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- Paulino, M., et al.
(författare)
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Studies of trypanocidal (inhibitory) power of naphthoquinones: : evaluation of quantum chemical molecular descriptors for structure-activity relationships
- 2008
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Ingår i: European Journal of Medicinal Chemistry. - : Elsevier BV. - 0223-5234. ; 43:10, s. 2238-2246
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Tidskriftsartikel (refereegranskat)abstract
- Electronic, lipophilic and steric descriptors included in QSAR-2D and -3D are analyzed for a set of ortho- and para-naphthoquinones that have proved to be powerful oxidative agents with potent trypanocidal activities specially against Leptomonas seymouri and Trypanosoma cruzi. Electronic properties are calculated by means of semiempirical (PM3), ab initio (HF/3-21G) and density functional theory (B3LYP/6-31 + G*) methodologies. Three different electronic states, neutral quinones, hydroquinones and semiquinones, are studied to investigate if any one of them are statistically related with the biological activities. The best correlations were obtained at the B3LYP level of theory because it includes electronic correlation. The QSAR-2D indicates that the best trypanocidal growth inhibitors are molecules in the semiquinone electronic state, with the following properties: (a) high negative value of EHOMO, (b) high negative charge in the oxygen atoms of the carbonyl groups, (c) high positive charge in the carbon atom of one of carbonyl moieties and (d) high electronegativity (χ). In a complementary way, the QSAR-3D indicates that the electrostatic field correlates with trypanocidal activity and the presence of bulk moieties would increase activity. The idea of comparing the three electronic states may prove to be of most importance in the general strategy to the design of new trypanocidal drugs. In fact, the experimental results showed that semiquinone is the one really statistically relevant indicating a clear connection between biochemical and theoretical aspects. Finally, we demonstrated that to be a good anti-trypanosomatid compound, the molecule must be a good electron acceptor to reach easily the essential semiquinone state. We expect that the present results motivate new experimental as well as theoretical investigations that confirm our findings.
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| 2. |
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| 3. |
- Iribarne, F., et al.
(författare)
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Interaction energies of nitrofurans with trypanothione reductase and glutathione reductase studied by molecular docking
- 2007
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Ingår i: Journal of Molecular Structure. - : Elsevier BV. - 0166-1280. ; 818:1-3, s. 7-22
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Tidskriftsartikel (refereegranskat)abstract
- A theoretical docking study was conducted on a sample of previously reported nitrofuran derivatives, at the binding sites of Trypanosoma cruzi trypanothione reductase (TR) and human erythrocyte glutathione reductase (GR), in order to examine interaction energies (affinities) towards the parasite enzyme and check for selectivity with respect to the human counterpart. A large proportion of nitrofurans were previously shown to be TR inhibitors and some of them have in vitro trypanocidal action as well. The analysis of data collected from the docking procedure was undertaken both from the numeric and graphical standpoints, including the comparison of force field energies, molecular contacts and spatial location of the different orientations that ligands acquired at the binding sites. The results clearly suggest that nitrofurans are not able to selectively bind at the active site of the parasite TR, attaining even larger interaction energies at GR active site. The reason for inhibitor specificity is two-fold: (a) the nitrofuran group acts as a strong electrostatic anchor in GR; (b) the compounds form more stable complexes when binding at the non-selective dimmer interface. Therefore, these two aspects should be specially considered when seeking good candidates for leaders in regards the development of drugs with selective inhibition of TR.
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| 4. |
- Iribarne, F., et al.
(författare)
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Assaying phenothiazine derivatives as trypanothione reductase and glutathione reductase inhibitors by theoretical docking and Molecular Dynamics studies
- 2009
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Ingår i: Journal of Molecular Graphics and Modelling. - : Elsevier BV. - 1093-3263 .- 1873-4243. ; 28:4, s. 371-381
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Tidskriftsartikel (refereegranskat)abstract
- A theoretical docking study, conducted on a sample of previously reported phenothiazine derivatives, at the binding sites of Trypanosoma cruzi trypanothione reductase (TR) and human erythrocyte glutathione reductase (GR), examines interaction energies (affinities) towards the parasite enzyme to check for selectivity with respect to the human counterpart. Phenothiazine compounds were previously shown to be TR inhibitors. The analysis of data collected from the docking procedure was undertaken both from the numeric and graphical standpoints, including the comparison of force field, energies, molecular contacts and spatial location of the different orientations that ligands acquired at the binding sites. Molecular Dynamics simulations were also carried out for derivatives with known quantitative inhibition kinetics (Ki). The results indicate that (positively) charged phenothiazines attain larger interaction energies at TR active site, in line with previous experimental information. Suitable molecular size and shape is also needed to complement the electrostatic effect, as clearly evidenced by graphical analysis of output docked conformations. Docking energies values are reasonably well correlated with those obtained by Molecular Dynamics as well as with the experimental Ki values, confirming once again the validity of this type of scoring methods to rapidly assess ligand–receptor affinities. Alongside newly discovered classes of TR inhibitors, the promazine (N-alkylaminopropylphenothiazine) nucleus should still be considered when good candidates are sought as leaders for selective TR inhibition.
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