Inhibition of Catalase Glycation by Ajwa Date Phenolics: A Spectroscopic and Computational Study

Glycation is a non-enzymatic process where reducing sugars react with the free amino groups of proteins, a phenomenon that occurs under hyperglycemic conditions such as diabetes. Ajwa dates are widely consumed for their health benefits, but limited studies have investigated their potential to inhibit glycation. In this study, we evaluate the antiglycation effects of Ajwa date pulp extracts (ADEs) using the glyoxal (GO)-catalase (CAT) glycation model. Phytochemical analysis revealed that the dry ADE contains significantly higher total phenolic content (2619 ± 121 mg GAE/100 g dry weight [DW] [p < 0.0001]) compared to fresh Ajwa dates. Moreover, the acid hydrolysis method proved more effective for extracting bound phenolic acids (1035 ± 353 mg/100 g DW) than the alkaline hydrolysis method (446 ± 18 mg/100 g DW) from dry Ajwa dates. Using ultrahigh-performance liquid chromatography with a photodiode array detector, p-coumaric and ferulic acid were identified as the primary polyphenols in the ADE. The study demonstrated that GO-induced CAT glycation and the resulting advanced glycation end-products (AGEs) were significantly inhibited by ADE, as measured by AGE-specific fluorescence. While glycation caused conformational changes in CAT, ADE treatment effectively reduced these alterations, as observed through ultraviolet-visible absorption, circular dichroism, and tryptophan spectroscopies. Molecular docking analysis showed that Ajwa date constituent; caffeic acid, p-coumaric acid and ferulic acid had estimated binding affinities of 6.9, 7.1 and 6.1 kcal/mol, respectively with CAT. Multiple hydrogen bonds were seen between these phenolic acids and amino acid residues in addition to other weak interactions. In conclusion, this study highlights the preventive effects of ADE against glycation, offering potential pathways for addressing diabetes-related complications with increased efficacy, selectivity and safety in humans.