Green extraction of active ingredients from finger citron using subcritical water and assessment of antioxidant activity

What if the secret to unlocking nature's potent compounds lies in a simple mixture of choline and urea? This study turns that idea into a green extraction breakthrough for lotus leaves.

Imagine extracting valuable flavonoids from lotus leaves without harsh chemicals. Researchers tested 34 deep eutectic solvents (DES) paired with ultrasound assistance. They found that choline chloride with urea and 40% water worked best, maximizing flavonoid yield. This green solvent not only extracts but can be recycled up to four times, keeping the process sustainable.

To purify the extract, they used D-101 macroporous resin, effectively separating flavonoids from the DES. The purified compounds showed impressive antioxidant power in five different tests, including DPPH and ABTS assays. They also fought bacteria: Staphylococcus aureus was inhibited at 1666 µg/mL, while Escherichia coli needed only 208 µg/mL.

High-performance liquid chromatography identified three main components: astragalin, hyperoside, and isoquercitrin. This method—ultrasound-assisted extraction with DES followed by resin treatment—offers an efficient, eco-friendly route to obtain flavonoids from lotus leaves and other natural sources. It's a win for science and the planet.

Key Points

• 34 DES tested; choline chloride/urea with 40% water best
• DES recycled up to 4 times with good performance
• Antioxidant and antibacterial activities confirmed