Structural characteristics of peach gum arabinogalactan and its mechanism of inhibitory effect on leukemia cells.

The polysaccharide PGP with a molecular weight of 5.48 × 106 Da was isolated from Peach gum using alkaline electrolyte water as a solvent. HPLC, FT-IR, UV-vis, GC-MS, and NMR results indicated that PGP consisted of arabinose, xylose, mannose, glucuronic acid, and galactose with a molar ratio of 1.00:0.23:0.08:0.04:0.83, and was an AG-II arabinogalactan with β-D-(1 → 6)-Galp backbone and O-3 and O-4 branched chains. The advanced structure showed that PGP was an irregular lamellar structure of polysaccharide molecules with a specialized structure formed by the combination of crystalline and amorphous forms. Cell experiments showed that PGP treatment significantly induced apoptosis in leukemia cells, resulting in a decrease in mitochondrial membrane potential and an increase in ROS production. Western blotting assay showed that PGP could inhibit the proliferation of K562 and HL60 cells through the combination of Fas/FasL-mediated exogenous death receptor pathway and endogenous mitochondrial pathway, blocking the cell cycle at G1 phase and causing apoptosis. This study provided new ideas for the conformational relationship of Peach gum polysaccharides and confirmed the potential application of PGP in the development of anti-leukemia drugs.