Antimicrobial peptides (AMPs) were recently determined to be potential candidates for treating drug-resistant
bacterial infections. The aim of this study was to develop shorter
AMP fragments that combine maximal bactericidal effect with minimal synthesis cost. We first synthesized a series of truncated forms of AMPs (anti-
lipopolysaccharide factor from shrimp, epinecidin from grouper, and
pardaxin from Pardachirus marmoratus). The minimum inhibitory concentrations (MICs) of modified AMPs against ten bacterial species were determined. We also examined the synergy between
peptide and non-
peptide antibiotics. In addition, we measured the inhibitory rate of
cancer cells treated with AMPs by MTS assay. We found that two modified antibacterial
peptides (epinecidin-8 and pardaxin-6) had a broad range of action against both gram-positive and gram-negative bacteria. Furthermore, epinecidin and
pardaxin were demonstrated to have high antibacterial and anticancer activities, and both AMPs resulted in a significant synergistic improvement in the potencies of
streptomycin and
kanamycin against methicillin-resistant Staphylococcus aureus. Neither
AMP induced significant
hemolysis at their MICs. In addition, both AMPs inhibited human epithelial
carcinoma (HeLa) and
fibrosarcoma (HT-1080) cell growth. The functions of these truncated AMPs were similar to those of their full-length equivalents. In conclusion, we have successfully identified shorter, inexpensive fragments with maximal bactericidal activity. This study also provides an excellent basis for the investigation of potential synergies between
peptide and non-
peptide antibiotics, for a broad range of antimicrobial and anticancer activities.