Better antibiotics are produced from frog skin

Danh Phuong

What do you discover when you combine a frog with a frying pan? Does the study remind you of a solution to the problem of insect repellent?

By creating " Teflon " versions of natural antibiotics found in frog skin, a team led by University of Michigan biologist E. Neil Marsh has developed a potential drug. Better to interfere with bacteria defense lines.

Marsh and colleagues conducted a study with a compound called antimicrobial peptide chain ( AMPS ), produced by almost all kinds of animals, from insects to frogs, including humans. . AMPs are the immune system's first line of defense, fighting off germs right in the first places they try to penetrate: skin, mucous membranes and other surfaces. They are very much produced, for example in injured or infected frog skin, human respiratory glands and stomach organs produce countless short proteins to respond to invasive pathogens. In addition to fighting bacteria, AMPs also attack viruses, fungi and even cancer cells, so drugs designed to mimic them can be widely used in medicine.

Scientists have been interested in exploiting natural antibiotics since the 1980s, but they have not overcome some shortcomings. More specifically, AMPs are easily broken down by protein-degrading enzymes (also called proteases ) secreted by bacteria and naturally present in the body. Increasing the concentration of AMPs to try to grasp the problem of causing toxic side effects such as the destruction of red blood cells - are the key sources of oxygen transport of blood in the body. This can happen because the parts of AMP molecules stick together interacting with cell membranes very harmful.

Marsh, a professor of chemistry at the University of Michigan, had the idea of ​​replacing the peptide that sticks together with non-stick substitutes. His inspiration comes from the kitchen and is like being in a chemistry lab: the non-stick product is coated with fluorinated polymer compounds, plastic-like compounds are made with intact chains. Carbon particles are completely covered by fluorine atoms. Not only does fluorine make Teflon slippery, it also makes the coating inert to most chemicals we know.

When Marsh and colleagues changed the parts of the AMP molecule with non-stick fluorine versions, the molecules became much more resistant to proteases.

He said: 'The difference is quite remarkable. When we treated them with protease, the non-fluorine AMPs were disintegrated within 30 minutes. Under the same state, fluorine AMP after 10 hours remained unchanged. This makes them more effective, as they will stay in the body longer. '

Next, the researchers plan to experiment to find out whether Teflon AMPs, while being less toxic than equivalent substances with more stickiness. If they are, and if further studies continue to show them the promise of the future, eventually the production of the amount of AMPs with fluorine is large enough to serve the tests. Clinical experience will be fully feasible.

Although the study now has practical applications, it has begun in the form of an exploration in basic science.

'We are only interested in turning artificial materials with useful properties into biological molecules,' Marsh said. 'But it is clear that recently, we have seen the potential to apply our basic scientific research to a very important medical examination and treatment problem, which is how more and more bacteria become. should be resistant to antibiotics on the day. '

Marsh presented the study at the 234th National Press Conference of the American Chemical Society in Boston. Researchers obtained research grant funds from the American Heart Association and the National Science Foundation.

Note: This report is adapted from a news release published by the University of Michigan