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Research Finds Fish-killing Toxin Holds Promising Cancer Applications

According to a new study by NOAA and the U.S. Department of Agriculture (USDA), a powerful fish-killing toxin produced by a type of freshwater algae called Euglena sanguinea could also have cancer-killing properties. The research team discovered that the toxin – euglenophycin – has a molecular structure similar to that of a naturally occurring chemical compound from fire ant venom known to inhibit tumor development. 

Euglenophycin could have a promising future as a cancer treatment. Laboratory tests have shown that even low concentrations of euglenophycin led to a significant decrease in cancer cell growth, and that the toxin can kill cancer cells. Preliminary studies have demonstrated the toxin to be highly effective against renal cancer, one of the most challenging cancers to treat.

Laboratory work

To find out why the 2002 fish kills happened, scientists from NOAA, USDA Agricultural Research Service, and Michigan State University isolated and analyzed dissolved compounds, bacteria, and algae from samples of the pond water the dead fish had lived in.

“This preliminary work demonstrates the tremendous potential for discovery of novel and effective new treatments for a variety of human diseases including cancer,” said Paul Sandifer, Ph.D., senior science advisor to the NOAA administrator. “By studying freshwater and marine organisms, NOAA and its partners stand to make important gains for human health and well being.”

The researchers identified this freshwater algae to be responsible for a mysterious disease that was killing fish in the ponds of a commercial aquaculture facility in North Carolina in 2002. More than 21,000 striped bass died in July and August of 2002, with losses valued at more than $100,000.

A NOAA scientist purified the active compounds in the algae and mapped the molecular structure of euglenophycin, the algal toxin responsible for the fish kills. Since 2002, there have been an additional 11 confirmed occasions in which euglenoid algae have caused fish to die in aquaculture ponds. Losses from these events, which have affected striped bass, tilapia, and channel catfish, may have exceeded $1.1 million.

The scientists are seeking patent protection while continuing to investigate whether the toxin can slow or prevent tumor formation. The research results were published in the online July 15 issue of Toxicon. Future research will test whether the toxin also can prevent the formation of tumors.