Green and efficient ultrasound-assisted extraction of Banqiao Codonopsis Radix polysaccharides: Process optimization, extraction mechanism, and in vivo anti-ulcerative colitis efficacy with mechanistic insight.

Banqiao Codonopsis Radix polysaccharides (BCRPs) exhibit promising anti-inflammatory activity, but conventional hot water (HW) extraction is limited by low extraction efficiency, high energy consumption, and substantial carbon emissions. To address these limitations, response surface methodology was used to optimize the ultrasound-assisted (UA) extraction process. The optimal extraction parameters were as follows: extraction power 400 W, ethanol concentration 87%, extraction time 34 min, and liquid-to-solid ratio 29 mL/g. Under these conditions, UA extraction yielded 21.31 ± 1.01% of BCRPs (UBCRPs), which was 42.07% higher than that obtained by HW extraction (HBCRPs). Furthermore, extraction time were reduced by 43.5%, energy consumption by 38.79%, and CO2 emissions by 56.91%. Mechanistically, ultrasonic cavitation and shear forces reduced the material particle size by 22.47%, altered the crystalline cellulose structure, decreased cell wall crystallinity, and loosened cell wall-associated components, thereby reducing mass-transfer resistance and facilitating polysaccharide dissolution. Structural analysis showed that UA extraction selectively increased rhamnose, arabinose and galactose contents by 43.5%, 27.0% and 16.9%, respectively, while the molecular weight changed by only 2.8% and polydispersity index by 4.5%, indicating an intact main chain. UA extraction also eliminated the nucleic acid/protein absorption signal at 260 nm, suggesting improved impurity removal, with no significant difference observed in crystal structure, zeta potential, or thermal properties. Importantly, UBCRPs exhibited anti-UC effects comparable to those of HBCRPs by regulating the gut microbiota, modulating serum corticosterone metabolism, and inhibiting the cytokine-cytokine receptor interaction pathway. Overall, this study provides mechanistic insight into the UA extraction of BCRPs, establishes a technical basis for the high-value utilization of UBCRPs, and highlights the application potential of UA extraction for the green and efficient production of polysaccharides.