Reflections on the Glycating Power of Simple Carbohydrates in the Maillard Reaction: The Conceptual DFT Viewpoint

This study features an assessment of multiple density functionals in calculating the molecular
structures and inherent properties in simple carbohydrates participating in nonenzymatic glycation
involving amino acids and proteins in Maillard reactions. The occurrences of nucleophilic addition
involving nonenzymatic glycation, initiate protein glycation reaction involving a carbonyl group derived
from reeducating sugars and free amino group forming a reversible Schiff base. Calculations of
chemical reactivity descriptors are attained in each molecular system using Conceptual DFT. A crosssectional
comparison of results obtained through ΔSCF procedure is attained to check for accuracy
and validity of the density functional in “Koopmans in DFT" (KID) procedure. The calculated HOMO
and LUMO of each carbohydrate are presented through graphical sketches overlapped to their
chemical structures. The Fukui function indices and condensed dual descriptor Δf(r) are used to
examine the active sites where nucleophilic and electrophilic attacks occur. The assessment identifies
several relationships involving glycating power and reactivity descriptors. The latter are found capable
of predicting glycating behaviour in complex carbohydrates. The results obtained for this work shows
the ability to predict the interaction sites of simple carbohydrates by applying DFT-based descriptors
of chemical reactivity. Such include global electronegativity, global hardness, global electrophilicity,
electrodonating powers, electroaccepting powers, net electrophilicity, Fukui function and condensed
dual descriptor. Their use in characterising and describing preferred reactivity sites generated a firm
explanation on the molecule reactivity.