Cytotoxicity and Genotoxicity of Senecio vulgaris L. Extracts: An In Vitro Assessment in HepG2 Liver Cells

Abstract

Senecio vulgaris L. is a herbaceous species found worldwide. The demonstrated occurrence of pyrrolizidine alkaloids in this species and its ability to invade a great variety of habitats result in a serious risk of contamination of plant material batches addressed to the herbal teas market; this presents a potential health risk for consumers. In light of the above, this work aimed to assess the cytotoxic and genotoxic activity of S. vulgaris extracts in HepG2 cells. Dried plants were ground and extracted using two different methods, namely an organic solvent-based procedure (using methanol and chloroform), and an environmentally friendly extraction procedure (i.e., aqueous extraction), which mimicked the domestic preparation of herbal teas (5, 15, and 30 min of infusion). Extracts were then tested in HepG2 cells for their cytotoxic and genotoxic potentialities. Results were almost superimposable in both extracts, showing a slight loss in cell viability at the highest concentration tested, and a marked dose-dependent genotoxicity exerted by non-cytotoxic concentrations. It was found that the genotoxic effect is even more pronounced in aqueous extracts, which induced primary DNA damage after five minutes of infusion even at the lowest concentration tested. Given the broad intake of herbal infusions worldwide, this experimental approach might be proposed as a screening tool in the analysis of plant material lots addressed to the herbal infusion market.

Keywords: Senecio vulgaris; comet assay; genotoxicity; herbal teas; pyrrolizidine alkaloids; safety assessment.

Figure 1

Effects of scalar concentrations of S. vulgaris chloroform and aqueous extracts on HepG2 cell viability expressed as percent of negative control (taken as the unit, 100%). The results of each experimental set are summarized as the mean (±SEM) of three independent experiments. Statistical analysis: * indicates statistically significant differences (p < 0.05) compared with the negative control, one-way ANOVA followed by Dunnett’s post hoc analysis. Cell viability (%) after treatment with the positive control (1% Triton-X-100): 34.94 ± 2.24.

Figure 1

Effects of scalar concentrations of S. vulgaris chloroform and aqueous extracts on HepG2 cell viability expressed as percent of negative control (taken as the unit, 100%). The results of each experimental set are summarized as the mean (±SEM) of three independent experiments. Statistical analysis: * indicates statistically significant differences (p < 0.05) compared with the negative control, one-way ANOVA followed by Dunnett’s post hoc analysis. Cell viability (%) after treatment with the positive control (1% Triton-X-100): 34.94 ± 2.24.

Figure 2

Primary DNA damage in HepG2 cells exposed for four hours to different concentrations of Senecium vulgaris chloroform and aqueous extracts. The extent of DNA strand breakage is expressed in terms of tail intensity (% DNA migrated in the comet tail). The results of each experimental set are summarized as the mean value of at least three independent experiments (±SEM). Statistical analysis: * indicates statistically significant differences (p < 0.05) compared with the negative control, one-way ANOVA followed by Dunnett’s post hoc analysis. Tail intensity of positive control (1 μM 4NQO): 18.55 ± 2.30.