Antimicrobial peptides: in vitro approx...
A real alternative to antibiotics?
LifeSciencesToday
Antibiotics are one of the greatest achievements of medical science. But recently, the previously multipurpose weapons have been failing in the fight against infectious diseases. Bacteria are increasingly developing resistance to antibiotics. Scientists have found a therapeutic equivalent that can replace penicillin and related pharmaceuticals.
More and more often, pathogens of infectious diseases are becoming resistant to the action of antibiotics. Some bacteria are already impossible to fight. The World Health Organization (WHO) warns about resistance to drugs that were previously considered highly effective. WHO Director-General Margaret Chan stresses that unless urgent measures are taken soon, it will be impossible to treat many widespread infections. According to data published by WHO, in 2010, about half a million people were infected with strains of tuberculosis bacillus resistant to many antibiotics – a third of these patients died. WHO states that the growing spread of resistant pathogens is a consequence of the indiscriminate use of penicillin and other antibiotics.
Scientists at the Fraunhofer Institute for Cell Therapy and Immunology (IZI) in Leipzig believe that antimicrobial peptides (Fraunhofer-Gesellschaft: An alternative to antibiotics) may take the place of traditional antibiotics in the fight against pathogenic microorganisms in the future.
"We have already identified 20 short chains of amino acids that kill many microorganisms, including enterococci, yeast and mold fungi, as well as bacteria pathogenic to humans, such as Streptococcus mutans, which is found in the human oral cavity and leads to tooth destruction [in the picture below, a circle is circled around the area of the nutrient medium where the carious monsters died under the action of an antimicrobial peptide – VM]. Even the multi–resistant hospital Staphylococcus aureus does not show resistance to them, and in our tests its growth was significantly suppressed," Dr. Andreas Schubert comments on the results of his group's work.
Scientists have created many variants of amino acid sequences based on already known fungicidal and bactericidal peptides, focusing on peptides with a length of less than 20 amino acids, and tested their effect in vitro on various microbes. Putrefactive bacteria, for example, were incubated for an hour with artificial antimicrobial peptides. The survival rate of pathogens was compared with the control. Since the new peptides contain positively charged amino acid residues, they bind to the negatively charged membranes of bacterial cells and penetrate them.
"Antimicrobial peptides show their bactericidal effect within a few minutes. They work at a concentration of less than 1 micromole, which is ten times lower than the effective concentration of traditional antibiotics," says Dr. Schubert, summarizing the results of the work. "The spectrum of effectiveness of the tested peptides includes not only bacteria and mold fungi, but also viruses with a lipid envelope. Another key factor is that such peptides do not damage healthy cells."
Antimicrobial peptides may well find application in the food industry, given that bacterial contamination of food leads to billions of dollars in annual losses. Fresh lettuce and other greens, for example, are affected by yeast and mold fungi. The shelf life of food products can be increased by the addition of antimicrobial peptides during their production. This is a very real possibility, since the tested short-chain peptides do not have an allergenic effect when added to food.
As a next step, Dr. Schubert and his group plan to test the effectiveness of antimicrobial peptides on animal models of infectious diseases.
Portal "Eternal youth" http://vechnayamolodost.ru14.06.2011