Validation of performances of some semiempirical Hamiltonians for predicting molecular structure calculation of natural brassinosteroids: Towards understanding their biological activity by electron exchange effects

Morera-Boado, Cercis; Alonso-Becerra, Esther; Montero‐Cabrera, Luis A.; González-Jonte, R. H.

doi:10.1016/j.theochem.2007.05.034

Cited by 8 publications

(4 citation statements)

References 23 publications

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“…The preferred conformations of BS side chain were subject of numerous studies, especially those involving molecular modeling approaches [5][6][7][8][9][10][11]. The obtained conclusions can be based on some speculations and should be verified experimentally.…”

Section: Introductionmentioning

confidence: 96%

NMR and X-ray studies of isomeric 22,23-dihydroxy stigmastanes

Хрипач¹,

Жабинский²,

Иванова³

et al. 2010

Journal of Molecular Structure

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Section: Introductionmentioning

confidence: 96%

NMR and X-ray studies of isomeric 22,23-dihydroxy stigmastanes

Хрипач¹,

Жабинский²,

Иванова³

et al. 2010

Journal of Molecular Structure

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“…Multiple Minima Hypersurface (MMH) methodology, which validity for the study of molecular associations and for conformational analysis has been widely demonstrated by some of the co-authors, [30][31][32][33][34][35][36][37][38] was employed for random generation and optimization at semiempirical level of theory of α−α'Py n SiOH (n = 2,3). Most stable structures were DFT-refined for conformational analysis.…”

Section: Introductionmentioning

confidence: 99%

“…Monomer reactivity was estimated by conceptual DFT through global reactivity descriptors and local (condensed) Fukui functions. Reported studies have indicated good correlation between these functions and experimental electrophilic substitution patterns for a range of aromatic heterocyclic compounds, − including pyrrole derivatives and silicon-based materials. , Multiple minima hypersurface (MMH) methodology, the validity of which for the study of molecular associations and for conformational analysis has been widely demonstrated by some of the coauthors, − was employed for random generation and optimization at semiempirical level of theory of α–α′Py n SiOH ( n = 2, 3). Most stable structures were DFT-refined for conformational analysis.…”

Section: Introductionmentioning

confidence: 99%

Pyrrolyl–Silicon Compounds as Precursors for Donor–Acceptor Systems Stabilized by Noncovalent Interactions

et al. 2015

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Pyrrolil-silicon compounds were investigated by different theoretical approaches.Model monomers consisted in pyrrole ring N-substituted with silylmethoxy and silylhydroxy end-groups through propyl chain spacer, designated as PySi and PySiOH. Geometrical, vibrational and electronic properties, as well as chemical reactivity, are discussed and compared with Pyrrole (Py) and N-propylpyrrole (N-PrPy) that were studied in parallel for reference purposes and methods validation. The electronic distribution between PySi and PySiOH importantly differs, being the former electron donor, as Py and N-PrPy. Conversely, PySiOH presents donor-acceptor character with LUMO energy level localized on the silanol end-group.Global and local reactivity descriptors predict PySiOH more reactive than PySi with two preferential reactive sites: electron-rich Py ring and electron-deficient silanol group. Based on experimental studies, oligomers of PySiOH linked α−α' via Py rings (α−α'Py n SiOH, n = 2,3) were considered as model molecules of hydrolyzed PySi. The most stable structures were derived from randomly generated α−α'Py n SiOH that were optimized at semiempirical AM1 and refined with M05-2X/6-31G(d,p). Conformational analysis of dimer and trimer structures points to stability enhanced by molecular packing. Nonetheless, NBO and RDG results indicate that oligomers stability is dictated by the cooperative contribution of hydrogen bonding between silanol end-groups and dispersive vdW interactions between silanol and the π system of Py ring.The latter interaction resulting from electron delocalization induced by electron deficient silanol group seems to determine the smaller gap energy of T-shaped OH-π arrangements. The theoretical findings support the peculiar chemical behavior revealed by experiment.

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“…The following structural features are known to be important for high bioactivity of BSs: (a) the presence of the 6-keto-or 7-oxa-6-keto-structural moiety in the B ring; (b) the presence of the 2α,3α-diol group in the A ring; (c) the existence of a diol system at positions 22 and 23 with the R,R * configuration and the presence of the methyl or ethyl group at position 24 (the side chain); (d) trans-fusion of the A/B rings [2] (see the structural formulas). In order to determine the mechanisms of the high biological activity and to explain its correlation with the structural features of BSs, we used the methods of studying the quantitative relation between the structure of the compounds and their activity (QSAR) [3,4] and the methods of molecular modeling: molecular mechanics (MM) [1] and quantum chemical AM1 [5] and PM3 [6] calculations. These works revealed an important role of functional groups containing oxygen atoms in the high biological activity of BSs.…”

Section: Introductionmentioning

confidence: 99%

Molecular mechanics and quantum chemistry evaluation of the effect of the side chain structure of brassinosteroids on their biological activity

Andrianov

Anishchenko

2015

J Struct Chem

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Using methods of molecular mechanics and quantum chemistry in the DFT approximation, a conformational analysis of one of the most biologically active compounds of the class of brassinosteroids, natural brassinolide, and less active natural 24-epibrassinolide and synthetic (22S,23S)-24-epibrassinolide is performed with a subsequent comparison of their side chain structures. Found that the 22R,23R,24S-configuration of two hydroxyl and one methyl groups of brassinolide provides the side chain structures in which its diol system forms an O6…H(O5) intramolecular hydrogen bond. Therewith, the O6H hydroxyl group is free and can participate in the formation of intermolecular hydrogen bonds with a receptor. On the contrary, the 22S,23S,24R-configuration of (22S,23S)-24-epibrassinolide corresponds to the side chain structures in which the O6H hydroxyl group is shielded by the 21-methyl group, which determines a lower biological activity of this hormone.

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Validation of performances of some semiempirical Hamiltonians for predicting molecular structure calculation of natural brassinosteroids: Towards understanding their biological activity by electron exchange effects

Cited by 8 publications

References 23 publications

NMR and X-ray studies of isomeric 22,23-dihydroxy stigmastanes

NMR and X-ray studies of isomeric 22,23-dihydroxy stigmastanes

Pyrrolyl–Silicon Compounds as Precursors for Donor–Acceptor Systems Stabilized by Noncovalent Interactions

Molecular mechanics and quantum chemistry evaluation of the effect of the side chain structure of brassinosteroids on their biological activity

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