Biologists have sifted through a roster of more than 2,000 sea creatures to obtain juices that could produce useful new drugs, said Dr. William McClure, director of the cellular biology program at UCLA, who reported on the work at the annual meeting of the American Association for the Advancement of Science here.
The best result so far, and the first new drug obtained from sea creatures in decades, is a powerful antiviral and anticancer substance called didemnin, according to McClure.
In laboratory tests on tissue cultures, didemnin promises to be one of the most effective antiviral drugs available, and has a good record at killing cells in cancer tests, as well. Upjohn pharmaceutical company has taken up the drug and begun animal tests with it.
"I think there will be a lot more good drugs coming from sea creatures in the future. It's logical -- there are thousands of living creatures which most protect themselves against disease and the environment much as any land creature does. So they are full of biologically active agents. We just thought we would try to tap some of them," McClure said.
Didemnin comes from sea squirts -- gelatinous creature that attach to rocks and piers. They are put in a blender to obtain the initial extract.
The substance has killed a variety of viruses in tests, including the herpes viruses which causes cold sores and other more serious lesions; some rhinoviruses, responsible for the common cold; influenza viruses, and some of the viruses which cause meningitis.
Powerful antiviral drugs are rare, McClure said, with only a few broadly useful ones available now. The special advantage of didemnin, if it proves itself in animal studies, is that it can attack two major classes of viruses, where current antivirals can kill only one class.
Didemnin may be a useful anticancer drug as well. It has doubled the life expectancy of leukemic mice in lab tests, according to Dr. Kenneth Rinehart of the University of Illinois, a colleague of McClure in the research.
McClure, Rinehart and others also have found a number of weak antibiotics in sea creatures as well as some potential psychoactive agents which work much the same way as current antipsychotic drugs.
Another substance extracted from sea creature, by Eugenie Clark of the University of Maryland, is a powerful shark repellent.
A fish called the Moses Sole excretes the substance, a milky white poison. When the Moses Sole is about to be attracted by sharks or other large predators, the poison is squirted from pores near the fish's tail.
Clark displayed pictures of a shark attacking the fish, opening its jaws and bringing the fish into its mouth. but when the sole squirted its poison, the shark jerked backward and left.
Unfortunately, the repellent is an unstable chemical, breaking down when removed from the water to a different temperature. The only way it can be used now is to take the Moses Sole by the tail and use it as a weapon directly, one scientist quipped.