Hot-water extracts from adzuki beans (Vigna angularis) suppress not only the proliferation of KATO III cells in culture but also benzo(a)pyrene-induced tumorigenesis in mouse forestomatch.

Treatment of human stomach cancer KATO III cells with hot-water extracts from adzuki beans led to their growth inhibition as well as apoptosis induction. There are morphological changes in the cultured cells treated with the extracts, by which DNA fragmentation characteristic of apoptosis was actualized both concentration- and time-dependently. In contrast, N-acetyl-L-cysteine suppressed such DNA fragmentation, implying that the extracts from adzuki beans might exert antitumorigenicity via active oxygen-induced apoptosis. In order to verify this hypothesis in animal experiment, the 40% ethanol fraction of hot-water extracts was examined for its preventive effect against benzo(a)pyrene-induced tumorigenesis in the forestomach of A/J mice, given as drinking water containing the above fraction at 0.5-2.0% levels. Consequently, forestomach cancer has turned out to be reduced by 36-62% in tumor weight relative to the control. These results suggest that the fraction of hot-water adzuki extracts may serve as a nutrapharmaceutical or functional food available for cancer prevention.