Anemarrhenae asphodeloides Polysaccharide Extraction Process Optimization and its Monosaccharide Composition and Antioxidant Activity of Correlation Analysis

Background: Anemarrhenae asphodeloides polysaccharides (RAP) have demonstrated notable antioxidant activity, which is believed to be closely related to their monosaccharide composition and extraction conditions. However, systematic optimization of the RAP extraction process and a detailed understanding of its structure-activity relationship remain insufficiently explored. Objectives: This study aimed to optimize the extraction process of RAP using the Box–Behnken design (BBD), analyze the monosaccharide composition of RAP from different origins using a PMP-UPLC-PDA method, and investigate the correlation between its antioxidant activity and monosaccharide constituents. Materials and Methods: Extraction parameters including ethanol concentration, material-to-liquid ratio, extraction time, and extraction frequency were optimized using BBD based on RAP yield. The monosaccharide composition of six RAP samples from different regions was determined using 1-phenyl-3-methyl-5-pyrazolone (PMP) pre-column derivatization combined with ultra-performance liquid chromatography and photodiode array detection (UPLC-PDA). Antioxidant activities were evaluated via DPPH, hydroxyl, and superoxide anion radical scavenging assays. Correlation between monosaccharide composition and antioxidant capacity was analyzed using Pearson correlation and multivariate statistics. Results: The optimal extraction conditions were identified as 77% ethanol concentration, a material-to-liquid ratio of 1:10 g/mL, extraction time of 124 minutes, and four extraction cycles, yielding RAP at 8.56% ± 2.74%. Antioxidant assays showed that higher RAP levels led to stronger free radical scavenging effects. Among all samples, the RAP from Yixian (a geoauthentic producing area) exhibited the highest antioxidant activity. Significant negative correlations were found between IC50 values and the proportions of Xyl, Fuc, Man, GalA, Ara, and GlcA, suggesting their contribution to antioxidant activity. Conclusion: This study systematically optimized the RAP extraction process and revealed significant correlations between its monosaccharide composition and antioxidant activity. These findings provide new insights into the structure-function relationship and material basis of the antioxidant pharmacodynamics of A. asphodeloides.