A peptide with potent antifungal and antiproliferative activities from Nepalese large red beans

An antifungal defensin-like peptide with a molecular mass of 7.1kDa was isolated from dried Nepalese large red beans (Phaseolus angularis). The purification protocol employed included ion exchange chromatography on DEAE-cellulose, affinity chromatography on Affi-gel blue gel, ion exchange chromatography on SP-Sepharose, and gel filtration by fast protein liquid chromatography on Superdex 75. The antifungal peptide was unadsorbed on DEAE-cellulose, and adsorbed on Affi-gel blue gel and SP-Sepharose. The antifungal peptide inhibited mycelial growth in Fusarium oxysporum and Mycosphaerella arachidicola with an IC(50) value of 1.4 and 1.8 microM, respectively. It did not inhibit HIV-1 reverse transcriptase when tested up to 200 microM. It exerted an antiproliferative action on L1210 leukemia cells and MBL2 lymphoma cells with an IC(50) of 15 and 60 microM, respectively.