Frogs and Alligators: New Sources for Antimicrobial Substances

Image Credit: David V. Raju

When you think of swamps, it is hard not to picture water moccasins, alligators, frogs and all manner of creatures that lurk within murky waters. That these same places might hold cures to diseases that humans are afflicted with is not very obvious. However, researchers at Emory University collaborating with scientists at Rajiv Gandhi Center for Biotechnology in India recently discovered that the skin mucus secreted by frogs has antiviral properties. 

Over the last few years, amphibians and reptiles have proved worthy sources for antibacterial and antiviral substances. The Komodo dragon, alligator, crocodile and cobra have all been found chock-full of them. They are special peptides: short strings of amino acids which are the elementary units of proteins. These peptides may be secreted out by frogs and toads or they may circulate in the blood of alligators and Komodo dragons. Scientists have found alligators that have immunity against HIV as well as several bacterial species. Earlier this year, Komodo dragons were also found to have antimicrobial peptides in their blood.

American Alligator

Given the environments these animals live in, it is no surprise that they would have a robust immune system. Alligators and Komodo dragons often indulge in fights that can leave them horribly injured. In addition, many amphibians live in bacterially rich surroundings that are the breeding ground for many infections. It is understandable that nature would have imbued them with properties that would protect them.

Komodo Dragon

Frogs release peptides through their skin which have previously been known to have antibacterial abilities.  It is only now that scientists have found them to be effective against the H1 influenza strains like the virus that causes swine flu. Discovered in a South Indian frog called Hydrophylax bahuvistara, the peptide has been named urumin after an ancient Indian sword called urumi.

The scientists infected unvaccinated mice with lethal doses of flu viruses and urumin was found to protect them from H1 strains. Unlike certain antimicrobial peptides that puncture cellular membranes and thus, are problematic for human cells, urumin targets a molecule present on the surface of the virus that helps it attach to the surface of cellular membranes. If the are not able to affix themselves to cells, the viruses cannot really infect the individual. Researchers now hope to find other peptides produced by frogs that might be effective against infectious diseases like Dengue and Zika that are prevalent in tropical and subtropical regions. 

With the rise in antibiotic resistance, superbugs and new outbreaks, there is an increasing need for novel antibacterial and antiviral substances. The dirtiest places – the same places that are teeming with life – might just be where scientists will find the answers to these problems.

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