Stability of salvia fruticosa mill. Polyphenols and antioxidant activity in a citrate-based natural deep eutectic solvent

What if the secret to unlocking Greek sage's healing power lies in a simple salt and lactic acid mixture? Scientists have found a green solvent that extracts polyphenols more efficiently than ever before.

Greek sage (Salvia fruticosa Mill.) is a treasure trove of polyphenols—natural antioxidants with impressive health benefits. But getting these compounds out of the plant has always been a challenge. Traditional methods often rely on harsh chemicals, which can degrade the very molecules we want to preserve.

Enter natural deep eutectic solvents (NADES). These eco-friendly liquids are made by mixing cheap, safe ingredients like lactic acid and glycerol. In a new study, researchers tested a series of citrate salts as hydrogen bond acceptors to create NADES. They found the star performer: a combination of lactic acid and sodium citrate dibasic at a 15:1 molar ratio (LA-SCDB15).

Using this solvent, they developed an efficient extraction process. By fine-tuning stirring speed (900 rpm), solvent concentration (77% w/v), and ultrasound pretreatment (15 minutes), they achieved a remarkable total polyphenol yield of 79.93 mg gallic acid equivalents per gram of dry mass. The process was energy-efficient, with a low activation barrier of 7.64 kJ/mol, and the major polyphenols identified were chlorogenic acid, luteolin 7-O-glucuronide, and rosmarinic acid.

This green solvent not only matches but surpasses other eco-friendly methods. It's a win for both science and sustainability—proving that nature's own chemistry can unlock the full potential of medicinal plants.

Key Points

• LA-SCDB15 is the champion NADES for extracting polyphenols.
• Optimal extraction: 77% solvent, 15 min ultrasound, 900 rpm stirring.
• Achieved high yield: 79.93 mg GAE/g dry mass, energy-efficient.