Green Extraction of Anthocyanins from Autumn Leaves: Comparative Evaluation of Food-Grade Solvent Systems

This study investigates the potential of autumn leaves of Smilax excelsa L., typically regarded as agricultural residue, for the green extraction of anthocyanin-rich bioextracts. Four food-grade solvent systems - ethanol (EtOH), citric acid (۱۰۰ mM), EtOH: Citric acid (۱:۱), and DMSO: EtOH: Citric acid (۱:۱:۱) were evaluated for their extraction efficiency of anthocyanins. The total anthocyanin content was determined using UV-Vis spectrophotometry at ۵۲۰ nm and expressed as cyanidin-۳-glucoside (C-۳-G) equivalents based on a calibration curve (R² = ۰.۹۸۹۹۴). The highest anthocyanin yield was obtained with the EtOH: Citric acid binary system (۱۱.۳۲۵ µg), followed by citric acid alone (۱۰.۲۵۴ µg), DMSO: EtOH: Citric acid (۹.۴۷۹ µg), and ethanol alone (۸.۷۳۶ µg). The EtOH: Citric acid extract also exhibited the strongest antioxidant activity (۸۹.۳۸±۰.۸۹ % inhibition), while the ethanol extract showed the lowest (۷۴.۲±۰.۸۱%). Interestingly, although the DES-like ternary system (DMSO: EtOH: Citric acid) demonstrated moderate anthocyanin yield, it displayed rapid free radical scavenging kinetics, suggesting the extraction of additional bioactive compounds beyond anthocyanins. These findings demonstrate that the combination of ethanol and citric acid provides synergistic effects, enhancing both extraction efficiency and antioxidant capacity. The utilization of post-vegetative autumn leaves represents a sustainable approach that aligns with circular economy principles, converting low-value biomass into high-value functional ingredients for the food industry.

کلیدواژه ها:

Green Chemistry ، food-grade solvent ، anthocyanins ، free radical scavenger kinetics ، anthocyanin yield