Newly synthesized 2-(2-((1
-indol-5yl)methylene)-hydrazinyl)-thiazole derivatives were evaluated for their in vitro cytotoxicity on two carcinoma cell lines A2780 and HeLa. Significant cytotoxic ...activity for 2-(2-((1
-indol-5-yl)methylene)hydrazinyl)-4-methylthiazole (
) and 2-(2-((1
-indol-5-yl)methylene)hydrazinyl)-4-phenylthiazole (
), on both A2780 IC
: 11.6 μM (
), and 12.4 μM (
) and HeLa IC
: 22.4 μM (
) and 19.4μM (
) cell lines is reported. Their antioxidant potential was evaluated by spectrophotometric method, using DPPH radical or Fe (TPTZ)
complex, and EPR spectroscopy, therefore the compounds
and
showed remarkable antioxidant activity simultaneously with a cytotoxic effect on A2780 and HeLa cell lines. Furthermore, based on theoretical quantum chemical calculation, the present study analyzed the chemoselectivity of the hydrogen extraction from the indolyl-hydrazinil-thiazoles in reaction with free radicals.
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•Propolis is an efficient green corrosion inhibitor for bronze surface.•The inhibitive effectiveness of propolis on bronze is time-dependent.•The main organic constituents of propolis ...sample were identified by HPLC-DAD.•The adsorption of propolis on bronze surface obeys Langmuir isotherm.
In the present work, the inhibitive action of natural propolis on bronze corrosion in a weakly acidic solution containing Na2SO4 and NaHCO3 at pH 5 was evaluated using multiscale electrochemical techniques, namely potentiodynamic polarization, electrochemical impedance spectroscopy and scanning vibrating electrode technique measurements. The major constituents of propolis were identified by HPLC. Surface characterization was performed by SEM-EDX and AFM analysis. Experiments were performed as a function of the propolis concentration and immersion time in the corrosive electrolyte. The obtained results showed that propolis presents good anticorrosive properties on bronze, acting as a mixed-type inhibitor, but its protective effectiveness is time-dependent. The highest inhibiting efficiency of 98.9% was obtained in the presence of 100ppm propolis, after about 12h of exposure to inhibitor-containing electrolyte through the stabilization of Cu2O on the bronze surface. The inhibitive properties of propolis on bronze corrosion are likely due to the adsorption of its main constituents (flavonoids and phenolic compounds), through the oxygen atoms in their functional groups and aromatic rings, which have been evidenced by FT-IR spectra. The adsorption of propolis on bronze was found to follow Langmuir adsorption isotherm.
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•Horse-chestnut extract (HCE) applied on bronze for corrosion protection.•HCE addition decreased corrosion current and enhanced the surface film resistance.•The best protection was ...achieved after 14 h in a solution containing 0.5 g L−1 HCE.•HCE-bronze interaction arises from physisorption described by Langmuir isotherm.•Novel analytical methodology for SECM kinetic study on inhibitor adsorption.
Horse-chestnut ethanolic extract was tested as potential corrosion inhibitor of bronze in simulated acid rain. The extract was analysed by FTIR, GC–MS and HPLC-PDA, and its anti-corrosion behaviour studied using a multiscale electrochemical approach by polarization curves, EIS and scanning electrochemical microscopy, along with SEM-EDS. 94 % inhibition efficiency was attained by developing a surface physisorbed film. A novel methodology for kinetic evaluation of dynamic adsorption of inhibitive species on metal surface is proposed using SECM, achieving good agreement with results from conventional electrochemical techniques. Excellent adsorption-desorption kinetic constants (ka = 0.102 s−1 mol−1 L; kd = 3.33 × 10-5 s−1) were determined.
Herein we report the synthesis of two novel series of 1,3-thiazole derivatives having a lipophilic C4-substituent on account of the increasing need for novel and versatile antifungal drugs for the ...treatment of resistant
-based infections. Following their structural characterization, the anti-
activity was evaluated in vitro while using the broth microdilution method. Three compounds exhibited lower Minimum Inhibitory Concentration (MIC) values when compared to fluconazole, being used as the reference antifungal drug. An in silico molecular docking study was subsequently carried out in order to gain more insight into the antifungal mechanism of action, while using lanosterol-C14α-demethylase as the target enzyme. Fluorescence microscopy was employed to further investigate the cellular target of the most promising molecule, with the obtained results confirming its damaging effect towards the fungal cell membrane integrity. Finally, the distribution and the pharmacological potential in vivo of the novel thiazole derivatives was investigated through the study of their binding interaction with bovine serum albumin, while using fluorescence spectroscopy.
New and known arylidene-hydrazinyl-thiazole derivatives have been synthesized by a convenient Hantzsch condensation. All compounds were evaluated for their in vitro cytotoxicity on two carcinoma cell ...lines, MDA-MB231 and HeLa. Significant antiproliferative activity for 2-(2-benzyliden-hydrazinyl)-4-methylthiazole on both MDA-MB-231 (IC50: 3.92 µg/mL) and HeLa (IC50: 11.4 µg/mL) cell lines, and for 2-2-(4-methoxybenzylidene) hydrazinyl-4-phenylthiazole on HeLa (IC50: 11.1 µg/mL) cell line is reported. Electrophoresis experiments showed no plasmid DNA (pTZ57R) cleavage in the presence of the investigated thiazoles.
Synthesis, structural characterization and photophysical properties for a series of new
-A
B
- and A
B-type ethynyl functionalized
-phenothiazinyl-phenyl porphyrin derivatives are described. The new ...compounds displayed the characteristic porphyrin absorption spectra slightly modified by weak auxochromic effects of the substituents and fluorescence emission in the range of 651-659 nm with 11-25% quantum yields. The changes recorded in the UV-vis absorption spectra in the presence of trifluoroacetic acid (TFA) are consistent with the protonation of the two internal nitrogen atoms of the free-base porphyrin (19 nm bathochromic shift of the strong Soret band and one long wave absorption maxima situated in the range of 665-695 nm). Protonation of the phenothiazine substituents required increased amounts of TFA and produced a distinct hypsochromic shift of the long wave absorption maxima. The density functional theory (DFT) calculations of a porphyrin dication pointed out a saddle-distorted porphyrin ring as the ground-state geometry.
► Phenothiazine derivatives are efficient inhibitors for bronze corrosion. ► Potentiodynamic polarization and EIS were used to elucidate inhibition mechanism. ► Adsorption of phenothiazine ...derivatives on bronze surface obeys Langmuir isotherm. ► A correlation between energy gaps and inhibition efficiencies values was obtained.
Four phenothiazine derivatives have been tested as inhibitors for bronze corrosion in a solution containing Na2SO4 and NaHCO3 (pH 5).
Electrochemical investigations (potentiodynamic polarisation and impedance measurements) revealed that all phenothiazine derivatives exert a protective effect against bronze corrosion and, in some cases their inhibition efficiency exceeds 90% at concentration level as low as 75μM. An adherent layer of organic molecules chemisorbed on bronze surface is responsible for the protective effect of the investigated compounds. Adsorption of phenothiazine derivatives on bronze obeys Langmuir isotherm. Correlation between quantum chemical calculations and inhibition efficiency of the investigated compounds was discussed using DFT method.
Series of new heterocyclic Schiff bases enclosing a systematic variation of the azomethine linker position on the phenothiazine building block were advantageously obtained by the microwave assisted ...condensation of constitutional isomers of 10-methyl-10Hphenothiazine-carbaldehyde with primary aryl-amines (2-aminonaphthalene, 2-aminofluorene, 2- and 3-amino-10-methyl-phenothiazine respectively). Their electronic properties were emphasized by means of UV–Vis absorption/emission spectroscopy and cyclic voltammetry. The phenothiazine chromophore unit appeared responsible for large Stokes shifts of the UV absorption maxima towards emission maxima situated in the visible range (471–597nm) largely influenced by the variation of the solvent polarity. Cyclic voltammetry experiments emphasized reversible redox processes suggesting the formation of phenothiazinium radical cation species in consecutive steps correlated to the number of phenothiazine units embedded in the molecular structure. The experimental outcomes and computational data simulating the molecular orbitals of the synthesized phenothiazine derivatives were corroborated for a rational understanding of the similarity in the properties of congeners.
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•Microwave assisted synthesis of mono- and bis-phenothiazinyl-azomethines.•Systematic variation of the azomethine position on the phenothiazine building block•Phenothiazinium/phenothiazine redox couple emphasized by cyclic voltammetry.•Positive solvatochromism of fluorescence emissions in the visible region (471–597nm)
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•New organic coatings for patinated bronze protection were tested in simulated rain.•Time-degradation of the coatings based on nitrocellulose lacquer was monitored by EIS.•Addition of ...organic inhibitors into lacquer enhance its protective properties.•MAT-added coating offers the highest long-lasting protection to patinated bronzes.•FTIR spectra evidenced interactions between inhibitor and lacquer functional groups.
In the present work, the efficiency and time-degradation of new protective organic coatings for artificially patinated bronze based on nitrocellulose lacquer containing thiadiazole derivatives (2-mercapto-5-amino-1,3,4-thiadiazole and 2-mercapto-5-methyl-1,3,4-thiadiazole) as corrosion inhibitors were investigated. The samples were intermittently exposed to a solution simulating an urban rain (pH 5) and their behaviour was monitored for nearly three months by electrochemical impedance spectroscopy (EIS) measurements.
Optical microscopy examination of cross sections of bronze samples covered with patina and nitrocellulose lacquer, without and with inhibitors, was used to determine the thickness of the coatings. Fourier transformed infrared spectroscopy (FT-IR) was employed to put on evidence the chemical interactions between the organic inhibitors and nitrocellulose lacquer functional groups.
The best results were achieved in the presence of 2-mercapto-5-amino-1,3,4-thiadiazole into the nitrocellulose lacquer coating, which offers the highest long-lasting protection to patinated bronzes, without changing the visual appearance of the bronze surfaces covered with patina. This approach proved to be a promising alternative to benzotriazole in the development of highly protective coatings for patinated bronzes.
The molecular frame of the reported series of new polyheterocyclic compounds was intended to combine the potent phenothiazine and benzothiazole pharmacophoric units. The synthetic strategy applied ...was based on oxidative cyclization of
-(phenothiazin-3-yl)-thioamides and it was validated by the preparation of new 2-alkyl- and 2-aryl-thiazolo5,4-
phenothiazine derivatives. Optical properties of the series were experimentally emphasized by UV-Vis absorption/emission spectroscopy and structural features were theoretically modelled using density functional theory (DFT). In vitro activity as antileukemic agents of thiazolo5,4-
phenothiazine and
-(phenothiazine-3-yl)-thioamides were comparatively evaluated using cultivated HL-60 human promyelocytic and THP-1 human monocytic leukaemia cell lines. Some representatives proved selectivity against tumour cell lines, cytotoxicity, apoptosis induction, and cellular metabolism impairment capacity. 2-Naphthyl-thiazolo5,4-
phenothiazine was identified as the most effective of the series by displaying against THP-1 cell lines a cytotoxicity close to cytarabine antineoplastic agent.
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