Integrated tandem ultrafiltration membrane technology for separating polysaccharides from Curcuma longa: Structure characterization, separation mechanisms, and protective effects on HUVECs.

Integrated tandem ultrafiltration membrane technology (UMT) was used to separate Curcuma longa polysaccharides (CLPs) into four grades: CLP-100, CLP-50, CLP-10, and CLP-5. CLP-10 was a purified polysaccharide consisting of d-glucose, L-arabinose, L-rhamnose, and D-galactose. Its backbone comprised →2)-α-L-Rhap-(1 → 2,4)-α-L-Rhap-(1 → 4)-α-D-Glcp-(1→. CLP-50 showed significant protective activity against HO-induced oxidative stress in human umbilical vein endothelial cells (HUVECs) through the VEGFA/AKT/SOD2 pathway. The structure-activity relationship of four CLPs was further analyzed. Molecular weight (Mw) distribution, monosaccharide composition, and morphology were the main factors affecting the activity. In addition, a preliminary investigation into the separation mechanisms by which UMT separated the polysaccharides was conducted, which revealed potential influences of intra-molecular aggregation and inter-molecular repulsion between the polysaccharides and membrane materials. These findings provide a profound elucidation of the complex relationship between UMT and factors such as Mw, conformation, particle size, charge number, and apparent viscosity during the separation process.