Phenolics from Polygonatum cyrtonema Hua extracted using natural deep eutectic solvents combined with auxiliary techniques: Composition, bioactivity, and mechanistic elucidation

Abstract

This study investigated the natural extraction of polyphenolic compounds from Polygonatum cyrtonema Hua (P. cyrtonema). Employing the combination of natural deep eutectic solvents (NADESs) and auxiliary extraction techniques, we mainly focused on yield, total phenolics, total flavonoids, antioxidant capacity, and enzyme inhibition efficiency. Compared to hot reflux extraction (HRE), the NADES extract using a 1:2 ratio of choline chloride-lactic acid (ChCl-Lac) significantly increased the total phenolic content (TPC), total flavonoid content (TFC), and α-glucosidase inhibition (p < 0.05). The HPLC-MS-MS identified the five most abundant phenolic compounds. Quantitative analysis showed that these compounds had the highest leaching rates in the ultrasonic-assisted extraction (UAE) combined with lactic acid-based NADES system, followed by microwave-assisted extraction (MAE), requiring less than 4 min. Notably, rutin exhibited the highest extraction rate of 281.1 μg/g in the UAE-ChCl-Lac system, 9.82 times higher than conventional methods. The extraction mechanism was elucidated from the perspectives of surface charge density distribution and interaction energy. Therefore, ultrasound or microwave-assisted NADES extraction aligns with sustainable development principles, offering a green approach to enrich polyphenolic compounds in P. cyrtonema.