2-mercaptobenzothiazole generates γ-H2AX via CYP2E1-dependent production of reactive oxygen species in urothelial cells.

Ortho (o)-toluidine is a widely known carcinogenic substance associated with cancers of the human bladder. A study on British chemical factory workers exposed to 2-mercaptobenzothiazole, phenyl-ß-naphthylamine, aniline, and o-toluidine demonstrated the crucial roles of o-toluidine, 2-mercaptobenzothiazole, and phenyl-ß-naphthylamine in the development of bladder cancer. As genotoxic events are crucial steps in the initiation of cancer, in the present study, we aimed to examine the genotoxic potential of the four chemicals using phosphorylated histone H2AX (γ-H2AX), which is a sensitive and reliable marker of DNA damage, in cultured human urothelial cells. Of the four chemicals, 2-mercaptobenzothiazole was a particularly potent DNA-damaging agent. Moreover, mechanistic studies revealed that γ-H2AX generation by 2-mercaptobenzothiazole was mainly associated with the generation of reactive oxygen species via cytochrome P450 2E1-mediated metabolism. The findings of this study may provide information that is important for the assessment of risks associated with chemicals as well as the interpretation of epidemiological studies investigating occupational bladder cancer.

Modern Approaches to the Synthesis and Transformations of Practically Valuable Benzothiazole Derivatives.

The review is devoted to modern trends in the chemistry of 2-amino and 2-mercapto substituted benzothiazoles covering the literature since 2015. The reviewed heterocycles belong to biologically active and industrially demanded compounds. Newly developed synthesis methods can be divided into conventional multistep processes and one-pot, atom economy procedures, realized using green chemistry principles and simple reagents. The easy functionalization of the 2-NH2 and 2-SH groups and the benzene ring of the benzothiazole moiety allows considering them as highly reactive building blocks for organic and organoelement synthesis, including the synthesis of pharmacologically active heterocycles. The review provides a summary of findings, which may be useful for developing new drugs and materials and new synthetic approaches and patterns of reactivity.

Patch Testing with a New Composition of Mercapto Mix: A Multi-centre Study by the Swedish Contact Dermatitis Research Group.

This study investigated whether more patients with contact allergies were detected by patch testing with mercapto mix with a higher concentration of 2-mercaptobenzothiazolinone (MBT) than the commonly used mercapto mix. A total of 3,143 dermatitis patients in 5 Swedish dermatology departments were patch- tested with 3 mercapto test preparations: MBT 2.0% petrolatum (pet.); mercapto mix 2.0% pet.; and mercapto mix 3.5% pet. Positive reactions to these mercapto mixes varied between 0-0.50%, 0-0.93%, and 0-1.4%, respectively, in the 5 centres. Numerically, mercapto mix 3.5% pet. detected all positive patients and more patch-test positive patients than did the 2 other substances, but the difference was not statistically significant. The authors recommend replacing mercapto mix 2.0% pet. in the Swedish baseline series with mercapto mix 3.5% pet., since the latter also detected those patients who would have been missed because MBT 2.0% is not included in the Swedish baseline series.

Synthesis and anticandidal evaluation of new benzothiazole derivatives with hydrazone moiety.

In this study, we have performed the synthesis of new N'-(arylidene)-4-[(benzothiazol-2-yl)thio]butanoylhydrazide derivatives (3a-s) bearing azole moiety and hydrazone group in a lipophilic structural framework. The target compounds were prepared by a three step synthetic procedure starting from 2-mercaptobenzothiazole. The structures of the target compounds were elucidated by IR, (1)H NMR, (13)C NMR spectra and elemental analysis. The antifungal activity of the obtained compounds has been determined against a number of clinic and fluconazole-resistant Candida strains by using microdilution method. Compounds (3a-3s) exhibited anticandidal activity in different ratios varying between the range of MIC: 50 and 200 µg/mL.

Gamma irradiation of 2-mercaptobenzothiazole aqueous solution in the presence of persulfate.

Recently, water treatment by ionizing radiation has gained increasing attention as a powerful technology for the destruction of refractory pollutants. 2-Mercaptobenzothiazole (MBT) is known as a widespread, toxic and poorly biodegradable pollutant. This paper studied the gamma irradiation of aqueous solutions of MBT. Moreover, the effect of the addition of persulfate (S2O8(2-)) on the radiolytic destruction of MBT was investigated. The main transformation products of the studied compound were detected and the sequence of occurrence of the products was described. The change of biodegradability of MBT solution was also observed. The main results obtained in this study indicated that gamma radiation was effective for removing MBT in aqueous solution. Persulfate addition, which induced the formation of reactive sulfate radicals (SO4(-)), greatly enhanced the degradation of MBT. Benzothiazole was identified as the first radiation product, followed by 2-hydroxybenzothiazole. Decomposition of MBT started with the oxidation of -SH groups to sulfate ions. Possible pathways for MBT decomposition by gamma irradiation were proposed. The BOD/COD ratios of MBT samples were increased after radiation, indicating the improvement of biodegradability and reduction of toxicity.

Design, Synthesis, and Spectral Properties of Novel 2-Mercaptobenzothiazole Derivatives.

This paper is focused on the optimalization of methods for the synthesis, isolation, and purification of 2-mercaptobenzothiazole-based acrylic and methacrylic monomers. The structures of the newly synthesized compounds were confirmed through infrared (IR) and nuclear magnetic resonance spectroscopy (NMR). Spectroscopic properties of the resulting 2-mercaptobenzothiazole derivatives were determined based on their absorption spectra and molar absorption coefficients in solvents with varying polarities. A correlation was established between the calculated density functional theory (DFT) energies and Frontier Molecular Orbitals and the experimental observations, confirming their consistency. The practical utility of the synthesized compounds, particularly in future polymerization processes, hinges on a thorough understanding of these properties.

An epidermal equivalent assay for identification and ranking potency of contact sensitizers.

The purpose of this study was to explore the possibility of combining the epidermal equivalent (EE) potency assay with the assay which assesses release of interleukin-18 (IL-18) to provide a single test for identification and classification of skin sensitizing chemicals, including chemicals of low water solubility or stability. A protocol was developed using different 3D-epidermal models including in house VUMC model, epiCS® (previously EST1000™), MatTek EpiDerm™ and SkinEthic™ RHE and also the impact of different vehicles (acetone:olive oil 4:1, 1% DMSO, ethanol, water) was investigated. Following topical exposure for 24h to 17 contact allergens and 13 non-sensitizers a robust increase in IL-18 release was observed only after exposure to contact allergens. A putative prediction model is proposed from data obtained from two laboratories yielding 95% accuracy. Correlating the in vitro EE sensitizer potency data, which assesses the chemical concentration which results in 50% cytotoxicity (EE-EC50) with human and animal data showed a superior correlation with human DSA05 (µg/cm(2)) data (Spearman r=0.8500; P value (two-tailed)=0.0061) compared to LLNA data (Spearman r=0.5968; P value (two-tailed)=0.0542). DSA05=induction dose per skin area that produces a positive response in 5% of the tested population Also a good correlation was observed for release of IL-18 (SI-2) into culture supernatants with human DSA05 data (Spearman r=0.8333; P value (two-tailed)=0.0154). This easily transferable human in vitro assay appears to be very promising, but additional testing of a larger chemical set with the different EE models is required to fully evaluate the utility of this assay and to establish a definitive prediction model.

Simultaneous determination of ultra trace amounts of lead and cadmium in food samples by adsorptive stripping voltammetry.

A selective and sensitive method for simultaneous determination of lead and cadmium by adsorptive differential pulse cathodic stripping voltammetry is presented. The method is based on adsorptive accumulation of the complexes of Pb (II) and Cd (II) ions with 2-mercaptobenzothiazole onto hanging mercury drop electrode (HMDE), followed by the reduction of the adsorbed species by differential pulse cathodic stripping voltammetry. Optimal conditions were obtained at pH 8.0, 2-mercaptobenzothiazole concentration of 1.0×10(-4)M, the accumulation potential of -0.4V (vs. Ag/AgCl), the accumulation time of 160s, and the scan rate of 100mV/s. Under optimised conditions, linear calibration curves were established for the concentration of Pb (II) and Cd (II) in the range of 0.5-70 and 0.2-30ng/ml, respectively, with detection limit of 0.017ng/ml for Pb (II) and 0.01ng/ml for Cd (II). The procedure was successfully applied to the simultaneous determination of both ions in food samples (rice, soya and sugar).

Realizing the synergistic effect of electronic modulation over graphitic carbon nitride for highly efficient photodegradation of bisphenol A and 2-mercaptobenzothiazole: Mechanism, degradation pathway and density functional theory calculation.

Here, we successfully synthesized a brown carbon nitride (CY-C3N4) co-modified with oxygen bridge and porous defects via a universal acylation method. Excitingly, density functional theory (DFT) calculation shows that the introduction of oxygen bridges in the calcination polymerization process can adjust the electronic structure and energy band position of the new material. Further, the results of elemental analysis and X-ray photoemission spectroscopy test indicate that the oxygen bridge structure was successfully introduced into the skeleton of carbon nitride. The results show that 0.1CY-C3N4 can remove bisphenol A (BPA) and 2-mercaptobenzothiazole (MBT) with a removal rate of approximately 99% in 90 min and 20 min, respectively. Its degradation rate is 17.94 times and 3.85 times faster than that the original carbon nitride, respectively. Further, through HPLC-MS analysis, the intermediate products of the reaction process were analyzed in depth to propose a possible photocatalytic degradation route. Free radical capturing test and ESR spectroscopy indicate that the formative hydroxyl radical (OH), superoxide radical (O2-), singlet oxygen (1O2) and hole (h+) all play a key role in the photodegradation. This study provides a new way to synthesize brown carbon nitrides with oxygen bridges and porous defects for environmental applications.

Confinement of ultrasmall CoFe2O4 nanoparticles in hierarchical ZnIn2S4 microspheres with enhanced interfacial charge separation for photocatalytic H2 evolution.

The charge carriers' separation efficiency, light absorption capacity and microstructure of photocatalysts are important factors affecting the photocatalytic performance. Herein, we prepared the hierarchical ZnIn2S4 (ZIS) microspheres-confined CoFe2O4 nanoparticles (CFO NPs) p-n junction (CFO/ZIS) with enhanced charge carriers' separation and extensive visible light response. Surprisingly, the 1% CFO/ZIS exhibits the optimal photocatalytic H2 evolution (PHE) activity, which is about over 3.7 times higher than pure ZIS. Furthermore, the apparent quantum yield (AQY) of the1% CFO/ZIS reaches 5.0% at 420 nm. In addition, the effects of various sacrificial reagent on the PHE were investigated in depth. And the formed photocatalytic reaction path of p-n junction effectively prevents the photocorrosion of ZIS. Hence, the photocatalytic activity and crystalline structure of 1% CFO/ZIS have no obvious change after five photocatalytic cycles, which shows that the photocatalyst possesses excellent chemical stability. Moreover, the as-prepared p-n junction shows outstanding photocatalytic performance for the degradation of 2-mercaptobenzothiazole (MBT). According to a series of experiments and characterizations, a possible photocatalytic mechanism for the CFO/ZIS p-n junction was proposed.

Degradation of 2-mercaptobenzothizaole in microbial electrolysis cells: Intermediates, toxicity, and microbial communities.

The compound 2-mercaptobenzothizaole (MBT) has been frequently detected in wastewater and surface water and is a potential threat to both aquatic organisms and human health (its mutagenic potential has been demonstrated). This study investigated the degradation routes of MBT in the anode of a microbial electrolysis cell (MEC) and the involved microbial communities. The results indicated that graphene-modified anodes promoted the presence of more enriched, developed, and specific communities compared to bare anodes. Moreover, consecutive additions of the OH substituent to the benzene ring of MBT were only detected in the reactor equipped with the graphene-treated electrode. Both phenomena, together with the application of an external voltage, may be related to the larger reduction of biotoxicity observed in the MEC equipped with graphene-modified anodes (46.2 eqtox∙m-3 to 27.9 eqtox∙m-3).

Synthesis of fluorescent pink emitting copper nanoparticles and sensitive detection of α-naphthaleneacetic acid.

Detecting NAA in food has drawn intense attention as it has imposed significant threat to people's health and the growth of food industry. Over the past few years, great importance has been attached to the application of copper nanomaterials as fluorescent probe to food and environmental detection. Here, the simple, rapid, cost effective and water soluble fluorescent copper nanoparticles were synthesized with chemical reduction sonochemical assisted method for highly selective and sensitive detection of α-naphthaleneacetic acid (NAA) by using 2-mercaptobenzothiazole (MBT) as a protecting agent and polyvinylpyrrolidone (PVP) as a stabilizing agent (MBT-PVP CuNPs). The resultant CuNPs has a spherical shape with an average diameter of 10-15 nm and strong fluorescent pink emission characteristic peak at 580 nm upon 334 nm excitation. Interestingly, upon the addition of NAA, the fluorescence of MBT-PVP CuNPs can be effectively quenched for the reason that NAA could interact with MBT via hydrogen bonding and conform copper-NAA clathrate with Cu+ via coordination bond, which shows a good linearity in the range of NAA from 0.5 to 50 µM and with a detection limit of 9.6 nM. Moreover, the prepared probe has good selectivity for NAA detection over other co-existing molecules. It is worth mentioning that this method has been successfully applied to authentic comestible sample analysis and obtained satisfying and promising results, which indicates that this strategy is likely to have a promising application potential for NAA detection in the field of food safety.

A comparative study of silver electrodeposition from pyrophosphate-cyanide and high concentration cyanide electrolytes in the presence of brighteners.

A study of the electrodeposition of silver from 2 different types of electrolytes; (1) neutral pyrophosphatecyanide electrolyte and (2) alkaline high concentrated cyanide electrolyte in the presence of a variety of additives such as 2-mercaptobenzothiazole, potassium selenocyanate, and potassium antimony tartrate was performed. Influence of additives and cyanide concentration on microstructure and kinetics of the cathodic processes were studied. A brightener couple, 2-mercaptobenzothiazole and potassium antimony tartrate, were combined within this investigation and detected to be highly effective for silver electrodeposition. The rapid increase in current density at the same potential interval related to grain refinement effect of potassium antimony tartrate was shown. The cyclic organic compound, 2-mercaptobenzothiazole, polarizes the reduction to high cathodic potential in pyrophosphate electrolyte. However, the sufficient levelling effect required for the mirror-bright appearance seems to be related to the high polarizing effect of the high concentration cyanide content. In the case of pyrophosphate electrolytes, sufficient levelling cannot be achieved, so semigloss coatings are obtained. The low cathodic potential electrodeposition of silver in pyrophosphate electrolyte, which is found to proceed by 3D instantaneous nucleation, is polarized to high cathodic potentials and grows into 3D progressive nucleation and diffusion-controlled growth in high concentration cyanide electrolyte.

Novel broad-spectrum-driven oxygen-linked band and porous defect co-modified orange carbon nitride for photodegradation of Bisphenol A and 2-Mercaptobenzothiazole.

Here, we successfully synthesized the oxygen-linked band and porous defect co-modified orange carbon nitride (AF-C3N4) using a simple method. Further, the band structure calculation of its simulated structure is performed by DFT, which shows that the introduction of oxygen-linked band can adjust its band structure. The photocatalytic degradation rates of 0.3AF-C3N4 for bisphenol A and 2-mercaptobenzothiazole were 8 times and 2.73 times that of the original g-C3N4, respectively. Moreover, 0.3AF-C3N4 also shows photocatalytic activity under different wavelength light (blue, green and red light), which indicates that the synthesized materials have a broad spectrum of photocatalytic activity. Further, we proposed a possible photocatalytic degradation pathway by HPLC-MS analysis. Free radical quenching test and ESR spectra show that the generated superoxide radicals (•O2-), hydroxyl radicals (•OH) and holes (h+) cause photodegradation, while enhancing singlet oxygen (1O2) and weaken the content of hydrogen peroxide has further proved that active oxygen groups play an important role in the photocatalytic degradation process. Additionally, the 0.3AF-C3N4 can also be a photoelectrochemical sensor to detect the concentration of bisphenol A (λ ≥ 550 nm). This study provides a new strategy for the synthesis of orange carbon nitride by oxygen-linked band and porous defect co-modification for photocatalytic applications.

Functionalized starch as a novel eco-friendly vulcanization accelerator enhancing mechanical properties of natural rubber.

A novel eco-friendly vulcanization accelerator, starch supported sodium isobutyl xanthate (SSX) has been synthesized firstly. The modification of starch using sodium isobutyl xanthate (SIBX) has improved the thermal stability significantly, and the vulcanization process of natural rubber (NR) could be accelerated by SSX at 145 ℃ accordingly. More importantly, SSX can be dispersed into NR matrix uniformly along with the strong interfacial interaction between SSX and NR, as evidenced by the constrained rubber chains around SSX surface. In addition, mechanical properties of the obtained NR have been enhanced remarkably, showing a 22.4 % increase in tensile strength when compared with traditional vulcanization accelerator. Laying on the fact that a novel vulcanization accelerator has been fabricated successfully using SIBX functionalized starch, new strategies for the preparation of green vulcanization accelerators and the functional application of biopolymers can be provided.

Electrochemical characterization of in situ functionalized gold organosulfur self-assembled monolayer with conducting polymer and carbon nanotubes for determination of rutin.

In this study, attempts were made to present a sensitive strategy for determining rutin. To reach the goal of the study, a poly(sulfosalicylic acid) film was electropolymerized on a gold electrode, which was modified by 2-mercaptobenzothiazole self-assembled monolayer and multi-walled carbon nanotubes (PSSA/CNTs/MBT/Au). The proposed sensor was characterized by different techniques including field emission scanning electron microscopy, energy dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy. The resulting sensor displayed electrocatalytic activity towards the oxidation of rutin which is attributed to the presence of the PSSA/MWCNTs nanocomposite. Under optimized conditions, the detection limit of 1.8nmolL-1 and two linear calibration ranges of 0.01-0.8 and 0.8-10.0µmolL-1 were obtained for rutin determination at the PSSA/CNTs/MBT/Au electrode. The proposed modified electrode was successfully applied for the determination of rutin in orange, red apple, red onion, strawberry, oat and salvia samples. The obtained results suggest that the proposed electrode has several advantages, such as high stability, repeatability and good reproducibility and it can be used for a sensitive, selective and rapid determination of rutin.

Microaerobic degradation of 2-Mercaptobenzothiazole present in industrial wastewater.

Microaerobic degradation of 2-Mercaptobenzothiazole (2-MBT) was investigated using an isolated bacterial strain CSMB1. It was identified as Alcaligenes sp. MH146 by genomic analysis. The isolate degraded 50mg/L concentration of 2-MBT which was measured in terms of Total organic carbon (TOC) (700mg/L). A maximum degradation of 86% with a residual TOC concentration of 101mg/L was obtained after 72h, with the biomass growth of 290mg/L. The presence of specific activity of catechol 2, 3 oxygenase was observed in all the tested derivatives of benzothiazoles and the benzene ring opening was observed through meta cleavage. By analyzing the 72h incubated culture supernatant, 2-MBT, and all its biotransformed products were degraded into polar compounds. With the analytical results obtained, a possible microaerobic degradative pathway was proposed and illustrated for 2-MBT. It is concluded that microaerophilic isolate CSMB1 was able to degrade 2-MBT and its intermediates by utilizing them as sole carbon and energy.

Impaired anterior swim bladder inflation following exposure to the thyroid peroxidase inhibitor 2-mercaptobenzothiazole part II: Zebrafish.

Disruption of the thyroid hormone (TH) system, an important mode of action, can lead to ecologically relevant adverse outcomes, especially during embryonic development. The present study characterizes the effects of disruption of TH synthesis on swim bladder inflation during zebrafish early-life stages using 2-mercaptobenzothiazole (MBT), a thyroid peroxidase (TPO) inhibitor. Zebrafish were exposed to different MBT concentrations until 120/168h post fertilization (hpf) and 32days post fertilization (dpf), in two sets of experiments, to investigate the effects of TPO inhibition on posterior and anterior swim bladder inflation respectively, as well as whole body thyroid hormone concentrations (triiodothyronine (T3) and its prohormone, thyroxine (T4)). At 120hpf, MBT did not directly impair posterior chamber inflation or size, while anterior chamber inflation and size was impaired at 32dpf. As previously shown in amphibians and mammals, we confirmed that MBT inhibits TPO in fish. Whole-body T4 decreased after MBT exposure at both time points, while T3 levels were unaltered. There was a significant relationship between T4 levels and the anterior chamber surface at 32dpf. The absence of effects on posterior chamber inflation can possibly be explained by maternal transfer of T4 into the eggs. These maternally derived THs are depleted at 32dpf and cannot offset TPO inhibition, resulting in impaired anterior chamber inflation. Therefore, we hypothesize that TPO inhibition only inhibits swim bladder inflation during late development, after depletion of maternally derived T4. In a previous study, we showed that iodothyronine deiodinase (ID) knockdown impaired posterior chamber inflation during early development. Our findings, in parallel with similar effects observed in fathead minnow (see part I, this issue) suggest that thyroid disruption impacts swim bladder inflation, and imply an important distinction among specific subtypes of TH disrupting chemicals. However, the existence of another - yet unknown - mode of action of MBT impacting swim bladder inflation cannot be excluded. These results can be helpful for delineating adverse outcome pathways (AOPs) linking TPO inhibition, ID inhibition and other TH related molecular initiating events, to impaired swim bladder inflation in fish during early life stages. Such AOPs can support the use of in vitro enzyme inhibition assays for predicting reduced survival due to impaired posterior and anterior chamber inflation.

Resonance Rayleigh scattering method for determination of 2-mercaptobenzothiazole using gold nanoparticles probe.

A sensitive, simple and novel method was developed to determine 2-mercaptobenzothiazole (2MBT) in water samples. This method was based on the interaction between gold nanoparticles (AuNPs) and 2MBT followed by increasing of the resonance Rayleigh scattering (RRS) intensity of nanoparticles. The change in RRS intensity (ΔIRRS) was linearly correlated to the concentration of 2MBT over the ranges of 5.0-100.0 and 100.0-300.0 µg L(-1). 2MBT can be measured in a short time (5 min) without any complicated or time-consuming sample pretreatment process. Parameters that affect the RRS intensities such as pH, concentration of AuNPs, standing time, electrolyte concentration, and coexisting substances were systematically investigated and optimized. Interference tests showed that the developed method has a very good selectivity and could be used conveniently for determination of 2MBT. The limit of detection (LOD) and limit of quantification (LOQ) were 1.0 and 3.0 µg L(-1), respectively. Relative standard deviations (RSD) for 20.0 and 80.0 µg L(-1) of 2MBT were 1.1 and 2.3, respectively. Possible mechanisms for the RRS changes of AuNPs in the presence of 2MBT were discussed and the method was successfully applied for the analysis of real water samples.