- If thoughts of frogs conjure up images
of slime and muck, you may have to change your thinking. Previously undiscovered
compounds on the skins of frogs can kill a wide range of bacteria in the
lab, a group of researchers have found.
- These new compounds, small proteins called
peptides, were found to be effective against Staphylococcus, certain strains
of E. coli and the yeast that causes the fungal infection thrush.
- The study has been accepted for publication
in the journal Peptides.
- What led researchers to frogs? "It
was serendipitous," says J. Michael Conlon, professor of biochemistry
at Nebraska's Creighton University and head of the study.
- Since it's believed that frogs have a
defense against mammalian predators -- exploding in the stomach of the
animal that consumes it, making it extremely ill -- Conlon thought frog
skins might contain other defenses too.
- "We extracted skins...and looked
to see if there were compounds defending against bacteria," says Conlon.
And they found many, on frogs such as the Korean frog (<IRana rugosa</I),
Japanese frog (<IRana brevipoda porsa</I), European frog (<IRana
esculenta</I) and the American Bullfrog (<IRana catesbeiana</I).
- With over 3,500 species of frogs, and
only 10 or 15 studied thus far, hopes are high that numerous different
antimicrobial agents will be discovered. According to experts, with antibiotic
resistant strains of bacteria on the rise, it's important that new disease-fighting
medicines be developed.
- "It was thought, ten years ago,
that the battle against infectious diseases had been won... that infectious
bacteria were on the way out. It's known now that that was far too optimistic,"
- "Bacteria are always evolving ways
of getting around antibiotics," says Gerald V. Stokes, acting chair
of microbiology at George Washington University in Maryland. "So the
pharmaceutical companies and researchers have to try and figure out new
types of antibiotics to anticipate these changes."
- "Because these are a new class of
peptide, potentially they're something bacteria have never seen before,
and so it may take them a much, much longer time to evolve resistance,"
- The researchers at Creighton aren't stopping
- "We're using nature as a basis from
which we can design new drugs," says Conlon. "We'll try to make
(the frog skins) more potent. To maybe target different microorganisms,
like TB or the organism that causes strep throat."