Monomeric analogues of halocidin.

Halocidin is a heterodimeric antimicrobial peptide isolated from a tunicate, Halocynthia aurantium. We used the most active of the two monomers, an 18 residue amidated peptide, as lead structure and determined the role of each amino acid with alanine scanning. The results obtained led to the synthesis of a first generation of analogues with antimicrobial activity. The selectivity towards bacterial versus mammalian cells has been explored, as well as the specificity for gram positive ( Staphylococcus aureus ATCC 25923) versus gram negative bacteria ( Escherichia coli ATCC 25922). GRAVY ( grand average of hydropathicity) was used to analyze the results.