Bioactive Antioxidants from Avocado By-Products: Mechanistic Study and Laboratory-Scale Extraction Optimization

This study aimed to develop an environmentally friendly and relatively efficient method for extracting natural antioxidants from avocado by-products while investigating the antioxidant mechanisms of their core bioactive components on multiple dimensions. In vitro antioxidant assays (ABTS, FRAP, SAFR, SFR, ORAC, DPPH) demonstrated that flavonoid procyanidin was the primary antioxidant component in avocado seeds, exhibiting the strongest activity (DPPH EC₅₀ = 3.6 µg/mL). The Hill model indicated a positive synergistic effect (<i>n</i> = 3.1). Chemical and molecular mechanism analyses revealed that avocado seeds exert antioxidant activity predominantly through hydrogen atom transfer (HAT) and electron transfer (ET) pathways. The model predictions suggested procyanidins may stably bind to protein targets in the Keap1-Nrf2 pathway and NOX2 via hydrogen bonding, hydrophobic interactions, and π-cation interactions. Furthermore, response surface methodology (RSM) was employed to optimize the extraction process of avocado seed antioxidants in an ethanol-water system. This study underscores the considerable health benefits and antioxidant capacity of avocado by-products, supporting their promising application in functional foods formulations.