RESUMO
The interest in Smallanthus sonchifolius (yacon) has strongly resurfaced due to its multiple beneficial effects on human health. This study aimed at determining the toxicity and the chemical profile of an ethanol extract (EE) and a crude lactone mixture (CLM) of yacon leaves. Cytotoxicity and genotoxicity tests were performed by the MTT assay and the alkaline version of the comet assay respectively. The phytochemical analysis, performed by chromatographic and spectroscopy techniques, revealed the presence of nine sesquiterpene lactones (STLs) and two acyclic diterpene acids. In all cases, cell viability was inversely proportional to the extract concentration employed. The effects obtained with the highest dose of EE were significantly different from those obtained with the negative and solvent controls. Conversely, no significant differences were observed between the lowest doses of EE and controls. As for CLM, all tested doses showed statistically significant increases, as compared to negative and solvent controls.
RESUMO
ETHNOPHARMACOLOGICAL RELEVANCE: Smallanthus sonchifolius (Poepp. & Endl.) H. Robinson, commonly known as yacon, is a medicinal plant belonging to the Asteraceae family used in traditional folk medicine. Its roots and leaves have been used by people suffering from diabetes or from various digestive or renal disorders. AIM OF THE STUDY: This study aimed at evaluating the in vitro potential genotoxic effects of the aqueous extract of yacon in order to determine its safety and at characterizing its phytochemical composition. MATERIALS AND METHODS: The aqueous extract of S. sonchifolius was prepared in a similar way to that commonly used in popular medicine as tea bags. Thin layer chromatography (TLC) and high-performance liquid chromatography (HPLC-MS/MS) were used to identify the main compounds. The MTT test was performed to determine the range of doses and the Cytochalasine B-blocked micronucleus (Cytome assay) was used to assess geneotoxicity. RESULTS: The chemical analysis of the aqueous extract revealed the presence of the sesquiterpene lactones (STLs) enhydrin and the dimer enhydrofolin, as the main compounds together with phenolic compounds. Increasing concentrations of the extract induced a cytotoxic effect on CHO-K1 and HepG2 cells. A statistically significant increase in the frequency of MNi, NBUDs and NPBs was observed in CHO-K1 cells, while in HepG2 cells a statistically significant frequency increase was observed with three of the four tested doses for MNi and only with the highest dose for NPBs and NBUs (genotoxic effect). CONCLUSION: Results demonstrated the inability of the metabolic system to counteract the genetic instability, allowing the safe consumption of the leaves as a 2% tea infusion in quantities of up to 250 mL/day.