Valorization of Avocado ( <i>Persea americana</i> ) Leaves through the Optimization of Microwave-Assisted Extraction and Assessment of Functional and Bioactive Properties

Avocado (Persea americana) pruning residues, particularly leaves, represent an underutilized biomass with potential high-value applications. This study optimized microwave-assisted extraction (MAE) to recover bioactive phenols under environmentally friendly and efficient conditions, supporting biomass valorization strategies. A screening of solvents identified 50% (v/v) aqueous ethanol as the most effective, and a Box–Behnken design was applied to evaluate temperature, liquid-to-solid ratio, and extraction time. The optimal conditions (48.7 °C, 14.8 mL/g, 12.2 min) yielded extracts with a high phenolic content and strong antioxidant activity. The optimized extract also showed antimicrobial effects, reinforcing its functional potential. The LC-HRMS/MS profile revealed that the predominant components were cinnamic acid, chlorogenic acid, procyanidins, quercetin, and kaempferol, all of which are associated with antioxidant and antimicrobial properties. These findings highlight a sustainable pathway for converting agricultural pruning waste into bioactive products for food and nutraceutical applications, promoting the principles of a circular economy through biomass transformation.