Peptides with a molecular weight of 5 kDa have been isolated from seeds of the pinto bean and red bean, respectively. The peptides manifest an N-terminal sequence with remarkable resemblance to those of cowpea 10-kDa protein precursor and garden pea disease resistance response protein. The bean peptides possess potent antifungal activity toward a variety of fungal species including Botrytis cinerea, Mycosphaerella arachidicola, and Fusarium oxysporum. The proteins also demonstrate mitogenic activity toward mouse splenocytes and an inhibitory action on HIV-1 reverse transcriptase.