- Dehydrogenation, oxidative denitration and ring contraction of N,N-dimethyl-5-nitrouracil by a Bacillus nitroreductase Nfr-A1
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Nfr-A1, a Bacillus subtilis nitroreductase, catalyzes the nitroreduction of a large panel of aromatic and heterocyclic nitro compounds, except those belonging to nitrouracil class of molecules. Besides nitroreduction, Nfr-A1 exhibits a strong NADH oxidase activity in the presence of oxygen, leading to high concentration of H2O2 (up to 200 μM). In the presence of (N,N)-dimethyl-5-nitrouracil 1 (dim-NU), Nfr-A1 achieves the reduction of dim-NU double bond to compounds 2 and 3 and in parallel the oxidation of dim-NU to the denitrated five membered derivatives 4 and 5. The reduction is catalyzed by the reduced flavin Fl-Red and resembles those catalyzed by dihydropyrimidine dehydrogenases (DPD), during the catabolism of pyrimidines. The oxidative denitration is catalyzed in part by hydrogen peroxide generated through the NADH-oxidase activity, and certainly by the peroxyflavin intermediate Fl-OOH for the other part. The mechanisms of reaction were proposed according to experimental data and literature. These findings together with our previous results on the potential biological role of Nfr-A1, confirm the large spectrum of catalysis supported by this enzyme. The oxidative denitration is sporadically reported in literature and represents a safe and green alternative for the remediation of nitro-compounds.
- Cortial, Sylvie,Chaignon, Philippe,Sergent, Didier,Dezard, Sophie,Ouazzani, Jamal
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experimental part
p. 1 - 8
(2012/04/17)
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- Oxidation of 1,3-dimethylthymine and 1,3-dimethyluracil with oxone in the solid to solid state
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The oxidation of the title substrates with Oxone in the presence of camphor in the solid to solid state afforded a simple and efficient method for epoxidation under mild reaction condition.
- Hong, Yongrae,Chang, Soonjae,Hahn, Bosup,Toda, Fumio
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p. 1455 - 1459
(2007/10/03)
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- Studies on the chemistry of pyrimidine derivatives with dimethyldioxirane: Synthesis, cytotoxic effect and antiviral activity of new 5,6-oxiranyl-5,6-dihydro and 5-hydroxy-5,6-dihydro-6-substituted uracil derivatives and pyrimidine nucleosides
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The oxidation of uracil derivatives and pyrimidine nucleosides performed in CH2Cl2 with dimethyldioxirane afforded new 5,6-oxiranyl-5,6-dihydro and cis-/trans-5,6-dihvdroxv-5,6-dihydro-derivatives. When the oxidations were performed in the presence of methanol as nucleophile cis- and trans- 5-hydroxy-6-methoxy-5,6-dihydro derivatives were obtained in acceptable yields. Cis- and trans-1,3- dimethyl-5-hydroxy-6-alkylamino-5,6-dihydro uracils were obtained by nucleophilic ring opening of the 1,3-dimethyl-5,6-oxiranyl-5,6-dihydro uracil in the purified form. Interestingly some of the new title products revealed low cytotoxicity and selective antiviral activity against DNA and RNA Viruses. In particular, compound 17b shows a strong and selective inhibition of the Sendai virus with lower effect on Herpes Simplex-1 virus. Compound 17b is also able to slightly inhibit HIV-1 virus at high concentrations, but in this case a cytotoxic effect was observed.
- Saladino, Raffaele,Bernini, Roberta,Crestini, Claudia,Mincione, Enrico,Bergamini, Alberto,Marini, Stefano,Palamara, Anna Teresa
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p. 7561 - 7578
(2007/10/02)
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- Oxidation of nucleic acid related compounds by the peroxodisulfate ion
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The treatment of nucleic acid bases, nucleosides, and nucleotides with peroxodisulfate ion in a phosphate buffer solution at pH 7.0 or water at 70-75°C was investigated. The reaction of thymine and 5-methylcytosine nucleosides and nucleotides resulted in the oxidation of the 5-methyl groups. The oxidation products from 1,3-dimethyluracils and the time-course of the reaction of uracils led to two plausible reaction mechanisms for the oxidation of uracils.
- Itahara,Yoshitake,Koga,Nishino
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p. 2257 - 2264
(2007/10/02)
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- γ-Radiolysis of 1,3-Dimethyluracil in N2O-Saturated Aqueous Solutions
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The γ-radiolysis of N2O-saturated aqueous solutions generates OH radicals and a small amount of H atoms.In 1,3-dimethyluracil solutions (10-3 M) these radicals add mainly to the 5-position of the C(5)-C(6) double bond of the solute.The resulting products have been identified by GC-MS after trimethylsilylation.The major products (G values in brackets) are dimers of the C(5)-OH-adduct radicals (3.4), 5,6-dihydro-5,6-dihydroxy-1,3-dimethyluracil (0.85), 5,6-dihydro-5-hydroxy-1,3-dimethyluracil (0.75), dimer of the C(5)-OH-adduct with the C(5)-H-adduct radical (0.2) and 5,6-dihydro-6-hydroxy-1,3-dimethyluracil (0.2).G(1,3-dimethyluracil consumption) has been found to be 5.7.The major reaction in this system is the dimerisation of the primary radicals.To a small extent the primary radicals also disproportionate by electron transfer to give the glycol 5,6-dihydro-5,6-dihydroxy-1,3-dimethyluracil as one of the products.Radiolytically formed H2O2 which could oxidise the C(5)-OH-adduct radical does not contribute to the formation of the glycol because the H2O2 yield is not reduced with respect to its expected "molecular yield" (G = 0.75).In contrast to the uracil system where it has been reported that drastic changes in radiolytic yields occur on going from neutral to alkaline irradiation conditions no such changes have been observed with 1,3-dimethyluracil.However, an acid-catalysed rearrangement from the C(5)-OH-adduct to the C(6)-OH-adduct radical is observed in the present system. - Keywords: Hydroxyl Radicals, Electron Transfer Reactions, Radical Reactions, DNA Model Systems
- Al-Sheikhly, Mohamed,Sonntag, Clemens von
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p. 1622 - 1629
(2007/10/02)
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