Natural Deep Eutectic Solvent Extraction of Flavonoids of Scutellaria baicalensis as a Replacement for Conventional Organic Solvents

What if we could ditch toxic traditional solvents and use completely natural ingredients to extract valuable plant compounds? Scientists are putting eco-friendly Natural Deep Eutectic Solvents to the test.

Traditional organic solvents like aqueous methanol or ethanol have long been the go-to for extracting plant compounds, but they come with environmental baggage. Enter Natural Deep Eutectic Solvents (NADES)—a greener, non-toxic alternative made exclusively from natural products. Researchers explored this potential by extracting flavonoids from the stem bark of Scutellaria baicalensis, examining how these green solvents stack up against conventional methods.

The team tested four distinct NADES combining citric acid with β-alanine, glucose, xylitol, or proline at a 1:1 molar ratio, along with varying amounts of water. Using HPTLC and HPLC to analyze the chemical profiles, they discovered that water concentration—ranging from 20 to 60%—played a crucial role in determining how well individual compounds dissolved.

The results were striking. For flavonoid aglycones like baicalein, scutellarein, wogonin, and oroxylin A, the NADES extraction yield soared to 2 to 6 times that of aqueous methanol. Their corresponding glycosides also saw higher yields, though more modestly at 1.5 to 1.8 times. Intriguingly, despite the high hydrophilicity of NADES, hydrophilic glycosides were less extracted than aglycones, proving these versatile solvents can successfully handle compounds with a wide range of hydrophilicity.

Key Points

• NADES offer a non-toxic, eco-friendly alternative to organic solvents.
• Aglycone extraction yields reached 2 to 6 times aqueous methanol.
• Water concentration (20-60%) heavily influences individual flavonoid extractability.