Structure-antifungal activity relationships of cecropin A-magainin 2 and cecropin A-melittin hybrid peptides on pathogenic fungal cells

In order to investigate a relationship of the structure-antifungal and hemolytic activities between cecropin A(1-8)magainin 2(1-12) and cecropin A(1-8)-melittin(1-12) hybrid peptides, several analogues with amino acid substitution at positions 10 (Ile) and 16 (Ser) were designed and synthesized. The increase of the hydrophobicity by substituting with Leu, Phe, and Trp at position 16 in cecropin A(1-8)-magainin 2(1-12) did not have a significant effect on antifungal activity but caused a remarkable increase in hemolytic activity. These results indicate that the hydrophobic property at position 16 of cecropin A(1-8)-magainin 2(1-12) is more correlated to hemolytic activity than to antifungal activity. Replacement with Pro at position 10 of cecropin A(1-8)magainin 2(1-12) and cecropin A(1-8)-melittin (1-12) caused a remarkable decrease in α-helical contents in the 50% TFE solution and induced a reduction in lyric activity against Aspergillus flavus, and Aspergillus fumigatus. These results demonstrate that flexibility at the central hinge region is essential for lyric activity against fungal cells and α-helicity of the peptides.