This invention concerns novel antibiotic peptide and peptide derivates,especially for use in medicine. Further, theinvention relates to compositions and methods for killing microbes, likebacteria or fungus, and methods to treat microbial infections.The invention further relates to a method for drug screening analysis. Thepeptides and peptide derivates have the general formulaSub1 - X1 N X2 X3 P V Y I P X4 X5 R P P H P - Sub2 wherein X1 is a neutral orpositively charged moiety, X2 is a polar or positivelycharged moiety, X3 is a positively charged moiety, X4 is a polar or positivelycharged moiety, X5 is a proline or a proline derivate,Sub1 being the free or modified N-terminus, and Sub2 being the free ormodified C-terminus. The peptides or peptide derivatesaccording to the invention possess at least one of the following advantagescompared to the natural occurring apidaecin peptides:(i) an increased half-live in mammalian serum due to a higher proteaseresistance and (ii) an increased antimicrobial activity againstone or several bacterial strains, especially human pathogens, or fungus orother microbial infections (iii) show an enlarged spectrumof antimicrobial activity, (iv) do induce less resistance in microbes and (v)are not toxic to human cells including erythrocytes.
