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 cross-sectional comparison of results obtained through ∆SCF 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 ∆f(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.

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