Determinação de biomarcadores associados ao amargor e avaliação da atividade citotóxica de infusões de Ilex paraguariensis

Abstract

Ilex paraguariensis (yerba mate) is a widely consumed plant and has an interesting diversity of secondary metabolites, which are responsible for the plant's sensory and biological properties. In this context, the prospection of secondary metabolites of interest has an advanced tool in the metabolomics approach, presenting the advantages of speed and accuracy in relation to the chemical mapping of an organism or biological system. The plant has three levels of bitterness that can vary in the range of high, medium and mild, however, little is known about which molecules may be responsible for this effect. As for the biological activities, studies involving its cytotoxic potential still do not have correlations in relation to the respective chemical profiles of the plant. In this study, the variations in bitterness, associated with the infusions of the mixture of leaves and yerba mate branches, were evaluated by determining the metabolic profile based on the application of the UPLC-QTOF-MSE technique. Fifteen metabolites were recorded, among which we can highlight saponins, methylxanthines, flavonoids, caffeic and chlorogenic acid derivatives, highlighting the signalpadehyde compound that was recorded for the first time in Ilex paraguariensis. The information related to the metabolic profiles were submitted to multivariate analyzes (PCA, HCA, PLS-DA and OPLS-DA), through which it was possible to tentatively establish a correlation between the chemical profiles and the respective sensory characteristics, thus determining the biomarkers responsible for the different levels of bitterness. From the combination of high resolution mass spectrometry data and multivariate analyses, matesaponins were considered the biomarkers responsible for the bitterness of yerba mate. Additionally, the metabolites sinapaldehyde and tricaffeoylquinic acid characterized the samples of yerba mate with mild content, which is the first time that these compounds are considered as markers of yerba mate. Data related to bitterness biomarkers are of great importance for plant genetic improvement systems, as they can guide the obtaining of cultivars with a degree of bitterness suitable for the interest of the market. Regarding the biological activities, the infusions of leaves and branches of yerba mate were studied separately to compare which part of the plant had the highest cytotoxic activity. Cytotoxicity assays were performed using the MTT method and six tumor cell lines and one non-tumor cell line were used. The test results showed that the infusions of leaves and branches (separately) of I. paraguariensis did not present cytotoxic activity against the studied strains, so it was not possible to make a correlation between this characteristic and the metabolites noted in mate. These results may be a consequence of the use of only water for the preparation of the extract or of the types of cells used in the work, as in the literature there are reports of cytotoxic activity for hydroalcoholic extracts of mate and for cell lines different from those used. Finally, the results presented in this work can assist in the implementation of advanced phenotyping methodologies that are used as modern tools used in the genetic improvement systems of yerba mate, especially with regard to the development of cultivars with specific sensory characteristics required by the market.