A chemical derived from sharks could help protect humans against viral infections such as hepatitis, American research out Tuesday showed.

Scientists found that a chemical called squalamine demonstrated effective antiviral activity against a range of human viruses from yellow fever to hepatitis B, C and D, in both lab and animal experiments.

As the chemical has already been used in human clinical trials for the treatment of cancer and eye disorders, it means it could quickly be tested as a new drug treatment for viral diseases, researchers at Georgetown University Medical Center, Washington, said.

"To realize that squalamine potentially has broad antiviral properties is immensely exciting, especially since we already know so much from ongoing studies about its behavior in people," lead researcher Professor Michael Zasloff, said.

"Squalamine appears to protect against viruses that attack the liver and blood tissues, and other similar compounds that we know exist in the shark likely protect against respiratory viral infections, and so on," he added.

Zasloff believes the research, published in the "Proceedings of the National Academy of Sciences" journal, also explains the mystery of how sharks, which have a very primitive immune system, can so effectively fight the viruses that plague other living creatures.

He continued, "We may be able to harness the shark's novel immune system to turn all of these antiviral compounds into agents that protect humans against a wide variety of viruses. That would be revolutionary. While many antibacterial agents exist, doctors have few antiviral drugs to help their patients, and few of those are broadly active."