Sustainable green extraction of polysaccharides from Caryophylli Flos using ultrasound-assisted DES: Process optimization, structural identification, and bioactivity.

An ultrasound-assisted deep eutectic solvent (DES) strategy was developed for green extraction of Caryophylli Flos polysaccharides (CFPs). Among 16 DES, betaine-propylene glycol (Bet-Pg, DES-8) afforded the highest yield of 55.93 mg/g, 3.4-fold that of conventional water extraction (16.30 mg/g). FTIR and 1H NMR confirmed a robust hydrogen-bonding network within DES-8 that facilitates polysaccharide solubility. Response surface optimization further raised the yield to 69.91 mg/g under mild conditions. DES-8 retained over 86.85% efficiency after three reuse cycles, demonstrating excellent recyclability. Compared with water-extracted CFPs, DES-8-extracted CFPs exhibited lower molecular weight (508.15 kDa), higher galactose content, and markedly superior antioxidant activity and α-glucosidase inhibitory activities, with IC₅₀ values of 0.6699 mg/mL (DPPH), 0.10524 mg/mL (·OH), 0.15962 mg/mL (ABTS), and 0.3981 mg/mL (α-glucosidase). The integrated DES-8/ultrasonication platform thus represents a highly efficient, recyclable, and eco-friendly route to bioactive polysaccharides with strong potential as natural food preservatives.