- Metal ion chelates of lipophilic alkyl diazinyl ketoximes as hydrolytic catalysts
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A series of lipophilic dodecyl hetaryl ketoximes (hetaryl = pyridin-2-yl, pyridazin-3-yl, pyrimidin-2-yl, pyrimidin-4-yl, pyrazin-2-yl as well as their methyl hetaryl homologues was synthesized and hydrolytic activity of their chelates with Co2+, Ni2+, Cu2+ and Zn2+ in a micellar matrix of hexadecyltrimethylammonium bromide or in homogeneous aqueous solutions was investigated using 4-nitrophenyl acetate, 4-nitrophenyl hexanoate and 4-nitrophenyl diphenyl phosphate as model substrates. While Co2+ and Cu2+ chelates are almost inactive, those of Ni2+ and Zn2+ exhibit considerable activity. None of the studied chelates promotes hydrolysis of the used phosphate. The effective species are chelates of the metal : ligand stoichiometry 1 : 3 and 1 : 1 with Ni2+ and Zn2+, respectively, when the ester cleavage proceeds in the micellar matrix. The 1 : 2 stoichiometry was found in aqueous solutions of Ni2+ and Zn2+ chelates of methyl ketoximes.
- Cibulka, Radek,Hampl, Frantisek,Martinu, Tomas,Mazac, Jiri,Totevova, Sonja,Liska, Frantisek
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- Synthesis and antiviral activity of thiosemicarbazone derivatives of pyridazinecarbaldehydes and alkyl pyridazinyl ketones
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Various novel thiosemicarbazones (TSCs) 15b-e, 16b-e, 17b-e, 18b-e, and 19b-e derived from 4-pyridazinecarbaldehyde, 3-pyridazinecarbaldehyde, 4-acetylpyridazine, 3-acetylpyridazine, and 3-propionylpyridazine were prepared and their cytotoxic and antiherpetic potentials were evaluated. It was found that the replacement of the 2-pyridyl-moiety in aldehyde derived compounds 20a-c by a 4-pyridazinyl group (compounds 15b-d) abolishes biological activity. However, in TSCs derived from 3-pyridazinecarbaldehyde (16b-d) the cytotoxic potency was considerably reduced (factor ~300), while the antiviral activity was largely retained. A total loss of biological activity occurred when the pyridyl group in TSC 20d, derived from 2-acetylpyridine, was replaced by the 4-pyridazinyl system (17d). By employment of the 3-pyridazinyl unit for isosteric modification, however, the cell toxicity could be reduced significantly (factor 100) without impairing the antiherpetic potential also in the series of TSCs derived from N-heteroaromatic ketones. It was observed that there is no obvious influence of the size of the cycloamino substituent on the biological activities in compounds 20a-d, 15b-d, 16b-d, 17b-d, and 18b-d. While the pyridine derived TSCs in our experiments proved clearly cytotoxic at lower concentrations than those being antivirally active, the aza-analogous compounds derived from 3-acetyl-pyridazine (18b-e) inhibited plaque formation at concentrations equal to those causing cytotoxic effects. The TSCs 16b-e derived from 3-pyridazinecarbaldehyde were found to show selective antiviral activity against HSV-1. In addition, a significant improvement of the water solubility of heteroaromatic TSCs could be achieved by the replacement of the CH-moiety in position 6 of the pyridine derivatives 20a-c by a nitrogen atom (compounds 16b-d).
- Easmon,Heinisch,Holzer,Rosenwirth
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p. 1196 - 1201
(2007/10/02)
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- ACIDIFYING EFFECTS OF AZA GROUPS IN THE NH ACIDITY OF AMINOAZINES AND THE CH ACIDITY OF ACETYLAZINES
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The pK values for a series of aminoazines and acetylazines containing one, two, or three aza groups in the ring were determined in dimethyl sulfoxide.There is a good linear correlation between pK values of the investigated NH and CH acids.The acidifying effects (ΔpK) of the aza groups at positions 2, 3, or 4 in relation to the side chain were determined and had values of 3.1, 2.4, and 4.5 logarithmic units in the aminoazines and 3.5, 2.9 and 4.8 logarithmic units respectively in the acetylazines.Except in the case of two ortho-located aza groups the effects are additive.Compared with dimethyl sulfoxide water has a differentiating effect on the acidity of the aminoazines, and this is explained by the formation of hydrogen bonds between the molecules of the proton-donating solvent and the aza groups of the anions of the aminoazines.
- Terekhova, M. I.,Petrov, E. S.,Mikhaleva, M. A.,Shkurko, O. P.,Mamaev, V. P.,Shatenshtein, A. I.
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