Ultrasound-assisted deep eutectic solvent extraction of polyphenols from peach leaves and their compositional characterization
Abstract
This work reports the extraction of polyphenols from peach leaves via ultrasound-assisted deep eutectic solvent extraction (UAE-DES) coupled with subsequent resin-based purification, along with comprehensive characterization of the resulting phenolic profile. Screening of various DES formulations identified the choline chloride–lactic acid system as the most effective for this purpose. Based on single-factor experiments and Box–Behnken response surface design, the optimal UAE-DES extraction parameters were determined as follows: liquid-to-solid ratio of 26.61 mL/g, ultrasonic temperature of 40 °C, choline chloride-to-lactic acid molar ratio of 1:3.715, water content of 20%, and sonication time of 10 min. Under these optimal settings, the total phenolic content (TPC) attained 16.79 mg gallic acid equivalents (GAE)/g, closely approaching the model-predicted value of 16.92 mg GAE/g. The crude extract was subsequently purified using AB-8 macroporous resin, and Fourier transform infrared spectroscopy (FTIR) analysis confirmed the presence of functional groups characteristic of phenolic and flavonoid structures. UPLC–MS/MS profiling further identified 25 distinct phenolic compounds, with flavonol glycosides representing the dominant category, accounting for 91.07% of the total quantified polyphenols. Among these, quercetin-3-O-glucoside (50.75%), kaempferol-3-O-glucoside (20.71%), and rutin (19.61%) were identified as the most abundant components. in vitro antioxidant evaluation revealed that the purified peach leaf polyphenols possessed potent concentration-dependent radical-scavenging capacity against both ABTS+ and DPPH radicals. Collectively, these results demonstrate that the UAE-DES/resin purification approach offers a green and effective means of recovering polyphenols from peach leaves, thereby providing a scientific foundation for the valorization of peach leaf resources and the production of natural antioxidant agents.