Sustainable extraction of polyphenols from Pleurotus eryngii using ultrasound-assisted deep eutectic solvents with process optimization and biological activity.

Ultrasound-assisted extraction using a deep eutectic solvent (UDES) represents sustainable strategy for recovering polyphenols from Pleurotus eryngii (PEPs). In this study, preliminary single-factor experiments were first conducted to evaluate the effect of individual extraction parameters. The conditions were subsequently optimized through response surface methodology (RSM), resulting in optimal parameters of 50 °C temperature, 320 W ultrasonic power, 60  g/L solid-to-solvent ratio, and 20 min extraction time, with a predicted PEPs yield of 39.60  mg GAE/g and an actual yield of 37.03 ± 1.3  mg GAE/g. Extraction kinetics were well described by a pseudo-second-order model (R2 > 0.99), while FTIR spectroscopy confirmed the integrity of key functional groups in the optimized DES components and verified the successful ultrasound-assisted extraction of polyphenols using different methods. Similarly, SEM analysis revealed clear morphological changes between the raw sample and the powder extracted using water, ethanol and DES both with and without ultrasonication highlighting clear structural changes during extraction process. HPLC identified vanillic acid (9.14 mg/g) and gallic acid (7.46 mg/g) as the main phenolic compounds. Furthermore, this study identified fumaric acid, 6,7-dihydroxycoumarin, and caffeic acid in Pleurotus eryngii for the first time, expanding its known polyphenolic profile. UDES-extracted PEPs showed greatly enhanced antioxidant activity across ABTS, DPPH, and FRAP assays and demonstrated strong antifungal effects, inhibiting Aspergillus niger growth by 86.6% at 0.35 mg/mL. Overall, these findings demonstrate that UDES is a high-efficient, sustainable approach for extracting bioactive polyphenols from P. eryngii. The results also highlight its potential for the green valorization of mushroom by-products and their application in functional food as well as nutritional values in food system.