Asymmetrical flow field-flow fractionation combined with ultrafiltration: A novel and high-efficiency approach for separation, purification, and characterization of Ganoderma lucidum polysaccharides

Ganoderma lucidum polysaccharide (GLP) has attracted increasing attention owing to its multiple pharmacological effects. However, the establishment of a structure-bioactivity relationship is possible only if highly purified and accurately characterized GLP is used. In this study, a combined technique based on asymmetrical flow field-flow fractionation (AF4), ultrafiltration, and the Sevag method was developed to improve the purification process of GLP. Deionized water was used throughout this study which avoids the dialysis desalting process. Furthermore, the molecular weight ( M w ) and radius of gyration ( R g ) of the purified GLP were characterized by AF4 coupled online ultraviolet–visible (UV), multiangle light scattering (MALS), and differential refractive index (dRI) detectors (AF4-UV-MALS-dRI). The results demonstrated that after removal of the larger size proteins, one highly purified GLP fraction (polysaccharide content of 108.37 ± 0.45%) and its structural information (i.e., M w , R g , and apparent density) were obtained in a single run owing to a combination of mechanisms of ultrafiltration and AF4 separation. The results suggested that the method developed in this study for separation, purification, and characterization of GLP is highly efficient, which could help to better understand its structure-function relationships. • A combined technique was developed to improve the purification process of GLP. • Small impurities could be filtered by RC membrane in AF4 channel in a short time. • Purification, separation and characterization of GLP were achieved by one AF4 run. • A highly purified GLP faction was obtained by the method developed in this study.