Extraction conditions of Polyphenol, Flavonoid compounds with Antioxidant activity from Veronia amygdalina Del. Leaves: Modeling and optimization of the process using the response surface methodology RSM

This study aims to determine optimal conditions for extraction of phenolic compounds with maximum antioxidant activity from Vernonia amygdalina Del. leaves using Response Surface Methodology and Central Composite Design (RSM-CCD). Results showed that extracting time, temperature and solvent to material ratio had a significant effect on phenolic content (p < 0.001). The interactions between the three factors were also found to be significant at 95% confidence level. The polyphenol content was 137.15 +/- 1.36 mg gallic acid /g dry weight (dw), the flavonoid content was 96.78 +/- 1.39 mg quercetin/g dw, the total antioxidant activity was 1.95 +/- 0.09 mg ascorbic acid/g dw and iron reduction activity was 5.90 +/- 0.12 mg FeSO4/g dw at optimum conditions of 34.82 hours at 53.09 degrees C with solvent to material ratio is 43.64 (ml /g). The determination coefficients of all models was greater than 0.995 suggesting that the regression model can represent the experimental data well. (C) 2019 Elsevier Ltd. All rights reserved.