Natural Deep Eutectic Solvents for the Green Extraction of Betulin from Birch Bark: Chemical Characterization and Evaluation of Antioxidant Activity

What if the key to unlocking birch bark's hidden treasure lies in a simple mix of natural compounds? A new study reveals that a blend of choline chloride and fructose can extract betulin more efficiently than ever, with antioxidant power to boot.

For centuries, birch bark has been a source of traditional remedies, but its modern potential is only now being fully tapped. The secret? Natural deep eutectic solvents, or NADES, are emerging as green champions in the extraction of bioactive compounds. In this study, researchers synthesized eight of these eco-friendly solvents and tested their ability to pull betulin, a valuable triterpene, from birch bark.

The standout performer was N4, a simple 1:1 mix of choline chloride and fructose, which delivered an impressive 243.32 mg of betulin per gram of dry extract. That's over twice the yield of its closest rival, N3, a choline chloride-urea mix. But N4 didn't stop at quantity—it also showed remarkable quality. The extract inhibited DPPH radicals by 63% and ABTS radicals by 97%, and boasted a total phenolic content of 12.12 mg GAE per gram.

What's more, the study found a strong link between betulin yield and antioxidant activity, suggesting that NADES not only extract more but also preserve the bioactivity of the compounds. This makes NADES a promising, sustainable alternative to conventional solvents, paving the way for greener technologies in biomass valorization and natural product processing.

Key Points

• NADES outperform conventional solvents for betulin extraction.
• N4 (choline chloride:fructose) yields 243.32 mg/g betulin.
• N4 extract shows high antioxidant activity (97% ABTS inhibition).