Quality evaluation of Astragalus membranaceus based on polysaccharide fingerprinting and chemometric analysis

Astragalus membranaceus is a representative medicinal and edible herb in China, with significant clinical value in traditional Chinese medicine. As cultivation becomes the primary source, regional quality variations have grown increasingly evident. Conventional quality assessments based on small molecules are inadequate for capturing its overall quality, underscoring the need for a polysaccharide-centred evaluation system. This study optimised the extraction process using single-factor experiments and response surface methodology (RSM), achieving a yield of 3.90 % Astragalus polysaccharides (APS). Notable differences in the in vitro anti-inflammatory activity among regional samples prompted further comparison of molecular weight distributions and monosaccharide compositions. Using high-performance gel permeation chromatography (HPGPC) and monosaccharide profiling, combined with multivariate analysis including HCA, PCA, and PLS-DA, we identified distinct regional features. Specific molecular weights (2355.23, 2.18, 1.13 kDa) and monosaccharides (rhamnose, d-glucose) served as markers for geographical discrimination. Further correlation analysis revealed that specific molecular weight ranges (374.27 kDa, 7.48 kDa, etc.) and monosaccharide components (rhamnose, D-mannose, D-xylose, etc.) were negatively correlated with the IC₅₀ values for anti-inflammatory activity, suggesting that these structural features may represent key bioactive determinants of APS. This study provides technical support for improving the quality evaluation system for Astragalus membranaceus and also serves as a reference for quality control of other Chinese herbal medicines.