Suppression of mouse skin tumor promotion and induction of apoptosis in HL-60 cells by Alpinia oxyphylla Miquel (Zingiberaceae)

There have been considerable efforts to search for naturally occurringsubstances for the intervention of carcinogenesis. Many components fromdietary or medicinal plants have been identified that possess substantialchemopreventive properties. An example is curcumin (Curcuma longa Linn.,Zingiberaceae), which has been shown to inhibit tumor promotion inexperimental carcinogenesis. Alpinia oxyphylla Miquel, another plant of theginger family used in oriental herbal medicine, contains diarylheptanoidswhose structures are analogous to that of curcumin. In the present study,we have tested A.oxyphylla for its ability to suppress tumor promotion.Thus, topical application of the methanolic extract of dried fruits ofA.oxyphylla significantly ameliorated 12-O-tetradecanoylphorbol-13-acetate(TPA)-induced skin tumor promotion as well as ear edema in female ICR mice.In another study, treatment of HL-60 cells with the methanolic extract ofA.oxyphylla significantly reduced the viability of the cells and alsoinhibited DNA synthesis. Microscopic examination of the treated cellsshowed characteristic morphology of apoptosis. Furthermore, cells treatedwith the extract of A.oxyphylla exhibited internucleosomal DNAfragmentation in time- and concentration-dependent manners. TPA- stimulatedgeneration of superoxide anion in differentiated HL-60 cells was alsoblunted by A.oxyphylla. Taken together, these findings suggest thatA.oxyphylla possesses potential chemopreventive and antitumorigenicactivities.