Synthesis, characterization, pharmacological and computational studies of 4, 5, 6, 7-tetrahydro-1, 3-benzothiazole incorporated azo dyes

Synergistic effect of Fenton oxidation and adsorption process in treatment of azo printing dye: DSD optimization and reaction mechanism interpretation

The main challenges to overcome within the Fenton process are the acidic pH as an optimal reaction condition, sludge formation in neutral pH medium and high toxicity of treated printing wastewater due to the generation of contaminating by-products. This research discusses the catalytic activity of homogeneous (FeSO4/H2O2) and heterogeneous (Fe2(MoO4)3/H2O2) Fenton processes in treatment of Yellow azo printing dye in synthetic aqueous solution and real printing effluent, with an integration of adsorption on functionalized biochar synthesized from wild plum kernels. The definitive screening design (DSD), was used to design the experiment. Independent variables were initial dye concentration (20-180 mg L-1), iron concentration (0.75-60 mg L-1), pH (2-10) and hydrogen peroxide concentration (1-11 mM). Higher decolourization efficiency of 79% was obtained within homogeneous Fenton treatment of printing wastewater, in comparison to heterogeneous Fenton treatment (54%), after a reaction time of 60 min. Same trend of mineralization degree was established: COD removal was 59% and 33% for homogeneous and heterogeneous Fenton process, respectively. The application of adsorption treatment has achieved significant advantages in terms of toxicity reduction (95%) and decolourization efficiency (90% of TOC removal and 22% of dye removal) of treated samples, even at neutral pH medium. Degradation mechanisms within Fenton and adsorption processes were proposed based on the qualitative gas chromatography/mass spectrometry analysis, physico-chemical properties of dye degradation products and functionalized biochar. Overall, the homogeneous Fenton/adsorption combined process can be potentially used as a treatment to remove azo dyes from contaminated water.

Investigation on intermolecular interaction of synthesized azo dyes with bovine serum albumin

This research was performed using spectroscopic techniques and molecular docking to elucidate the mechanisms of interaction between bovine serum albumin (BSA) and two novel synthesized azo dyes. The titration of dyes into BSA solution results in quenching of fluorescence emission by complex formation. The UV-Vis spectroscopy confirms that formation of complex in ground state between both dyes and BSA induces conformational and micro environmental changes of the protein. Based on the calculation of the thermodynamic parameters, it can be concluded that both dyes spontaneously bind onto BSA, and van der Waals force and hydrogen bonding interaction played a predominant roles in the process of spontaneous bonding. The average binding distance (r) between protein and both dyes was calculated by Förster energy transfer measurements and revealed both dyes bind to the BSA residues of tryptophan over short distances. The results of molecular docking studies indicated that the probable binding location of both dyes is subdomain IB of BSA via hydrophobic interaction and hydrogen bond. Furthermore, as shown by synchronous fluorescence and Fourier transform infrared spectroscopy, both dyes can lead to conformational changes of BSA, which alter its biological functions.Communicated by Ramaswamy H. Sarma.

Binding elucidation of azo dyes with human serum albumin via spectroscopic approaches and molecular docking techniques

The large number of synthesized azo dyes is widely applied in the food, pharmaceutical, cosmetic, textile, and leather industries. In this study, the binding mechanism of two synthesized dyes with human serum albumin (HSA); as the most abundant protein in plasma; was elucidated by fluorescence spectroscopy, Fourier-transform infrared spectroscopy and molecular modeling methods. The fluorescence quenching measurements showed that each dye can quench the intrinsic fluorescence of HSA via a dynamic quenching mechanism with an increase in concentration. From the thermodynamic data observations, revealed that the binding process is a spontaneous molecular force for each dye with HSA due to hydrophobic interactions and hydrogen bonding. FT-IR spectra showed that the secondary structure of the protein changes due to interaction of each dye with HSA. Furthermore, docking simulation demonstrated that the probable binding location of both dyes is subdomain IIA of HSA (Sudlow site I) and that complex formed is stabilized by hydrophobic interactions and hydrogen bonding.Communicated by Ramaswamy H. Sarma.

Multi technique investigation on interaction between 5-(2-thiazolylazo)-2,4,6-triaminopyrimidine and HSA and BSA

In research laboratories and in various industries, azo compounds are among the most effective and commonly used organic dyes. The association between human (HSA) and bovine (BSA) serum albumins with 5-(2-thiazolylazo)-2,4,6-triaminopyrimidine (TTP) was investigated in this research using spectroscopy methods and molecular modeling study. The fluorescence quenching results showed that the quenching mechanisms were static and dynamic processes for HSA and BSA, respectively. From the thermodynamic observations, it is clear that the binding process is a spontaneous molecular interaction, in which van der Waals and hydrogen bonding interactions for HSA and hydrophobic interaction for BSA play the major roles. According to Förster energy transfer, non-radiative energy transferred from HSA and BSA to TTP, is provided by close distance (r₀) between TTP and Trp residues of HSA and BSA. The synchronous fluorescence spectroscopy, FT-IR findings and UV-Vis absorption data confirm that TTP can induce conformational and micro environmental changes in both the proteins. Furthermore, docking results predicted the probable binding site of TTP in subdomain IIA of HSA and BSA molecules where Trp residues are located. Types of amino acid residues surrounding the TTP molecule supported that van der Waals forces, hydrophobic forces and electrostatic forces play important roles in stabilization of drug-protein complexes formed.Communicated by Ramaswamy H. Sarma.

Fluorescent and Phosphorescent Nitrogen-Containing Heterocycles and Crown Ethers: Biological and Pharmaceutical Applications

Fluorescent molecules absorb photons of specific wavelengths and emit a longer wavelength photon within nanoseconds. Recently, fluorescent materials have been widely used in the life and material sciences. Fluorescently labelled heterocyclic compounds are useful in bioanalytical applications, including in vivo imaging, high throughput screening, diagnostics, and light-emitting diodes. These compounds have various therapeutic properties, including antifungal, antitumor, antimalarial, anti-inflammatory, and analgesic activities. Different neutral fluorescent markers containing nitrogen heterocycles (quinolones, azafluoranthenes, pyrazoloquinolines, etc.) have several electrochemical, biological, and nonlinear optic applications. Photodynamic therapy (PDT), which destroys tumors and keeps normal tissues safe, works in the presence of molecular oxygen with light and a photosensitizing drugs (dye) to obtain a therapeutic effect. These compounds can potentially be effective templates for producing devices used in biological research. Blending crown compounds with fluorescent residues to create sensors has been frequently investigated. Florescent heterocyclic compounds (crown ether) increase metal solubility in non-aqueous fluids, broadening the application window. Fluorescent supramolecular polymers have widespread use in fluorescent materials, fluorescence probing, data storage, bio-imaging, drug administration, reproduction, biocatalysis, and cancer treatment. The employment of fluorophores, including organic chromophores and crown ethers, which have high selectivity, sensitivity, and stability constants, opens up new avenues for research. Fluorescent organic compounds are gaining importance in the biological world daily because of their diverse functionality with remarkable structural features and positive properties in the fields of medicine, photochemistry, and spectroscopy.

Pyridine Scaffolds, Phenols and Derivatives of Azo Moiety: Current Therapeutic Perspectives

Synthetic heterocyclic compounds have incredible potential against different diseases; pyridines, phenolic compounds and the derivatives of azo moiety have shown excellent antimicrobial, antiviral, antidiabetic, anti-melanogenic, anti-ulcer, anticancer, anti-mycobacterial, anti-inflammatory, DNA binding and chemosensing activities. In the present review, the above-mentioned activities of the nitrogen-containing heterocyclic compounds (pyridines), hydroxyl (phenols) and azo derivatives are discussed with reference to the minimum inhibitory concentration and structure–activity relationship, which clearly indicate that the presence of nitrogen in the phenyl ring; in addition, the hydroxyl substituent and the incorporation of a diazo group is crucial for the improved efficacies of the compounds in probing different diseases. The comparison was made with the reported drugs and new synthetic derivatives that showed recent therapeutic perspectives made in the last five years.

Diaryl azo derivatives as anti-diabetic and antimicrobial agents: synthesis, in vitro, kinetic and docking studies

In the present study, a series of azo derivatives (TR-1 to TR-9) have been synthesised via the diazo-coupling approach between substituted aromatic amines with phenol or naphthol derivatives. The compounds were evaluated for their therapeutic applications against alpha-glucosidase (anti-diabetic) and pathogenic bacterial strains E. coli (gram-negative), S. aureus (gram-positive), S. aureus (gram-positive) drug-resistant strain, P. aeruginosa (gram-negative), P. aeruginosa (gram-negative) drug-resistant strain and P. vulgaris (gram-negative). The IC₅₀ (µg/mL) of TR-1 was found to be most effective (15.70 ± 1.3 µg/mL) compared to the reference drug acarbose (21.59 ± 1.5 µg/mL), hence, it was further selected for the kinetic studies in order to illustrate the mechanism of inhibition. The enzyme inhibitory kinetics and mode of binding for the most active inhibitor (TR-1) was performed which showed that the compound is a non-competitive inhibitor and effectively inhibits the target enzyme by binding to its binuclear active site reversibly.

Rapid, sensitive, and selective copper (II) determination using sensitive chromogenic azo dye based on sulfonamide

A simple methods have been developed for determination of Cu(II) ions in aqueous solutions. The spectrophotometric method relied mainly on the reaction between Cu(II) ions and the azo dye ligand named N-diaminomethylene-4-(2,4-dihydroxy-phenylazo)-benzenesulfonamide (H₂L) at pH 10.0. The influence of parameters such as concentration, pH and reaction time were inspected. A linear relationship (R² = 0.9992) between absorbance and the concentration of Cu(II) was obtained at themaximum absorptionpeak of 474 nm within 1.6-9.6 × 10^-6 mol L^-1 concentration range. The limit of detection for Cu(II) ion and limit of quantitation were 1.1 × 10^-7 mol L^-1 and 3.7 × 10^-7 mol L^-1, respectively.The potentiometric method is based on a novel poly(vinyl chloride) membrane, containing the synthesized azo dye as an ionophore, was used to developed a Cu(II)- selective sensor. This newly developed sensor revealed a Nernstian response over Cu²⁺ ion in a concentration range 1.0 × 10^-6-1.0 × 10^-2 mol L^-1 with cationic slopes of 29.5 ± 0.2 mV decade^-1 and detection limits of 3.0 × 10^-6 mol L^-1 copper(II) for o-nitrophenyl-octyl ether (o-NPOE) based membrane sensor. The electrode showed good discrimination toward Cu²⁺ ions with respect to most common cations. The advantages of the proposed methods are their simplicity, selectivity, and high sensitivity. In addition, the sensor has been used as indicator electrode in the potentiometric titration of Cu²⁺ ion against EDTA. The structure and geometry of the complex formed between Cu(II) and H₂L ligand was identified via isolation of the solid complex; Co(II) an Ni(II) complexes were synthesized as well. The geometrical structure around the metal centers were proved to be square planar for Cu(II) complex and tetrahedral for Co(II) an Ni(II) complexes.

Synthesis, Anti-Bacterial and Anti-Oxidant Activity of Azo-Oxazolone and Their Ring Opening Azo-Benzamide Derivatives

This article describes the controlled synthesis and characterization of azo oxazolone scaffold compounds containing multifunctional groups such as carbonyl group, imine and carbon-carbon double bond. The reaction of the azo-oxazolone with aromatic amines led to the ring-opening of the azo-oxazolone into the corresponding azo-benzamide derivatives in a short time (average 10 min), resulting in high yield (>90%). All newly synthesized compounds were characterized by the common spectral analysis such as UV, IR, ¹H-NMR, ¹³CNMR, Elemental analysis and MS spectrometry.

OBJECTIVE

The aim of the study was to synthesize new bioactive azo-benzamides by using azo-oxazolone as a synthon utilizing its ring-opening function.

MATERIALS AND METHODS

Azo-benzamide derivatives were prepared in very good yield via ring-opening reaction of azo-oxazolone with aromatic amines in the presence of acetic acid under reflux for few minutes.

RESULTS AND DISCUSSION

Chemical structures of the newly synthesized compounds were characterized by UV, IR, ¹H-NMR, ¹³C-NMR, Elemental analysis and MS spectrometry.

CONCLUSION

The new azo-oxazolone 4 and azo-benzamide compounds 5a, 5c, 5f, 5h, 5j were screened against Escherichia coli as G(-ve) and Staphylococcus aureus as G(+ve) using ciprofloxacin as a standard. All compounds showed high inhibition potency against E-Coli but low inhibition for S-aureus. Compounds 4, 5c, and 5J showed more reactivity against E-coli. Others: Also, the compounds were tested for their anti-oxidant activity by both DPPH and FRAP methods. The results showed that some compounds possessed moderate anti-oxidant activity in comparison to ascorbic acid as control, typically the compounds bearing OCH₃ and OCH₂CH₃ groups.

UV protective heterocyclic disperse azo dyes: Spectral properties, dyeing, potent antibacterial activity on dyed fabric and comparative computational study

Disperse azo dyes are synthesized and characterized by ¹H NMR, ¹³C NMR, LC-MS, Elemental analysis, UV-visible, and fluorescence spectroscopy methods. The azo dyes show absorption maxima in the range of 460-493 nm. Dye with benzothiazole moiety i.e. VM7a and VM8a show a bathochromic shift in absorption maxima of 90 and 26 nm respectively in a polar aprotic solvent (i.e. DMF, DMSO). The dyes show deep red emission in a polar aprotic solvent (i.e. DMF, DMSO) with a Stokes shift of 62 to 180 nm. The dyes are applied on polyester fabric and the dyed fabric exhibit excellent to a good wash and sublimation fastness property. They show a very good UPF rating and almost blocking 95 to 98% of harmful UV radiation. Antibacterial activity of dyed polyester fabric is assessed qualitatively and quantitatively by using AATCC 147 and 100 test method respectively. The dyed fabrics exhibit excellent antibacterial activities against S.aureus (Gram-positive) and K. pneumoniae (Gram-negative). DFT method was used to identify the stable conformer. HOMO-LUMO gap and global reactivity descriptors were calculated using DFT method and correlated with antibacterial activities and light fastness properties respectively.