Marine compound shows promise against deadly brain-eating amoeba

Primary amoebic meningoencephalitis (PAM), a parasitic disease that causes the rapid deterioration of brain tissue, is one of the most lethal infections known, with a fatality rate exceeding 97%. Caused by the free-living amoeba Naegleria fowleri (N. fowleri), the disease progresses with devastating speed, often leaving patients with only a few days to respond to treatment.

Now, researchers at the University of California San Diego have isolated a marine-derived compound that may provide a faster, more effective way to stop the parasite in its tracks. The study, published in Marine Drugs, was led by Debnath, Fenical, and Hayley Fong, PhD, who completed this project as part of her doctoral research at UC San Diego.

A deadly brain infection

The researchers report that rutamycin B - a compound isolated from a marine bacterium — demonstrates significant potency at low concentrations against multiple clinical strains of N. fowleri. Most notably, the compound achieves full potency within just four hours, significantly outpacing amphotericin B, the current gold-standard treatment.

“Current treatments for PAM often act too slowly or carry heavy toxicity,” said Anjan Debnath, PhD, associate professor at UC San Diego Skaggs School of Pharmacy and Pharmaceutical Sciences and co-director of UC San Diego’s Center for Discovery and Innovation in Parasitic Diseases. “By identifying a compound that is both faster and more selective, we are moving closer to a treatment that can stop the infection before it causes irreversible damage, which could fundamentally change the prognosis for people who contract this parasite.”

A compound from the ocean

The findings also speak to the therapeutic potential of compounds isolated from the ocean.

“The ocean contains a diverse library of chemicals, and we’ve only just scratched its surface,” said William Fenical, PhD, Distinguished Professor emeritus at UC San Diego’s Scripps Institution of Oceanography. “These results are a powerful reminder that the solutions to some of our most challenging medical problems may be hiding in unexpected places.”

The researchers’ key findings were:

• Rutamycin B worked faster than the current standard treatment, reaching full strength within four hours versus 16 hours.
• The compound was 200 to 300 times more lethal to the parasite than to human cells.
• The compound works by shutting down an enzyme that the parasite uses to produce energy.
• When combined with the current standard treatment, the researchers found they could achieve the same results using as little as 3% to 10% of the original dose of rutamycin B.

Next steps towards treatment

Beyond its immediate potency, the team believes the structural properties of rutamycin B make it a promising candidate for further pharmacological optimization. Because the infection targets the central nervous system, the researchers are planning future studies to evaluate the compound’s ability to cross the blood-brain barrier and its efficacy in live disease models.

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While further research will be needed to bring this approach into the clinic, the study points toward a promising new therapeutic strategy for a disease that has historically left almost no survivors.