Evaluation of in vitro cytotoxicity and investigation of immunostimulant activity of bauhinia rufescens and euphorbia hirta

Background: Herbal medicine is a natural medicine. However, phytotherapy does not have only beneficial effects. Like any active product, it can have undesirable, toxic effects. Plants with very interesting potentials on the therapeutic level can present a toxicity which limits their use. The objective of this study is to evaluate the cellular toxicity of hydroethanolic extracts of Bauhinia rufescens and Euphorbia hirta and to investigate their immunostimulant activities. Methodology: Cytotoxicity evaluation was performed on a cell culture for 24h under 5% CO2.Cell death was evaluated by the propidium iodide exclusion method by flow cytometry. The immunostimulating activity was measured on the cell culture supernatant for 24 hours under 5% CO2.the TNFα cytokine was measured on the cell culture supernatant collected after 24 hours by Sandwich ELISA technique. Results: The hydroethanol extract of Bauhinia rufesccens showed a dose-dependent cytotoxicity. The highest concentrations of the extract (500 µg/mL to 25 µg/mL) were found to be highly toxic compared to 100% DMSO. The cytotoxicity of the hydroethanol extract of Euphoria hirta does not show a dose-dependent relationship. This relationship is established only from the concentration 12.5 µg/mL. Only the concentrations of 50 µg/mL, 25 µg/mL, 3.125 µg/mL, 1.5625 µg/mL and 0.78125 µg/mL are significantly less toxic than 100% DMSO. The hydroethanolic extract of Bauhinia rufescens cultured with peripheral blood mononuclear cells showed a dose-dependent immunostimulatory capacity. The concentration of 500ug/mL induced a high production of TNF compared to the positive control (PHA). This significant immunostimulatory activity was observed also for the concentrations of 250 µg/mL, 125 µg/mL and 0.78125 µg/mL for Euphorbia hirta, that the concentration of 0.78125µg /ml significantly stimulated the production of proinflammatory cytokine, TNFα compared to phytohemagglutin (PHA). Conclusion: the studied plants showed toxicity at high concentration. Compared to the immunostimulatory activity, Euphorbia hirta, the lowest concentration caused high production of TNFα. These results may pave the way on further studies for possible use of Bauhinia rufescens and Euphorbia hirta as natural immunostimulants.