Induction of apoptosis in human leukemia cells by black tea and its polyphenol theaflavin

Regulation of p53, nuclear factor kappaB and cyclooxygenase-2 expression by bromelain through targeting mitogen-activated protein kinase pathway in mouse skin

Bromelain is a pharmacologically active compound, present in stems and immature fruits of pineapples (Ananas cosmosus), which has been shown to have anti-edematous, anti-inflammatory, anti-thrombotic and anti-metastatic properties. In the present study, antitumorigenic activity of bromelain was recorded in 7,12-dimethylbenz(a)anthracene (DMBA)-initiated and 12-O-tetradecanoylphorbol-13-acetate (TPA)-promoted 2-stage mouse skin model. Results showed that bromelain application delayed the onset of tumorigenesis and reduced the cumulative number of tumors, tumor volume and the average number of tumors/mouse. To establish a cause and effect relationship, we targeted the proteins involved in the cell death pathway. Bromelain treatment resulted in upregulation of p53 and Bax and subsequent activation of caspase 3 and caspase 9 with concomitant decrease in antiapoptotic protein Bcl-2 in mouse skin. Since persistent induction of cyclooxygenase-2 (Cox-2) is frequently implicated in tumorigenesis and is regulated by nuclear factor-kappa B (NF-kappaB), we also investigated the effect of bromelain on Cox-2 and NF-kappaB expression. Results showed that bromelain application significantly inhibited Cox-2 and inactivated NF-kappaB by blocking phosphorylation and subsequent degradation of IkappaBalpha. In addition, bromelain treatment attenuated DMBA-TPA-induced phosphorylation of extracellular signal-regulated protein kinase (ERK1/2), mitogen-activated protein kinase (MAPK) and Akt. Taken together, we conclude that bromelain induces apoptosis-related proteins along with inhibition of NF-kappaB-driven Cox-2 expression by blocking the MAPK and Akt/protein kinase B signaling in DMBA-TPA-induced mouse skin tumors, which may account for its anti-tumorigenic effects.

Membrane dielectric responses of bufalin-induced apoptosis in HL-60 cells detected by an electrorotation chip

A non-invasive electrorotation (ROT) technique was used to monitor the apoptosis-induced changes in HL-60 cells. The specific membrane capacitance of the cells fell from 15.6 +/- 0.9 mF/cm(2) to 6.4 +/- 0.6 mF/cm(2) after 48 h treatment with 10 nM bufalin, a component of bufadienolides in traditional Chinese medicine, Chan Su. However, the average membrane conductance remained almost constant during the first 24 h of treatment and then increased afterwards. Apoptosis was verified by a DNA fragmentation assay and scanning electron microscopy. The results demonstrate that the ROT technique gives a quantitative analysis of the toxic damage by chemicals to cells and can be exploited in the testing and development of new pharmaceuticals and active cell agents.

Inhibitory effects of various plant polyphenols on the toxicity of Staphylococcal α-toxin

Staphylococcal alpha-toxin, known for its wide spectrum of biological activities, is involved in the pathogenesis of Staphylococcal infectious diseases. In recent years, various phytochemicals have been found to have antimicrobiological, including antibacterial, antiviral and antifungal, and antitoxic activities. We investigated whether several plant polyphenols inhibit alpha-toxin activities in vitro and in vivo. We found hop bract tannin (HBT) and apple condensed tannin (ACT) to exert inhibitory effects on alpha-toxin cytotoxicity. HBT also reduced the murine skin inflammatory effect and the lethality of alpha-toxin. These polyphenols formed aggregates with alpha-toxin and thereby inhibited its activities. Inhibition of alpha-toxin by HBT and ACT was dose dependent, suggesting that these polyphenols may be a useful adjunct to current treatments for alpha-toxin catalyzed Staphylococcal infectious diseases.

A new extract of the plant Calendula officinalis produces a dual in vitro effect: cytotoxic anti-tumor activity and lymphocyte activation

Background

Phytopharmacological studies of different Calendula extracts have shown anti-inflamatory, anti-viral and anti-genotoxic properties of therapeutic interest. In this study, we evaluated the in vitro cytotoxic anti-tumor and immunomodulatory activities and in vivo anti-tumor effect of Laser Activated Calendula Extract (LACE), a novel extract of the plant Calendula Officinalis (Asteraceae).

Methods

An aqueous extract of Calendula Officinalis was obtained by a novel extraction method in order to measure its anti-tumor and immunomodulatory activities in vitro. Tumor cell lines derived from leukemias, melanomas, fibrosarcomas and cancers of breast, prostate, cervix, lung, pancreas and colorectal were used and tumor cell proliferation in vitro was measured by BrdU incorporation and viable cell count. Effect of LACE on human peripheral blood lymphocyte (PBL) proliferation in vitro was also analyzed. Studies of cell cycle and apoptosis were performed in LACE-treated cells. In vivo anti-tumor activity was evaluated in nude mice bearing subcutaneously human Ando-2 melanoma cells.

Results

The LACE extract showed a potent in vitro inhibition of tumor cell proliferation when tested on a wide variety of human and murine tumor cell lines. The inhibition ranged from 70 to 100%. Mechanisms of inhibition were identified as cell cycle arrest in G0/G1 phase and Caspase-3-induced apoptosis. Interestingly, the same extract showed an opposite effect when tested on PBLs and NKL cell line, in which in vitro induction of proliferation and activation of these cells was observed. The intraperitoneal injection or oral administration of LACE extract in nude mice inhibits in vivo tumor growth of Ando-2 melanoma cells and prolongs the survival day of the mice.

Conclusion

These results indicate that LACE aqueous extract has two complementary activities in vitro with potential anti-tumor therapeutic effect: cytotoxic tumor cell activity and lymphocyte activation. The LACE extract presented in vivo anti-tumoral activity in nude mice against tumor growth of Ando-2 melanoma cells.