In Vitro Cytotoxic Activity of Extremophile Plants on WI-38 and J774 Cell Lines

In arid and semi-arid regions, as encountered in Tunisia, plants are often subjected to severe environmental conditions, such as salinity or drought that strongly influence the production of some secondary metabolites involved in stress plant defence mechanisms 2. Some of them may have interesting biological activities. These plants and natural products can be promising candidates with an important nutritional, medicinal and economic potential [2].

In this context, eight extremophile plants have been collected in different areas in Tunisia, including 3 xerophytic plants (2 Asteraceae and 1 Caprifoliaceae) and 5 halophytic plants (1 Juncaceae, 1 Poaceae, 1 Amaranthaceae, 1 Plumbaginaceae and 1 Caryophyllaceae). Crude methanolic extracts of these eight plants have been evaluated for their cytotoxic activity against J774 (murine macrophage-like tumor) and WI-38 (human lung fibroblast) cell lines. The extract of Cirsium scabrum Bonnet & Barratte (Asteraceae) leaves exhibited a high cytotoxic activity against the cancerous cell lines J774 (IC₅₀ = 11.56 ± 2.70 µg/mL), but was much less toxic against the non-cancerous cell lines WI38.

Bioguided fractionation using liquid-liquid partition showed that the petroleum ether partition was most likely responsible for this activity with an IC₅₀ equal to 12.11 ± 0.88 µg/mL against J744 cell line. From this partition, several compounds were isolated by column chromatography and centrifugal partition chromatography. One of the major compounds was identified as lupeol, a triterpenoid widely distributed in various plant families and already known for this kind of activity. For example, this natural product is able to modulate different molecular mechanisms contributing to the melanoma development [3, 4]. Other compounds are in identification process. All of the identified compounds will be tested for their cytotoxic activity to identify the compound(s) responsible for the activity of Cirsium scabrum.

Acknowledgements: The authors wish to thank CUMA (Pr. J.F. Goossens) and LARMN (Pr. N. Azaroual) from University of Lille 2 (France) for access to equipment and the members of these platforms for their skillfull technical assistant.

Keywords: Cirsium scabrum, Asteraceae, leaves, cytotoxic activity, lupeol.

References:

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