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1

Sweetness-Vibrational Spectra Relationship in Aldopyranoses and Sucrose/Galactosucrose System

Pietrzycki W.

Polish Journal of Chemistry

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2003

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Vol. 77 / nr 9

1163-1173

EN

Correlation of the RS relative sweetnesses of 6 aldopyranoses, maltose and lactose on the structures of their PM3 vibrational spectra are analysed. The QSAR correlations of log(RS) versus squares of _(OH) stretching, _(COH) bending and T(OC) torsion calculated frequencies are examined. High correlations are found for _2(4-OH), _2(4-COH) and T2(4-OC) parameters, so the corresponding vibrations are called "sweet vibrations". Computational QSAR procedure with two _2(O-H) vibrational parameters is applied to localize AH,B Shallenberger glycophore. The high correlation reached by author for _(4-OH) and _(3-OH) frequencies makes agree 4-OH, O-3 structure with AH,B glycophore. It allows to recover B = O-3 subsite, which is inactive in aldopyranoses due to electrostatic model. Analysis of the PM3 vibrational spectra of sucrose, galactosucrose and their chlorodeoxy derivatives is carried out. Based on QSAR procedure with four _2(O-H) vibrational parameters one can define Nofre-Tinti four-subsite sweetener in sucrose and galactosucrose molecules. Computations indicate for contribution of 4-OH, 3-OH pyranose groups and 1'-OH, 6'-OH fructofuranose groups. It speaks well for XH1, B2, E1, E4 sweetener in the sucrose/galactosucrose structure.

2

Nofre-Tinti E1 and E4 Sweetener Subsites Activity on High Sweetness of Chlorodeoxy Derivatives of Sucrose and Galactosucrose

Pietrzycki W.

Polish Journal of Chemistry

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2002

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Vol. 76 / nr 6

875-889

EN

PM3 quantum chemical population analysis in the ground state was performed for sucrose and galactosucrose, their 8 chlorodeoxy derivatives and threonine as a moiety of sweet taste receptor. QSAR (Quantitative Structure-Activity Relationship) studies on RSj relative sweetness of these sugars is carried out based on calculated quantum chemical parameters derived from independent particle model. It excellently explains very high sweetness of 1_,4,6_-trichloro-1_,4,6_-trideoxy-galactosucrose (RSj = 2000), 1_,4,6,6_-tetrachloro-1_,4,6,6_-tetradeoxy-galactosucrose (RSj =1000) and other chlorosugars. Presented QSAR analysis brings rather a limited contribution of the G4(1_-CH2) and G1(6_-CH2) dispersion fructofuranose subsites to Nofre-Tinti sweetener and reveals a great activity of E4(Cl-1_) and E1(Cl-6_) charge-transfer fructofuranose subsites in this sweetener. The latter subsites have a character of strong n-electron donors. According to Brand and Feigin, such a property may result in substantial increase of probability of a stimulus-gated ion channel transduction scheme for sweet taste.

3

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

Pietrzycki W.

Polish Journal of Chemistry

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2001

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Vol. 75, nr 10

1569-1582

EN

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.

4

QSAR Studies on Bioorganic and Pharmacological Effects of the Antidepressants

Pietrzycki W.

Polish Journal of Chemistry

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2000

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Vol. 74, nr 1

89-108

EN

Quantitantive Structure-Activity relationship (QSAR) studies on 19 most important antidepressants were performed using the PM3 quantum chemical parameters. The ground state population analysis was performed for all the antidepressants (Antds).

5

Ab initio S-T gap energies and the triplet radical reactivity of phenyl-, pyridyl- and 1-oxido-pyridylnitrenes

Pietrzycki W., Tomasik P.

Polish Journal of Chemistry

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1998

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Vol. 72, nr 5

893-900

EN

The geometric parameters of phenylnitrene, all the isomeric pyridylnitrenes and 1-oxido-pyridylnitrenes in their lowest singlet and triplet states were found emploing SCF/6-311 calculations. SingletE(S)-i and triplet E(T)-i lowest state energies of the corresponding nitrene structures were calculated using both SCF/6-311G as well as MP2/6-311G methods. The E(S)-i energies of nitrenes correspond with their closed shell (RHF) configurations, whereas E(T)-i energies are related to open shell (UHF) configurations. Following the analysis of the gap energies, DeltaE(gap)-i=E(T)-i - E(S)-i, electronic alpha-spin orbital density excesses(t-N), the total atomic alpha-spin density excesses (T-N) on the N nitrene nitrogen atom as well as on the 1-oxide oxygen atom (T-O) and the triplet radical reactivity of these nitrenes are explained.