In vitro toxicity evaluation of estragole-containing preparations derived from Foeniculum vulgare Mill. (fennel) on HepG2 cells.

Estragole, a common component of herbs and spices, is a wellknown genotoxic hepatocarcinogen in rodents, whereas its potential toxic effect in humans is still debated. In the European contest, one of the major sources of human exposure to this phytochemical is Foeniculum vulgare Mill. (fennel). Therefore, the aim of this study was to evaluate the in vitro toxicity of estragole in the context of two complex phytochemical mixtures derived from fennel: fennel seed powder (FSPw) and fennel seed essential oil (FSEO). The estragole-containing preparations were analysed for their ability to cause cytotoxicity, genotoxicity, apoptosis and cell cycle perturbation in the human hepatoma (HepG2) cell line. None of the tested concentrations of FSPw induced DNA damage, nor apoptosis or cell cycle perturbation. Although FSEO did not induce any genetic damage as well, it exerted marked dose-dependent apoptotic effects on HepG2 cells with a concurrent cell cycle arrest in G2/M at the highest tested dose. Although prospective analyses are required to clarify the observed toxic effects of FSEO, our results support the hypothesis that the genotoxicity of estragole may be significantly reduced or null in the context of botanical mixtures.