The venom of anguimorph lizards, including the Komodo dragon, could provide targeted treatments to prevent strokes and heart attacks. A study of the venoms of these lizards, and the teeth they use to deliver them, has revealed considerable diversity, which could lead to highly targeted medicines.
Until recently, it was thought that venom was rare among lizards. However, Dr Bryan Fry of the University of Queensland demonstrated it is widespread, including in the Komodo dragon, the world's largest lizard.
This fact went unnoticed partly because many lizards don’t produce toxins powerful enough to kill their prey. However, as Fry notes in the journal Venom, to provide an evolutionary benefit, “A venom system need only marginally increase a predator’s chances of successfully securing a meal, e.g., by slightly weakening a potential prey animal, making it easier to subdue physically.” The Komodo dragon's truth was also obscured by the popular myth their mouths contain lethal bacteria.
Studies of snake venom led to captopril, the blood pressure-reducing drug that has prevented hundreds of thousands of heart attacks, and pit vipers are being pressed into service against strokes. Fry's paper suggests lizards' big medical moment could be specialized prevention of blood clots.
Fry told IFLScience clots form from a combination of three different chains on the protein fibrinogen. Different venomous species inject molecules that vary, depending on which chain they cut, or where the incision is made. This diversity could be valuable since it is possible that cutting in particular locations will be more effective for people suffering from specific conditions.
Bringing such a drug to market will not be easy. “Now comes the real drudgery,” Fry told IFLScience. He added that even if we never produce a drug specifically based on a lizard venom molecule, the understanding gained from seeing how they act on blood may help in perfecting other drugs.
While the prevention of blood clotting is a common feature of venom, and one that has an obvious application, venoms are so rich with biologically active molecules they can be good places to find more unexpected drugs. The gila monster was the source of exenatide, already used as an anti-diabetes drug and being trialed against obesity and Parkinson’s Disease. Fry said studies are underway of novel versions of exenatide from five species of gila relatives, some of which might have advantages over the existing drug. Unfortunately, all these lizards are endangered.
The study also investigated the diversification of lizards' teeth. The authors expected to find connections between changes in tooth shape and venom evolution. Fry was disappointed not to confirm this theory, but told IFLScience “It was still fun to look inside the mouths of a lot of big lizards.”