An ethnopharmacological field study was performed among traditional healers in the Ashanti region of Ghana regarding their treatment of different kinds of cancer. A total of 151 plant species were mentioned as remedies used by the healers and these species were classified according to the frequency they were named in the survey, followed by intensive literature review regarding data on the cytotoxic potential of these plants [1].
13 plant species were chosen for an in vitro screening against different cancer cell lines, either because they were frequently mentioned for this indication or because they have not been assessed for cytotoxicity up to now. 22 hydro-ethanolic extracts (50:50) were prepared from different plant parts of the 13 selected species according to their traditional use and the cell viability was assessed in vitro in an MTT assay against MCF-7 (breast cancer), HepG2 (liver cancer) or A431 (skin cancer) cells.
Extracts from Alstonia boonei leaves and Paullinia pinnata climbers showed moderate cytotoxicity against MCF-7 cells at concentrations ≥ 50 µg/mL, whereas the bark extract from Kalanchoe integra strongly decreased the cell viability (IC50 4.8 µg/mL). Doxorubicin was used as positive control (IC50 1.4 µg/mL). The three extracts were also active against HepG2 and A431 cells, but at higher concentrations.
A preliminary phytochemical screening by LC-qTOF-MS revealed the presence of substances tentatively identified as bufadienolides. As this class of compounds is widely distributed among the genus Kalanchoe and known for its cytotoxic properties against various cell lines [2], bufadienolides could be responsible for the in vitro activity of the K. integra extract.
References:
[1] Agyare C, Spiegler V, Asase A, Scholz M, Hempel G, Hensel A. J Ethnopharmacol 2018; 212: 137-152.
[2] Kolodziejczyk-Czepas J, Stochmal A. Phytochem Rev 2017; 16: 1155-1171.