A green and efficient SUPRADES-ultrasound extraction strategy for isoflavones from Pueraria lobata root: process optimization, molecular interaction mechanism, and sustainability assessment.

Supramolecular deep eutectic solvents (SUPRADES) have are promising green extraction media for the sustainable extraction of bioactive compounds from plant materials. In this study, a combined strategy of SUPRADES with ultrasound-assisted extraction (UAE) was developed for the efficient extraction and enrichment of isoflavones from the root of Pueraria lobata. The extraction process was systematically optimized using single-factor experiments followed by Box-Behnken design (BBD) response surface methodology. The optimal SUPRADES system consisted of L‑proline and urea at a 1:2 molar ratio, supplemented with 5 wt% β‑cyclodextrin and 30 wt% water. Under these conditions, the yield of puerarin reached 70.4 ± 0.6 mg/g, which is 1.33‑ to 5.33‑fold higher than those obtained with conventional methods. The self‑assembled structure of the SUPRADES and its molecular‑level interaction mechanism with isoflavones were further elucidated by FT‑IR spectroscopy, ¹H NMR spectroscopy, and density functional theory (DFT) calculations. These results confirmed that the extraction process is synergistically driven by hydrogen bonding and β‑cyclodextrin‑mediated host-guest complexation. GAPI evaluation demonstrated the excellent environmental friendliness and sustainability of the established method. Collectively, this study provides a novel and efficient extraction strategy for isoflavones from Pueraria lobata root and offers a theoretical basis for green the extraction of natural products in traditional Chinese medicine.