A novel and exploitable antifungal peptide from kale (Brassica alboglabra) seeds

The aim of this study was to purify and characterize antifungal peptides from kale seeds in view of the paucity of information on antifungal peptides from the family Brassicaceae, and to compare its characteristics with those of published Brassica antifungal peptides. A 5907-Da antifungal peptide was isolated from kale seeds. The isolation procedure comprised affinity chromatography on Affi-gel blue gel, ion exchange chromatography on SP-Sepharose and Mono S, and gel filtration on Superdex Peptide. The peptide was adsorbed on the first three chromatographic media. It inhibited mycelial growth in a number of fungal species including Fusarium oxysporum, Helminthosporium maydis, Mycosphaerella arachidicola and Valsa mali, with an IC(50) of 4.3 μM, 2.1 μM, 2.4 μM, and 0.15 μM, respectively and exhibited pronounced thermostability and pH stability. It inhibited proliferation of hepatoma (HepG2) and breast cancer (MCF7) cells with an IC(50) of 2.7 μM and 3.4 μM, and the activity of HIV-1 reverse transcriptase with an IC(50) of 4.9 μM. Its N-terminal sequence differed from those of antifungal proteins which have been reported to date.