Influence of time, temperature and solvent on the extraction of bioactive compounds of Baccharis dracunculifolia: In vitro antioxidant activity, antimicrobial potential, and phenolic compound quantification

Abstract

The suitability of a protocol for the extraction of antioxidant compounds from plant biomass is of extreme 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 (AA) of the Baccharis dracunculifolia DC (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 an 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 min at 80 °C in water, 90 min at 80 °C in 40% ethanol, and 90 min at 80 °C in 40% acetone. The extracts with a greater quantity of TPC presented higher AA, and there was a strong and positive correlation between TPC and the AA assays (DPPH, ABTS, and FRAP). The EC50 value, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and High-Performance Liquid Chromatography (HPLC) of the extracts at their optimal points were determined. The compounds extracted with 40% ethanol demonstrated higher inhibitory activity against the tested bacteria (MIC and MBC) and better values of EC50. The HPLC analysis showed that among all phenolic acids identified and quantified, ferulic acid was the major component. Therefore, the compounds extracted from the Bd plant, through the optimum extraction points determined by the FFD, present potential for industrial application.