Selective extraction and stabilization of bioactive compounds from rosemary leaves using a biphasic NADES

What if one green solvent could pull both oil-loving and water-loving antioxidants from a single herb—simultaneously? That's exactly what a new study achieves with rosemary leaves.

Rosemary has been a medicinal herb since ancient times, prized for its antioxidant power. Now, scientists are finding modern ways to unlock it—using natural deep eutectic solvents, or NADES, which are biodegradable, low-toxicity, and kind to the environment. The goal? Extract key bioactives like rosmarinic acid, carnosol, and carnosic acid without harsh chemicals.

Two NADES systems were tested: one made of menthol and lauric acid (2:1) showed a clear preference for nonpolar compounds, pulling out carnosic acid and carnosol. The other, lactic acid and glucose (5:1), favored the polar rosmarinic acid. Instead of choosing one, the team combined them into a biphasic system—two liquids that don't mix—and extracted both types in a single step.

The results were striking: the polar phase yielded 1.00 mg of rosmarinic acid and 0.26 mg of caffeic acid per gram of rosemary, while the nonpolar phase delivered 2.30 mg of carnosol and 17.54 mg of carnosic acid. Even better, these compounds stayed stable for months. Carnosic acid in NADES lost only 25% of its antioxidant activity after three months, whereas in methanol it vanished within 15 days.

This single-step, selective, and stabilizing approach could be a game-changer for the pharmaceutical, food, and cosmetic industries—turning a humble herb into a sustainable source of potent bioactives.

Key Points

• Biphasic NADES extracts polar and nonpolar bioactives in one step.
• Menthol:lauric acid (2:1) selectively targets carnosic acid and carnosol.
• Carnosic acid in NADES stable for 3 months; only 25% activity loss.