Green Extraction of Phenolic Compounds from Aronia melanocarpa Using Deep Eutectic Solvents and Antioxidant Activity Investigation

This study explores the green extraction of phenolic antioxidants from <i>Aronia melanocarpa</i> fruit using choline-chloride-based deep eutectic solvents (DESs) as an eco-friendly alternative to conventional solvents. Sixteen DESs, prepared by combining choline chloride with various hydrogen bond donors, were characterized for their physical properties, including viscosity, polarity, and pH, and applied to extract phenolics from <i>Aronia melanocarpa</i>. High-performance liquid chromatography (HPLC) quantified key phenolic compounds, including neochlorogenic and chlorogenic acid, quercetin derivatives, and cyanidin derivatives, as well as total phenolic acids, flavanols, and anthocyanins. The results revealed that DES composition and physical properties significantly influenced extraction efficiency and antioxidant activity. Additionally, the intrinsic antioxidant activity of DESs contributed substantially to the overall activity of the extracts, particularly in DESs containing organic acids or thiourea. Choline chloride/tartaric acid DES demonstrated the highest total phenolic content, attributed to its high viscosity and strongly acidic pH, while choline chloride/thiourea DES, with low viscosity and slightly acidic pH, exhibited the greatest antioxidant activity. This study highlights how tailoring DES formulations can optimize the extraction of target compounds while accounting for the solvent's intrinsic properties. The findings support the potential application of DESs as environmentally friendly solvents in the food, pharmaceutical, and cosmetic industries.