An antifungal peptide with antiproliferative activity toward tumor cells from red kidney beans

A 7.3-kDa antifungal peptide was purified from dried red kidney beans. The purification procedure entailed ion exchange chromatography on DEAE-cellulose, affinity chromatography on Affi-gel blue gel, ion exchange chromatography on CM-cellulose, followed by fast protein liquid chromatography-gel filtration on Superdex 75. The peptide was unadsorbed on DEAE-cellulose but adsorbed on Affi-gel blue gel and CM-cellulose. It exhibited a molecular mass of 7.3 kDa in gel filtration and also in SDS-polyacrylamide gel electrophoresis, indicating that it is a single-chained protein. The N-terminal sequence of the peptide was DGVCFGGLANGDRT. The peptide exerted an antifungal action on Fusarium oxysporum with an IC₅₀ of 3.8±0.4 µM (mean±SD, n=3). It also inhibited mycelial growth in Mycosphaerella arachidicola. It suppressed growth of lymphoma MBL2 cells and leukemia L1210 cells with an IC₅₀ of 5.2±0.4 µM and 7.6±0.6 µM, respectively. HIV-1 reverse transcriptase was inhibited with an IC₅₀ of 40±3.2 µM. However, no activity was demonstrated toward other viral enzymes.