Otimização de extração de compostos bioativos de Baccharis drancunculifolia visando aplicação em processo produtivo industrial

Abstract

The suitability of a protocol for the extraction of antioxidant compounds from plant biomass is of importance for the standardization of extraction of compounds of industrial interest. The objective of this work was to study the best conditions for the extraction of phenolic compounds with antioxidant activity of the Baccharis dracunculifolia (Bd) plant using response surface methodology (RSM). A full factorial design (FFD) 2³ was conducted to analyze the effects of time, temperature, and solvent concentration for ethanol and acetone solvents and a FFD 22 for time and temperature, using water as a solvent. The total phenolic compounds (TPC) and antioxidant capacity (DPPH, ABTS and FRAP) were the dependent variables analyzed for all FFD. There was a variation for TPC from 19.81 to 37.22 mg (GAE) g-1 (Gallic acid equivalent), for DPPH from 64.68 to 222.07 (µmol Trolox g-1), for ABTS from 140.26 to 399.67 (µmol TEAC g-1), and for FRAP from 308.62 to 704.56 (mmol Fe2+ g-1). The optimal extraction conditions determined by FFD were: 90 minutes at 80 °C in water, 90 minutes at 80 °C in 40% ethanol, and 90 minutes at 80 °C in 40% acetone. The extracts with a greater quantity of TPC presented higher antioxidant activities, and there was a strong and positive correlation between TPC and the antioxidant activity assays (DPPH, ABTS and FRAP). A Simplex-Lattice mixing design (SLD), was used to verify the efficiency of the extraction of bioactive compounds from Bd when the solvents water, ethanol, and acetone were mixed in different proportions. Through the SLD, it was possible to detect, through the desirability profile, that the best proportion among the three solvents, which yielded the highest yield of bioactive compounds was (56:0:44 / water:ethanol: acetone). For the reason of comparison with the desirability profile, the mixing ratio (33:33:33 / water:ethanol:acetone), referring to the central point of the SLD, was also selected as the best condition. The efficient concentration value (EC50), minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and High-Performance Liquid Chromatography (HPLC-UV) of the extracts at their optimal points, were determined by selecting the best conditions determined by PFC’s and SLD. The compounds extracted with 40% ethanol demonstrated higher inhibitory activity against the tested bacteria (MIC and MBC) and better values of EC50. Analysis of HPLC-UV showed that among the phenolic acids identified and quantified, ferulic acid (FA) was the major component for the optimum points analyzed by PFC’s and the catechin (CAT) followed by FA for SLD. Therefore, the compounds extracted from Bd, through the optimum extraction points determined by the FFD and SLD, present potential for industrial application. Based on the higher effectiveness against pathogenic bacteria and additional studies, the 40% ethanol solvent was selected, to extract for 180 minutes, at a temperature of 80 °C, 2.5 grams of sample of the Bd previously lyophilized, as extraction methodology to generate a lyophilized product of Bd (LP-Bd). Such a product concentrated the bioactive activities of the Bd plantas well as reduced the necessary concentration of the prepared extract promoting better bactericidal and bacteriostatic effects. Finally, an active film was produced, by casting methodology, with addition of LP-Bd, which promoted the release of the antioxidant compounds contained in the LP-Bd previously added, demonstrating antimicrobial activity and regular mechanical properties, it being possible in the studied format, to become it a product of pharmaceutical use.