ABSTRACT
Kaempferia parviflora Wall. ex. Baker is a Thai herb containing many flavonoids that have anti-inflammatory, anti-allergic and antioxidant activities. The objective of this study was to demonstrate apoptotic effects of Kaempferia parviflora Wall. ex. Baker rhizome ethanolic extract on HL-60 cells in vitro. The extract suppressed HL-60 cell growth and decreased cell viability in a dose- and time-dependent manner. Apoptotic cell death was demonstrated by changes in cell morphology, externalization of phosphatidylserine on the cell surface, loss in mitochondrial transmembrane potential and activation of caspase 3. Apoptosis induced by K. parviflora Wall. ex. Baker rhizome ethanolic extract was enhanced by treatment with paclitaxel or doxorubicin, and inhibitors of Akt, PI3-K and MEK.
ABSTRACT
Curcumin is the main biologically active phytochemical compound in turmeric. It has been shown to have anticarcinogenic activity. The aims of the study were to identify the mechanism of apoptosis of HL-60 human promyelocytic leukemic cells induced by curcumin and to determine the effects of water-soluble antioxidants, ascorbic acid, Trolox (a water-soluble form of vitamin E), glutathione (GSH) and N-acetylcysteine (NAC) on this process. HL-60 cells were incubated with curcumin for 24 h and apoptotic cells were quantitated by flow cytometry following staining with annexin V-FITC and propidium iodide. Curcumin-treated HL-60 cells produced reactive oxygen species as detected by the dichlorofluorescein fluorescent assay. Apoptosis occurred via the mitochondria pathway as curcumin reduced mitochondrial membrane potential in a dose-dependent manner. In the presence of 10 microM curcumin, vitamin C (56 nM-5.6 microM) inhibited apoptosis of HL-60 cells; GSH at low concentration (1 microM) reduced apoptosis but had no effect at higher concentrations (10, 100 microM); and Trolox and NAC at 10 and 100 microM, respectively, enhanced apoptosis, but this effect was abolished at higher concentration (1 mM) of NAC. MAPKK/MEK inhibitor PD98059, enhanced curcumin-induced HL-60 apoptotic cell death.