Manganese-based antioxidant complex of Deinococcus protects mice from gamma radiation

Aug 9 2016

They call it "Conan the Bacterium," and now it may be used to help save lives in the event of a nuclear disaster or terrorist attack.

Researchers at the Uniformed Services University of the Health Sciences have discovered a potent manganese (Mn)(II)-based antioxidant complex of the bacterium Deinococcus radiodurans that can be used to protect animals from radiation injury. The report, "MDP: A Deinococcus Mn2+-Decapeptide Complex Protects Mice from Ionizing Radiation," was released today in PLOS ONE.

The team, led by Dr. Paridhi Gupta, a research assistant in the USU Department of Pathology, wanted to know whether (Mn)-peptide antioxidants (called "MDP") could be used to protect proteins in other animals in the event of radiation exposure. They synthesized MDP in the laboratory, then administered it to mice exposed to doses of the most lethal form of radiation - gamma rays. All of the mice treated with MDP prior to radiation exposure survived, with substantially reduced levels of radiation sickness, in comparison to 63% mortality and weight loss in the untreated animals.

Deinococcus radiodurans is, according to the Guinness Book of World Records, the toughest bacterium on the planet. It can survive - and even thrive - in the most extreme environments, from the glaciers of Antarctica to the desiccated landscape of the Mojave Desert. It has even been found in highly radioactive soils at nuclear waste sites, and it is this unique ability to withstand extremely high doses of ionizing radiation (gamma rays) that has drawn generations of researchers hoping to harness the mechanisms of its resiliency for practical purposes.

"D. radiodurans has taught us - if you want to survive radiation: protect your proteins," explained study co-author Dr. Michael Daly, professor of Pathology at USU, who has devoted more than 25 years to studying the bacterium. "Past research has shown that Deinococcus bacteria accumulate high concentrations of manganese (a metal element similar to iron) and peptides. The secret, it seems lies in its ability to protect its proteins - the "machines" of the cell - from radiation damage. And, the unusual protein-protecting antioxidants accumulated in Deinococcus cells are readily synthesized in the laboratory. Such Deinococcus antioxidants now have been shown to be highly protective of mice exposed to lethal doses of gamma rays."

The mice were dosed with MDP prior to radiation exposure, but the protective properties of MDP could still be useful when given after exposure. The complex is patented and very easy to mass produce.

"Imagine being able to take a pill that would protect you from radiation," asked Daly. "Our study is the first to demonstrate that these antioxidants are safe and can protect animals from radiation injury and death. These results open the door to all kinds of possibilities in the development of radioprotective pharmaceuticals."