front in the battle against cancer uses specific compounds from these snakes’ venom to target tumors’ blood supplies. By cutting off the supply, the toxin kills the tumor itself. Since these compounds only work on their intended targets, they are seen as more desirable than chemotherapy and other treatments, which kill everything in their paths.
Another researcher in California isolated a venom protein called contortrostatin, which prevented cancer cells from attaching to each other and developing a blood supply. The compound reduced the spread of breast cancer in mice by 90 percent—the next step is creating a formula to treat breast cancer in humans. Traditional Chinese medicine has been using venom for centuries. A medicine called huachansu, derived from toad venom and recently studied in the United States, has been shown to slow the progression of cancer in some patients.
Venoms that don’t cause bleeding can cause paralysis, neurological problems, or interference with the nervous system. Neurotoxic venoms work by binding to the receptor sites on nerve cells, disrupting messages sent between the brain and the body. Snakes such as the extremely poisonous Black Mamba have incredibly specialized venoms that only bind to certain receptor sites. Scientists are currently researching neurotoxic snake venoms like the Black Mamba’s to learn what it is about the venom that causes it to bind to only those certain sites. Finding a way to make a chemical bind to a particular receptor could lead to advances for drugs that selectively treat Parkinson’s or Alzheimer’s disease.
Although snake venom gets most of the credit for scientific breakthroughs, all venom is a promising new area of study. Scientists are examining venom from toads, scorpions, bees, spiders, and octopi to see if there’s anything we can learn from their special chemical makeup. Following the leads provided by venom, researchers have found therapies for erectile dysfunction, asthma, and arthritis. Studying venom has even led to better, more organic pesticides. It may be hard to look at a poisonous snake and see a heart medicine or a new breakthrough cancer drug, but studying their venom is giving new insight to how our own bodies work and how we can keep them healthy.