Planta Med 2011; 77(1): 32-39
DOI: 10.1055/s-0030-1250112
Biological and Pharmacological Activity
Original Papers
© Georg Thieme Verlag KG Stuttgart · New York

Differential and Stereoselective In Vitro Cytotoxicity of Eremophilane Sesquiterpenes of Petasites hybridus Rhizomes in Rat Hepatocytes

Antje Bodensieck1 , Frank Gaunitz2 , Rolf Gebhardt3 , Ulrich Danesch4 , Rudolf Bauer1
  • 1Institute of Pharmaceutical Sciences – Pharmacognosy, Karl-Franzens University of Graz, Graz, Austria
  • 2Medical Centre and Clinic for Neurosurgery, Medical Centre of the University of Leipzig, Leipzig, Germany
  • 3Institute of Biochemistry, Medicinal Faculty, University of Leipzig, Leipzig, Germany
  • 4Weber & Weber, Research & Development, Inning, Germany
Further Information

Publication History

received Dec. 28, 2009 revised June 5, 2010

accepted June 10, 2010

Publication Date:
22 July 2010 (online)

Abstract

We tested two CO2 extracts of Petasites hybridus L. rhizomes, A (rich in furanoeremophilanes) and B (rich in petasins), for in vitro cytotoxicity in rat hepatocytes by means of the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay (EC50 values of 0.64 mg/mL for A and 0.32 mg/mL for B). Eight eremophilane sesquiterpene lactones (SL) (18) and one petasin (9) isolated from A were nontoxic or showed moderate cytotoxicity. The presence and type of the ester side chain most probably control the extent of cytotoxicity of the eremophilanolides. (8R)-2-[(angeloyl)oxy]eremophil-7(11)-en-12,8-olide (1) damaged the hepatocytes most. The 8α-stereoisomers of both 8-H epimeric couples of the 2-angeloyloxy- and 2-methacroyloxy-esters seem to be more cytotoxic (up to approx. 10-fold) than the corresponding 8β-H stereoisomers. Moreover, the results of the MTT assay depended on the cell density being more pronounced with both 8α-stereoisomers. Further investigations were conducted to study the influence of the stereochemistry on cell respiration, energy metabolism, and membrane integrity [release of lactate dehydrogenase (LDH)] with both couples of the 2-angeloyloxy- and 2-methacroyloxy-esters. In the LDH-leakage assay, (8R)-2-[(methacroyl)oxy]eremophil-7(11)-en-12,8-olide (2) was the most toxic eremophilane. The stereoselectivity of cell damage of some SL points to a specific, yet unidentified molecular cytotoxicity target.

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Prof. Dr. Rudolf Bauer

Institute of Pharmaceutical Sciences – Pharmacognosy
Karl-Franzens University of Graz

Universitaetsplatz 4

8010 Graz

Austria

Phone: + 43 31 63 80 87 00

Fax: + 43 31 63 80 98 60

Email: rudolf.bauer@uni-graz.at

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