Antibacterial activities of ferrocenoyl- and cobaltocenium-peptide bioconjugates

The peptide and metallocene-peptide bioconjugates R-Arg-Arg-Phe-NH2, R-Phe-Arg-Phe-NH2 where R = H, Fe(Cp)(C5H4–CO), Co(Cp)(C5H4–CO)+ and R′-Gly-Trp-Arg-Arg-Phe-NH2, R′-Trp-Arg-Arg-Phe-NH2, where R′ = n-C5H11CO, Fe(Cp)(C5H4–CO), Co(Cp)(C5H4–CO)+, and Arg = l-arginine, Gly = l-glycine, Phe = l-phenylalanine, Trp = l-tryptophan were prepared by solid phase peptide synthesis (SPPS). The compounds were purified by RP-HPLC and characterized by ESI–MS and NMR spectroscopy. Antibacterial properties of the compounds were determined by minimum inhibitory concentration (MIC) tests against Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus.