Box-Behnken Design for DPPH Free Radical Scavenging Activity Optimization from Microwave-Assisted Extraction of Polyphenolic Compounds from Agave lechuguilla Torr. Residues

The guishe is a by-product of the fiber extraction from Agave lechuguilla. This material has no commercial value, although it contains metabolites that could be used as a resource for producing high-value products. This study optimized the DPPH• (2,2-diphenyl-1-picrylhydrazyl) antioxidant activity through microwave-assisted extraction (MAE) of polyphenolic compounds from Agave lechuguilla residues. The MAE process was optimized using a Box-Behnken design, with extraction time (5–15 min), temperature (40–50 °C), and solvent: sample ratio (1:20–1:30 m/v) as independent variables. In contrast, the dependent variable was DPPH• free radical scavenging activity. As a result, the highest antioxidant activity was at 8 min of irradiation, extraction temperature of 45 °C, and solvent: sample ratio 1:30 w/v, obtaining a total flavonoid content of 19.25 ± 0.60 mg QE/g DW, a total polyphenol content of 6.59 ± 0.31 mg GAE/g DW, a DPPH• free radical scavenging activity of 73.35 ± 1.90%, and an ABTS+• ([2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonate)]) free radical scavenging activity of 91.93 ± 0.68%.