Microwave-assisted extraction of luteolin from peanut shells using natural deep eutectic solvents and its molecular mechanism

Peanut shells, a byproduct of peanut cultivation, have limited uses but contain bioactive compounds like luteolin, a flavonoid with antioxidant, antibacterial, and anti-inflammatory properties. This study employed microwave-assisted extraction (MAE) technology combined with Natural Deep Eutectic Solvents (NADESs) to enhance the extraction process and clarify the underlying mechanisms. The most effective NADES, composed of choline chloride and ethylene glycol, was employed. Single-factor experiments assessed the effects of microwave time, power, and liquid-solid ratio on luteolin extraction. Following this, response surface methodology (RSM) and artificial neural network-genetic algorithm (ANN-GA) were applied for further optimization. The optimal extraction conditions were identified as 92 s of microwave time, 601 W of power, and a liquid-solid ratio of 32 mL/g, yielding a maximum luteolin extraction of 2.90 ± 0.02 mg/g. The ANN-GA and RSM models showed strong agreement with experimental values, with correlation percentages of 99.66 % and 98.95 %, respectively, indicating their reliability for optimizing extraction. Additionally, using the Conductor-like Screening Model for Real Solvents (COSMO-RS), quantum chemical calculations revealed that luteolin had the lowest logarithm of the infinite dilution activity coefficient (-16.43) and the most negative intermolecular interaction energy (-87.82 kJ/mol) in the NADES. These findings were consistent with validation test results, confirming the effectiveness of the NADES-MAE technology for luteolin extraction.