Compostos bioativos de um coproduto da colheita de Ilex paraguariensis: caracterização e otimização multivariada de um extrato comestível

Abstract

During the pruning of Ilex paraguariensis, 2 to 5 tons of co-products (thick branches) are generated per hectare, a natural resource that is still commercially unexplored. This study aimed to characterize the polar compounds present in this co-product, from plants grown in full sun and shade, as well as the comparison with the parts of the plant used in the raw material (leaves and fine branches) of commercial products. In addition, it aimed to determine the optimal conditions for extraction of these compounds using green solvent for application in food, through a multivariate planning, in addition to the evaluation of the extract obtained for its antioxidant and antimicrobial activity. The characterization of the raw material and the co-product was performed by HPLC-ESI-QTOF-MS with methanol:water extraction, resulting in the identification of 46 compounds, and the sum of quinic acid, 3-caffeoylquinic, 5-caffeoylquinic, 3, 5-di-caffeoylquinic and 4,5-di-caffeoylquinic and rutin represent, on average, 93% and 91% of the concentration of phenolic compounds present in the leaves and in the co-product, respectively. For the extraction optimization, the variables time, extraction temperature and percentage of solvent (ethanol) in the extracting solution were evaluated through a central rotational composite design (23 ) with central point. All models obtained significant regression, random residuals and showed no lack of fit, and of the 55 models, 51 were characterized as quadratic. From the optimal extraction condition (31.3 minutes, 85 °C and 43.7% ethanol) it was possible to extract approximately 15 g 100g-1 of compounds from the co-product, which include the 42 compounds identified previously, in addition to others 13 compounds not extracted with methanol:water. The extract obtained from the optimal extraction conditions showed an antioxidant activity of 1857.51 µmol of Trolox equivalents per gram of extract. After determining the minimum inhibitory concentration and minimum bactericidal concentration of this extract against four bacterial species of interest to the food industry (Listeria monocytogenes, Staphylococcus aureus, Salmonella typhimurium e Escherichia coli), promising results were observed regarding the inhibition of the microorganism Staphylococcus aureus. The results obtained showed that the co-product of I. paraguariensis harvest pruning is a matrix with high potential for applications in food and pharmaceuticals due to the high concentration of phenolic compounds present.