Lifesaving Venom

By Medical Discovery News

Sept. 1, 2012

People have evolved a fear of snakes out of necessity. One bite from a venomous snake can prove fatal, so it’s ironic that a number of remarkable drugs are derived not only from poisonous snakes, but other deadly creatures as well. Researchers increasingly prize this group of animals, believing their venom holds the promise of effective treatments for major disorders ranging from high blood pressure to heart disease to cancer.

Depending on the type of poisonous snake, a bite can cause a drop in platelets and lead to uncontrollable bleeding. Or it can, like the venom of the Brazilian pit viper, incapacitate victims by causing their blood pressure to plummet. But in smaller doses these same characteristics can reverse disease.

One group of drugs, called ACE inhibitors, brings down blood pressure by decreasing chemicals that tighten blood vessels so that blood flows more smoothly. Another drug, called tirofiban, comes from the saw-scaled viper, which has venom that thins the blood and causes victims to bleed out. As a drug, it’s an anticoagulant used to dissolve blood clots in people with a minor or impending heart attack.

Another venom with similar mechanisms comes from the Malayan pit viper, except it also possesses a protein that may dissolve clots for as long as six hours after stroke symptoms start. An international study is targeting this venom’s potential to expand the three-hour window required for current drugs to be effective. Allowing people more time to get to a hospital for evaluation and treatment makes a significant difference on their prognosis.

Other deadly creatures also have lifesaving potential. Scientists are studying the fatal Deathstalker scorpion native to North Africa and the Middle East. Yet, its venom contains Chlorotoxin, which just happens to attach to cancer cells by binding strongly to a cancer-specific protein called matrix metalloproteinase-2. By fluorescently labeling Chlorotoxin, surgeons can easily identify cancer tissues and remove them. Scientists also figured out that by radioactively labeling Chlorotoxin, the toxin targets tumor cells and the radiation kills them.

Another example is Cobratoxin, which Western pharmacists began experimenting with as early as the 1930s on patients with diseases such as multiple sclerosis (MS) and asthma. More recently, a modified form of Cobratoxin has been shown to block the development of induced MS in 90 percent of lab rats. Cobratoxin seems to stimulate a molecule called interleukin 27, which slows an overactive immune response that scientists believe may be causing the disease. A related toxin molecule called Cobrotoxin has been shown in studies to impede the spread of HIV by blocking the receptors the virus uses to infect cells.

While the field of venom study has grown, researchers are concerned that negative environmental impacts on some of the threatened venomous species will limit their work. Ultimately that reduces the number of potential life saving or life changing drugs that are possible.

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