Ethyl acetate and ethanol extracts of the tuber parts of Maerua pseudopetalosa were subjected to further separation by column chromatography technique and eight fractions were obtained for the former and twelve for the latter one. The brine shrimp lethality assay was used for assessment of the toxicity. Remarkable cytotoxicity against brine shrimp larvae was shown, for the first time, by the ethanol extract. The fractions F8, F9, F11 and F12, with high cytotoxic values (1.25, 7.98, 0.185, 0.041 µg/ml, respectively), were subjected to gas chromatography/mass spectrometry analysis. Thirty three compounds were detected; which were not recorded in any previous work in the available literature. Fractions 8 and 9 were found to be cytotoxic due to the presence of oleate and linoleate compounds; with more cytotoxicity in fraction 8 as a result of the additional presence of decenoic acid. Also, fraction 12 was more cytotoxic than fraction 11 and this was attributed to the presence of a proline derivative (proline-N-methyl-butyl ester). This compound might be considered as the cause of the high toxicity of the fraction; since free proline was used as an inhibitor of breast cancer development. Surprisingly, M. pseudopetalosa tubers were used in the folkloric medicine by the natives of the South Blue Nile State for the treatment of breast cancer growth without any knowledge of its chemical constituents.
Key words: Capparaceae, brine shrimp larvae, bioactive compounds, column chromatography, GC/MS analysis, proline derivative.