Polyphenol-enriched extraction from Thunbergia laurifolia using natural deep eutectic solvents for enhanced antioxidant and anti-inflammatory activities

What if the key to unlocking a plant's healing power lies not in harsh chemicals, but in nature's own green solvents? A new study reveals that swapping traditional ethanol for natural deep eutectic solvents can triple the polyphenol yield from a Southeast Asian medicinal herb.

Thunbergia laurifolia, a herb revered in Southeast Asian folk medicine for its detoxifying and anti-inflammatory properties, has long been extracted using boiling water or ethanol. But these methods are slow and often miss valuable compounds. Now, researchers are turning to a new class of green solvents called Natural Deep Eutectic Solvents (NADES) to do the job better.

In a head-to-head comparison, NADES made from choline chloride or L-proline significantly outperformed traditional 95% ethanol. HPLC analysis revealed that NADES extracts contained roughly three times more polyphenols—the plant's key medicinal molecules—than the ethanolic extract. This means a more potent brew with less environmental footprint.

The extracts were then tested for biological activity. Using DPPH and FRAP assays, plus a macrophage cell model, the team found that an L-proline and 1,4-butanediol combination showed enhanced antioxidant power and effectively dampened inflammation. It reduced the expression of key inflammatory genes—iNOS, COX-2, 5-LOX, and IL-6—without harming the cells.

This study positions L-proline and 1,4-butanediol as a universal, safe, and ready-to-use green solvent for extracting phytochemicals. It's a step toward more sustainable, effective, and health-boosting natural products.

Key Points

• NADES extracts yielded ~3x more polyphenols than 95% ethanol.
• L-proline/1,4-butanediol showed enhanced antioxidant and anti-inflammatory activity.
• Reduced iNOS, COX-2, 5-LOX, IL-6 gene expression without cell toxicity.