WE ALL BENEFIT FROM THE FROG PHARMACY ONE DAY?
by Whit Gibbons
August 20, 2006
I asked University
of Georgia graduate student Brian Todd to respond to this two-part question:
What good are frogs and why should ecologists study them? He titled his
reply "The Frog Pharmacy."
many people, the connection between frogs, research, and human society
may seem tenuous at best. Beyond remembering (not always fondly) the frog
they dissected in biology class, most people would be hard put to describe
even a single contribution frogs have made to humankind. But frogs have
played an important, though little-known, role in scientific endeavors
for many years. And current research suggests they will continue to do
the 1930s, frogs were important contributors to the medical field. Well
before the advent of modern pregnancy tests, two scientists discovered
that the African clawed frog could be used to test for pregnancy in women.
In the next two decades, tens of thousands of these animals were imported
from their native Africa as hospitals in North America began stocking
them for use in early, rapid pregnancy detection.
recently, scientists have discovered that most frog species produce skin
secretions of amino acid compounds called peptides. These peptides help
protect frogs' otherwise sensitive and porous skin from bacterial and
fungal infections. Some even discourage predators, which find the peptides
distasteful. The discovery of these peptide secretions and their properties
has produced several avenues of research with applications for human medicine.
research team from the United Kingdom has identified an important set
of antibiotics in the skin of an Australian tree frog. These scientists
have discovered that the peptides from the tree frog kill bacteria that
are resistant to conventional antibiotics. Modern medicines typically
combat bacteria by targeting vital enzymes, to which the bacteria can
develop a resistance, an increasingly alarming problem in modern medicine.
The frog peptides eliminate bacteria by dismantling bacterial cell membranes,
making the frog-derived antibiotics more permanently effective.
other developments, the poison from a beautiful but deadly South American
poison dart frog is finally being thoroughly analyzed for use as a painkiller.
In 1976, extract from the skin of a rare frog from Ecuador was found to
be more effective than morphine at blocking pain but was also highly toxic
to most animals. The difficulty in isolating and identifying the precise
chemical compound responsible for the painkilling effect among the suite
of toxic compounds present in the frog’s skin secretions prevented
it from being thoroughly evaluated. However, in 1998, researchers with
the National Institutes of Health used new analytical tools to decipher
the chemical structure of the compound, leading to the discovery of a
new drug more effective than morphine with fewer negative side effects.
" By some estimates, as many as 40 million Americans depend on morphine
for pain relief for medical conditions and postoperative pain treatment.
However, side effects from morphine, such as dependency and heart and
respiratory problems, have long plagued its use and application. With
the discovery of the new compound ABT-594, which lacks these serious side
effects, many millions of Americans who suffer from pain may look forward
to brighter futures.
may soon make another contribution to human society that would provide
relief to many people. A team of researchers led by Craig Williams of
the University of South Australia has begun testing the application of
frog skin secretions as a mosquito repellant. The scientists have demonstrated
that certain natural compounds in frog skin secretions repel mosquitoes--welcome
news for people who enjoy outdoor activities in the warmer months but
worry about using chemical repellants.
and toads stand to make even more contributions to human society as scientists
continue to investigate the thousands of unstudied chemical compounds
present in their skin secretions. As Craig Williams put it, 'Frog skin
is really a portable pharmacy.' And the next few years may see products
developed from research on frogs that fill our own pharmacies.
for many folks the sheer enjoyment derived from listening to the seasonal
songs of frogs is enough. Whether you appreciate frogs for their intrinsic
value or for their other fine contributions, they are welcome friends."
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