Antiproliferative activities of some selected Nigerian medicinal plants against breast, liver, and cervical cancer cells

Abstract

Background: Phytochemicals have become a growing source of alternative medicine in developing countries due to the poor prognosis, high cost of conventional pharmaceuticals, and undesirable effects associated with mainstream cancer treatment.

Objective: This study was aimed at investigating the anticancer effect of some selected Nigerian medicinal plants used in cancer treatment. These include ethanol extracts of Dialium guineense root (DGR), Dialium guineense leaves (DGL), Jateorhiza macrantha leaves (JML), Musanga cecropioides leaves (MCL), Musanga cecropioides stembark (MCSB), Piptadeniastrum africanum stembark (PASB), Piptadeniastrum africanum root (PAR), Pupalia lappacea flower tops (PLF), Raphiostylis beninensis root (RBR), Raphiostylis beninensis leaves (RBL), Ritchiea capparoides leaves (RCL), Ritchiea capparoides stembark (RCSB), and Triplochiton scleroxylon stembark (TSB).

Methods: The cytotoxic activity of the extracts was examined using a brine shrimp lethality assay and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay against three cancer cell lines, including MCF-7, HUH-7, and HeLa. The selectivity of all extracts towards cancer cells was investigated using normal lung fibroblasts (MRC-5). Cell migration and colony-forming assays of active extracts against MCF-7 cells were also performed. Additionally, the total polyphenolic contents of the active extracts were estimated using standard methods.

Results: The extract of PASB had the highest cytotoxicity (LC₅₀ = 1.58 μg/mL) on the brine shrimps compared to vincristine sulphate (LC₅₀ = 2.24 μg/mL). In the cell viability assay, all the extracts produced significant (p < 0.05) growth inhibitory effects against all cell lines tested in a dose-dependent manner. All extracts were selective to cancer cells at varying degrees. Worth mentioning are the extracts of MCL, DGR, RBR, and PASB, which exhibited 14-, 7-, 6- and 2-fold selectivity toward MCF-7 cancer cells relative to normal lung fibroblast (MRC-5), respectively. These four extracts also significantly inhibited cell migration and colony formation in MCF-7-treated cells in dose-dependent manners. Considerable amounts of phenolics, flavonoids, and proanthocyanidins were detected in all extracts evaluated.

Conclusion: These findings advocate the continued development of MCL, DGR, RBR, and PASB as potential chemotherapeutic agents.

Keywords: Chemotherapeutic agent; Cytotoxicity; Medicinal plants; Phytochemicals; Polyphenolic content.