non - hemolytic cytolytic agents selected from peptides , complexes of bundled peptides , mixtures of peptides or random peptide copolymers have a selected cytolytic activity manifested in that they have a cytolytic activity on pathogenic cells , being cells which are non - naturally occurring with the body consisting of microbial pathogenic organisms and malignant cells ; and are non - hemolytic , having no cytolytic effect on red blood cells . the peptides may be cyclic derivatives of natural peptides such as pardaxin and mellitin and fragments thereof in which l - amino acid residues are replaced by corresponding d - amino acid residues , or are diastereomers of linear peptides composed of varying ratios of at least positively charged amino acid and at least one hydrophobic amino acid , and in which at one of the amino acid residues is a d - amino acid . pharmaceutical compositions comprising the non - hemolytic cytolytic agents can be used for the treatment of several diseases caused by pathogens including antibacterial , fungal , viral mycoplamsa and protozoan infections and for the treatment of cancer .