Green extraction of bioactive polysaccharides from Zanthoxylum bungeanum using deep eutectic solvents: enhanced...

An ultrasound-assisted deep eutectic solvent (DES) method was developed for extracting polysaccharides from Zanthoxylum bungeanum pericarps (ZBP) and leaves (ZBLP). A choline chloride-oxalic acid (2:1) DES was selected. Under optimized conditions, yields of ZBP-D and ZBLP-D reached 25.88% and 29.79%, significantly higher than ultrasound-assisted water extraction (6.27% and 12.13%). DES-extracted polysaccharides shared similar structures but showed selectively enhanced antioxidant activity, with significantly lower IC₅₀ values against DPPH and hydroxyl radicals (0.231 mg/mL and 0.513 mg/mL for ZBP-D and ZBLP-D) compared to ultrasound-assisted water-extracted samples, although the latter performed better in the ABTS⁺ assay. The polysaccharides were formulated into hydrogels with dense porous networks, high swelling ratios (∼1200%), high loading ratios (∼69%), antioxidant retention, and hemocompatibility (safe load: 2.0 mg/mL for ZBP-D, 4.0 mg/mL for ZBLP-D). This green DES method enables efficient, bioactive polysaccharide extraction and hydrogel fabrication, providing a sustainable strategy for the value-added utilization of Z. bungeanum by-products.