Estudo fitoquímico, obtenção de nanopartículas de prata por síntese verde a partir de Jatropha mollissima (Euphorbiaceae) e avaliação das atividades antimicrobiana e citotóxica

Abstract

Jatropha mollissima is a shrubby plant of the Euphorbiaceae family, endemic to the Caatinga biome. It is a species that has little reference, however it is used in folk medicine mainly for the treatment of ulcers and snake bites. The main objectives of this work were: to perform the phytochemical study of J. mollissima, to obtain silver nanoparticles by green synthesis using its aqueous extract and to evaluate its antibacterial and cytotoxic capacity. In this work the aqueous extract of J. mollissima was reported for the first time as a silver ion reducer. The plant material (leaves) was collected in the city São Raimundo Nonato-PI, in the rainy season and, after the drying and maceration of the material, crude ethanol extract (Jm-CEE) was obtained. After this procedure, the Jm-CEE was partitioned using the vacuum liquid chromatography method with solvents in increasing order of polarity, obtaining the hexane (Jm-Hex), chloroform (Jm-CHCl3), ethyl acetate (Jm-AcOEt) and methanol (Jm-MeOH). The aqueous extract for biosynthesis of silver nanoparticles, in turn, was obtained using 10 g of the powder of the leaves immersed in doubly distilled water, the mixture being then boiled for ten minutes. The material was centrifuged, filtered and stored at 4 °C. The crude extract and phases were submitted to GC-MS analysis for the identification of their chemical constituents. The chloroform and ethyl acetate phases were subjected to fractionation by column liquid chromatography using the solvents hexane, chloroform, ethyl acetate and methanol individually or in binary mixtures. In addition, all extracts were submitted to biological tests of antimicrobial activity (MIC and MBC) and cytotoxic activity, to determine the IC50 against the three tumor cell lines. The chromatographic fractionation allowed the isolation of two substances that, after being subjected to the uni and bidimensional 13C and 1H NMR analyzes, were identified as triacontanol and β-sitosterol. GC-MS analyzes revealed the presence of 51 peaks for Jm-CEE, 24 peaks for Jm-Hex, 60 peaks for Jm-CHCl3, 36 peaks for Jm-AcOEt and 16 peaks for Jm-MeOH, the compounds of class of the most representative terpenes. Several constituents were identified, such as phytol, lupeol, palmitic acid, linolenic acid and α-tocopherol, all with important biological activities reported in the literature. Analyzes by HPLC-DAD-IT-MS / MS and molecular networking application were also performed, making it possible to identify eight flavonoids described for the first time in this species. In the antimicrobial activity test, J. mollissima was able to promote a moderate inhibition of bacterial species of clinical importance, being Serratia marcescens the most sensitive species. In the tests of modulatory activity with antibiotics, it was evidenced that J. mollissima established an antagonistic relation with the antibiotic Norfloxacina, that is part of the class of fluoroquinolonas. The silver nanoparticles obtained by green synthesis, in turn, obtained significant antibacterial activity against all strains tested. Regarding the cytotoxic activity, J. mollissima showed a strong antiproliferative potential, mainly against prostate cancer cell lines (IC50 < 30 μg/mL). The same could be observed for the biosynthesized silver nanoparticles, whose best IC50 was 2.93 μg/mL, also against the prostate cancer lineage. These results are unprecedented for the species, which further encourages studies with this plant, in order to elucidate possible mechanisms of action.