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.