Inhibitory Effects of Watercress on Tumor Promotion in a Mouse Model of Two-stage Skin Carcinogenesis

Cancer prevention is one of the most urgent problems in the field of public health worldwide. The methanol extract of watercress ( Nasturtium officinale) inhibits 12-O-tetradecaonoylphorbol-13-acetate (TPA)-induced ear edema in mice. The extract also exhibits marked antitumor activity in in vivo two-stage carcinogenesis test in mice using 7,12-dimethylbenz[α]anthracene as an initiator and TPA as a promoter. From the active fraction of the methanol extract, sitosterol 3-O-glucopyranoside (1) was isolated and identified. This compound was evaluated for its inhibitory effects on TPA-induced inflammation (1 µg/ear) in mice, and had a 50% inhibitory dose of 299 nmol/ear. These results indicate that watercress extracts are useful in cancer prevention.