Synthetic peptoids hold forth promise for new a...( Drug-resistant bacterial infections ...),Health

Drug-resistant bacterial infections are a growing concern, and much research has been devoted to finding new classes of antibiotics to fight them.

Stanford researchers may have found some answers in peptoids, a class of manmade molecules very similar to natural proteins that play an important role in the human immune system.

"Peptoids could be an entirely new class of antibiotic drugs, which would be hugely important," said Annelise Barron, associate professor of bioengineering at Stanford and senior author of a paper describing the research in the Feb. 26 issue of the Proceedings of the National Academy of Sciences.

Anti-microbial peptides are evolutionarily ancient infection fighters found in organisms from grasses to amphibians to humans. In the human body, the peptides show up in the mouth, lungs and intestines, and in body fluids like sweat and tears. Anti-microbial peptides target a variety of pathogens and generally kill by punching holes in the invaders' cell membranes.

"You can think of these types of antibiotics as the body's 'land mines' against invading pathogens," Barron said.

Because of this, bacterial resistance to the peptides is rarely observed. Bacteria can thwart other anti-microbial drugs by inactivating the drug, pumping it out of the cell, altering the drug's binding site so it is no longer recognized or working around the specific cell part attacked by the drug.

But it is much tougher for bacteria to develop resistance to the damage caused by anti-microbial peptides. "The bacteria can't fundamentally alter their entire outer membrane," Barron said.

Such peptides seem like a natural choice for new antibiotics. One type showed promise in the treatment of diabetic foot ulcers. Unfortunately, their applicability has been limited so far to topical use; natural peptides are quickly degraded in the stomach. Thus, a peptide-based drug must be injected
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