Marine Life Tapped for New Drugs : Medicine: The ocean, like the rain forest, holds invaluable pharmaceutical resources. Scientists hope pollution won’t limit its potential.
Teetering on the edge of a dock, biochemist Douglas Prasher dips a net into Vineyard Sound and scoops up a mass of jellyfish. He gingerly nudges the slimy blob.
“The uniqueness of this organism is very important to me,” Prasher said. “The ocean provides completely different kinds of animals to work with.”
Back in his lab at Woods Hole Oceanographic Institution, Prasher cuts off the outer ring of tentacles and places the jellyfish in a large freezer. Stored at minus-158 degrees Fahrenheit, the small, doughnut-shaped chunk of organic matter will later be defrosted, ground into mush and used in a war against human suffering.
The ocean is yielding an ever-increasing number of previously unknown chemical compounds that are manufactured by animals such as jellyfish. Scientists hope that one day these substances will be useful against cancer, lung diseases such as asthma and emphysema, and inflammatory ailments such as arthritis and psoriasis. Some researchers look for an AIDS immunization agent to emerge from the sea.
“About half of all drugs known today are derived from plants or animals--including quinine, quinidine, digitalis, cortisone and even aspirin, which comes from tree bark,” said pharmacologist Robert Jacobs of UC Santa Barbara. “But over the past 200 years, we’ve not been able to study marine organisms systematically, the way we’ve studied terrestrial organisms. Now we have the technology to do it.”
The blood of horseshoe crabs has long been used in human cell diagnostic testing. Drugs derived from compounds found in marine animals already are available in pharmacies. The anti-cancer agent cytarabine and the anti-viral agent vidarabine both were derived from sponges. Acyclovir, made from compounds found in Caribbean Sea creatures, has been used since 1982 to treat genital herpes and encephalitis.
Testing of a promising anti-cancer drug, didemnin B, in cancer patients at about 20 clinics is now nearly complete. Developed from tunicates, or sea squirts, it also has proved useful against herpes, equine encephalitis and yellow fever. By suppressing the body’s immune system, it could help prevent rejection of organ transplants.
The tunicate-derived compound ecteinascidin, whose toxicity in animals is under study, is also being considered as a cancer treatment.
“We have here two classes of compounds that look very promising as anti-tumor agents,” Kenneth L. Rinehart, a chemist at the University of Illinois at Urbana-Champaign, said. “What’s exciting is that they’re quite different from any others currently in use, both in the way they work and the chemical entities they provide.”
Scientists reason that many sea creatures, especially soft-bodied animals such as tunicates and sponges, contain chemical structures not found on land because of the way they evolved defenses against predators.
Unable to move about and lacking hard shells, claws or teeth, these animals developed chemical compounds to repel or kill predatory fish. These same compounds are being found to have pharmaceutical uses such as killing cancer cells in test tubes.
After about 20 years of development, the relatively new field of marine bio-organic chemistry and pharmacology has grown rapidly in recent years. Japan is supporting major efforts to develop marine sources of medicine as well as food.
In the United States, the National Cancer Institute, the National Science Foundation and the National Sea Grant College Program have been awarding study grants. All major U. S. pharmaceutical companies test promising compounds and work to develop them for the market.
At a meeting in Chicago last October, a Sea Grant College Program committee proposed a “national strategic research initiative” that would allocate $1.5 million a year for six years to support further research and postdoctoral fellowships in the field.
