Supressão de oxigênio singlete, composição mineral e atividade antimicrobiana de extratosde ora-pro-nóbis (Pereskia grandifoliaHaw)

Abstract

Among so many plant species that are poorly studied regarding their biological activities, Pereskia grandifolia Haw. (ora-pro-nóbis), an unconventional food plant (UFP), arouses interest for having known therapeutic and nutritional properties. The objectives of the work were to quantify and evaluate micro and macronutrients in different parts of the plant, as well as the antioxidant and antimicrobial activity of extracts of P. grandifolia Haw. To analyze the components present in the plant, Energy Dispersive X-ray Fluorescence (EDXRF) and combustion in a combustion oven were used; for the antioxidant action, UV-vis and Fluorescence Spectroscopy was used to assess the suppression of singlet oxygen; and the antimicrobial action was performed through disc diffusion technique and halo of inhibition against strains of Staphylococcus aureus, Listeria monocytogenes and Escherichia coli. Fruits, flowers, stem, leaves and root of P. grandifolia Haw. were collected from plants located in the Medicinal Plants Garden of the Federal University of Lavras. Extracts were prepared from the dried leaves with solvents in increasing order of polarity using: hexane, chloroform, ethyl acetate, ethanol, methanol and water. X-ray Fluorescence results showed the high contents of minerals such as calcium and potassium; and proteins found in different parts of P. grandifolia. As for the analysis of UV-vis and Fluorescence Spectroscopy, the results indicated that the best singlet oxygen-suppressing extracts were those obtained with chloroform followed by hexane and ethyl acetate. Through the results, it was possible to elucidate the nutritional characteristics of the plant and confirm the antioxidant potential of nonpolar extracts of P. grandifolia compared to polar extracts. The microbiological results of this study showed that the different extracts of P. grandifolia, at the concentrations tested, did not show antimicrobial action against the bacteria evaluated.