Cecropins, antibacterial peptides from insects and mammals, are potently fungicidal against Candida albicans

Natural products are the major source of lead compounds for drugs against h uman pathogens. Among the first natural peptides from animals for which a p otent antibacterial activity has been recognized were the cecropins. The 30 - to 40-residue alpha -helical peptides display their activity by permeabil izing the membranes of bacteria. Although originally isolated from insect h emolymph, a structural and functional correlate was also found in a mammal. Here, we report on the finding that cecropin A and B from the silk moth Ce cropia as well as the porcine cecropin P1 are capable of inhibiting the gro wth of and to kill yeast-phase Candida albicans. The peptides were tested i n radial diffusion and microbroth dilution assays. They displayed potent ac tivity against a clinical isolate as well as against defined culture strain s of the pathogenic yeast but ar-e of exceedingly low cytotoxicity towards the human cell line Jurkat. The candidacidal properties of the intensely st udied molecules known to be highly active against Gram-positive and Gram-ne gative bacteria may renew the interest in these natural broad-spectrum pept ide antibiotics and their limited cytotoxicity to human cells may be exploi ted for the development of topical therapeutics against pathogens resistant to classical antibiotics.