2-Amino-5-mercapto-1,3,4-thiadiazole

A novel electrochemical biomimetic sensor based on poly(Cu-AMT) with reduced graphene oxide for ultrasensitive detection of dopamine.[Pubmed:27837888]

Talanta. 2017 Jan 1;162:80-89.

A polymerized film of copper-2-Amino-5-mercapto-1,3,4-thiadiazole (Cu(II)-AMT) complex (poly(Cu-AMT)) was successfully achieved via a simple and low-cost electrochemical methodology. Subsequently, a noncovalent nanohybrid of poly(Cu-AMT) with reduced graphene oxide (rGO) (rGO-poly(Cu-AMT)) was prepared through pi-pi stacking interaction as an efficient mimetic enzyme for the ultrasensitive and selective detection of dopamine (DA). The rGO-poly(Cu-AMT) nanocomposites showed considerable mimetic enzyme catalytic activity, which may be attributed to the significant promotion of the electron transfer between the substrate and graphene-based carbon materials, and also the synergistic electrocatalytic effect in mimetic enzyme between rGO sheet and poly(Cu-AMT). The electrocatalytic and sensing performances of the biomimetic sensor based on the rGO-poly(Cu-AMT) nanocomposites were evaluated in detail. The biomimetic sensor enables a reliable and sensitive determination of DA with a linear range of 0.01-40muM and a detection limit of 3.48nM at a signal-to-noise ratio of 3. In addition, we applied the proposed method to detect DA in real sample with satisfactory results. Accordingly, the rGO-poly(Cu-AMT) is one of the promising mimetic enzyme for electrocatalysis and biosensing.

The nanocrystalline coordination polymer of AMT-Ag for an effective detection of ciprofloxacin hydrochloride in pharmaceutical formulation and biological fluid.[Pubmed:27236138]

Biosens Bioelectron. 2016 Nov 15;85:529-535.

The present report highlights a cost effective and portable AMT-Ag nanocrystalline coordination polymer (NCCP) based electrochemical sensor for an efficient sensing of biologically active drug molecule ciprofloxacin hydrochloride (CFX). The AMT-Ag NCCP, is synthesized using an easily accessible organic ligand 2-Amino-5-mercapto-1,3,4-thiadiazole (AMT) with silver nitrate. In the infinite polymer array of AMT-Ag, silver (I) centers are bridged by tecton AMT through the exocyclic thiol and amino linkage. A successful ultratrace detection of CFX has been achieved due to the prominent electron channeling through the pores of polymeric nano-crystallites. The efficient charge transfer arises at the interface of electrolyte and AMT-Ag nano-crystals anchored electrode through hydrophobic interaction and pi-pi electron coupling. The voltammogram reveals the critical redox features of CFX and provides a clear representation about the steps involved in the AMT-Ag assisted oxidation of CFX. This specific signature further applied in the voltammetric assay of CFX in pharmaceutical formulation (eye drops) and biological fluid (urine) by a significantly high sensitivity (0.002microA/microM and 0.007microA/microM) and detection limit (22nM and 60nM) respectively without any interference. Therefore, the developed AMT-Ag NCCP could serve as a highly valuable platform for the fabrication of high-performance electrochemical sensors for the detection of biologically important drug molecules.

Photochemical degradation of bismerthiazol: structural characterisation of the photoproducts and their inhibitory activities against Xanthomonas oryzae pv. oryzae.[Pubmed:26174501]

Pest Manag Sci. 2016 May;72(5):997-1003.

BACKGROUND: Bismerthiazol is a commonly used bactericide against rice bacterial leaf blight in China. Although previous research determined that bismerthiazol is susceptible to photolytic degradation, the photodegradation pathway and degradation products, except for 2-Amino-5-mercapto-1,3,4-thiadiazole, have remained unknown. RESULTS: The photodegradation of bismerthiazol was investigated after 4 and 8 h of irradiation in a solar simulator. Inhibition of Xanthomonas oryzae pv. oryzae (Xoo) was greater with a photolysed solution than with a non-photolysed solution of bismerthiazol. Six photoproducts of bismerthiazol were characterised by liquid chromatography coupled with mass spectrometry, and, based on these products, a photodegradation pathway was inferred. Inhibition of Xoo was significantly greater with bismerthiazol and 2-Amino-5-mercapto-1,3,4-thiadiazole than with 5-amino-1,3,4-thiadiazole. In addition, Xoo strain 2-1-1 was bismerthiazol- and 2-Amino-5-mercapto-1,3,4-thiadiazole resistant in vivo. CONCLUSION: Photodegradation increased the inhibitory activity of bismerthiazol against Xoo. The photodegradation pathway was inferred on the basis of the photoproducts of bismerthiazol. In vitro assays indicated that the sulfhydryl group was crucial for the inhibition of Xoo by bismerthiazol and its photoproducts. Bismerthiazol and 2-Amino-5-mercapto-1,3,4-thiadiazole might have a similar mode action in vivo and in vitro.

Cotransport of bismerthiazol and montmorillonite colloids in saturated porous media.[Pubmed:25805364]

J Contam Hydrol. 2015 Jun-Jul;177-178:18-29.

While bismerthiazol [N,N'-methylene-bis-(2-Amino-5-mercapto-1,3,4-thiadiazole)] is one of the most widely used bactericides, the transport of bismerthiazol in subsurface environments is unclear to date. Moreover, natural colloids are ubiquitous in the subsurface environments. The cotransport of bismerthiazol and natural colloids has not been investigated. This study conducted laboratory column experiments to examine the transport of bismerthiazol in saturated sand porous media both in the absence and presence of montmorillonite colloids. Results show that a fraction of bismerthiazol was retained in sand and the retention was higher at pH7 than at pH 4 and 10. The retention did not change with ionic strength. The retention was attributed to the complex of bismerthiazol with metals/metal oxides on sand surfaces through ligand exchange. The transport of bismerthiazol was enhanced with montmorillonite colloids copresent in the solutions and, concurrently, the transport of montmorillonite colloids was facilitated by the bismerthiazol. The transport of montmorillonite colloids was enhanced likely because the bismerthiazol and the colloids competed for the attachment/adsorption sites on collector surfaces and the presence of bismerthiazol changed the Derjaguin-Landau-Verwey-Overbeek (DLVO) interaction energies between colloids and collectors. The transport of bismerthiazol was inhibited if montmorillonite colloids were pre-deposited in sand because bismerthiazol could adsorb onto the colloid surfaces. The adsorbed bismerthiazol could be co-remobilized with the colloids from primary minima by decreasing ionic strength. Whereas colloid-facilitated transport of pesticides has been emphasized, our study implies that transport of colloids could also be facilitated by the presence of pesticides.

Functionalized CMK-3 mesoporous carbon with 2-amino-5-mercapto-1,3,4-thiadiazole for Hg(II) removal from aqueous media.[Pubmed:25080004]

J Environ Sci (China). 2014 Jul;26(7):1541-8.

Ordered mesoporous carbon (CMK-3) was synthesized and functionalized with 2-Amino-5-mercapto-1,3,4-thiadiazole groups (AMT-OCMK-3) for Hg(II) removal from aqueous solution. The modified CMK-3 was characterized by X-ray diffraction, N2 adsorption-desorption isotherm, scanning electron microscopy and Fourier transform infrared spectroscopy. The effects of solution pH, contact time, initial Hg(II) concentration and matrix effect were studied. The adsorption data were successfully fitted with the Langmuir model, exhibiting high adsorption capacity of 450.45 mg/g of AMT-OCMK-3. In the solid-phase extraction system a series of experimental parameters such as sample flow rate, sample volume, eluent volume and concentration of the eluent solution have been investigated and established for preconcentration of Hg(II) in aqueous solution. The results showed that the enrichment factor for Hg(II) was 250, the precision (relative standard deviation (RSD), %) for six replicate measurements was 2.05% and the limit of detection for Hg(II) was achieved at 0.17 mug/L.

Application of magnetic solid phase extraction for separation and determination of aflatoxins B (1) and B(2) in cereal products by high performance liquid chromatography-fluorescence detection.[Pubmed:24814005]

J Chromatogr B Analyt Technol Biomed Life Sci. 2014 Jun 1;960:200-8.

A simple and sensitive method based on the magnetic solid phase extraction with modified magnetic nanoparticles followed by high performance liquid chromatography with fluorescence detection has been developed for extraction and determination of aflatoxins B1 (AFB1) and B2 (AFB2) in cereal products. Magnetic nanoparticle coated with 3-(trimethoxysilyl)-1-propanthiol (TMSPT) and modified with 2-Amino-5-mercapto-1,3,4-thiadiazole (AMT) was used as an antibody-free adsorbent. Under the optimal conditions, the calibration curves for AFB1 and AFB2 were linear in the ranges of 0.2-15 mug L(-1) and 0.04-3 mug L(-1), respectively. Detection limit was 0.041 mug L(-1) for AFB1 and 0.013 mug L(-1) for AFB2. The proposed method was successfully applied to the determination of AFB1 and AFB2 in spiked corn and rice samples with an average recovery of 93.5%. The results demonstrated that the developed method is simple, rapid, inexpensive, accurate and remarkably free from interference effects.

Enhanced spectrofluorimetric determination of aflatoxin M1 in liquid milk after magnetic solid phase extraction.[Pubmed:24691373]

Spectrochim Acta A Mol Biomol Spectrosc. 2014 Jul 15;128:583-90.

A simple and sensitive method using magnetic solid phase extraction (MSPE) followed by spectrofluorimetric detection has been developed for separation and determination of aflatoxin M1 (AFM1) in liquid milk. The method is based on the extraction of AFM1 on the modified magnetic nanoparticles (MMNPs) and subsequent derivatization of extracted AFM1 to AFM1 hemi-acetal derivative (AFM2a) by reaction with trifluoroacetic acid (TFA) for spectrofluorimetric detection. Magnetic nanoparticles (MNPs) coated by 3-(trimethoxysilyl)-1-propantiol (TMSPT) and modified with 2-Amino-5-mercapto-1,3,4-thiadiazole (AMT) were used as adsorbent in MSPE procedure. Influential parameters affecting the extraction efficiency were investigated and optimized. Under the optimum conditions the calibration curve for AFM1 determination showed good linearity in the range 0.030-10.0 mug L(-1) (R(2) = 0.9991). The repeatability and reproducibility (RSD%) for 0.050 mug L(-1) of AFM1 were 4.5% and 5.3%, respectively and limit of detection limit (S/N = 3) was estimated to be 0.010 mug L(-1). The developed method was successfully applied for extraction of AFM1 from spiked liquid milk and natural contaminated liquid milk. The good spiked recoveries ranging from 91.6% to 96.1% were obtained. The results demonstrated that the developed method is simple, inexpensive, accurate and remarkably free from interference effects.

Determination and study on dissipation and residue of bismerthiazol and its metabolite in Chinese cabbage and soil.[Pubmed:24065135]

Environ Monit Assess. 2014 Feb;186(2):1195-202.

A simple and accurate method for the determination of bismerthiazol and its metabolite 2-Amino-5-mercapto-1,3,4-thiadiazole was developed in Chinese cabbage and soil by high-performance liquid chromatography-diode array detection in this study. The limits of detection were 0.06 mg/kg for bismerthiazol and 0.03 mg/kg for 2-Amino-5-mercapto-1,3,4-thiadiazole, respectively. Recoveries of cabbage and soil were investigated at three spiking levels and were in the range of 84.0-96.0% for bismerthiazol and 71.0-74.6% for 2-Amino-5-mercapto-1,3,4-thiadiazole, with relative standard deviations below 7.0%. For field experiments, the half-life of bismerthiazol was 2.4-2.5 days in Chinese cabbage and 2.5-4.8 days in soil at the two experimental locations in China. Dissipation residues of 2-Amino-5-mercapto-1,3,4-thiadiazole were lower than 0.72 mg/kg. Terminal residues of bismerthiazol and its metabolite were less than 3.0 and 0.3 mg/kg in Chinese cabbage, respectively. No bismerthiazol or metabolite residues were detected in soil on days 5, 7, 10, and 14 after the last spraying at the two dosage levels.

Solid phase extraction of trace amounts of Ag, Cd, Cu, and Zn in environmental samples using magnetic nanoparticles coated by 3-(trimethoxysilyl)-1-propantiol and modified with 2-amino-5-mercapto-1,3,4-thiadiazole and their determination by ICP-OES.[Pubmed:21561711]

J Hazard Mater. 2011 Jun 15;190(1-3):1023-9.

A fast, sensitive, and simple method using magnetic nanoparticles (MNPs) coated by 3-(trimethoxysilyl)-1-propantiol and modified with 2-Amino-5-mercapto-1,3,4-thiadiazole, as an adsorbent has been successfully developed for extraction, preconcentration, and determination of trace amounts of Ag, Cd, Cu, and Zn from environmental samples. The prepared nanoparticles were characterized by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). These magnetic nanoparticles can be easily dispersed in aqueous samples and retrieved by the application of external magnetic field via a piece of permanent magnet. The main factors affecting the extraction efficiency such as pH value, sample volume, eluent concentration and volume, ultrasonication time, and coexisting ions have been investigated and established. Under the optimal conditions, high concentration factors (194, 190, 170, and 182) were achieved for Ag, Cd, Cu, and Zn with relative standard deviations of 5.31%, 4.03%, 3.62%, and 4.20%, respectively. The limits of detection for Ag, Cd, Cu, and Zn were as low as 0.12, 0.12, 0.13 and 0.11 ng mL(-1). The prepared sorbent was applied for preconcentration of trace amounts of Ag, Cd, Cu, and Zn in the various water samples with satisfactory results.

Solvent-assisted slow conversion of a dithiazole derivative produces a competitive inhibitor of peptide deformylase.[Pubmed:19922819]

Biochim Biophys Acta. 2010 Apr;1804(4):704-13.

Due to its potential as an antibiotic target, E. coli peptide deformylase (PDF(Ec)) serves as a model enzyme system for inhibitor design. While investigating the structural-functional and inhibitory features of this enzyme, we unexpectedly discovered that 2-Amino-5-mercapto-1,3,4-thiadiazole (AMT) served as a slow-binding inhibitor of PDF(Ec) when the above compound was dissolved only in dimethylformamide (DMF), but not in any other solvent, and allowed to age. The time dependent inhibitory potency of the DMF-dissolved AMT was correlated with the broadening of the inhibitor's 295 nm spectral band toward the visible region, concomitant with the increase in the mass of the parent compound by about 2-fold. These data led to the suggestion that DMF facilitated the slow dimerization of AMT (via the formation of a disulfide bond), and that the dimeric form of AMT served as an inhibitor for PDF(Ec). The latter is not caused by the simple oxidation of sulfhydryl groups by oxidizing agents such as H(2)O(2). Newly synthesized dimeric/dithiolated form of AMT ("bis-AMT") exhibited similar spectral and inhibitory features as given by the parent compound when incubated with DMF. The computer graphic modeling data revealed that bis-AMT could be reliably accommodated within the active site pocket of PDF(Ec), and the above enzyme-ligand interaction involves coordination with the enzyme resident Ni(2+) cofactor. The mechanism of the DMF-assisted activation of AMT (generating bis-AMT), the overall microscopic pathway for the slow-binding inhibition of PDF(Ec) by bis-AMT, and the potential of bis-AMT to serve as a new class of antibiotic agent are presented.

Novel pyrimidinediones and thiazolidinones as anti depressants.[Pubmed:8527101]

Boll Chim Farm. 1995 Oct;134(9):492-6.

2-Mercapto-5-[4'-methoxy phenyl thiourea]-1,3,4-thiadiazole (2a-c) prepared by the condensation of 2-Amino-5-mercapto-1,3,4-thiadiazole (1) with substituted phenyl isothiocyanates. Further on cyclisation with malonic acid in the presence of acetyl chloride gave the corresponding 2-mercapto-5-[3-(4-methoxy phenyl)-2-thioxo-2-5-dihydro-4, 6-pyrimidionoyl]-1,3,4-thiadiazole (3a-c) [sequence: see text]. This on further reaction with substituted aryl aldehydes in presence of zinc chloride gave 2-mercapto-5-[3-(4'-methoxy phenyl)-2'-thioxo-2',5'-dihydro-4',6' -pyrimidionoyl 5'-phenyl carboxaldehyde]-1,3,4- thiadiazole (4a-g) [sequence: see text]. The compounds were screened for antidepressant activity and compared with antidepressant (imipramine).