|
|
 |
ON THE HEALTH FRONT - Mining the ocean for new medicine
BY SARAH LESHER - Miami Herald
Tue, Jun. 29, 2004
Going to the Amazon -- and then to a Caribbean resort -- to look for drugs isn't like making quick stops at Walgreen
or Eckerd. But Eloy Rodriguez and his students from the University of Miami and Cornell University aren't getting a
prescription filled. They're trying to find naturally occurring compounds that can ultimately go into those little
bottles to help fight intractable pain, or cancer, or other illnesses.
To find these compounds -- especially ones that act differently from existing drugs -- Rodriguez wants to investigate
the organisms in their natural settings.
"I've got to start with the organism, see where it lives. It does help me to see where those [special] molecules play
an important part, for say, a sponge," he said.
Sponges are being mined for medically useful compounds by other researchers, including a group affiliated with Harbor
Branch Oceanographic Institution of Fort Pierce and Florida Atlantic University.
IDEAL LOCATION
Rodriguez, from Cornell's department of chemistry, is a visiting professor at the University of Miami. He said South Florida
is an ideal base from which to search for new drug possibilities because the tropics and subtropics -- Florida, the Caribbean
and the Amazon -- are such richly diverse places.
"Oceans are the last frontier for discovering medicines. They're vast -- you can't imagine what lives in there," Rodriguez
said. Over millennia, sponges, corals, fish and other reef dwellers have evolved powerful chemicals to protect themselves
from predators.
An obvious place to look for medically promising compounds are poisonous fish, though not many people have done such research,
Rodriguez said. Pufferfish, for instance, contain a poisonous compound, tetrodotoxin, that can kill predators -- and humans --
by blocking the movement of sodium ions that help carry nerve signals. But in very small doses the compound can also stop the
nerve signals that cause severe pain, without the addiction and other side effects of opiates.
"It's all a matter of dosage, whether it's going to kill us, or make us good," Rodriguez said.
The pufferfish poison is made by bacteria the fish eat. Pufferfish have evolved to be immune to the toxin, while the bacteria
that are eaten presumably benefit by having a better place to live.
CONSIDERING HABITAT
Relationships between organisms, such as those between the pufferfish and the poison-making bacteria, make complex natural
habitats important as sources of diverse and potent chemicals, Rodriguez said.
Sea whips, a shallow water coral, produce invaluable anti-inflammatory compounds used in commercial skin creams. These compounds,
called pseudoptercins, also show potential for treating more serious inflammatory diseases, including asthma and arthritis, said
Russell Kerr, a professor in the marine natural products group at FAU. But because of their use in skin cream, the sea whip that
makes this compound is drastically overharvested, and drug companies are reluctant to test it for new uses without a better source.
Thomas Brueck, from the chemistry and biotechnology department of FAU, is trying with Kerr and others to figure out another way
to create pseudoptercins. The real biological manufacturers of these pseudoptercins are thought to be smaller organisms that live
in the tissues of sea whips.
Brueck is trying to figure out exactly how sea whips, shallow water corals that harbor algae, differ from deep water corals, that
don't (because algae can't grow in the dark depths). Brueck is trying to figure out how evolution has changed the genetic machinery
as a way of helping relocate this machinery more quickly.
"We ultimately want to clone the genes these marine organisms use for making drugs and put them into bacteria and higher plants,"
Kerr said.
Another anti-inflammatory compound, topsentin, has been isolated from the sponge Spongosorites ruetzleri . Sponges, too, have smaller
organisms, such as bacteria, living in their tissues that may be the real synthesizers of their potent compounds.
GROWING SPONGES
Bacteria are fairly easy to grow. Researchers are trying to learn how to culture sponges and other marine animals to obtain their
compounds while protecting those in the wild, but growing sponges is very tricky.
"Different sponges like eating different things. There's no Purina sponge chow," said researcher Kathleen Janda of the division of
biomedical research at Harbor Branch.
Both Rodriguez and the Harbor Branch and FAU researchers emphasized the importance of reducing pollution from sewage, fertilizer,
anchor-dragging and fishing, so that the world's endangered coral reefs and other marine habitats are preserved for future research.
"We need to figure out how to keep from damaging coral reefs. As scientists we are obliged to help," Rodriguez said.
"Those destroying the great diversity of coral reefs are not only destroying the beauty used to promote resorts, but also
depleting potential sources of medicines."
|
|
