A novel temperature-responsive biphasic deep eutectic solvent for one-step extraction and selective enrichment of multi-polarity bioactives from green tea.

Green tea contains bioactive components with varying polarities. Single deep eutectic solvents (DESs) struggle to achieve simultaneous extraction of different polarity targets. This study developed a temperature-responsive biphasic DES (TRBDES) system for the selective extraction of six bioactive substances with distinct polarities from green tea. The system exhibited reversible biphasic-monophasic transition via temperature modulation. Under optimal conditions, the total extraction efficiency reached 158.24 ± 6.30 mg/g, significantly higher than conventional methods. Hydrophilic (e.g., EGCG) and hydrophobic (e.g., chlorophyll) components were almost completely partitioned into the lower and upper phases, respectively, while caffeine was distributed between both phases. Notably, the TRBDES extracts exhibited superior antioxidant activity (4.4-fold increase over ethanol extraction) and low melting points, confirming structural formation and functionality. Density functional theory calculations elucidated the interaction mechanisms. Demonstrating environmental friendliness, operational simplicity, and strong cell fiber structure disruption capability, this system provides a novel strategy for multi-polarity bioactive substance extraction.