Ultrasound-assisted NADES extraction of catechins from Longjing tea: Process optimization and bioactivity evaluation

Obese asthma (OA) is a metabolic-inflammatory disease characterized by airway inflammation and dysregulated lipid metabolism. Although green tea catechins possess well-documented antioxidant and anti-inflammatory properties, their efficient green extraction and functional relevance in OA remain insufficiently understood. In this study, natural deep eutectic solvents (NADESs) combined with ultrasound-assisted extraction (UAE) were employed to extract catechins from Longjing tea. Among nine NADES systems evaluated, NADES_9 composed of L -proline and urea exhibited the highest extraction efficiency, and the extraction conditions were further optimized using single-factor experiments. The extraction parameters were optimized using response surface methodology (RSM) and a genetic algorithm–back propagation (GA-BP) neural network model. In a high-fat diet (HFD) combined with house dust mite (HDM)-induced OA mouse model, the NADES_9 extract significantly alleviated airway inflammation, improved histopathological injury, and corrected lipid metabolism disorders, accompanied by reduced inflammatory cytokines in serum and bronchoalveolar lavage fluid (BALF). Multi-omics analysis revealed that the extract mainly regulated lipid metabolism-related pathways and suppressed NF-κB and NOD-like receptor signaling pathways. Molecular docking showed strong binding affinities between galloylated catechins and both NF-κB p65 and NLRP3, which was further validated by Western blot results. Overall, this study demonstrates that NADES-based green extraction is an efficient and sustainable strategy for producing catechin-rich bioactive extracts, and suggests that it may exert protective effects against obese asthma through modulation of metabolic-inflammatory pathways.