Comparison of cytotoxicity, saponin, and protoanemonin contents of medicinal plant extracts from Helleborus niger L. and Helleborus foetidus L.

Abstract

BackgroundComplementary treatment options for tumors and hematological malignancies constitute a strong therapeutic need. Medicinal plant extracts from Helleborus niger L. and Helleborus foetidus L. are effective in corresponding clinical applications, but their composition and bioactivity still await further investigations. Due to their cytotoxicity, saponins and protoanemonin might be related to effectiveness of pharmaceutical extracts from H. niger and H. foetidus. PurposeThe goal of this study was to evaluate the cytotoxic and apoptosis-inducing capacity of different pharmaceutical extracts from H. niger and H. foetidus in selected in-vitro assays and to compare their protoanemonin and saponin concentration levels. MethodsAqueous extracts from H. niger and H. foetidus were obtained according to two different pharmacopoeial methods as stated in European Pharmacopoeia and German Homoeopathic Pharmacopoeia. Cytotoxic and apoptosis inducing activities of extracts were analyzed using tumor cell lines MOLT4, SK-UT-1b and HT-144, as well as cultured human PBMC. Protoanemonin and saponin concentrations were determined by HPLC-DAD analysis. ResultsSaponin and protoanemonin contents were different dependent on the pharmacopoieal method applied, as well as on the plant species and parts used for extract production. Maceration according to Ph. Eur. 1.3.1 yielded extracts with almost opposite protoanemonin and saponin contents from H. foetidus and H. niger (H. foetidus: low saponin level, high protoanemonin level; H. niger: vice versa). Fermented H. niger extracts showed saponin and protoanemonin contents ranging between those of the Ph. Eur. 1.3.1 extracts from both species. Both H. niger and H. foetidus extracts exhibited cytotoxicity in the selected cell line assays. H. foetidus extract was about 10 times more cytotoxic than H. niger extract. Investigated cell lines showed different responses towards the pharmaceutical extracts. Tumor cells were more prone to apoptosis induction than human PBMC cells. ConclusionsThe present investigation demonstrates that the contents of protoanemonin and saponins in the medicinal plant extracts from studied Helleborus sp. differ significantly. While both plant extracts were found to be cytotoxic against selected tumor cells, H. foetidus exhibited much stronger cytotoxic activities than H. niger. The individual metabolic profiles of saponins and protoanemonin in H. niger and H. foetidus could contribute to these differences in cytotoxic potential. To obtain defined plant extracts for medicinal purposes it is essential to use official manufacturing procedures and accurately specified plant species and parts.