Estudo químico e avaliação do potencial antifúngico das folhas e frutos de Lantana trifolia L. (Verbenaceae)

Abstract

Lantana trifolia L. (Verbenaceae), popularly known as milho de grilo, calmante de pomba and uvinha do mato, is a shrubby plant used in folk medicine in the form of infusions and syrups to treat several illnesses. Studies found in the literature report the antimicrobial potential of the compounds present in the leaves of this plant, which aroused our interest for a more detailed study aiming to evaluate the chemical profile and the antifungal potential of the extracts from the L. trifolia leaves and fruits. Further, it was performed a chemical and pharmacological comparison between ethanol extracts and fractions of leaves and fruits from different specimens collected in Pontal/SP and Peirópolis/MG. In the antifungal activity assay was observed that the ethyl acetate fractions presented a highest activity against the three Candida strains evaluated (C. albicans, C. tropicalis and C. glabrata), with emphasis on the ethyl acetate fraction of the fruits collected in Pontal and Peirópolis and n-butanol fraction from fruits collected in Peirópolis, which presented minimum inhibitory concentration (MIC) values of 1.46, 2.93 and 2.93 μg mL–1, respectively, against C. glabrata, that were close to the positive control amphotericin (0.5–1.0 μg mL–1). The extracts and fractions were evaluated as cytotoxicity and used to calculate the selectivity index (SI), which allowed us to notice that the most active fractions in the antifungal assay were more selective against C. glabrata strain than healthy cells. Furthermore, chemometric techniques and molecular networks (global natural products social molecular networking - GNPS) gave support to analyze the chemical profile of the fractions, as well as to annotate 29 phenolic compounds (phenylpropanoids and flavonoids); among then 9 biomarkers were indicated by the variable importance in projection (VIP) and partial least-squares discriminant analysis (PLS-DA). The chemical study of the ethyl acetate fraction from leaves collected in Peirópolis allowed the isolation of the flavonoid scutellarein-7-O-apioside and protocatechuic acid, as well as the study of the n-butanol fraction from leaves collected in Peiropolis allowed the isolation of the phenylpropanoid verbascoside, which was also annotated by the molecular networks. Additionally, gas chromatography-mass spectrometry analysis (GC-MS) of hexane fractions from leaves collected in Peirópolis allowed the identification of 16 compounds, including terpenes, fatty acids and derivatives. Therefore, the present work proves the antifungal potential of L. trifolia and contributes to the chemical and biological knowledge of this species present in the Brazilian territory that are used in medicine folk.