Phytomedicine

Volume 22, Issue 1, 15 January 2015, Pages 1–4

Short communication

Cytotoxic effects of stem bark extracts and pure compounds from Margaritaria discoidea on human ovarian cancer cell lines

• Okiemute Rosa Johnson-Ajinwo,
• Alan Richardson,
• Wen-Wu Li^,

doi:10.1016/j.phymed.2014.09.008

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Abstract

Margaritaria discoidea (Baill.) G. L. Webster (Euphorbiaceae) is a well-known medicinal plant in Africa used for the treatment of various diseases. So far, no cytotoxic effects of plant extracts on cancer cell lines have been reported.

Aim of the study

To evaluate the cytotoxicity against human ovarian cancer cells of extracts of M. discoidea and characterize the major bioactive compounds.

Methods

Both organic and aqueous extracts of this plant were obtained by maceration. The sulforhodamine B cell proliferation assay was used for evaluation of their cytotoxic activities and the potential bioactive compounds were characterized by gas chromatography–mass spectrometry.

Results

The organic extract of M. discoidea showed stronger cytotoxicity than the aqueous extract with IC₅₀ values of 14.4 ± 3.0, 14.2 ± 1.2 and 34.7 ± 0.5 µg/ml on OVCAR-8, A2780 and cisplatin-resistant A2780cis ovarian cancer cells, respectively. The organic extract was further subjected to bioassay-guided fractionation by partitioning with n-hexane, ethyl acetate, and n-butanol in water. The ethyl acetate fraction was the most potent on the three ovarian cancer cell lines. A GC–MS analysis of trimethylsilyl derivatives of this fraction indicated the presence of phenolic compounds such as gallic acid and the alkaloid securinine. The IC₅₀ values of these two compounds were determined to be in the range of 3–16 µM, which indicated that they could contribute to the cytotoxic activity of the extract of M. discoidea.

Conclusions

This study has evaluated the cytotoxicity of stem bark extracts of M. discoidea against ovarian cancer cells and provided a basis of further development of this plant for the treatment of ovarian cancer.

Abbreviations

• BSTFA, N,O-bis(trimethylsily)trifluoroacetamide;
• EI, electron ionization;
• FBS, foetal bovine serum;
• GC–MS, gas chromatography–mass spectrometry;
• NCI, National Cancer Institute;
• SRB, sulforhodamine B;
• TCA, trichloroacetic acid;
• TMCS, chlorotrimethylsilane;
• TMSi, trimethylsilyl

Keywords

• Ovarian cancer;
• Margaritaria discoidea;
• GC–MS;
• Gallic acid;
• Securinine

Corresponding author. Tel.: +44 01782 674382; fax: +44 01782 747319.

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