Biorefinery approach with green solvents for the valorization of Citrus reticulata leaves to obtain antioxidant and anticholinergic extracts

What if the leaves you sweep away could hold the key to fighting oxidative stress and Alzheimer's? A new biorefinery turns mandarin leaves into powerful bioactive extracts using only green solvents.

Mandarin leaves are the unsung heroes of the citrus industry—abundant post-harvest leftovers packed with bioactive compounds, yet routinely discarded. Now, scientists have designed a two-step biorefinery to unlock their hidden value, using nothing but environmentally friendly solvents.

First, supercritical CO2 (SC-CO2) was applied to extract terpenoids. The sweet spot? 200 bar at 60°C, yielding the highest bioactive terpenoid content. But the story doesn't end there. The leftover residue was then treated with ultrasonic-assisted extraction (UAE) combined with Natural Deep Eutectic Solvents (NaDES)—a green, tailor-made solvent system.

A Box-Behnken design revealed the optimal NaDES recipe: choline chloride and glycerol (1:2) with 57% water, at 25°C for 50 minutes. This combination maximized phenolic content from the SC-CO2 residue. The final extract outperformed both water-only and NaDES-only extracts, showing the highest bioactivity and polyphenol levels, as confirmed by LC-DAD-MS.

This approach demonstrates that agricultural waste can be a treasure trove of antioxidants and anticholinergic agents—offering a sustainable path toward functional ingredients for health applications.

Key Points

• SC-CO2 at 200 bar, 60°C maximizes terpenoids.
• NaDES with 57% water optimizes phenolic extraction.
• Final extract shows highest bioactivity and polyphenols.