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Background: The purpose of this study is to determine the effect of in vitro anticancer activity and cytotoxicity of 13 Papaver alkaloids (amurine, armepavine, berberine, isocorydine, isothebaine, macranthine, mecambrine, mecambridine, narkotine, orientalidine, oripavine, salutaridine and thebaine) against the human cervical cancer cell line (HeLa) compared to the normal African green monkey kidney epithelial cell line (Vero) using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Materials and Methods:The Vero and HeLa cell lines were treated with various concentrations (1-300 μg/mL) of alkaloids for 48 h. Values for cytotoxicity measured by MTT assay were expressed as the concentration that causes a 50% decrease in cell viability (IC 50 ) (μg/mL). Results: Berberine and macranthine were the most active alkaloids. Salutaridine exhibited no cytotoxic activity against two types of cell lines. Dose-dependent studies presented IC 50 of 12.08 μg/mL and IC 50 of 71.14 μg/mL for berberine and IC 50 of 24.16 μg/mL and IC 50 of >300 μg/mL for macranthine on the HeLa cells and the Vero cells respectively. Conclusion:The degree of selectivity of the compounds can be expressed by its Selectivity Index (SI) value. High SI value (>2) of a compound gives a selective toxicity towards cancer cells (SI = IC 50 for normal cells/IC 50 for cancer cells). Two alkaloids showed significant SI values, which are 12.42 for macranthine and 5.89 for berberine. Hence, macranthine and berberine display potential to be further exploited in the discovery and development of new anticancer agents.

High expression of Hsp27 in glioma cells has been closely associated with tumor cell proliferation and apoptosis inhibition. The aim of the present study was to asses the effects of rosmarinic acid (RA) on Hsp27 expression and apoptosis in non-transfected and transfected human U-87 MG cells. The effect of rosmarinic acid was compared to quercetin, which is known to be a good Hsp27 inhibitor. In order to block the expression of Hsp27 gene (HSPB1), transfection with specific siRNAs was performed. Western blotting technique was used to assess the Hsp27 expression, and caspase-3 colorimetric activity assay was performed to determine apoptosis induction. According to the results, it was found that RA and quercetin effectively silenced Hsp27 and both agents induced apoptosis by activating the caspase-3 pathway. Eighty and 215 μM RA decreased the level of Hsp27 by 28.8 and 46.7% and induced apoptosis by 30 and 54%, respectively. For the first time, we reported that rosmarinic acid has the ability to trigger caspase-3 induced apoptosis in human glioma cells. As a result of siRNA transfection, the Hsp27 gene was silenced by ~ 50% but did not cause a statistically significant change in caspase-3 activation. It was also observed that apoptosis was induced at a higher level as a result of Hsp27 siRNA and subsequent quercetin or RA treatment. siRNA transfection and 215 μM RA treatment suppressed Hsp27 expression level by 90.5% and increased caspase-3 activity by 58%. Herein, we demonstrated that RA administered with siRNA seems to be a potent combination for glioblastoma therapy.

Viscum album L. is a semiparasitic plant grown on trees and widely used for the treatment of many diseases in traditional and complementary therapy. It is well known that some activities of Viscum album extracts are varied depending on the host trees, such as antioxidant, apoptosis-inducing, anticancer activities of the plant. The aim of the present study is to examine the comparative effects of methanolic extracts of V. album grown on three different host trees (locust tree, lime tree, and hedge maple tree) on H2O2-induced DNA damage in HeLa cells. Oxidative damage in mitochondrial DNA and two nuclear regions was assessed by QPCR assay. The cells were pretreated with methanolic extracts (10 μg/mL) for 48 h, followed by the treatment with 750 μM H2O2 for 1 hour. DNA damage was significantly induced by H2O2 while it was inhibited by V. album extracts. All extracts completely protected against nuclear DNA damage. While the extract from lime tree or white locust tree entirely inhibited mitochondrial DNA damage, that from hedge maple tree inhibited by only 50%. These results suggest that methanolic extracts of V. album can prevent oxidative DNA damage, and the activity is dependent on the host tree.

GBM cells can easily gain resistance to conventional therapy, and therefore treatment of glioblastoma multiforme (GBM) is difficult. One of the hallmark proteins known to be responsible for this resistance is heat shock protein 27 (Hsp27) which has a key role in the cell survival. Resveratrol, a natural compound, exhibits antitumor effects against GBM, but there are no reports regarding its effect on Hsp27 expression in gliomas. The aim of the present study was to asses the effect of resveratrol on Hsp27 expression and apoptosis in non-transfected and transfected U-87 MG human glioblastoma cells. In order to block the Hsp27 expression, siRNA transfection was performed. Non-transfected and transfected cells were treated with either 10 or 15 μM resveratrol. The effects of resveratrol were compared with quercetin, a well-known Hsp27 inhibitor. Resveratrol was found to induce apoptosis more effectively than quercetin. Our data showed that resveratrol induces dose-and time-dependent cell death. We also determined that silencing of Hsp27 with siRNA makes the cells more vulnerable to apoptosis upon resveratrol treatment. The highest effect was observed in the 15 μM resveratrol and 25 nM siRNA combination group (suppressed Hsp27 expression by 93.4% and induced apoptosis by 101.2%). This study is the first report showing that resveratrol reduces Hsp27 levels, and siRNA-mediated Hsp27 silencing enhances the therapeutic effects of resveratrol in glioma cells. Our results suggest that resveratrol administration in combination with Hsp27 silencing has a potential to be used as a candidate for GBM treatment.