The venom of deadly animals mightn't seem like a great place to look for life-saving medicines, but scientists are continually sifting through these toxins to discover compounds with huge potential. Now researchers at Stanford studying scorpion venom have identified a pair of compounds that were shown to kill off both staph and tuberculosis bacteria. And better yet, they were able to create synthetic versions in the lab.
Scorpion venom has proven a rich source of medical discovery, despite its obvious deterrents. Scientists have tapped into the toxic substance for the development of immunosuppressants, malaria medication and cancer research. Just last month, researchers discovered how an amino acid in scorpion venom could be used to help clinicians more easily detect lethal brain tumors.
The latest breakthrough comes courtesy of the scorpion Diplocentrus melici, which is native to eastern Mexico and was being studied by researchers of molecular medicine at the National University of Mexico. As you can probably imagine, extracting scorpion venom isn't easy. In fact, in 2017 a group of researchers in Morocco even developed a scorpion-milking machine to make things safe for humans and the animal itself.
Using the more traditional method of stimulating the animal's tail with mild electrical pulses, the team in Mexico was able to extract small samples of the venom. In doing so, the researchers observed a change in its color, from clear to brownish, as it was exposed to air. Diving further into the reasons why, the team found two compounds to be behind the transformation, with one changing to red and the other to blue as the substance was exposed.
It was at that point that the National University of Mexico researchers called in the chemistry experts at Stanford University to learn more. Working with just 0.5 microliters of venom, the Stanford team led by Richard Zare was able to work out the molecular structure of the compounds and determine that they were two new examples of benzoquinones.
These are a class of molecules already known to have antimicrobial properties, so at this point the researchers were optimistic about the possibilities. With the structure of the compounds confirmed, the team then got to work recreating synthetic versions in the lab, a critical step in achieving practical outcomes.
"By volume, scorpion venom is one of the most precious materials in the world," says Zare, a senior author on the paper. "It would costs US$39 million to produce a gallon of it. If you depended only on scorpions to produce it, nobody could afford it, so it's important to identify what the critical ingredients are and be able to synthesize them."
After successfully synthesizing the compounds, the scientists began exploring their biological possibilities in mouse tissue. Their testing shows that the red benzoquinone was very effective at killing off staphylococcus bacteria and the blue one at killing off regular tuberculosis-causing bacteria, including strains that had developed resistance to existing drugs. Importantly, the testing in mice left the lung lining intact.
"We found that these compounds killed bacteria, but then the question became 'Will it kill you, too?'" Zare said. "And the answer is no."
There's still plenty of work to do before these results translate into drugs to treat tuberculosis and staph, but the researchers from Stanford University and Mexico are buoyed by the results, with further collaborations already planned to pursue that aim.
The research was published in the journal Proceedings of the National Academy of Sciences.
Source: Stanford University
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