Cytotoxicity of methanol extracts of , and nine other Cameroonian medicinal plants towards multi-factorial drug-resistant cancer cell lines.

Background: Cancer cells rapidly acquire resistance leading to treatment failures. In the present study, we have evaluated the cytotoxicity of 17 methanol extracts from 11 Cameroonian medicinal plants against the sensitive leukemia CCRF-CEM cells and the best ones were further tested on a panel of 8 other human cancer cell lines, including various MDR phenotypes as well as against the normal AML12 hepatocytes.

Methods: The cytotoxicity of the extracts was determined using a resazurin reduction assay meanwhile flow cytometry was used to measure cell cycle, apoptosis, mitochondrial membrane potential (MMP), and reactive oxygen species.

Results: In an initial screening using leukemia CCRF-CEM cells, ten extracts from five plants namely , , , and displayed IC values below 20 µg/mL. They were further tested in 8 other cell lines as well as in normal AML12 hepatocytes. All selected extracts were active against leukemia CEM/ADR5000 cells with IC value below 40 µg/mL. IC values ranging from 10.13 µg/mL (towards CEM/ADR5000 cells) to 72.01 µg/mL [towards resistant colon carcinoma HCT116 () cells] for roots and from 0.11 µg/mL (towards CCRF-CEM cells) to 108 µg/mL (towards P-glycoprotein-over-expressing CEM/ADR5000 cells) for doxorubicin were obtained in the eight other cancer cell lines studied. Extracts from leaves (AML) and seeds (AMS), and fruit (PEF) had IC values below 1 µg/mL against CCRF-CEM cells and below 10 µg/mL against its MDR subline CEM/ADR5000 cells. AML, AMS and PEF induced MMP-loss-mediated apoptosis in CCRF-CEM cells.

Conclusions: Results of the present study suggest that some of the tested plants namely , , , and represent a source of anticancer drugs. and are good cytotoxic plants that could be exploited to develop phytomedicine to fight mostly hematological cancers including MDR phenotypes.