Search

Due to their ubiquity and the rise of drug-resistant forms, Candida albicans infections pose a serious threat to world health. Exploring new molecular possibilities is essential in order to create newer antifungal medicines to address this challenge. Herein, the use of density functional theory at the B3LYP-D3BJ/aug-cc-pVDZ method along with the in silico molecular docking was utilized to examine the effects of polar (DMSO, ethanol, water) solvation on the reactivity, spectral (NMR, UV, FT-IR) investigation, and the antifungal potential of a bis[ethyl2-(4-hydroxy-3-{(E)-[(1,3-benzothiazol-2-yl)inimo]methyl} phenyl)-4-methyl-1,3-thiazole-5-carbo -xylate (BTZ). The study finds that polar solvents exert a notable influence on BTZ's reactivity, with the highest energy gap observed in the gas phase with a value of 3.4939 eV while in the solvents; the values are 3.4477, 3.4477, and 3.4422 eV for DMSO, ethanol, and water, respectively. This observation implies that BTZ may exhibit varying degrees of reactivity under different solvents. To evaluate BTZ's suitability as a potential antifungal agent, absorption, distribution, metabolism, excretion, and toxicity (ADMET) studies were conducted which reveals that BTZ adheres to Lipinski's rule of five, demonstrating its drug-like potential. Molecular docking simulations against Candida albicans proteins (1ZAP and 6ZDU) show promising binding affinities, with BTZ exhibiting a strong interaction with 1ZAP (-5.4 kcal/mol). The findings of this research contribute valuable insights into the reactivity and potential antifungal activity of BTZ, providing a promising candidate for further exploration in the quest for effective treatments against Candida infections.

[Display omitted] • A lysosome-targetable fluorescent probe for H 2 O 2 has been reported. • The probe displays high sensitivity and high selectivity for H 2 O 2. • The probe can be utilized for determination of H 2 O 2 within the lysosomes of living cells. As an important member of reactive oxygen species, hydrogen peroxide (H 2 O 2) plays a key role in oxidative stress and cell signaling. Abnormal levels of H 2 O 2 in lysosomes can induce damage or even loss of lysosomal function, leading to certain diseases. Therefore, real-time monitoring of H 2 O 2 in lysosomes is very important. In this work, we designed and synthesized a novel lysosome-targeted fluorescent probe for H 2 O 2 -specific detection based on a benzothiazole derivative. A morpholine group was used as a lysosome-targeted unit and a boric acid ester was chosen as the reaction site. In the absence of H 2 O 2 , the probe exhibited very weak fluorescence. In the presence of H 2 O 2 , the probe showed an increased fluorescence emission. The fluorescence intensity of the probe for H 2 O 2 displayed a good linear relationship in the concentration range of H 2 O 2 from 8.0 × 10−7 to 2.0 × 10−4 mol·L−1. The detection limit was estimated to be 4.6 × 10−7 mol·L−1 for H 2 O 2. The probe possessed high selectivity, good sensitivity and short response time for the detection of H 2 O 2. Moreover, the probe had almost no cytotoxicity and had been successfully applied to confocal imaging of H 2 O 2 in lysosomes of A549 cells. These results illustrated that the developed fluorescent probe in this study could provide a good tool for the determination of H 2 O 2 in lysosomes. [ABSTRACT FROM AUTHOR]

Background: Colorectal cancer (CRC) is one of the most common malignancies causing the third highest mortality rate in the world. It is particularly urgent to explore effective therapeutic strategies to overcome this disease. We identified a novel benzothiazole derivative (BTD) that may serve as a potentially effective agent against CRC. Method: MTT assays, cell colony formation assays, EdU staining assays, flow cytometry, RNA-seq, Western blotting, and migration and invasion assays were used to examine the effects of BTD on cell proliferation, apoptosis, metastasis, and the cell cycle, The antitumor activity of BTD in vivo was investigated in a CT26 tumor-bearing mouse model, Immunohistochemistry (IHC) was performed to examine the protein expression in mouse tumors, Hematology, biochemical analysis, and H&E staining were used to assess the biosafety of BTD. Results: We observed that BTD suppressed cell proliferation and metastasis and promoted the apoptosis of tumor cells in vitro, Treatment with BTD at a tolerable dose significantly reduced tumor growth in CT26-tumor-bearing mice and appeared to be safe, Treatment of BTD induced apoptosis by increasing the generation of reactive oxygen species (ROS) and evoking the loss of mitochondrial transmembrane potential, Overall, BTD suppressed cell proliferation and metastasis, and induced apoptosis of colorectal tumor cells through the ROS-mitochondria-mediated apoptotic pathway, The preliminary proof of the antitumor activity and relative safety of BTD were validated in a mouse model. Conclusion: Our findings suggest that BTD could serve as a potentially safe and effective candidate for CRC treatment. [ABSTRACT FROM AUTHOR]

• A fire-new corrosion inhibitor AMB is found to prevent the corrosion of copper. • Using more than one technique investigated the inhibition performance of AMB. • The inhibition efficiency of 3 mm AMB was more than 90% at different temperatures. • AMB had remarkable corrosion inhibition performance for Cu in H 2 SO 4 by AFM analysis. The corrosion problem of Cu has aroused people's high attention while it is used in various fields of society. Organic compounds have great potential as high-efficiency corrosion inhibitors because of their practical and economical. The anti-corrosion performance of 2-Amino-6-(Methylsulfonyl)Benzothiazole (AMB) was studied by electrochemical experiment, weight loss measurements complemented by surface analysis using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The interaction between AMB and copper was studied at molecular level by using theoretical calculation. The electrochemical experiment demonstrated that as the consistence of AMB augmented, the anti-corrosion effect increased, and when the concentration reached 3 mM, the anti-corrosion efficiency (η) was 95.95%. And the change of temperature has no significant effect on the corrosion inhibition efficiency. Weight loss measurements effectively support the phenomenon of electrochemical experiment. Besides the phenomenon of FTIR and XPS intuitively show the information of bonding between AMB and copper. Employing SEM and AFM, proving AMB can effectively adsorb on the interface of copper. Langmuir adsorption model illustrates that the adsorption of AMB is mixed adsorption. The mechanism of corrosion inhibition is further elucidated by quantum chemical calculation and molecular dynamics simulation. [Display omitted] [ABSTRACT FROM AUTHOR]

A mononuclear platinum(II) complex, [PtLCl]Cl (1, where L = N-(4-(benzo[d]thiazol-2-yl)phenyl)-2-(bis(pyridine-2-ylmethyl)-amino)acetamide), was synthesized by covalently tethering a benzothiazole derivative 2-(4-aminophenyl)benzothiazole to the 2,2′-dipicolylamine (DPA) chelating PtII center by an amidic bond. 1 showed a cytotoxicity comparable to that of cisplatin against MCF-7 cell lines and more potent activities against HeLa and A-549 cell lines. Investigation of the reaction of 1 with 5′-GMP displayed 1 could coordinate with N7-GMP to form the Pt-GMP adduct. Thus 1 has potential to form Pt-DNA adducts in vivo. Similarly, the glutathione (GSH) ligand could also coordinate to the PtII center to form a monodentate Pt-GS complex. The competition experiments of 1 with 5′-GMP and GSH showed that the coordination binding of 1 with GSH did not prevent formation of a certain amount of the Pt-GMP adduct in the reaction process. DNA binding experiments displayed that 1 could bind to DNA through multiple binding modes involving non-covalent interaction and monofunctional platination of the platinum(II) moiety, and induce a visible conformational change of DNA. The evaluation of the protein binding ability showed that 1 could bind to human serum albumin (HSA) with a moderate binding affinity, quench the intrinsic fluorescence of HSA, and destroy the tertiary structure of HSA. [ABSTRACT FROM AUTHOR]

A benzothiazole-based near-infrared (NIR) ratiometric fluorescent probe (HBT-Cys) was developed for discriminating cysteine (Cys) from homocysteine (Hcy) and glutathione (GSH). The probe was designed by masking phenol group in the conjugated benzothiazole derivative with methacrylate group that could be selectively removed by Cys, and therefore an intramolecular charge transfer (ICT) fluorescence was switched on in the NIR region. In the absence of Cys, the probe exhibited a strong blue fluorescence emission at 431 nm, whereas a NIR fluorescence emission at 710 nm was significantly enhanced accompanied by a decrease of emission at 431 nm in the presence of Cys, allowing a ratiometric fluorescence detection of Cys. The fluorescence intensity ratio (I710nm/I431nm) showed a good linear relationship with Cys concentration of 1–40 μM with the detection limit of 0.5 μM. The sensing mechanism was explored based on MS experimental analysis and DFT theoretical calculation. Moreover, the fluorescent probe was successfully used for fluorescence bioimaging of Cys in living cells.

A simple structured reaction-based probe for peroxynitrite (ONOO − ) was developed by using benzothiazole hydrazone base of the excited-state intramolecular proton transfer (ESIPT) dye. It was constructed from 2-hydrazinylpyridine and 3-(benzo[d]thiazol-2-yl)-2-hydroxy-5-methylbenzaldehyde which possesses itself weak fluorescence and displayed prominent fluorescence response towards ONOO − by oxidizes the C=N bond to an aldehyde in aqueous solution. The probe exhibited excellent selectivity and high sensivity towards ONOO − with a low dectection limit of 5.8 × 10 −8  M in physiological condition. Moreover, the probe could realize fast recognition to ONOO − in as short as 60 s. In addition, the probe was also successfully used for living cell imaging. [ABSTRACT FROM AUTHOR]

A simple benzothiazole fluorescent chemosensor was developed for the fast sequential detection of Cu 2 + and biothiols through modulating the excited-state intramolecular proton transfer (ESIPT) process. The compound 1 exhibits highly selective and sensitive fluorescence “ on - off ” recognition to Cu 2 + with a 1:1 binding stoichiometry by ESIPT hinder. The in situ generated 1 -Cu 2 + complex can serve as an “ on - off ” fluorescent probe for high selectivity toward biothiols via Cu 2 + displacement approach, which exerts ESIPT recovery. It is worth pointing out that the 1 -Cu 2 + complex shows faster for cysteins (within 1 min) than other biothiols such as homocysteine (25 min) and glutathione (25 min). Moreover, the compound 1 displays 160 nm Stoke-shift for reversibly monitoring Cu 2 + and biothiols. In addition, the probe is successfully used for fluorescent cellular imaging. This strategy via modulation the ESIPT state has been used for determination of Cu 2 + and Cys with satisfactory results, which further demonstrates its value of practical applications. [ABSTRACT FROM AUTHOR]

Copper is a highly toxic environmental pollutant in the environmental, biological and chemical fields. Therefore, sensitive, selective and visual detection of Cu 2+ is very important for human health and practical applications. Herein, a novel hybrid ratiometric fluorescent nanosensor was developed for rapid and on-site visualization of Cu 2+ on the basis of integrating benzothiazole fluorophore (MDBT) and red-emissive quantum dots (QDs) embedded in silica nanospheres. Such hybrid ratiometric fluorescent nanosensor exhibits dual emissions at 420 and 640 nm under a single excitation wavelength. Due to the ions promoted oxidation reaction of Cu 2+ towards MDBT, the fluorescence of MDBT can be selectively enhanced. Although the embedded QDs are insensitive to the analyte, variations of the dual emission intensity ratios display continuous colour changes from red to blue. The ratiometric fluorescent approach shows high sensitivity and selectivity towards Cu 2+ against other interfering metal ions. The detection limit of Cu 2+ for the hybrid ratiometric fluorescent nanosensor is determined to be 41.71 nM, which is much lower than the allowable level of Cu 2+ (∼20 μM) in drinking water set by U.S. Environmental Protection Agency. Furthermore, this kind of novel nanosensor can also be applied for Cu 2+ detection in actual water samples and exhibits excellent detection ability. This hybrid ratiometric fluorescent nanosensor is simple, fully self-contained and thus potentially attractive for visual identification without the need of elaborate equipments. [ABSTRACT FROM AUTHOR]

A novel acidic pH fluorescent probe 1 based on a benzothiazole derivative has been designed, synthesized and developed. The linear response range covers the acidic pH range from 3.44 to 6.46, which is valuable for pH researches in acidic environment. The evaluated p Ka value of the probe 1 is 4.23. The fluorescence enhancement of the studied probe 1 with an increase in hydrogen ions concentration is based on the hindering of enhanced photo-induced electron transfer (PET) process. Moreover, the pH sensor possesses a highly selective response to H + in the presence of metal ions, anions and other bioactive small molecules which would be interfere with its fluorescent pH response. Furthermore, the probe 1 responds to acidic pH with short response time that was less than 1 min. The probe 1 has been successfully applied to confocal fluorescence imaging in live HeLa cells and can selectively stain lysosomes. All of such good properties prove it can be used to monitoring pH fluctuations in acidic environment with high sensitivity, pH dependence and short response time. [ABSTRACT FROM AUTHOR]

Triphenylamine based fluorophore ( BTP ) containing benzothiazole and vinyl pyridine was synthesized with very good yield and characterized by various spectral techniques. BTP exhibits excellent solid state luminescence and responds to the external stimuli like mechanical force, heating and an acid vapour (acidochromism). In addition to that BTP is used in the colorimetric detection of Fe 3+ ion in the solution as well as solid states by a cost effective method. Further BTP sensing picric acid colorimetrically and ratiometrically with the detection limit of 23 ppm. [ABSTRACT FROM AUTHOR]

Photo-release of Zn 2+ with fluorescence monitoring has been described using 8-(2,3-dihydrobenzothiazol-2-yl)-7-hydroxy-4-methyl-2H-chromen-2-one ( 1 ) as ligand. It is found that 1 binds to Zn 2+ to yield a 1:1 complex ( 2 ) with a large binding constant (log K = 13.35), 2 exhibits photo-active and occurs photo-release in aqueous micelle solution. Upon irradiation with 365 nm light, 2 undergoes efficient (ϕ = 0.56) Zn 2+ -release in buffer solution (PBS, pH = 7.2) to give 8-(benzothiazol-2-yl)-7-hydroxy-4-methyl-2H-chromen-2-one ( 3 ) as photo-product. 3 exhibits turn-on fluorescence, which is beneficial for monitoring the photo-release. [ABSTRACT FROM AUTHOR]

It is crucial to monitor intracellular pH values and their fluctuation since the organelles of cells have different pH distribution. Herein we construct a new small molecule fluorescent probe HBT-O for monitoring the subtle pH values within the scope of neutral to acid in living cells. The probe exhibited good water solubility, a marked turquoise to olivine emission color change in response to pH, and tremendous fluorescence hypochromatic shift of ∼50 nm (1718 cm −1 ) as well as the increased fluorescence intensity when the pH value changed from neutral to acid. Thus, the probe HBT-O can distinguish the subtle changes in the range of normal pH values from neutral to acid with significant fluorescence changes. These properties can be attributed to the intramolecular charge transfer (ICT) process of the probe upon protonation in buffer solutions at varied pH values. Moreover, the probe was reversible and nearly non-toxic for living cells. Then the probe was successfully used to detect pH fluctuation in living cells by exhibiting different fluorescence colors and intensity. These findings demonstrate that the probe will find useful applications in biology and biomedical research. [ABSTRACT FROM AUTHOR]

Two novel altenusin-thiazole hybrids named altenusinoides A and B (1 and 2), a new benzothiazole derivative (3), and three known altenusin derivatives (4⁻6) have been obtained from the solid culture of the marine sponge-derived fungal strain, Alternaria sp. SCSIOS02F49. The structures of these new compounds were characterized by NMR, HRESIMS, and X-ray single crystal analysis. Compounds 1 and 2 possess an unusual altenusin-thiazole-fused skeleton core (6/6/5), and compound 3 represents the first benzothiazole derivative from fungi. Compounds 4 and 5 showed significant DPPH free-radical-scavenging activities with the prominent IC50 values of 10.7 ± 0.09 μM and 100.6 ± 0.025 μM, respectively. Additionally, compound 5 exhibited COX-2 inhibitory activity with an IC50 value of 9.5 ± 0.08 μM.

Background: Colorectal cancer (CRC) is one of the most common malignancies causing the third highest mortality rate in the world. It is particularly urgent to explore effective therapeutic strategies to overcome this disease. We identified a novel benzothiazole derivative (BTD) that may serve as a potentially effective agent against CRC. Method: MTT assays, cell colony formation assays, EdU staining assays, flow cytometry, RNA-seq, Western blotting, and migration and invasion assays were used to examine the effects of BTD on cell proliferation, apoptosis, metastasis, and the cell cycle. The antitumor activity of BTD in vivo was investigated in a CT26 tumor-bearing mouse model. Immunohistochemistry (IHC) was performed to examine the protein expression in mouse tumors. Hematology, biochemical analysis, and H&E staining were used to assess the biosafety of BTD. Results: We observed that BTD suppressed cell proliferation and metastasis and promoted the apoptosis of tumor cells in vitro . Treatment with BTD at a tolerable dose significantly reduced tumor growth in CT26-tumor-bearing mice and appeared to be safe. Treatment of BTD induced apoptosis by increasing the generation of reactive oxygen species (ROS) and evoking the loss of mitochondrial transmembrane potential. Overall, BTD suppressed cell proliferation and metastasis, and induced apoptosis of colorectal tumor cells through the ROS-mitochondria-mediated apoptotic pathway. The preliminary proof of the antitumor activity and relative safety of BTD were validated in a mouse model. Conclusion: Our findings suggest that BTD could serve as a potentially safe and effective candidate for CRC treatment., Competing Interests: The author FT employed by the company China Tobacco Sichuan Industrial Co., Ltd. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Zhou, Zhao, Zhou, Yang, Tao, Xie, Wang and Yun.)

Two benzothiazole derivatives, namely 2 - ( n -hexylamino)-4-(3′- N,N -dimethylamino-propyl)amino-6-(benzothiazol-2-yl)thio-1,3,5- s -triazine (BTC 6 T) and 2-( n -octylamino)-4-(3′- N,N -dimethylamino-propyl)amino-6-(benzothiazol-2-yl)thio-1,3,5- s -triazine (BTC 8 T), were synthesized to study their corrosion inhibiting effect against steel in a 1 M HCl solution. The corrosion inhibition efficiency was measured using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, and weight loss methods. Both inhibitors offered extra stability and higher inhibition efficiencies again steel corrosion than previously reported benzothiazole family inhibitors. These inhibitors can be adsorbed onto surfaces by both physical and chemical means. Finally, quantum chemical parameters were calculated using the density functional theory method (DFT) and the correlation between the theoretical and experimental results are discussed. [ABSTRACT FROM AUTHOR]

Chemical detection of Zn 2+ ion plays an important role in both environmental and biological systems. In this paper, a new chemosensor based on benzothiazole was designed and synthesized. The fluorescent intensity of the chemosensor enhanced significantly with existence of Zn 2+ ion. The control experiments show that the analogous ions (Pb 2+ , Co 2+ , Ni 2+ , Mn 2+ , Cu 2+ , Mg 2+ , Cd 2+ , Na + and K + ) do not have fluorescence enhancement effect; and some of them even quench the fluorescence dramatically. The intensity increase upon addition of Zn 2+ is due to the coordination between Zn 2+ and benzothiazole. This chemosensor shows a high sensitivity for Zn 2+ with a detection limit as low as 7.5 × 10 −7 mol L −1 and high selectivity through a ‘turn-on’ fluorescence response over the other tested metal ions. [ABSTRACT FROM AUTHOR]

We kinetically studied the reaction between endogenous thiols such as -γ-glutamylcysteine (γ-Glu-Cys), cysteine (Cys), glutathione (GSH), homocysteine (Hcy), cysteinylglycine (Cys-Gly), and dihydrolipoic acid (DHLA)- with ( E )-2-(benzo[ d ]thiazol-2-yl)-3-(4-morpholinophenyl)acrylonitrile ( JGB ). Studies conducted by NMR and ESI-MS/MS have demonstrated that this reaction occurs via thiol-addition toward the double bond present in JGB . Considering the product analysis and the pH-dependence of the second order rate constant ( k N ), we proposed a mechanism that involves the rapid protonation of JGB giving place to an intermediate following by the thiolate attack yielding a final product. Moreover, this probe could successfully sense thiols in the human neuroblastoma SH-SY5Y cells. [ABSTRACT FROM AUTHOR]

A water soluble benzothiazole derivative having polyamide arms has been designed and synthesized. The sensor selectively detects Hg 2+ ion in aqueous medium in presence of alkali, alkaline earth, first row transition metal and heavy metal ions. The reversible behaviour of the sensor can be achieved in presence of iodide ion. [ABSTRACT FROM AUTHOR]

Abstract: Benzothiazoles are multitarget agents with broad spectrum of biological activity. 2-Acetyl-3-(6-methoxybenzothiazo)-2-yl-amino-acrylonitrile (AMBAN) is a new synthetically prepared derivative, which in our previous study showed cytotoxic effects towards tumor cells. The aim of the present study was to examine the antiproliferative and apoptosis inducing activities of AMBAN towards human leukemia HL60 and U937 cells. Further, the molecular mechanism involved in AMBAN-induced apoptosis was investigated. Benzothiazole inhibited the growth and induced programmed cell death of HL60 and U937 cells. In addition, AMBAN elevated the level of reactive oxygen species, decreased the mitochondrial membrane potential, activated caspases 9 and 3, induced the cytochrome c release and PARP cleavage and led to intranucleosomal DNA fragmentation. Further, p38 MAPK was associated with the apoptotic activity of AMBAN. It can be concluded that AMBAN-induced apoptosis in HL60 and U937 cells through mitochondrial/caspase 9/caspase 3-dependent pathway. [Copyright &y& Elsevier]

A quantitative structure-activity relationship (QSAR) of a series of benzothiazole derivatives showing a potent and selective cytotoxicity against a tumorigenic cell line has been studied by using the density functional theory (DFT), molecular mechanics (MM+) and statistical methods, and the QSAR equation was established via a correlation analysis and a stepwise regression analysis. A new scheme determining outliers by “leave-one-out” (LOO) cross-validation coefficient ( q ) was suggested and successfully used. In the established optimal equation (excluding two outliers), the steric parameter ( MR R) and the net charge ( Q FR) of the first atom of the substituent (R), as well as the square of hydrophobic parameter (Ig P)2 of the whole molecule, are the main independent factors contributing to the anticancer activities of the compounds. The fitting correlation coefficient ( R 2) and the cross-validation coefficient ( q 2) values are 0.883 and 0.797, respectively. it indicates that this model has a significantly statistical quality and an excellent prediction ability. Based on the QSAR studies, 4 new compounds with high predicted anticancer activities have been theoretically designed and they are expected to be confirmed experimentally. [ABSTRACT FROM AUTHOR]

3H-2-imino-4-methylbenzothiazoline was obtained from o-methylaniline to form 4. The yielded product 6 was confirmed by Elemental analyses, NMR, MS, IR spectra and X-ray crystallography. Compound 6, C8H8N2S, Mr=164.23, crystallized in the monoclinic space group P21/c with unit cell parameters a=4.0949(15), b=11.790(2), c=15.837(2) A˚, α=89.975(14), β=96.510(19), γ=90.09(2)°, V=759.7(3) A˚3, Z=4, Dm=1.436 Mgm−3. The intermolecular attraction of 3H-2-imino-4-methylbenzothiazoline in crystal structure is discussed. [Copyright &y& Elsevier]

[Display omitted] • Four HBT-based Schiff base derivatives incorporating different substituents are synthesized. • The effects of different substituents on the luminescence properties and aggregate state of the molecules were investigated. • Compound HBT-4 has excellent detection performance for N 2 H 4 by both absorbance and fluorescence spectra. • HBT-4 can be prepared into a simple test paper as an efficient tool for the rapid detection of N 2 H 4 in real water samples. Four 2-(2-hydroxyphenyl)benzothiazole-based Schiff base derivatives incorporating different substituents were synthesized. Their optical properties were characterized by UV–visible and fluorescence spectra. The electron-withdrawing and electron-donating actions of substituents can change the orbital energy level distributions of molecules resulting in the difference of their luminescence properties. And the fluorescence microscopic images showed that these derivatives had different aggregation behaviors to form aggregates of different shapes. Furthermore, compound HBT-4 has been proved to have excellent recognition performance for N 2 H 4 in real aqueous solution. Finally, HBT-4 could be prepared into a simple test paper as an efficient tool for the rapid detection of N 2 H 4. [ABSTRACT FROM AUTHOR]

Although benzothiazole and its derivatives (BTHs) are considered emerging contaminants in diverse environments and organisms, little information is available about their contamination profiles and health impact in ambient particles. In this study, an optimized method of ultrasound-assisted extraction coupled with the selected reaction monitoring (SRM) mode of GC-EI-MS/MS was applied to characterize and analyze PM 2.5 -bound BTHs from three cities of China (Guangzhou, Shanghai, and Taiyuan) during the winter of 2018. The total BTH concentration (ΣBTHs) in PM 2.5 samples from the three cities decreased in the order of Guangzhou > Shanghai > Taiyuan, independently of the PM 2.5 concentration. Despite the large variation in concentration of ΣBTHs in PM 2.5 , 2-hydroxybenzothiazole (OTH) was always the predominant compound among the PM 2.5 -bound BTHs and accounted for 50–80% of total BTHs in the three regions. Results from human exposure assessment and toxicity screening indicated that the outdoor exposure risk of PM 2.5 -bound BTHs in toddlers was much higher than in adults, especially for OTH. The developmental and reproduction toxicity of OTH was further explored in vivo and in vitro. Exposure of mouse embryonic stem cells (mESCs) to OTH for 48 h significantly increased the intracellular reactive oxygen species (ROS) and induced DNA damage and apoptosis via the functionally activating p53 expression. In addition, the growth and development of zebrafish embryos were found to be severely affected after OTH treatment. An overall metabolomics study was conducted on the exposed zebrafish larvae. The results indicated that exposure to OTH inhibited the phenylalanine hydroxylation reaction, which further increased the accumulation of toxic phenylpyruvate and acetylphenylalanine in zebrafish. These findings provide important insights into the contamination profiles of PM 2.5 -bound BTHs and emphasize the health risk of OTH. Unlabelled Image • BTHs were detected in 26 outdoor PM 2.5 samples from Guangzhou and Taiyuan, China. • OTH was the predominant compound among the PM 2.5 -bound BTHs in the three regions. • OTH and the outdoor exposure risk of toddlers were much higher than that of adults. • OTH has potential developmental and reproduction toxicity. [ABSTRACT FROM AUTHOR]

• New fluorescent chemosensor based on conjugated benzothiazole under an intramolecular sensing mechanism was developed. • High selectivity toward sulfur dioxide derivatives (SO 3 2−/HSO 3 ‒) in aqueous solution. • Imaging of sulfur dioxide derivatives (SO 3 2−/HSO 3 ‒) in living cells was achieved. A new colorimetric and fluorescent probe 2 for SO 3 2−/HSO 3 ‒ detection was developed based on a conjugated benzothiazole derivative. The probe 2 was red color in aqueous solution and became colorless in the presence of SO 3 2−/HSO 3 ‒, accompanied by a fluorescence quenching. It was rationalized by an intramolecular charge transfer (ICT) mechanism, where the addition of SO 3 2−/HSO 3 ‒ to the vinyl double bond broken the conjugation and blocked the ICT process. This probe showed highly selective detection of SO 3 2−/HSO 3 ‒ compared with other sulfur-containing species and featured a detection limit of 2.01 μM. Moreover, the present probe was also successfully used for the fluorescence imaging of intracellular sulfur dioxide derivatives in living HeLa cells. [ABSTRACT FROM AUTHOR]

A simple fluorescent chemosensor WS1 (N' -[(Z)-1 H -indazol-3-ylmethylidene]imidazo [2,1- b ] [1,3]benzothiazole-2-carbohydrazide) based on imidazole [2,1- b ]benzothiazole was designed and synthesized. The probe showed specific recognition towards Cu2+ through colorimetric and "turn-off" fluorescence response in MeOH/H 2 O (9:1 V/V) buffer solution (10 mM Tris, pH = 7.4) with detection limit of 4.32 × 10−8 M. In addition, WS1 was a reversible fluorescence probe for the detection of Cu2+, the fluorescence intensity recovered to the similar state of free WS1 as PPi was added. And it showed a favorable potency for actual water monitoring. The proposed binding mode of WS1 with Cu2+ was verified by DFT calculation using Gaussian 09. • The probe showed specific recognition towards Cu2+ through colorimetric and fluorescence response. • The LOD for Cu2+ were 4.63 × 10−7 M and 4.32 × 10−8 M by colorimetric and fluorescence response, respectively. • The proposed binding mode of WS1 with Cu2+ was verified by DFT calculation. • WS1 can detect Cu2+ in tap water samples with acceptable recovery and RSD. [ABSTRACT FROM AUTHOR]

Increasing benzothiazole derivatives containing amino or N-acyl structures in position 2 have been largely developed as pesticides and medicines. However, the structure-function relationship of 2-substituted benzothiazole derivatives has seldom been illustrated from the perspective of their albumin-binding nature. Herein, to probe the influence of carbamylation on the albumin-binding nature of benzothiazole derivatives, formyl group was introduced to the amine group of 2-amino benzothiazole (ABT) to yield a novel modified ABT (MABT). Their protein-binding properties were systematically deciphered by spectroscopy, molecular modeling and density functional theory (DFT) calculations. The interaction mechanisms, recognition thermodynamics and binding geometry were investigated and compared. The structural alteration of human serum albumin was explored using synchronous fluorescence emission and circular dichroism spectrum technologies. Based on experimental results, the structures of protein complex with MABT and ABT were revealed by molecular docking method. The differences in energy transfer efficiency and molecular orientation of ABT and MABT in new complexes were tentatively explained by DFT calculations. The work was expected to help to understand the impact of different substituents on the bioactivity of benzothiazole derivatives and guide for structural designs of new compounds. The hydrophobic heterocyclic scaffold of benzothiazole guided ABT and MABT to Sudlow's site I in the subdomain IIA of HSA, while the carbamylation of ABT on position 2 resulted in the opposite molecular orientation and significantly increased energy reception efficiency, which were reasonably explained by the alterations of dipole moment and energy gap between HOMO and LUMO. Image 1 • MABT exhibited higher energy transfer efficiency and binding constants with HSA. • The heterocyclic scaffold of benzothiazole and nitrogen atom guided ABT/MABT to Sudlow's site I. • Their interactions with HSA were entropy-driven but with different heat effects. • The opposite molecular orientations of ABT and MABT in new complex correlated with their directions of dipole moments. • The energy gaps between HOMO and LUMO of ligand molecules explained their different energy transfer efficiency with HSA. [ABSTRACT FROM AUTHOR]

A benzothiazole-based near-infrared (NIR) ratiometric fluorescent probe ( HBT-Cys ) was developed for discriminating cysteine (Cys) from homocysteine (Hcy) and glutathione (GSH). The probe was designed by masking phenol group in the conjugated benzothiazole derivative with methacrylate group that could be selectively removed by Cys, and therefore an intramolecular charge transfer (ICT) fluorescence was switched on in the NIR region. In the absence of Cys, the probe exhibited a strong blue fluorescence emission at 431 nm, whereas a NIR fluorescence emission at 710 nm was significantly enhanced accompanied by a decrease of emission at 431 nm in the presence of Cys, allowing a ratiometric fluorescence detection of Cys. The fluorescence intensity ratio (I 710nm /I 431nm ) showed a good linear relationship with Cys concentration of 1-40 μM with the detection limit of 0.5 μM. The sensing mechanism was explored based on MS experimental analysis and DFT theoretical calculation. Moreover, the fluorescent probe was successfully used for fluorescence bioimaging of Cys in living cells.

Two novel altenusin-thiazole hybrids named altenusinoides A and B (1 and 2), a new benzothiazole derivative (3), and three known altenusin derivatives (4–6) have been obtained from the solid culture of the marine sponge-derived fungal strain, Alternaria sp. SCSIOS02F49. The structures of these new compounds were characterized by NMR, HRESIMS, and X-ray single crystal analysis. Compounds 1 and 2 possess an unusual altenusin-thiazole-fused skeleton core (6/6/5), and compound 3 represents the first benzothiazole derivative from fungi. Compounds 4 and 5 showed significant DPPH free-radical-scavenging activities with the prominent IC50 values of 10.7 ± 0.09 μM and 100.6 ± 0.025 μM, respectively. Additionally, compound 5 exhibited COX-2 inhibitory activity with an IC50 value of 9.5 ± 0.08 μM. [ABSTRACT FROM AUTHOR]