thiourea and acetylthiourea

Currently used thiourea-based two-component dental materials may release bitter compounds if they are not properly cured. To address this issue, the objective of this study was to evaluate the potential of acylthiourea oligomers as reducing agents for the development of self-cure composites.. Acylthiourea oligomers ATUO1-3 were successfully synthesized in good yields. Both the oligomer molecular weight and the amount of thiourea groups were varied. Self-cure composites containing ATUO1 or ATUO2 as reducing agents exhibited excellent mechanical properties and high double-bond conversions. The amounts of reducing agent, cumene hydroperoxide and copper(II) acetylacetonate were shown to have a significant impact on the working time. Moreover, a correlation between flexural modulus and the amount of metal salt was clearly established. Self-cure composites containing the oligomer ATUO1 exhibited a longer working time than materials containing ATU1 or acetylthiourea. Contrary to acetylthiourea, ATUO1 was not able to leach out of light-cured composites.. Acylthiourea oligomers are promising reducing agents for the formulation of two-component dental materials that do not induce a bitter taste in mouth.

Topics: Bisphenol A-Glycidyl Methacrylate; Composite Resins; Dental Materials; Materials Testing; Methacrylates; Pliability; Polymethacrylic Acids; Reducing Agents; Thiourea

Lysine deacetylases (KDACs) are enzymes that reverse the post-translational modification of lysine acetylation. Recently, a series of N-acetylthioureas were synthesized and reported to enhance the activity of KDAC8 with a fluorogenic substrate. To determine if the activation was general, we synthesized three of the most potent N-acetylthioureas and measured their effect with peptide substrates and the fluorogenic substrate under multiple reaction conditions and utilizing two enzyme purification approaches. No activation was observed for any of the three N-acetylthioureas under any assayed conditions. Further characterization of KDAC8 kinetics with the fluorogenic substrate yielded a kcat/KM of 164 ± 17 in the absence of any N-acetylthioureas. This catalytic efficiency is comparable to or higher than that previously reported when KDAC8 was activated by the N-acetylthioureas, suggesting that the previously reported activation effect may be due to use of an enzyme preparation that contains a large fraction of inactive enzyme. Further characterization with a less active preparation and additional substrates leads us to conclude that N-acetylthioureas are not true activators of KDAC8 and only increase activity if the enzyme preparation is below the maximal basal activity.

Topics: Enzyme Assays; Fluorescamine; Histone Deacetylases; Humans; Kinetics; Recombinant Proteins; Repressor Proteins; Substrate Specificity; Thiourea

We report, for the first time, that certain N-acetylthiourea derivatives serve as highly potent and isozyme selective activators for the recombinant form of human histone deacetylase-8 in the assay system containing Fluor-de-Lys as a fluorescent substrate. The experimental data reveals that such activating feature is manifested via decrease in the K(m) value of the enzyme's substrate and increase in the catalytic turnover rate of the enzyme.

Topics: Benzamides; Binding Sites; Dose-Response Relationship, Drug; Drug Design; Drug Discovery; Enzyme Activation; Enzyme Activators; Fluorescent Dyes; Histone Deacetylases; Humans; Isoenzymes; Kinetics; Models, Chemical; Molecular Targeted Therapy; Phenylthiourea; Software; Structure-Activity Relationship; Substrate Specificity; Thiourea

Treatment with concd HCl/MeOH transformed N-(tetra-O-acetyl-beta-D-glucopyranosyl)-N'-acetylthiourea, via selective cleavage of the primary alcoholic ester group, into the title compound.

Topics: Hydrochloric Acid; Methanol; Molecular Structure; Thiourea

The oxidation reactions of N-acetylthiourea (ACTU) by chlorite and chlorine dioxide were studied in slightly acidic media. The ACTU-ClO(2)(-) reaction has a complex dependence on acid with acid catalysis in pH > 2 followed by acid retardation in higher acid conditions. In excess chlorite conditions the reaction is characterized by a very short induction period followed by a sudden and rapid formation of chlorine dioxide and sulfate. In some ratios of oxidant to reductant mixtures, oligo-oscillatory formation of chlorine dioxide is observed. The stoichiometry of the reaction is 2:1, with a complete desulfurization of the ACTU thiocarbamide to produce the corresponding urea product: 2ClO(2)(-) + CH(3)CONH(NH(2))C=S + H(2)O --> CH(3)CONH(NH(2))C=O + SO(4)(2-) + 2Cl(-) + 2H(+) (A). The reaction of chlorine dioxide and ACTU is extremely rapid and autocatalytic. The stoichiometry of this reaction is 8ClO(2)(aq) + 5CH(3)CONH(NH(2))C=S + 9H(2)O --> 5CH(3)CONH(NH(2))C=O + 5SO(4)(2-) + 8Cl(-) + 18H(+) (B). The ACTU-ClO(2)(-) reaction shows a much stronger HOCl autocatalysis than that which has been observed with other oxychlorine-thiocarbamide reactions. The reaction of chlorine dioxide with ACTU involves the initial formation of an adduct which hydrolyses to eliminate an unstable oxychlorine intermediate HClO(2)(-) which then combines with another ClO(2) molecule to produce and accumulate ClO(2)(-). The oxidation of ACTU involves the successive oxidation of the sulfur center through the sulfenic and sulfinic acids. Oxidation of the sulfinic acid by chlorine dioxide proceeds directly to sulfate bypassing the sulfonic acid. Sulfonic acids are inert to further oxidation and are only oxidized to sulfate via an initial hydrolysis reaction to yield bisulfite, which is then rapidly oxidized. Chlorine dioxide production after the induction period is due to the reaction of the intermediate HOCl species with ClO(2)(-). Oligo-oscillatory behavior arises from the fact that reactions that form ClO(2) are comparable in magnitude to those that consume ClO(2), and hence the assertion of each set of reactions is based on availability of reagents that fuel them. A computer simulation study involving 30 elementary and composite reactions gave a good fit to the induction period observed in the formation of chlorine dioxide and in the autocatalytic consumption of ACTU in its oxidation by ClO(2).

Topics: Catalysis; Chlorides; Chlorine Compounds; Computer Simulation; Halogens; Hydrogen-Ion Concentration; Kinetics; Models, Chemical; Oxidation-Reduction; Oxides; Sulfates; Sulfenic Acids; Sulfhydryl Compounds; Sulfinic Acids; Sulfites; Sulfur; Thiourea; Urea

The authors have examined the possibility of replacing sodium arsenite with acetyl thiourea and of using butanol acidified with phosphoric acid in measuring sialic acids in biologic material. The results evidence a sufficient specificity, reproducibility, higher sensitivity and lower toxicity of the modification as compared to the routine technique, for this modification does not involve the use of highly toxic sodium arsenite and of highly volatile aggressive butanol/hydrochloric acid mixture.

Topics: Arsenic; Arsenites; Humans; Indicators and Reagents; N-Acetylneuraminic Acid; Sialic Acids; Sodium Compounds; Thiobarbiturates; Thiourea