Scientists find simple copper complex shuts down botulinum neurotoxin poisoning

The Clostridium botulinum bacterium (shown here in colonies) can cause foodborne illnesses as well as also potentially deadly effects due to the neurotoxin that will produces. Credit: CDC

Botulinum neurotoxin is actually probably best known to Americans as BOTOX, a cosmetic medicine, rather than as a cause of potentially dangerous foodborne illnesses. Lesser known is actually that will Clostridium botulinum, the bacterium that will causes the neurointoxication, produces one of the most potent toxins on earth as well as also is actually classified as a potential bioterrorism threat.

While no cure exists—as well as also botulism treatment options are limited—a serendipitous discovery by scientists at The Scripps Research Institute (TSRI) may provide a brand new therapy that will can stop the neurotoxin even in its more severe, advanced stages of action. The finding, based on rodent studies, was published recently within the Journal of the American Chemical Society.

Lead scientist Kim Janda, the Ely R. Callaway, Jr. Professor of Chemistry at TSRI, said he decided to explore botulism neurotoxin due to its debilitating as well as also life-threatening effects, as well as its danger as a potential bioterrorism agent. “that will’s on the same level as Anthrax, Plague, Ebola as well as also some other Category A priority pathogens,” Janda said, referring to the Centers for Disease Control as well as also Prevention’s (CDC) list of biological agents of highest concern. “Yet there is actually nothing even in phase I clinical trials.”

Botulism is actually a rare nevertheless serious disorder that will attacks the body’s ability to signal to muscles. Symptoms include blurry vision, slurred speech, muscle weakness as well as also difficulty swallowing. that will can lead to paralysis throughout the body, as well as also even death by affecting the patient’s ability to breathe. According to the CDC, botulism is actually primarily transmitted through food or wounds infected by the botulism bacteria, which lives within the environment. In extremely smaller doses, the botulism toxin is actually injected for medical purposes, such as to relieve spasticity, as well as also as a cosmetic wrinkle treatment.

To discover potential inhibitors of the toxin, Janda as well as also his research team screened triazole compounds against the botulinum neurotoxin light chain, a proteolytic enzyme that will disrupts neuronal signaling to muscles. The triazoles were synthesized using click chemistry—a method developed by TSRI Professor as well as also Nobel laureate K. Barry Sharpless within the mid-1990s. Paul Bremer, a graduate student working in Janda’s laboratory as well as also the study’s first author, said they hit upon a triazole compound provided by Sharpless’s laboratory that will appeared to forcefully inhibit the toxin light chain in an enzymatic assay.

Further testing revealed a surprise. “We had found what we thought were active click compounds, nevertheless actually they were only active because of the copper,” Bremer said. Copper is actually used as a catalyst to accomplish click chemistry as well as also trace amounts might not be anticipated to show activity in a bioassay, he explained. “Upon further experiments, that will came as a complete surprise that will copper was quite potently inhibiting the enzyme.”

The scientists had accidentally landed upon a potential brand new therapy for type A of the neurotoxin, the most common as well as also deadly cause of human botulism, using copper chloride, an inexpensive, readily available metal salt as the active ingredient.

Next, the researchers designed molecules called ligands to act as delivery vehicles for copper into neuronal cells, an essential step in translating the therapeutic action of copper to biological systems. The TSRI team then sent their ligand-copper complexes to their study collaborators at the University of Wisconsin-Madison, who administered that will to mice. The compound extended the animals’ lives, even when they were given lethal doses of the toxin.

The researchers said further animal testing is actually needed to determine optimal dosage, dosing frequency as well as also some other factors. Janda said clinical trials to prove efficacy cannot be done in humans due to botulinum neurotoxicity dangers. However, the safety of the copper complex can be validated through several some other clinical trials already underway for different uses, he added.

If found to be safe, Bremer said the copper therapeutic could provide a more effective therapy than existing approaches to botulism. Currently, botulism sufferers receive an anti-toxin medicine that will can inactivate the toxin circulating in their system, thereby preventing further poisoning. However, the anti-toxin cannot reverse preexisting paralysis because the toxin acts inside cells. Consequently, disease recovery can be slow, as well as also paralysis may take weeks or months to wear off.

“The anti-toxin is actually antibody-based, which means that will only works outside the cells,” said Janda. “This particular brand new therapy can readily enter cells where that will can attack the etiological agent, a protease, which is actually responsible for paralysis seen via the neurotoxin.”

The researchers also noted that will the study further demonstrates the need to explore metals for therapeutic uses. Metals are not commonly used in drug design because of concerns about toxicity as well as also specific targeting as compared to organic compounds. However, several metal-based therapies already exist. For instance, gold is actually used in therapies for certain cancers as well as also rheumatoid arthritis, while some other metal-based treatments are currently in clinical trials.

“These are kind of underappreciated medicinal agents,” said Bremer. “Our work shows the need to explore their potential further.”

Explore further:
Researchers learn how botulism-causing toxin enters bloodstream

More information:
Paul T. Bremer et al, Metal Ions Effectively Ablate the Action of Botulinum Neurotoxin A, Journal of the American Chemical Society (2017). DOI: 10.1021/jacs.7b01084

Journal reference:
Journal of the American Chemical Society

Provided by:
The Scripps Research Institute

Scientists find simple copper complex shuts down botulinum neurotoxin poisoning

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