Hydroglycerolic solvent and ultrasonication pretreatment: A green blend for high-efficiency extraction of Salvia fruticosa polyphenols

Greek sage hides a treasure of polyphenols, but extracting them has long been a chemical puzzle. Now, a green blend of glycerol and sound waves unlocks it efficiently.

Salvia fruticosa, the Cretan sage, is no ordinary herb. Its medicinal power lies in polyphenols, but traditional extraction methods are far from green. Researchers set out to change that by pairing a glycerol-based solvent—a by-product of biodiesel—with a quick ultrasonic pretreatment. Just 40 minutes of ultrasound, followed by stirred-tank extraction, dramatically boosted polyphenol yield compared to stirring alone. The sweet spot was 50°C, delivering an impressive 92 mg of gallic acid equivalents per gram of dry mass. The extracts matched the antioxidant activity of a previous method using methyl β-cyclodextrin, with key polyphenols like luteolin 7-O-glucuronide and rosmarinic acid nearly identical. This sustainable approach offers a practical way to produce polyphenol-rich extracts for food antioxidants, antimicrobials, or cosmetics—no harsh chemicals required.

Key Points

• Glycerol-based solvent plus 40-min ultrasound boosts polyphenol yield.
• 50°C optimal, yielding 92 mg GAE per gram dry mass.
• Antioxidant activity matches cyclodextrin method; key polyphenols equal.