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 occurring substances for the intervention of carcinogenesis. Many components fr om dietary or medicinal plants have been identified that possess subst antial chemopreventive properties. An example is curcumin (Curcuma lon ga Linn,, Zingiberaceae), which has been shown to inhibit tumor promot ion in experimental carcinogenesis. Alpinia oxyphylla Miquel, another plant of the ginger family used in oriental herbal medicine, contains diarylheptanoids whose structures are analogous to that of curcumin, I n the present study, we have tested A,oxyphylla for its ability to sup press tumor promotion. Thus, topical application of the methanolic ext ract of dried fruits of A,oxyphylla significantly ameliorated 12-O-tet radecanoylphorbol-13-acetate (TPA)-induced skin tumor promotion as wel l as ear edema in female ICR mice. In another study, treatment of HL-6 0 cells with the methanolic extract of A. oxyphylla significantly redu ced the viability of the cells and also inhibited DNA synthesis. Micro scopic examination of the treated cells showed characteristic morpholo gy of apoptosis, Furthermore, cells treated with the extract of A. oxy phylla exhibited internucleosomal DNA fragmentation in time- and conce ntration-dependent manners. TPA-stimulated generation of superoxide an ion in differentiated HL-60 cells was also blunted by A. oxyphylla, Ta ken together, these findings suggest that A,oxyphylla possesses potent ial chemopreventive and antitumorigenic activities.