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Seaweed Found in Fiji May Help Fight Cancer, AIDS

Brian Handwerk
for National Geographic News
October 17, 2005
 
A type of seaweed discovered in Fiji could someday be used to fight bacterial infections, cancer, or even AIDS, researchers report.

The red seaweed species (Callophycus serratus) is found on shallow coral reefs along the South Pacific island's coastline. Georgia Institute of Technology researchers studying the plant have recently identified ten new molecular compounds that might be developed for pharmaceutical use.

Some of the natural compounds showed promise as antibacterial fighters—even against nasty strains that are resistant to antibiotics.

A compound dubbed bromophycolide A was also intriguing. It was able to kill human tumor cells by triggering "programmed cell death," a type of cellular suicide that is considered a promising lead in the development of new anticancer drugs.

"We're only at the test tube level so far," Julia Kubanek, a Georgia Tech biochemist involved in the study, explained in a press statement. "The next step is to discover how these compounds work and then to study them in a more complex model system."

Kubanek and colleagues reported several of the new compounds in the journal Organic Letters.

Seaweed-Based Drugs

If the seaweed does turn out to have pharmaceutical uses, it could prove a boon for the Fijian economy.

The research is part of a larger project funded by the National Institutes of Health that involves Georgia Tech, the University of the South Pacific, and Fijians from several coastal villages.

The initiative blends environmental conservation and economic development by promoting the growth of new reef rock. It also preserves the reef species that may yield future drug discoveries.

But it might take at least a decade before any seaweed-based drugs are available, if indeed any are possible.

Many potential roadblocks remain, including one common to cancer treatments. The high doses needed to effectively knock out pathogens may be so strong that they would harm patients, researchers say.

"We can cure cancer with a shotgun, so curing cancer is not the problem," explained Georgia Tech biologist Mark Hay. "Curing cancer without harming patients is a whole different thing that's very difficult to figure out.

"Many compounds have been found to have a negative effect on cancer cells, but almost none of them have gone to market because of adverse side effects that make them unusable.

"These [newly discovered] compounds might also have those kind of constraints, but the exciting thing is that they are a new structural class, so they have the potential, although it is only potential, to be useful with fewer side effects."

The compounds found in the seaweed are unique because they have a previously unknown type of carbon skeleton.

"It's very unusual," Kubanek explained in her press statement. "[The compounds] represent a new category of organic molecules. It's exciting as a biochemist to observe that living organisms have evolved the ability to synthesize such unique and exotic structures compared to other molecules typically produced by seaweeds."

Nature's Chemical Weapons?

The seaweed likely developed its unique germ-killing compounds to attack its predators and protect itself from disease.

Marine organisms can create molecules and compounds for reproduction, defense, and disease resistance. The compounds can deter predators by poisoning them, slowing their growth, sterilizing them, or even killing them outright.

"If you think about the different life forms on an ocean reef, for example, lots of organisms have structural defenses, but seaweed generally doesn't," said Paul Jensen of the Scripps Institution of Oceanography in La Jolla, California.

"These nice, fleshy plants are sitting out there, and you're wondering why something isn't eating them. … [There] are all kinds of organisms looking for something to eat. Some of them cause infection in marine plants. So why aren't all these seaweeds decomposing and becoming infected?"

It's difficult to isolate the role of chemical compounds in such resistance, Jensen said, but evidence suggests that they are very important in the plants' natural defenses.

"We're trying to understand how these organisms solve their own problems with these compounds," Georgia Tech's Hay said.

This may also help researchers find ways to create valuable medicines from the red seaweed and other reef species.

"There's some serendipity involved," Scripps Institution's Jensen said. "If you're looking at things that may be designed to kill bacteria in nature, there's a reasonable chance that they may work pretty well to kill bacteria in a clinical application."

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