2-thiobarbituric Acid Reaction Research Articles

Co-crystals of thiobarbituric acid and N-heterocyclic compounds: Synthesis, structural, solubility, computational, and antilymphoma activity

Two new co-crystals (1–2) were prepared by the reaction of 2-thiobarbituric acid with N-heterocyclic compounds, and successfully characterized. X-ray analysis shows that 1 and 2 have zig-zag and ladder like supramolecular frameworks, respectively. HOMO-LUMO analysis of optimized geometries confirmed the lesser band gap of 1 and 2. Co-crystals 1–2 have solubility values of 19.737 and 25.652 mg/ml, respectively, and they may have good bioactivity. The cytotoxic activity of 1–2 indicated the tumor growth inhibitory ability of 1 and 2 against T cell lymphoma. Interestingly, apoptosis evaluation by Wright-Giemsa and DAPI staining suggested that 1 and 2 mediated tumor cell death through apoptosis induction. In addition, the estimation of glucose, pH, and NO also indicated the possible role of inhibited glucose uptake and augmented NO production in the cell death mediated by 1 and 2.

Immobilized Ni on TMEDA@βSiO2@αSiO2@Fe3O4: as a novel magnetic nanocatalyst for preparation of pyrido[2,3-d:6,5-d']dipyrimidines.

In the current body of research, a very quick and effectual procedure for the synthesis of pyrido[2,3-d:6,5-d']dipyrimidines has been developed. This method is accomplished through the one-pot multi-component reaction of 2-thiobarbituric acid, NH4OAc and aldehydes utilizing Ni-TMEDA@βSiO2@αSiO2@Fe3O4 as a novel mesoporous nanomagnetic catalyst at room temperature. This protocol is one of the few reports of the preparation of these derivatives without the use of conventional heating as well as energies such as microwave and ultrasound radiation. The characterization of the prepared catalyst was well accomplished by different techniques such as FT-IR, ICP-OES, SEM, TEM, BET, XRD, VSM, TGA, EDX and Elemental mapping. This organometallic catalyst was reusable for seven times with negligible decrement in its catalytic performance. In addition, all of the products were produced with high TON and TOF values, which demonstrates that our catalyst has a very high level of activity in the preparation of pyrido[2,3-d:6,5-d']dipyrimidines.

Growth inhibition of bacterial pathogens by photo-catalyst process of nano-alloys FeCuNi doped TiO2 under ultraviolet irradiation

This study reports the application of FeCuNi nano-alloy doped TiO2 synthesized via the sol-gel method as an antibacterial with a sterilization rate greater than 95% under ultra-violet (UV) irradiation. The performance was characterized using X-ray diffraction (XRD), thermal analysis (TG-DTA), scanning electron microscope (SEM-EDX), and transmission electron microscope (TEM). The results showed that the sterilization process of FeCuNi–TiO2 in cell suspension of Escherichia coli, Staphylococcus aureus and Bacillus subtilis increased the effectiveness of UV irradiation at wavelength (λ) ≥ 385 nm after 120 min. The optimum growth inhibition of FeCuNi–TiO2 was observed in the concentrations 1.5 g/L of E. coli, 1.5 g/L of S. aureus and 2.0 g/L of B. subtilis. The highest antimicrobial efficiency of FeCuNi–TiO2 powder was provided by a particle size of 16.8 nm, surface area of 70.98 m2/g. The increased antimicrobial activity in multiplied-three doped ions was related to the increase of illumination energy of UV absorption in the photo-catalyst process. The inhibition mechanism reaction of the three species of bacteria cell affects the lipid peroxidation process at the microbe cell’s wall. This was indicated by the formation of malondialdehyde (MDA). Lipid oxidation was based on the reaction of 2-thiobarbituric acid (TBARS) as an indicator of primary and secondary oxidation.

Selectivity in the Formation of Straight-Chain Versus Cyclised products on Knoevenagel Condensation between Thiobarbituric acid and Naphthaldehydes

The prevalence of Clostridium difficile (CD) infection has grown rapidly due to resistance and the emergence of new, highly virulent strains of the organism that have become less sensitive to many antibiotics. Vancomycin and metronidazole are front-line treatments of CD infection that still show good efficacy, but their effectiveness has declined for the treatment of recurrent infection and less sensitive strains of CD. More recently, the macrolide antibiotic fidaxomicin been introduced in the treatment of CD infection. Its high cost and limited usefulness against recurrent infection has prompted the search for new, narrow spectrum agents. We identified the CD dihydroorotate dehydrogenase (DHODase) as a potential enzyme target for the design of Knoevenagel products formed from reaction of 2-thiobarbituric acid and naphthaldehyde substrates. The presence of a hydroxyl substituent at position C2 in the naphthaldehyde ring offers the possibility to form the Knoevenagel product and to cyclize to give the tetracyclic, oxadeazaflavine with benzo-homologation. In this work, the selectivity for straight-chain formation over competing cyclisation on Knoevenagel condensation between thiobarbituric acid and naphthaldehyde substrates was examined. The outcomes of uncatalyzed condensations in refluxing ethanol were investigated by various methods including high field 1H and 13C NMR. Unsubstituted naphthaldehyde and its 2-methoxyl derivative favored straight-chain product formation whereas use of 2-hydroxynaphthaldehyde favored cyclisation and concomitant Michael addition of a second molecule of the corresponding acid to the newly formed exocyclic C=C bond. The pattern of reactivity was mirrored in the benzaldehyde series where the presence of the 2-hydroxyl function led to cyclized products with concomitant formation of the Michael adducts. The Knoevenagel products and the benzo-homologated oxadeazaflavine derivatives are candidates for evaluation as potential growth inhibitors of CD.

Microwave-assisted synthesis of pyrido-dipyrimidines using magnetically CuFe2O4 nanoparticles as an efficient, reusable, and powerful catalyst in water

An efficient and direct procedure for the synthesis of pyrido[2,3-d:6,5-d′]dipyrimidine derivatives has been described under microwave-assisted conditions. The reaction of 2-thiobarbituric acid with aromatic aldehydes and ammonium acetate catalyzed by CuFe2O4 nanoparticles was resulted in the formation of pyrido[2,3-d:6,5 d′]dipyrimidine derivatives. The corresponding products have been obtained in excellent isolated yields with high purity, in short reaction times and easy workup.

Photoinduced Electron Transfer Reaction of 2-Thiobarbituric Acid and Methylene Blue: Mechanism and Kinetics

Barbiturates are known to have hypnotic properties and are used as active moiety on central nervous system. Depends up on the experiments conditions and functional group present on the drugs, make the drugs labile to photodecomposition. The photosensitized reaction of 2-thiobarbituric acid (2TBA) with methylene blue (MB) in alkaline medium using visible light has been studied. 2TBA exists in protonated and deprotonated form in equilibrium in alkaline medium. Photosensitized electron transfer from the deprotonated 2TBA to excited state MB takes place and the energy is transferred to 2TBA molecule which undergoes chemical reaction. The interconversion of protonated form to deprotonated form during the reaction is observed. The rate of the reaction has been calculated and the effect of pH, concentration of the sensitizer, the light intensity on the rate of the reaction has been studied. The quantum efficiency of the photo chemical reaction is calculated using potassium ferrioxalate actinometer and the effect of the concentration of the substrate on the quantum efficiency is calculated. The reaction mechanism and the excited states involved have been suggested.

Spectrophotometric Determination and Kinetic Studies of Condensation of Aromatic Aldehydes with 2-Thiobarbituric Acid

The condensation reaction of 2-thiobarbituric acid with aromatic aldehydes in ethanol has been investigated spectrophotometrically at 30-50°;C. The reaction was catalyzed by HCl solutions. The reaction follows overall second order kinetics, first order each in reactant. Activation parameters have been calculated from the dependence of the rate constants on temperature. The rate of condensation increases with the presence of electron donating groups on the aromatic ring of the aldehyde. The rate-determining step involves dehydration of the aldol intermediate. Based on this reaction, determination of 13 aromatic aldehydes in a concentration range of 0.149-76 mu;g/ml is proposed.

Elimination of spectral interferences in the reaction of 2-thiobarbituric acid with malonaldehyde, 2-furfuraldehyde and 5-hydroxymethyl-2-furfuraldehyde by partial least squares multivariate calibration (PLS)

The spectral resolution of ternary mixtures of malonaldehyde (MLD), 2-furfuraldehyde (FUR) and 5-hydroxymethyl-2-furfuraldehyde (HMF) in the presence of glyoxal and biliverdine is achieved by partial least squares multivariate calibration (PLS). The spectrophotometric method is based on the reaction of these substances with 2-thiobarbituric acid (TBA). A calibration set of standard samples has been statistically designed in the presence of adequate amounts of both interferent compounds in several degrees of concentration. The possibility of a spectrophotometric determination of mixtures of MLD, FUR and HMF in the presence of glyoxal and biliverdine is demonstrated. A comparative study of the results found by application of PLS-1 and PLS-2 methods is presented.

Base Catalyzed Condensation of Thiobarbituric Acid with Some Aromatic Aldehydes

In this paper the base catalyzed condensation reaction of 2-thiobarbituric acid with some aromatic aldehydes resulting in the formation of 5-arylidene-2-thiobarbituric acids is described. The condensation reaction of 2-thiobarbituric acid was carried out with 4-methoxybenzaldehyde, 4-ethoxybenzaldehyde, 4-benzyloxybenzaldehyde, and 1-naphthaldehyde using morpholine as a catalyst.

The reaction of 2-thiobarbituric acid with biologically active alpha, beta-unsaturated aldehydes

The standard assay for lipid peroxidation is the measurement of the pink, 532 n, absorbing chromogen which is formed upon reaction of 2-thiobarbituric acid (TBA) with the lipid peroxidation product malonaldehyde (MDA). The present studies indicate that the toxic lipid peroxidation product trans-4-hydroxynonenal and its dehydration product trans, trans-nonadienal react with TBA to form chromogens which absorb maximally at 530 and 532 nm, respectively. Other biologically active alpha, beta-unsaturated aldehydes, such as acrolein and crotonaldehyde, short-chain homologs of alkenals formed during lipid peroxidation, and trans,trans-muconaldehyde, a novel diene dialdehyde, react with TBA to form products which absorb maximally at 495 nm. The molar extinction coefficients of the aldehyde: TBA chromogens formed were found to vary widely, suggesting that only small contributions to the 532 nm absorption by TBA adducts of reactive aldehydes other than MDA may be encountered during the use of the TBA assay.

The reaction of 2-thiobarbituric acid with biologically active alpha, beta-unsaturated aldehydes

The reaction of 2-thiobarbituric acid with biologically active alpha, beta-unsaturated aldehydes

2-Thiobarbituric acid as a reagent for the determination of bismuth(III) by normal and derivative spectrophotometry

A spectrophotometric study of the reaction of 2-thiobarbituric acid (TBA; 4,6-dihydroxy-2-mercaptopyrimidine) with bismuth(III) is presented. Bismuth(III) forms a coloured complex with an absorbance maximum at 416 nm with TBA in acid solution (pH 1.2–1.7). The maximum absorbance value is achieved within about 25 min. Beer's law is obeyed for a bismuth concentration of up to 10.2 µg ml–1. The molar absorptivity of the complex is 2.4 × 104 l mol–1 at 416 nm and the sensitivity of the reaction is, according to Sandell's calculation, 8.7 × 10–3µg cm–2 per 0.001 absorbance unit. Cobalt(II), nickel(II), magnesium(II), tin(II), lead(II), zinc(II), barium(II), manganese(II) and aluminium(III) do not interfere in the determination. The same procedure can also be used for the spectrophotometric determination of copper(II), which seriously interferes in the bismuth determination. A satisfactory method for the determination of bismuth in the presence of copper by derivative spectrophotometry is, however, reported.