Flow cytometry analysis of cancer cell death induced by the extract of Thai plant Ellipeiopsis cherrevensis.

  The mechanism of cancer cell death induced by KP018, an ethanol extract of the Thai plant Ellipeiopsis cherrevensis, was examined in paclitaxel-resistant HepG2 (PR-HepG2) and colon-26 cells using flow cytometry. In PR-HepG2 cells, KP018 induced necrosis in a concentration-dependent manner. Necrosis of PR-HepG2 cells induced by KP018 as well as by hydrogen peroxide was suppressed by co-treatment of the cells with N-acetylcysteine. KP018 decreased the viability of colon-26 cells with an IC50 value of 15.1 µg/mL, which was estimated by XTT assay. As observed in PR-HepG2 cells, KP018 induced necrosis and the necrosis was suppressed by N-acetylcysteine in colon-26 cells. In addition, using colon-26 solid tumor-bearing mice, KP018 was found to suppress tumor growth without apparent toxicities under in vivo conditions. These results indicate that KP018 induces necrosis rather than apoptosis in these cancer cells, and reactive oxygen species such as hydrogen peroxide would be involved in KP018-induced necrosis. KP018 may be a useful source to search for a new anticancer drug that can be used for the chemotherapy of multidrug-resistant tumors.

Effect of Thai plant extracts on P-glycoprotein function and viability in paclitaxel-resistant HepG2 cells.

The effects of ethanol extracts from Thai plants on P-glycoprotein (P-gp) function and cell viability were examined using paclitaxel-resistant HepG2 (PR-HepG2) cells. KP018 from Ellipeiopsis cherrevensis and AT80 from Ancistrocladus tectorius increased both rhodamine 123, a typical P-gp substrate, and [(3)H]paclitaxel uptake in PR-HepG2 cells. However, some extracts such as MT80 from Microcos tomentosa increased rhodamine 123, but not [(3)H]paclitaxel, uptake, while MM80 from Micromelum minutum increased only [(3)H]paclitaxel uptake. Thus, the effects of extracts of Thai plants on rhodamine 123 uptake were not necessarily the same as those on [(3)H]paclitaxel uptake. Purified compounds such as bergapten did not affect the uptake of either substrate. KP018, AT80, and MM80 increased [(3)H]paclitaxel uptake and decreased the cell viability in a concentration-dependent manner. Among these extracts, KP018 showed the most potent cytotoxicity. The cytotoxic potency of KP018 on PR-HepG2 cells was similar to that on wild-type HepG2 cells, and was not potentiated by verapamil. At concentrations resulting in no cytotoxicity, AT80 and MM80 potentiated paclitaxel-induced cytotoxicity in PR-HepG2 cells. These results indicate that K018 may be a useful source to search for a new anticancer drug, while AT80 and MM80 may be useful as modulators of P-gp-mediated multidrug resistance in cancer cells.

Dicentrine production from a hairy roots culture of Stephania suberosa.

A hairy roots culture of Stephania suberosa was established using Agrobacterium rhizogenes ATCC15834. The production of dicentrine was found to be (8.92 +/- 0.07) mg/g dry wt on day 35 of culture. Effects of sucrose content, tyrosine, and medium strength on growth and dicentrine production of S. suberosa were investigated. 6% (w/v) sucrose was an optimum content for the growth and dicentrine accumulation in S. suberosa hairy roots. The utilization of a precursor from tyrosine feeding enhanced the dicentrine production. The medium with 1.0 mM of tyrosine had the highest effect on dicentrine accumulation in hairy roots at day 40 of culture [(14.73 +/- 0.47) mg/g dry wt]. In addition, 1/4 Murashige and Skoog medium was suitable for biomass and dicentrine production in hairy roots. This culture system has a potential to produce dicentrine from hairy roots of S. suberosa.

Modulation of function of multidrug resistance associated-proteins by Kaempferia parviflora extracts and their components.

In this study, the effects of extracts and flavone derivatives from the rhizome of Kaempferia parviflora on multidrug resistance associated-proteins (MRP)-mediated transport in A549 cells were examined. The cells employed express MRP1 and MRP2, but not P-glycoprotein. The cellular accumulation of calcein, an MRP substrate, was significantly increased by various MRP inhibitors without being affected by verapamil, a typical P-glycoprotein inhibitor. Ethanol and aqueous extracts from K. parviflora rhizome increased the accumulation of calcein and doxorubicin in A549 cells in a concentration-dependent manner. The inhibitory potency of the ethanol extract for MRP function was greater than that of the aqueous extract. Among six flavone derivatives isolated from K. parviflora rhizome, 5,7-dimethoxyflavone exhibited a maximal stimulatory effect on the accumulation of doxorubicin in A549 cells. The accumulation of doxorubicin was increased by four flavone derivatives without 5-hydroxy group, but not by the other two flavone derivatives with 5-hydroxy group. In addition, 5,7-dimethoxyflavone and 3,5,7,3',4'-pentamethoxyflavone decreased resistance to doxorubicin in A549 cells. These findings indicate that extracts and flavone derivatives from the rhizome of K. parviflora suppress MRP function, and therefore may be useful as modulators of multidrug resistance in cancer cells.

Effects of Kaempferia parviflora extracts and their flavone constituents on P-glycoprotein function.

The purpose of this study was to examine the effects of extracts and flavone derivatives from the rhizome of Kaempferia parviflora on P-glycoprotein (P-gp)-mediated transport in LLC-GA5-COL150, a transfectant cell line of a porcine kidney epithelial cell line LLC-PK1 with human MDR1 cDNA. Ethanol extract obtained from Kaempferia parviflora rhizome significantly increased the accumulation of rhodamine 123 and daunorubicin, P-gp substrates, in LLC-GA5-COL150 cells, but not in LLC-PK1 cells. The aqueous extract also increased the accumulation in LLC-GA5-COL150 cells with lower potency than the ethanol extract. The effects of flavone derivatives isolated from the rhizome of Kaempferia parviflora on P-gp function were examined. Among six flavones tested, 3,5,7,3',4'-pentamethoxyflavone most potently increased the accumulation of rhodamine 123 and daunorubicin in LLC-GA5-COL150 cells in a concentration-dependent manner. In addition, 5,7-dimethoxyflavone to lesser degree increased rhodamine 123 accumulation in LLC-GA5-COL150 cells. In contrast, the other four flavone derivatives had no significant effect on the accumulation of rhodamine 123 in LLC-GA5-COL150 cells in a concentration range tested. These results indicate that extracts and flavone derivatives from the rhizome of Kaempferia parviflora can inhibit P-gp function, which may be useful for overcoming P-gp-mediated multidrug resistance and improving the oral bioavailability of anticancer agents.