Natural Deep Eutectic Solvents as Green Alternatives for Extracting Bioactive Compounds from Sideritis Taxa with Potential Cosmetic Applications

What if the secret to greener cosmetics lies in a humble mixture of sugar, glycerol, and betaine? A new study shows that these natural deep eutectic solvents can outperform traditional ethanol in extracting health-boosting compounds from mountain tea.

Forget harsh chemicals—nature's own solvents are stepping into the spotlight. Researchers tested five natural deep eutectic solvents (NADESs) made from betaine, glycerol, glucose, urea, citric acid, and sucrose against conventional solvents like water and 70% ethanol. Their mission: to pull out bioactive compounds from two mountain tea species, Sideritis clandestina and Sideritis raeseri, known for their antioxidant potential.

The results were striking. Water proved to be a poor extractor, but most NADESs—especially a betaine–glycerol–glucose mix called BGG4—matched or even beat ethanol in extracting phenolics and antioxidant activity. Using HPLC-MS, the team found that BGG4 extracts were rich in chlorogenic acid, verbascoside, and several acetylated hypolaetin glycosides. While quantitative differences existed between the two plant taxa and compared to ethanol extracts, S. clandestina consistently yielded more secondary metabolites than S. raeseri.

These findings hint at a greener future for cosmetics. NADESs, particularly BGG4, offer a sustainable, effective alternative to traditional solvents, potentially paving the way for eco-friendly skincare products that harness the power of mountain tea.

Key Points

• NADESs, especially BGG4, matched or beat 70% ethanol in extraction efficiency.
• BGG4 extracts rich in chlorogenic acid, verbascoside, and hypolaetin glycosides.
• S. clandestina had higher secondary metabolite content than S. raeseri.