Structural characterization and functional evaluation of polysaccharides extracted from the heart of date palm (Phoenix dactylifera L.): Insights into α-amylase inhibition and antidiabetic potential

Plant-derived polysaccharides are gaining increasing attention for their diverse bioactive properties, particularly in the management of metabolic disorders such as diabetes. This study aims to isolate, characterize, and evaluate a novel polysaccharide from the heart of the date palm (Phoenix dactylifera L.), designated PHDP, for its potential antidiabetic activity. The extraction process yielded a recovery rate of 43 %, with comprehensive structural characterization performed using colorimetric assays, Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), gas chromatography coupled with mass spectrometry (GC–MS), and size exclusion chromatography (SEC). Monosaccharide composition analysis revealed the presence of glucose (41.3 %), mannose (38.8 %), galactose (14.9 %), arabinose (2.6 %), and rhamnose (2.3 %), along with 27.1 % uronic acids, indicative of a weakly esterified pectic polysaccharide structure characteristic of galactomannoglucan (GMG). Conformational analysis by SEC confirmed a random coil architecture. In vitro α-amylase inhibition assays revealed a mixed-type inhibition mechanism, demonstrating PHDP's ability to modulate carbohydrate metabolism. Furthermore, in vivo experiments using alloxan-induced diabetic rats showed significant hypoglycemic effects, improved lipid profiles, and regulation of key plasma enzymes, thereby confirming its antioxidant and antidiabetic activities. These findings highlight PHDP as a viable natural agent for developing safe, plant-based antidiabetic treatments.