Frog skin may be an important source of new antibiotics to treat superbugs say researchers.
So far, more than 100 potential bacteria-killing substances have been identified from more than 6,000 species of frog.
The team at the United Arab Emirates University are now trying to tweak the substances to make them less toxic and suitable for use as human medicines.
The work was presented at the American Chemical Society meeting.
Drug resistant bacteria, such as MRSA, are becoming an increasing problem worldwide.
Yet there is a lack of new treatments in the pipeline.
Among the substances found by the researchers are a compound from a rare American species that shows promise for killing MRSA.
Another fights a drug-resistant infection seen in soldiers returning from Iraq.
The idea of using chemicals from the skin of frogs to kill bacteria, viruses and other disease-causing agents is not a new one.
But it is not a straightforward process to use these chemicals in humans because they are either destroyed in the bloodstream or are toxic to human cells.
Tweaks
After identifying the key chemicals, the researchers have altered their molecular structure to make them less dangerous to human cells while retaining their bacteria-killing properties
They hope their work means some of the substances could be in clinical trials within five years.
They are also investigating how to help the chemicals resist breakdown by the body before they have a chance to act.
Experiments have shown the changes they have made so far do make the antibiotics last longer in the bloodstream.
Study leader Dr Michael Conlon said: “Frog skin is an excellent potential source of such antibiotic agents.
“They’ve been around 300 million years, so they’ve had plenty of time to learn how to defend themselves against disease-causing microbes in the environment.
“Their own environment includes polluted waterways where strong defences against pathogens are a must.”
The work underscored the importance of preserving frog diversity, he added.
“Some frog species, including those that may contain potentially valuable medicinal substances, are in jeopardy worldwide due to loss of habitat, water pollution, and other problems.”