Isolation of alliumin, a novel protein with antimicrobial and antiproliferative activities from multiple-cloved garlic bulbs

A protein designated alliumin, with a molecular mass of 13 kDa and an N-terminal sequence similar to a partial sequence of glucanase, and demonstrating antifungal activity against Mycosphaerella arachidicola, but not against Fusarium oxysporum, was isolated from multiple-cloved garlic (Allium sativum) bulbs. The protein, designated as alliumin, was purified using ion exchange chromatography on DEAE-cellulose, CM-cellulose and Mono S, affinity chromatography on Affi-gel blue gel, and gel filtration on Superdex 75. Alliumin was unadsorbed on DEAE-cellulose, but was adsorbed on Affi-gel blue gel, CM-cellulose and Mono S. Its antifungal activity was retained after boiling for 1 h and also after treatment with trypsin or chymotrypsin (1:1, w/w) for 30 min at room temperature. Alliumin was inhibitory to the bacterium Pseudomonas fluorescens and exerted antiproliferative activity toward leukemia L1210 cells. However, it was devoid of ribonuclease activity, protease activity, mitogenic activity toward mouse splenocytes, and antiproliferative activity toward hepatoma Hep G2 cells.     

An antifungal peptide from Phaseolus vulgaris cv. brown kidney bean

A 5.4-kDa antifungal peptide, with an N-terminal sequence highly homologous to defensins and inhibitory activity against Mycosphaerella arachidicola (IC(50)= 3 μM), Setospaeria turcica and Bipolaris maydis, was isolated from the seeds of Phaseolus vulgaris cv. brown kidney bean. The peptide was purified by employing a protocol that entailed adsorption on Affi-gel blue gel and Mono S and finally gel filtration on Superdex 75. The antifungal activity of the peptide against M. arachidicola was stable in the pH range 3-12 and in the temperature range 0°C to 80°C. There was a slight reduction of the antifungal activity at pH 2 and 13, and the activity was indiscernible at pH 0, 1, and 14. The activity at 90°C and 100°C was slightly diminished. Deposition of Congo red at the hyphal tips of M. arachidicola was induced by the peptide indicating inhibition of hyphal growth. The lack of antiproliferative activity of brown kidney bean antifungal peptide toward tumor cells, in contrast to the presence of such activity of other antifungal peptides, indicates that different domains are responsible for the antifungal and antiproliferative activities.