Planta Med 2012; 78(09): 881-889
DOI: 10.1055/s-0031-1298473
Biological and Pharmacological Activity
Original Papers
Georg Thieme Verlag KG Stuttgart · New York

In Vitro Cytotoxicity of Cyclodextrin-bonded Birch Bark Extract

Anke Hertrampf
1   Center for Complementary Medicine, Department of Environmental Health Sciences, University Medical Center Freiburg, Freiburg, Germany
,
Carsten Gründemann
1   Center for Complementary Medicine, Department of Environmental Health Sciences, University Medical Center Freiburg, Freiburg, Germany
,
Sebastian Jäger
2   Birken AG, Niefern-Öschelbronn, Germany
4   Betulin-Institute, Darmstadt, Germany
,
Melanie Laszczyk
2   Birken AG, Niefern-Öschelbronn, Germany
4   Betulin-Institute, Darmstadt, Germany
,
Torsten Giesemann
3   Oncotest GmbH, Freiburg, Germany
,
Roman Huber
1   Center for Complementary Medicine, Department of Environmental Health Sciences, University Medical Center Freiburg, Freiburg, Germany
› Author Affiliations
Further Information

Publication History

received 28 January 2012
revised 22 February 2012

accepted 28 March 2012

Publication Date:
09 May 2012 (online)

Abstract

Triterpenoids from birch bark, like betulin, seem to have an anticancer potential which needs to be further investigated. Aim of this study was first to explore whether a cyclodextrin-solubilised triterpenoid extract (STE) from birch bark induces selective cytotoxic effects in primary liver cancer cells compared to healthy human hepatocytes. Second, selective cytotoxicity against several tumour cell lines should be analysed. For this purpose, human liver cancer cells derived from mouse xenografts (LIXF 575), healthy human hepatocytes, and 42 different human tumour cell lines were incubated with different concentrations of STE corresponding to 4.3 µM – 137.5 µM betulin (BE). Cytotoxicity was tested with the WST-1 cell proliferation assay, apoptosis with caspase 3/7-activity, and necrosis was determined by the propidiumiodid uptake assay. The pathway of cytotoxic effects was further investigated by immunoblotting of apoptosis inducing factor (AIF) and p53. The monolayer assay was used to analyse selectivity of STE towards different tumour cell lines. STE significantly (p < 0.001) reduced viability and induced apoptosis of LIXF cells in low concentrations corresponding to 8.6 µM BE, while human hepatocytes were affected only in concentrations ≥ 68.8 µM. Cell death occurred in a p53 independent manner, and AIF was not involved. The mean IC50 in the 42 tumour cell lines corresponded to 4.3 µM BE and ranged from 2.05 µM to 8.95 µM BE content. Selectivity was, therefore, rather low. In conclusion, STE exhibits in low concentrations cytotoxicity in a broad spectrum of primary cancer cells and cancer cell lines, which is, at least in LIXF cells, induced by caspase 3/7 mediated apoptosis. STE is far less toxic in hepatocytes. The anticancer potential of STE should be further characterised and also investigated in animal models.

 
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