Primary Study on Effect of Extraction Methods on the Properties and Activities of Polysaccharides from Geum japonicum var. Chinense F. Bolle

Geum japonicum Thunb. var. Chinese F. Bolle, a traditional Miao medicine with significant clinical potential, is rich in polysaccharides. Despite its importance, there is a scarcity of research on the structure and activities of these polysaccharides. In this study, polysaccharides from Geum japonicum (GJPs) were extracted using various methods, including heated reflux extraction (HRE), acidic extraction (ACE), alkaline extraction (AAE), microwave-assisted extraction (MAE), enzymatic extraction (EAE), pressurized liquid extraction (PLE), and deep eutectic solvents extraction (DESE). The extraction yield, physicochemical properties, structural characteristics, and antioxidant activities of these polysaccharides were comprehensively investigated and compared. Physicochemical analysis, including FT-IR spectral features and monosaccharide compositions, revealed that the GJPs are acidic heteropolysaccharides with both α- and β-configurations. DESE and ACE were the most effective methods for obtaining the highest neutral and acidic sugars with yields of 29.1%/64.2%, and 39.8%/55.6%, respectively. Meanwhile, AAE was preferable for extracting the polysaccharide–protein complex, achieving a