Natural Deep Eutectic Solvents Combined with Supercritical Carbon Dioxide for the Extraction of Curcuminoids from Turmeric

Curcuminoids, the bioactive compounds found in turmeric, exhibit potent antioxidant, anti-inflammatory, and neuroprotective properties. This study aims to enhance the extraction of curcuminoids from turmeric using environmentally friendly solvents supercritical CO (scCO ) combined with natural deep eutectic solvents (NADESs) in one process, and to evaluate the resulting biological activity. A Box-Behnken statistical design was applied to optimize scCO extraction conditions-pressure, CO volume, and temperature-to maximize curcuminoid yield. Next, the menthol and lactic acid NADESs were selected, and these two solvents were combined into a single turmeric extraction process. The biological activity of the resulting extract was evaluated using antioxidant assays (ferric reducing antioxidant power and 2,2-diphenyl-1-picrylhydrazyl) and enzyme inhibition assays (acetylcholinesterase, butyrylcholinesterase, and tyrosinase). Toxicity assessments were conducted on the aquatic invertebrates , sp., and . The most effective extraction was achieved using a menthol-lactic acid NADES as a cosolvent, integrated at a 1:20 ratio of plant material to NADESs while in combination with scCO . The optimized scCO -NADES extraction resulted in a high curcuminoid yield (33.35 mg/g), outperforming scCO extraction (234.3 μg/g), NADESs ultrasound-assisted extraction (30.50 mg/g), and alcohol-based solvents (22.95-26.42 mg/g). In biological assays, the extract demonstrated significant antioxidant activity and effective inhibition of enzymes (acetylcholinesterase, butyrylcholinesterase, and tyrosinase). Toxicity studies showed a concentration-dependent response, with EC for at the level of 0.098 μL/mL and exhibiting high sensitivity to the extract. This study highlights the potential of combining NADESs and scCO extraction in one process, demonstrating the effectiveness of scCO -NADES extraction in maximizing curcuminoid yield and enhancing bioactivity.