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

Peanut shells are usually burned or thrown away—but hidden inside them is a golden molecule called luteolin, a powerful antioxidant with anti-inflammatory and antibacterial superpowers.

Every year, millions of tons of peanut shells go up in smoke—a waste that pollutes the air and squanders a treasure trove of bioactive compounds. Among them is luteolin, a flavonoid known for its antioxidant, antibacterial, and anti-inflammatory properties. Now, scientists have found a smarter way to unlock it: microwave-assisted extraction, powered by natural deep eutectic solvents (NADESs). These green solvents, made from cheap and biodegradable ingredients, are the perfect partners for this task.

The team tested several NADES combinations and found the best one: choline chloride mixed with ethylene glycol. Using single-factor experiments, they zeroed in on the key variables—microwave time, power, and liquid-to-solid ratio. Then, they applied two optimization models: response surface methodology (RSM) and an artificial neural network-genetic algorithm (ANN-GA). The results were striking: the optimal conditions were just 92 seconds, 601 watts, and a 32 mL/g ratio, producing an impressive 2.90 mg of luteolin per gram of shell.

But they didn't stop there. To understand why this solvent worked so well, they used quantum chemical calculations with COSMO-RS. The numbers revealed that luteolin had the lowest infinite dilution activity coefficient (-16.43) and the most negative intermolecular interaction energy (-87.82 kJ/mol) in the NADES, confirming a strong affinity. Both the ANN-GA and RSM models matched experimental values with 99.66% and 98.95% accuracy, respectively.

This isn't just about peanut shells—it's a blueprint for turning agricultural waste into high-value compounds. With NADES and microwaves, we can extract nature's best molecules faster, greener, and smarter than ever before.

Key Points

• NADES-MAE extracts 2.90 mg/g luteolin from peanut shells
• Optimal: 92 s, 601 W, 32 mL/g liquid-solid ratio
• COSMO-RS confirms strong luteolin-solvent interaction