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QSAR Computationa Model of Nofre-Tinti Theory on Sweetness of Mono- and Disaccharides Composed by Pyranose Units

Pietrzycki W.

Polish Journal of Chemistry

2001

Vol. 75, nr 10

1569-1582

PM3 quantum chemical population analysis in the ground state was performed for about 32 anomeric ring-conformers of aldopyranoses and ketopyranoses, maltose and lactose, as well as lysine cation _ sweet taste receptor moiety. Thermodynamic equation was formulated for RSj relative sweetness, originated from LFER (linear free energy relationship) for sugar glycophore - sweet taste receptor interactions. From this equation, QSAR (Quantitative Structure - Activity Relationship) studies are carried out on a sweetness of 10 natural, most known and important mono- and disaccharides, composed by pyranose units. Using RSj measured values, QSAR correlation equations were performed, which apply exclusively PM3 calculated quantum chemical parameters. The ln RSj expl demonstrates linear correlation against Qj(O) oxygen as well asQj(H) hydrogen atomic electron net charges of 4-OH group in aldopyranoses and 2-OH group in ketopyranoses. These O andHatoms are B1 andXH1 subsites, respectively, which strongly predominate in {XH2, XH1, B1, B2, AH1, AH2} sweetener of j-th aldopyranose in Nofre-Tinti theory. On the other hand, L-sorbose represents B1, AH1, B2 system, where B2 subsite is n-electron donor situated on the ketopyranose O-1 oxygen atom. The _-D-fructopyranose sweetener provides additionally E3 subsite (ketopyranose O-3 atoms). The NHOMO(pyr) _ LUMO( recp) transition in this sugar reveals E1(O-5) and E2(O-4) subsites.