Antifungal activities of peptides with the sequence 10-17 of magainin 2 at the N-termini against Aspergillus fumigatus

Two peptides, MA-inv and MA-ME, with the sequence 10-17 of magainin 2 at their N-termini were designed and synthesized. The peptides had higher antifungal activities against Aspergillus fumigatus without hemolytic activities. The minimal inhibition concentratory (MIC) values of both peptides against A. fumigatus were 5 μg/ml, whereas those of the native peptides, magainin 2 and melittin, were 10 μg/ml. At 3 μg/ml, MA-inv and MA-ME inhibited the mycelium growth of A. fumigatus by 94.6% and 97.3%, respectively, whereas magainin 2 and melittin inhibited by 62.2% and 32.4%, respectively. MA-inv showed up to 80% inhibition of (1,3)-β-D-glucan synthase activity of A. fumigatus. The peptides also showed antifungal activities for other fungi of Aspergillus sp. However, the antibiotic activities of MA-ME against Escherichia coli, Bacillus subtilis and Fusarium oxysporum were more effective than those of MA-inv, suggesting that the C-terminal sequences of MA-inv and MA-ME may also influence their antibiotic activities. These results suggest that the N-terminal sequence of the designed peptides, KKFGKAFV, is important for their antifungal activities against A. fumigatus and their C-terminal sequences are related to the organism selectivity.