Anti-leukaemic effects of two extract types of Lactuca sativa correlate with the activation of Chk2, induction of p21, downregulation of cyclin D1 and acetylation of alpha-tubulin.

The water extract of the lettuce Lactuca sativa, but not the ethyl acetate extract, inhibited the growth of HL-60 leukaemia cells and MCF-7 breast cancer cells. This correlated with the activation of checkpoint kinase 2 (Chk2), the induction of the tumour suppressor p21, and the severe downregulation of the proto-oncogene cyclin D1. The ethyl acetate extract, but not the water extract, induced HL-60 cell death, which correlated with the acetylation of alpha-tubulin. The acetylation of alpha-tubulin is indicative for microtubuli stabilisation such as induced by taxol. The calculated amount for human intake would require approximately 3 kg lettuce to reach the required concentration shown to inhibit 50% HL-60 proliferation.

In vitro anti-leukemic activity of the ethno-pharmacological plant Scutellaria orientalis ssp. carica endemic to western Turkey.

AIM OF THIS STUDY: Within the genus Scutellaria various species are used in different folk medicines throughout Asia. Traditional Chinese Medicine (TCM) uses S. baicalensis (Labiatae) to treat various inflammatory conditions. The root shows strong anticancer properties in vitro and was suggested for clinical trials against multiple myeloma. Further, S. barbata was successfully tested against metastatic breast cancer in a phase I/II trial. Therefore, we investigated the anti-cancer properties of S. orientalis L. ssp. carica Edmondson, an endemic subspecies from the traditional medicinal plant S. orientalis L. in Turkey, which is used to promote wound healing and to stop haemorrhage. MATERIALS AND METHODS: Freeze-dried plant material was extracted with petroleum ether, dichloromethane, ethyl acetate, and methanol and the bioactivity of these extracts was analysed by proliferation assay, cell death determination, and by investigating protein expression profiles specific for cell cycle arrest and apoptosis. RESULTS: The strongest anti-leukemic activity was shown by the methanol extract, which contained apigenin, baicalein, chrysin, luteolin and wogonin, with an IpC50 of 43 microg/ml (corresponding to 1.3mg/ml of dried plant material) which correlated with cyclin D1- and Cdc25A suppression and p21 induction. At 132 microg/ml (=4 mg/ml of the drug) this extract caused genotoxic stress indicated by substantial phosphorylation of the core histone H2AX (gamma-H2AX) followed by activation of caspase 3 and signature-type cleavage of PARP resulting in a 55% apoptosis rate after 48 hours of treatment. CONCLUSIONS: Here, we report for the first time that S. orientalis L. ssp. carica Edmondson exhibited potent anti-leukaemic properties likely through the anti-proliferative effect of baicalein and the genotoxic property of wogonin.

In vitro anti-neoplastic activity of the ethno-pharmaceutical plant Hypericum adenotrichum Spach endemic to Western Turkey.

Hypericum perforatum (St. John's wort) is well-established for its antidepressant activity throughout the world and also various other species within this genus are used in different folk medicines. Hyperforin of St. John's wort inhibited growth of cancer cell lines and the use of hypericin (another compound of H. perforatum) in cancer photodynamic therapy is proposed. Therefore, we investigated the anti-cancer properties of H. adenotrichum Spach (Guttiferae), an endemic species in Turkey called 'kantaron', which is used for wound healing and antiseptic effects. Freeze-dried plant was extracted with petroleum ether, dichloromethane, ethyl acetate, and methanol and the bioactivity of these extracts was analysed by proliferation assay, cell death determination, by investigating protein expression profiles specific for cell cycle arrest and apoptosis as well as composition by HPLC. The strongest anti-proliferative activity was determined for the petroleum ether extract with an IpC50 of approximately 5.8 microg/ml medium (referring to 1 mg dried plant) which correlated with cyclin D1 suppression and p21 induction. This extract also induced phosphorylation of H2AX, and activated caspase-3 followed by signature-type cleavage of PARP resulting in approximately 50% apoptosis at 23.2 microg/ml after 24 h of treatment. Neither hyperforin, hypericin, or amentoflavone contributed to these properties. To the best of our knowledge, we report for the first time that the endemic plant H. adenotrichum Spach exhibits potent p53-independent anti-neoplastic properties due to yet unexplored Hypericum constituents.

A polar extract of the Maya healing plant Anthurium schlechtendalii (Aracea) exhibits strong in vitro anticancer activity.

The Aracea Anthurium schlechtendalii and Syngonium podophyllum are traditional remedies for the treatment of severe and chronic inflammatory conditions. We cross-examined these plants regarding their anti-neoplastic properties, because several anti-inflammatory molecular targets are common for both pathologic conditions due to similar signalling pathways. Two malignant cell lines, HL-60 and MCF-7, were treated with increasing concentrations of plant extracts of increasing polarity. The potential of the extracts to inhibit the cell cycle and to induce cell death was investigated, because these are relevant endpoints to assess the anti-cancer potential in vitro and the protein expression and cell cycle distribution upon exposure to the strongest extract was analysed. Extracts from S. podophyllum were rather ineffective, but the freeze-dried (but not air-dried) roots of A. schlechtendalii exhibited strong growth inhibitory and apoptosis-inducing properties. In HL-60 cells 50% proliferation inhibition was achieved by 1.7 microg dichloromethane extract/ml medium and correlated with the activation of Chk2, down-regulation of Cdc25A, suppression of cyclin D1 level, and transient induction of p21. This extract efficiently triggered apoptosis, which was confirmed by caspase 3 activation. The polymerisation of alpha-tubulin and its subsequent degradation that depleted the cells from the G2/M contributed to apoptosis induction, because proper spindle-formation during mitosis is mandatory for survival. In conclusion, we demonstrated that A. schlechtendalii root extract specifically targeted carcinogenic mechanisms, because Cdc25A and cyclin D1 are oncogenes that are frequently overexpressed in a variety of cancer entities and further, this extract affected microtubule function reminiscent of taxol.

In vitro anti-cancer activity of two ethno-pharmacological healing plants from Guatemala Pluchea odorata and Phlebodium decumanum.

Many traditional healing plants successfully passed several hundred years of empirical testing against specific diseases and thereby demonstrating that they are well tolerated in humans. Although quite a few ethno-pharmacological plants are applied against a variety of conditions there are still numerous plants that have not been cross-tested in diseases apart from the traditional applications. Herein we demonstrate the anti-neoplastic potential of two healing plants used by the Maya of the Guatemala/Belize area against severe inflammatory conditions such as neuritis, rheumatism, arthritis, coughs, bruises and tumours. Phlebodium decumanum and Pluchea odorata were collected, dried and freeze dried, and extracted with five solvents of increasing polarity. We tested HL-60 and MCF-7 cells, the inhibition of proliferation and the induction of cell death were investigated as hallmark endpoints to measure the efficiency of anti-cancer drugs. Western blot and FACS analyses elucidated the underlying mechanisms. While extracts of P. decumanum showed only moderate anti-cancer activity and were therefore not further analysed, particularly the dichloromethane extract of P. odorata inhibited the cell cycle in G2-M which correlated with the activation of checkpoint kinase 2, and down-regulation of Cdc25A and cyclin D1 as well as inactivation of Erk1/2. In HL-60 and MCF-7 cells this extract was a very strong inducer of cell death activating caspase-3 followed by PARP signature type cleavage. The initiating death trigger was likely the stabilization of microtubules monitored by the rapid acetylation of alpha-tubulin, which was even more pronounced than that triggered by taxol. The dichloromethane extract of P. odorata contains apolar constituents which inhibit inflammatory responses and exhibit anti-cancer activity. The strong proapoptotic potential warrants further bioassay-guided fractionation to discover and test the active principle(s).