Involvement of p53 and nuclear factor-kappaB signaling pathway for the induction of G1-phase cell cycle arrest of cholangiocarcinoma cell lines by isomorellin.

Cell cycle arrest is closely linked to apoptosis. Isomorellin-a caged xanthone isolated from Garcinia hanburyi-induced apoptosis in cholangiocarcinoma (CCA) cell lines. To elucidate potential anticancer mechanisms, we investigated the effects of isomorellin on the growth, cell cycle progression, cell cycle regulated protein expression and nuclear factor-kappa B (NF-κB) activation of KKU-100 and KKU-M156 CCA cell lines; using sulforhodamine B assay, flow cytometry and Western blot analysis. The growth of both CCA cell lines was significantly inhibited by isomorellin treatment in a time- and dose-dependent manner. The respective IC(50) value of isomorellin for KKU-100 cells was 6.2±0.13, 5.1±0.11 and 3.5±0.25 µM at 24, 48 and 72 h. By comparison, the respective IC(50) value for KKU-M156 cells was 1.9±0.22, 1.7±0.14 and 1.5±0.14 µM at 24, 48 and 72 h. The growth inhibition of CCA cells by isomorellin was through the G0/G1 phase arrest mediated by inhibition of NF-κB activation, up-regulation of p53, p21 and p27 and down-regulation of cyclin D1, cyclin E, Cdk4 and Cdk2 protein levels. Our research suggests that isomorellin induces cell cycle arrest and apoptosis in CCA cell lines through p53 and the NF-κB-signaling pathway. The growth inhibitory potential of isomorellin was comparable to that of gambogic acid. Isomorellin shows potential as a therapeutic agent against human cholangiocarcinoma.

In vitro and in vivo antiplasmodial activity and cytotoxicity of water extracts of Phyllanthus emblica, Terminalia chebula, and Terminalia bellerica.

OBJECTIVE: To evaluate the in vitro and in vivo antiplasmodial activity and the cytotoxicity of Phyllanthus emblica Linn, Terminalia chebula Retz, and Terminalia bellerica (Gaertn) Roxb extracts. MATERIAL AND METHOD: Standard phytochemical screening tests were used to detect metabolites in the plant extract. The water extracts of medicinal plants were tested for their antiplasmodial activity in vitro by assessing their ability to inhibit the uptake of [3H] hypoxanthine into the Plasmodium falciparum K1 multidrug-resistant strain. Cytotoxicity of all extracts was determined on Vero cell line. The in vivo antiplasmodial activity in Plasmodium berghei infected mice was evaluated by the standard 4-day suppressive test. RESULTS: Phytochemical screening of the water extracts of three plants revealed the presence of flavonoids, hydrolysable tannins, saponin and terpenes. All plant extracts showed antimalarial activity (IC50 values ranging from 14.33 +/- 0.25-15.41 +/- 0.61 microg/ml). The water extract of Terminalia bellerica (Gaertn) Roxb had the highest in vitro antiplasmodial activity followed by Phyllanthus emblica Linn. and Terminalia chebula Retz. The cytotoxic activity was exhibited by all plant extracts on Vero cells with IC50 values of 157.86 to 238.70 mg/ml. All of the plant extracts showed selectivity with the selectivity index (SI) ranged from 11 to 17. A standard 4-day suppressive test on P. berghei infected mice was used to evaluate the in vivo antiplasmodial activity of the extracts at 250 mg/kg/day. The results revealed that in vivo antiplasmodial activity with good suppression activity ranged from 53.40% to 69.46%. CONCLUSION: All of the plant extracts exhibited interesting in vitro and in vivo antiplasmodial activity with good selectivity.

Synergistic growth inhibitory effects of Phyllanthus emblica and Terminalia bellerica extracts with conventional cytotoxic agents: doxorubicin and cisplatin against human hepatocellular carcinoma and lung cancer cells.

AIM: To examine the growth inhibitory effects of Phyllanthus emblica (P. emblica) and Terminalia bellerica (T. bellerica) extracts on human hepatocellular carcinoma (HepG2), and lung carcinoma (A549) cells and their synergistic effect with doxorubicin or cisplatin. METHODS: HepG2 and A549 cells were treated with P. emblica and T. bellerica extracts either alone or in combination with doxorubicin or cisplatin and effects on cell growth were determined using the sulforhodamine B (SRB) assay. The isobologram and combination index (CI) method of Chou-Talalay were used to evaluate interactions between plant extracts and drugs. RESULTS: P. emblica and T. bellerica extracts demonstrated growth inhibitory activity, with a certain degree of selectivity against the two cancer cell lines tested. Synergistic effects (CI < 1) for P. emblica/doxorubicin or cisplatin at different dose levels were demonstrated in A549 and HepG2 cells. The T. bellerica/cisplatin or doxorubicin also showed synergistic effects in A549 and HepG2 cells. In some instances, the combinations resulted in antagonistic effects. The dose reduction level was different and specific to each combination and cell line. CONCLUSION: The growth inhibitory activity of doxorubicin or cisplatin, as a single agent, may be modified by combinations of P. emblica or T. bellerica extracts and be synergistically enhanced in some cases. Depending on the combination ratio, the doses for each drug for a given degree of effect in the combination may be reduced. The mechanisms involved in this interaction between chemotherapeutic drugs and plant extracts remain unclear and should be further evaluated.