Deep Eutectic Solvent-Based Extraction of Carminic Acid: A Computational–Experimental Approach for Sustainable Process Development

Conventional extraction methods reliant on volatile organic solvents pose sustainability issues for carminic acid, a natural anthraquinone pigment with vibrant coloration and bioactivities. This study combines quantum chemical calculations (QCs) and experiments to develop a green extraction process using deep eutectic solvents (DESs). For 96 DES candidates, QCs predicted the solvation capacity and hydrogen-bonding interactions via infinite dilution activity coefficients and σ-profile analysis. Experimental validation identified choline chloride/ethylene glycol (ChCl/EG) as optimal. The extraction parameters were then optimized using response surface methodology, yielding 61.23 mg/g─1.8- and 2.1-fold higher than those of methanol and ethanol, respectively. According to a comparative life cycle assessment for the carminic acid extraction, the DES-based process exhibited the lowest endpoint indicators and the least standardized environmental impacts. It also reduced greenhouse gas emissions by one-third to two-thirds and lowered fossil resource scarcity impacts to 59.9–61.4% of conventional solvents. Meanwhile, energy-intensive centrifugation and solvent production were identified as environmental hotspots. Incorporating renewable energy and process intensification were proposed as mitigation strategies. Using ChCl/EG to extract carminic acid offers increased efficiency and sustainability while aligning with green chemistry principles. This work establishes a replicable paradigm combining computational solvent design, process optimization, and environmental assessment for ecofriendly natural product extraction.