Artemisia selengensis Leaves, a Vegetable Waste: LC-MS-Based Chemical Profiling, Ultrasound-Assisted DES Extraction, and Xanthine Oxidase Inhibitory Activity

Artemisia selengensis is a medicinal and edible plant, whose tender stems are widely consumed as a folk vegetable in China. However, due to their bitterness, Artemisia selengensis leaves (ASL) are often discarded as a waste material, resulting in resource wastage. This study aimed to characterize ASL's chemical composition, develop a “green” extraction method, and explore its potential bioactivity. Using LC-MS, 72 compounds were identified. To extract 7 representative caffeoylquinic acids (CQAs), the mixture of choline chloride and ethylene glycol (1:6) was selected as the optimal deep eutectic solvent (DES), and the extraction parameters were optimized as follows: extraction time of 21 min, temperature of 44°C and ultrasonic power of 420 W. Based on molecular docking analysis, both 3,5-diCQA and 1,5-diCQA exhibited strong binding affinity to xanthine oxidase (XO), consistent with their potent XO inhibitory effects (IC 50 = 3.69 and 3.35 nmol/mL, respectively). In addition, a greater XO inhibition was observed for the DES extract (IC 50 = 6.05 μg/mL) compared with the methanol extract (IC 50 = 22.5 μg/mL). This study not only helps to reduce ASL disposal's environmental load and boost its agricultural value, but also sets a green model for similar vegetable waste to aid circular agriculture.