[Natural antimicrobial peptides--promising new antibiotics or a problem later on?].

Background: Antimicrobial proteins and peptides are important elements of host defence that are found in virtually all living species examined so far.

Material And Methods: This review is based on the author's own research and a search of Medline (key words: antimicrobial peptides, biochemistry, mode of action, resistance).

Results: In animals, antimicrobial peptides are found on mucosal epithelial surfaces, in body fluids and in the microbicidal organelles of phagocytic cells. The peptides vary in size, structure and activity, but most are amphiphilic and positively charged. They act on a broad range of bacteria, fungi, viruses, parasites and certain tumour cells. Cationic peptides can be classified into several groups on the basis of sequence similarities, secondary and tertiary structure, function and origin. Their main acting mechanism is thought to be the disruption of the cytoplasmic membrane which kill bacteria swiftly and thoroughly.

Interpretation: Antimicrobial peptides are promising novel antibiotic candidates for clinical use, topically as well as systemically. So far, development of resistance against antimicrobial peptides has not been a problem, but this will have to be monitored closely in the years ahead.