Microorganisms, bacteria in particular, which show resistance to all antibiotics, even the newest ones, can be defeated with a natural substance, existing for millions of years on our planet.

Russian biologists from the Institute of Protein and the chemical faculty of Krasnoyarsk University have synthesized chemical compounds, called branched peptides, which show antimicrobial properties. Researches hope that these chemical compounds will be an effective substitute for antibiotics, to which many of pathogenic bacteria have become resistant.

During recent years, pathogenic microbes acquired strong resistance to various antibiotics, which cause major problems with successful treating of various diseases. Some bacteria aren’t “hurt” either by penicillins, or by tetracyclines and sulpha drugs. At the same time, nature has antimicrobial agents, which protect plants and animals from pathogenic bacteria for millions of years. These agents are called peptides, and scientists already know about several hundreds of peptides. Mentioned substances kill bacterial cells so quickly and effectively, that pathogens have no time to become resistant to them. Antimicrobial peptides are effective due to existing difference in cell membranes of bacteria and higher organisms or eukaryotes. Exterior of bacterial cells contains negatively charged phospholipids groups, which interact with antimicrobial peptides, which remain non-toxic to animal and human cells. New antimicrobial agents affect membranes of bacterial cells, thus being a universal therapy for various ailings, as for antibiotics, they get involved into various stages of bacterial metabolism.

 

 

Russian biologists have analyzed amino acid sequences of various antibacterial peptides and noticed some specific patterns in their structure. These compounds often contain certain fragments – tetrapeptides, which consist of two positively charged amino acids with one or two hydrophobic amino acids situated between them. Such fragments are known as main structural elements of natural antimicrobial peptides. Tetrapeptides do not possess antimicrobial activity by themselves, but can serve as a basis for synthesis of either linear or branched antimicrobial substances.

Researchers have synthesized several branched amino acid sequences and tested their antimicrobial activity on cells of intestinal bacteria (Escherichia coli). Experiments showed that antimicrobial activity became stronger, the more peptides were branched, moreover, the most branched compounds were as active as well-known natural antimicrobial peptides as temporin (a peptide, excreted by brown frog’s skin cells) and magainin (antimicrobial peptide from skin of African clawed frogs or Xenopus laevis). Not a single newly synthesized peptide caused erythrocyte lysis – the very important fact from medical point of view. Perhaps, we will finally get a strong weapon against our invisible enemies.

Source: Science & Technology

Kizilova Anna