Search

New bis-semicarbazides were obtained by the reaction of hexamethylene diisocyanate with aliphatic and aromatic acids hydrazides, as well as semicarbazide, thiosemicarbazide, and 4-substituted thiosemicarbazides.

New 2-Mercaptobenzimidazole derivatives were synthesized. 4,5-disubsitituted 1,2,4-Triazole compounds 1b-2c were synthesized from 2-(benzylthio) benzimidazole compound a, which was then reacted with (NaH) in dioxane at a temperature of (0-5 C°) to produce the salt of compound a. Then the salt was reacted with ethyl chloro acetate to yield Ethyl 2-(benzylthio) benzimidazole acetate compound b. Compound b was converted to triazole derivatives by two pathways. The first pathway was reacting compound b with semicarbazide, thiosemicarbazide and phenylsemicarbazide in DMSO as a solvent to gain compounds 1b-3b, which were then cyclized by refluxed with 2N (NaOH) to yield 1,2,4-triazole derivatives compounds 4b-6b. The second pathway involved the treatment of compound b with hydrazine hydrate to produce N-acetohydrazide-2-(benzyl thio) benzimidazole c. Compound c was refluxed with carbon disulfide (CS2) in KOH alcoholic solution to obtain the salt compound 1c. The salt was treated with hydrazine hydrate to yield 1,2,4-triazole derivative compound 2c. The newly synthesized compounds b-2c were identified by FTIR, 1H-NMR and 13C-NMR and their physical properties were measured. Furthermore, their anti-microbial activities were tested against two Gram-positive and two Gram-negative bacteria and against one strain of fungi. Also, some of these synthesized compounds were tested for their anti-inflammatory activities.

A new approach is suggested herein for the synthesis of pyrazole derivatives by reacting 4-nitrosemicarbazide with acetylacetone. Additional studies were done on the reaction of acetylacetone with semicarbazide and its derivatives (4-aminosemicarbazide, methylsemicarbazide, and dimethylsemicarbazide). The study on the reaction with acetylacetone resulted in monocyclic 3,5-dimethyl-N-nitropyrazole-1-carboxamide, monocyclic 5-hydroxy-3,5-dimethyl-2-pyrazoline, and bicyclic bis(3,5-dimethylpyrazole-1-carbonyl)hydrazine, and conditions for the formation of acetone semicarbazone were identified. The structures of the resultant compounds were validated by physicochemical analytical methods, including X-ray diffraction. The computer-aided screening in the PASS prediction software discovered a high biological activity of the newly obtained compounds.

The solute-solute and solute-solvent interactions of drug semicarbazide hydrochloride with carbohydrates ( d -glucose/ d -sucrose) are investigated by using volumetric, viscometric and acoustic properties. The measurements of the densities ρ, ultrasonic speeds u, and viscosities η. of semicarbazide hydrochloride in 5% and 10% d -glucose/ d -sucrose + water (w/w) solutions were carried out at temperatures (293.15–318.15) K and at pressure, p = 101 kPa. The apparent molar volumes, Vϕ, limiting apparent molar volumes, V ϕ ° , apparent molar compressibilities, Ks, ϕ, limiting apparent molar compressibilities, K s , ϕ ° , partial molar expansibilities, E ϕ ° , transfer volumes, V ϕ , tr ° and transfer compressibilities, K s , ϕ , tr ° have been calculated from the experimental data. The viscosity data were examined by using the Jones-Dole equation and the viscosity A and B coefficients were evaluated. The results are discussed in terms of solute-solute and solute-solvent interactions in these solutions. The structure making/breaking ability of semicarbazide hydrochloride is examined using the sign of temperature derivative of B-coefficient, dB/dT.

Influence of nitrogen precursors urea, semicarbazide and N,N’-dimethyl urea on the photocatalytic activity of the N-doped TiO2 were studied by a simple decomposition method. The nano N-TiO2 catalysts were synthesized via two different modified approaches by calcination at 500 oC. The synthesized samples were characterized by IR, UV-DRS, Raman, TG-DTA, XRD, EDX, XPS, SEM, TEM and BET analysis. Of the synthesized six samples of N-TiO2 five samples showed better photocatalytic activity towards direct sunlight photo-degradation of methylene blue (MB) and rhodamine B (RhB) than Degussa P25. The catalysts obtained using semicarbazide samples F3 and F4 having large surface area of 76 and 85.8 m2/g displayed maximum photocatalytic activity. The sample F4 was 1.5 times more active than Degussa P25 for the decolourisation of MB and 1.9 times more active for the decolourisation of RhB. The presence of nitrogen, large surface area and coupling of rutile-anatase phases were found to be the main responsible factors for the enhanced photocatalytic activity. The exclusive formation of the anatase phase in the case of urea precursor is attributed to the slow evaporation of urea due to the formation of melamine derived products. The calcination temperature is the deciding factor responsible for the photocatalytic activity of the N-TiO2 samples prepared from precursors which can potentially form the melamine and its oligomerized products on the surface of TiO2.

2-Amino glucose ((2S,3R,4S,5S,6R)-2-amino-6-(hydroxymethyl)tetrahydro-2H-pyran-3,4,5-triol) as a substrate for the synthesis of NiFe2O4@SiO2 Pr@amino glucose supply an eco-friendly procedure for the synthesis of novel 3-pyrazolyl-4H-1,2,4-triazoles through a one-pot three-component reaction of semicarbazide (hydrazinecarboxamide), alcohol and synthetized pyrazolecarbaldehydes. NiFe2O4@SiO2 Pr@amino glucose supply an environmentally friendly procedure for the synthesis of some of these compounds in high yields and short reaction times. The catalyst could be easily recovered and reused for six cycles with almost consistent activity. The structures of the synthesized 3-pyrazolyl-4H-1,2,4-triazole compounds were confirmed by 1H NMR, 13C NMR and FTIR spectral data and elemental analyses.

Colorimetric indicators can provide quick results for instant, in-field detection of analytes without expensive equipment and expertise. A simple, cost-effective 1-m-nitrobenzoyl semicarbazide based indicator has been developed for reversible colorimetric cascade detection of fluoride and moisture. The detection is highly selective for fluoride over other halides and different anions. On addition of fluoride, a sharp brown colour appeared immediately and fluorescence quenching was observed. The fluorescence turn off is due to complex formation with fluoride, almost immediately and can be observed with the naked eye, which is necessary for a real-time sensor without any sophisticated and expensive instruments and quicker response time. Moreover the 1-m-nitrobenzoyl semicarbazide–fluoride complex acts as a reusable probe for moisture showing high selectivity, sensitivity, instant response and stability. In the presence of moisture, the sharp brown colour disappears immediately and the fluorescence bounces back. The entire detection process is reversible in nature and helps to develop a re-writable device and an encryption–decryption system as security ink.

Tridentate O,N,O-donor Schiff base ligand (E)-1-(2-hydroxybenzylidene)semicarbazide (H2L1) and its Mn(II) complex have been synthesized. Both the ligand and the complex have been characterized by analytical and spectroscopic techniques. X-ray crystal structure determination of the Mn(II) complex shows that the Mn(II) atom is in a distorted octahedral environment and there are two crystallographically different manganese atoms in the unit cell. The Mn(II) complex shows very high catalytic activity for catechol oxidation (kcat = 3.10 × 106 h−1, kcat/KM = 3.25 × 108 h−1 M−1), which is the highest catalytic efficiency for catechol oxidation by a manganese complex reported in the literature. The probable mechanism of the catalytic reaction is explored using ESI-MS and EPR spectroscopy.

A family of tetranuclear Ni-4f coordination aggregates (CAs) from the support of a carbazido ligand is described. The option of altering the 4f ions during synthesis within the family, without altering the core topology, gave the four members of the family. Tetranuclear (2 : 2) heterometallic compounds [NiII2LnIII2(μ3-L)2(μ3-OH)2(μ-OAc)3(AcO)(H2O)3]Cl2·4H2O (Ln = Gd, 1; Tb, 2; Dy, 3; Ho, 4) have been assembled through the utilization of all the coordination sites of the anionic form of 1-(2-hydroxy-3-methoxybenzylidene)semicarbazide (HL) and bridging supports from HO− and AcO− ions. The four metal ion centers of two different types, are held together by two μ-L−, two μ3-HO− and three μ1,3-AcO− bridges to self-assemble into Ni2Ln2O4 hetero-cubane structures. In each cube, LnIII ions are linked by two hydroxido and one phenoxido bridge and each NiII ion is linked by two phenoxido and one hydroxido bridge, so that each hydroxido group in μ3-mode is linked to two LnIII and one NiII and each phenoxido ion in μ3-mode is linked to two NiII and one LnIII. Variable temperature magnetic properties have been examined to find the role of magnetic anisotropy for the single molecule magnet (SMM) behavior. All of them show large ground state magnetic moment values and absence of out-of-phase ac susceptibility signals. The absence of SMM behavior is ascribed to the lack of axial magnetic anisotropy.

Two novel semicarbazide [HL1, 1, 1-((4-nitrophenyl)(phenyl)methylene)semicarbazide] and thiosemicarbazide [HL2, 2, 1-((4-nitrophenyl)(phenyl)methylene)thiosemicarbazide] ligands were generated from 4-nitrobenzophenone and the corresponding (thio)semicarbazide precursors. Compounds 1 and 2 were fully characterized and their X-ray crystal structures were established. These organic derivatives were further applied as bioactive building blocks for the self-assembly synthesis of silver(i) coordination compounds. The reactions of silver(i) nitrate with HL1/HL2 in the presence of aqueous NH4OH resulted in new silver(i) coordination compounds formulated as [Ag(HL1)(NO3)]·H2O (3) and [Ag6(?3-L2)6] (4). These complexes were characterized by standard methods (FT-IR, NMR, ESI-MS, and elemental analysis) as well as single-crystal X-ray diffraction. The structure of 3 features a two-coordinate silver(i) center with a distorted linear AgNO geometry, wherein an unusual coordination of HL1 through the nitrogen atom of the amine group is realized. The structure of 4 reveals a discrete Ag6 cluster composed of two joined trisilver(i) rings, wherein the three-coordinate Ag(i) centers adopt an AgNS2 environment. The antimicrobial activity of 14 was screened against Gram-positive (S. epidermidis and S. aureus) and Gram-negative (P. aeruginosa and E. coli) bacteria. Compound 4 presented antimicrobial activity against Gram-positive bacteria, including the ability to impair biofilm formation. This study thus contributes to a still limited research area on the development of new silver coordination compounds with potential antibiofilm activity., Fundação para a Ciência e Tecnologia (FCT) and Portugal 2020 (projects PTDC/QUI-QIN/29697/2017, LISBOA-01-0145-FEDER-029697, UIDB/00100/2020, UIDP/00100/2020, SFRH/BSAB/150368/2019 and REM2013). The publication was also prepared with the support of the RUDN University Program 5-100. TAF acknowledges the FCT for BPD grant SFRH/BPD/119980/2016, info:eu-repo/semantics/publishedVersion

A green and efficient synthesis of 3-pyrazolyl indoles was developed by the cyclocondensation reaction of β-ethylthio-β-indolyl-α, β-unsaturated ketones with semicarbazide hydrochloride as hydrazine equivalent in the presence of 3 equiv. of PEG-400(1a/PEG mole ratio of 1:3) in reflux water. This procedure did not require toxic hydrazine and product purification, eliminating the use of toxic liquid chemicals.

In the presence of semicarbazide hydrochloride (SCH) and traces of AgI, the tetrazolium salt 2,5-diphenyl-3-(1-naphmyl)-2H-tetrazolium chloride (Tetrazolium violet, TV) is reduced in alkaline medium to intensely colored chloroform-extractable 3,5-diphenyl-1-(1-naphthyl)formazan (Tetrazolium violet formazan, TVF). The following experimental parameters have been examined for finding optimal conditions for color development and extraction-spectrophotometric determination of AgI: concentration of reagents, extraction time, volume of the two phases, presence of dissolved oxygen, and light. Under the optimal conditions (cTV = 4.0 × 10−5 mol/dm3, cSCH = 2.4 × 10−3 mol/dm3, cNaOH = 4 × 10−1 mol/dm3, Vaq.phase = 25 cm3, Vchloroform = 4 cm3, extraction time t = 5 min) an isomer of TVF with λmax = 511–512 nm is predominantly extracted. The calibration curve (at 512 nm) is linear in the concentration range of 0.013–0.028 µg cm−3 of AgI. The following ions do not interfere in determination of 0.65 µg of AgI; Li+, Na+, K+, $$\rm{NH}_4^+$$, $$\rm{H}_2PO_4^-$$, F−, Cl−, $$\rm{SO}_4^{2-}$$, $$\rm{B}_4O_7^{2-}$$, $$\rm{ReO}_4^-$$, tartrate, and citrate (5000-fold excess); MgII and EDTA (1000-fold excess); PbII and BaII (500-fold excess); AlIII (300-fold excess); ZnII and CaII (100-fold excess); VV (50-fold excess); HgII, HgI, MoVI and FeIII (25-fold excess); and CuII and WVI (10-fold excess). CrIII interferes in the process at a mass ratio of 1 : 1, however small amount of this cation (1.5-fold excess) can be masked by EDTA.

The butyl ester of 3-oxoglycyrrhetinic acid reacted with semicarbazide in EtOH in the presence of NaOAc to produce the 3-semicarbazone, Hurd–Mori cyclization of which gave in 85% yield a 1,2,3-thiadiazole annelated to ring A.

This research aims to analyze the biosynthetic pathway of endogenous semicarbazide (SEM) in shrimps using Litopenaeus vannamei as the model target. To achieve this objective, the content of SEM in L. vannamei throughout the whole growth cycle was monitored under the strict control of external environmental interference. Experimental results showed that SEM was found in the shrimp shell at all stages, with its content decreasing first and then increasing, and no SEM was detected in the shrimp muscle of each growth stage. This indicated that endogenous SEM in L. vannamei was derived from the shrimp shell. At the same time, the content of amino acids in the shrimp shell and the corresponding substances involved in the urea cycle in the entire growth cycle of shrimp were monitored. The correlation analysis between them and the changes in the SEM content in shrimp showed that arginine had the largest correlation coefficient (0.952) with the changes in the SEM content. The main substances of the urea cycle may be related to the production of SEM. In combination with the water environmental test of high ammonia nitrogen, it was presumed that the formation of endogenous SEM was related to the amidine group of arginine and amide structure of citrulline and urea. Arginine, citrulline, and urea in the urea cycle of L. vannamei eventually produced SEM via an oxaziridine intermediate under the action of hydrogen peroxide and ammonia, and a standardized reaction test was conducted to verify the hypothesis and, thus, provided a new idea for future endogenous SEM research.

2-(1-(3,4-Dihydroxyphenyl)ethylidene)hydrazine-1-carboxamide was synthesized as a precursor for generation of redox polymer. In acidic media, the opposite charge on the surface of this monomer and graphene quantum dots make feasible monomer electrodeposition. Fourier transform infrared spectroscopy and field-emission scanning electron microscopy were used for chemical band identification and morphological characteristics of coated film at electrode. Polymer-modified electrode enhances electron-transfer process of catechol amines such as dopamine and dobutamine selectively. Graphene quantum dots/polymer film-modified electrode produce more oxidation current compared to polymer-modified electrode alone. Under optimized condition, the concentration of dobutamine and its oxidation signal was well fitted to the linear regression function in the range of 0.05–35.0 µM with the detection limit of 0.01 µM. The accuracy evaluation of modified electrode was determined by measuring concentration of dobutamine in serum samples.

To exploit novel ferrocene-based small molecules with long conjugated structures as visible and electrochemical multichannel chemosensors, four conjugated ferrocene ethynyl semicarbazide derivatives (Fc-X-An) were synthesized via the Sonogashira coupling reaction. The synthesized Fc-X-Ans are 2-(4-(ferrocenylethynyl)benzylidene) hydrazine-1-carboxamide (Fc-Ph-An), 2-((5-(ferrocenylethynyl)thiophen-2-yl)methylene)hydrazine-1-carboxamide (Fc-Thie-An), 2-((9-ethyl-6-(ferrocenylethynyl)-9H-carbazol-3-yl) methylene)hydrazine-1-carboxamide (Fc-Cz-An) and 2-((10-ethyl-7-(ferrocenylethynyl)-10H-phenothiazin-3-yl) methylene)hydrazine-1-carboxamide (Fc-PTZ-An). The recognition abilities of the semicarbazide derivative Fc-X-Ans for several anions were evaluated from visible absorption spectra, 1H NMR, and electrochemical technique.

A sensitive method was developed for the simultaneous detection of four nitrofuran (NF) metabolites (3-amino-2-oxazolidinone (AOZ), semicarbazide (SEM), 3-amino-morpholinomethyl-2-oxazolidinone (AMOZ) and 1-aminohydantoin (AH)) in marine products. Samples were derivatized using 7-(diethylamino)-2-oxochromene-3-carbaldehyde (DAOC) under the assistance of a microwave within 20 min, followed by analysis by high performance liquid chromatography–fluorescence detection (HPLC-FLD). These NF metabolite derivatives were completely separated on a reversed-phase Eclipse XDB-C18 column within 10 min at specific excitation and emission wavelengths (λex = 450 and λem = 510 nm). Excellent linearity (R > 0.998) of all NF metabolite compounds was achieved with the limits of detection (LODs) and the limits of quantitation (LOQs) in the range of 0.22–0.29 μg kg−1 and 0.69–0.95 μg kg−1, respectively. Satisfactory recoveries ranging from 91.39–104.93% were obtained for all the NF metabolites. This method was successfully applied for the identification and quantitation of the NF metabolites in marine products. Furthermore, the proposed method should have powerful potential in the analysis of AOZ, AH, AMOZ and SEM in foodstuffs.

An ultra-performance liquid chromatography coupled with electrospray ionisation tandem mass spectrometry (UPLC-ESI-MS/MS) with pre-column derivatisation was developed and validated for the determination of semicarbazide in human urine. Urine samples were derivatised with 2-nitrobenzaldehyde and subsequently extracted with acetonitrile. Extracts were concentrated and then analysed by UPLC-MS/MS. The time per run was 7 min. Good results were observed for the linearity of matrix-matched calibration curves (R

The heterometallic bridging potential of the anion of 1-(2-hydroxy-3-methoxybenzylidene)semicarbazide (HL) to CoII and four 4f ions was examined during a 4f ion coordination-driven cleavage of [Co2(μ-OH2)(O2CCMe3)4(HO2CCMe3)4] (Co2-Piv) and scrambling of pivalate anions from the starting material. Room-temperature reactions with four different lanthanide nitrate salts yielded [CoLnL(μ2-OOCCMe3)4(CH3OH)]·3CH3OH [Ln = Gd (1), Tb (2), Dy (3) and Ho (4)]. The formation in solution and the crystallization in the solid state indicated that the reactions inhibit any further aggregation of Co-Ln cores to higher order aggregates. After scrambling, the pivalate ions in [Co-Ln] show three types of coordination modes to sustain the dinuclear aggregates with varying degrees of distortion in the dinuclear entities bound to a single L− ion. Atom economy was maintained with respect to the pivalate ions as no external addition of these anions was made. The dc magnetic measurements revealed the presence of weak ferromagnetic interactions in complexes 1 and 2 and weak antiferromagnetic interactions in complexes 3 and 4.

The synthesis of 3-alkyl-5-trifluoromethyl-1H-pyrazole-1-carboxamides, 3-alkyl5-trifluoromethyl-1H-pyrazole-1-thiocarboxamides, and 2-(3-alkyl-5-trifluoromethyl-1H-pyrazol1-yl)-thiazoles derivatives are reported. [3 + 2] cyclocondensations for a series of long alkyl chain 1,1,1-trifluoro-4-methoxyalk-3-en-2-ones and semicarbazide or thiosemicarbazide were carried out in ethanol, an eco-friendly medium. The series of trifluoromethyl-1H-pyrazol-1-ylthiocarboxamide following a [3 + 2] cyclocondensation with 2-bromoacetophenone were converted into two series of 2-(3-alkyl-5-trifluoromethyl-1H-pyrazol-1-yl)-thiazoles. Good yields (69-96%) of the isolated products were obtained. The structures of the new long alkyl chain 1H-pyrazoles and 2-(1H-pyrazol-1-yl)thiazoles were characterized using 1 H, 13C, and 19F nuclear magnetic resonance (NMR) spectroscopy and electrospray ionization tandem mass spectrometric (ESI MS/MS) data. Moreover, some of the products were evaluated for their antimicrobial activity against Gram-negative Escherichia coli American Type Culture Collection (ATCC) 35218, Salmonella enteritidis ATCC 13076, and Pseudomonas aeruginosa ATCC 15692; and Gram-positive Staphylococcus aureus ATCC 6538, methicillin resistant Staphylococcus aureus (MRSA clinical isolate), Streptococcus sp. (clinical isolate), and Candida albicans ATCC 14053 and Candida krusei ATCC 6258 fungi. All the tested 1H-pyrazoles exhibited antibacterial and antifungal activities at the tested concentrations. The compounds from series 4 were found to be powerful against MRSA.

New multipotent antioxidants (MPAOs), namely semicarbazides and thiosemicarbazides bearing thiolated butylated hydroxytoluene (BHT), were synthesized. The antioxidant activity of the synthesized compounds was evaluated using in vitro DPPH assay. Compounds containing thiosemicarbazides (5a′–h′) were found more active in free radical scavenger than semicarbazides (5a–h). Among the other compounds, compound 5f′ (IC50 of 25.47 ± 0.42 μM) showed the best antioxidant activity against DPPH radicals compared to standard antioxidant butylated hydroxytoluene (BHT). Based on DPPH results, compound 5f′ and its corresponding semicarbazide 5f were blended into trimethylolpropane trioleate (TMPTO) and isothermal differential scanning calorimetry (DSC) was carried out for the investigation of oxidative stability. At 125 °C isothermal DSC, TMPTO with 0.25 wt% of 5f′ showed 1.5 times higher oxidation stability than its corresponding semicarbazide 5f and was 2 times better than BHT. It was anticipated that due to the strong auto-synergistic effect, compound 5f′ showed promising oxidative stability to TMPTO by protecting from pre-mature oxidative degradation.

This paper studies the potential of 3 newly synthesized low molecular weight gelling agents (2 of them with azo groups) with the semicarbazide group as a H-bonding motif to gel the smectic phase of a commercial chiral smectic C material. To detect gelation two methods were used: the stabilization of the director pattern, which measures the interaction of the physical gel network with the LC-director, and the suppression of the onset of electrohydrodynamic instabilities, which measures the increase of viscosity. Special emphasis was put on the influence of the photochemical - isomerization of the gelling agents on gelation.From the stabilization of the director pattern an elastic component can be seen by the memory effect (two different switching times). Photochemical - isomerization destroys this memory effect. The increase of the threshold field for the onset of electrohydrodynamic instabilities in free-standing films measures the increase of viscosity and the supression of flow. Both methods detect the same melting temperature of the gel and the same reduction of the gelling ability upon - isomerization. This proves that the gelling abilities of the new azo-containing gelling agents can be reversibly switched on and off by photoisomerization.

The semicarbazone derivative mol­ecule is almost planar. In the crystal, the mol­ecules are linked by O—H⋯O, N—H⋯O and O—H⋯N hydrogen bonds., In the title compound, C13H14N4O·2H2O, the organic mol­ecule is almost planar. In the crystal, the mol­ecules are linked by O—H⋯O, N—H⋯O and O—H⋯N hydrogen bonds, forming a two-dimensional network parallel to (10). Hirshfeld surface analysis and two-dimensional fingerprint plots indicate that the most important contributions to the crystal packing are from H⋯H (55.4%), H⋯O/O⋯H (14.8%), H⋯C/C⋯H (11.7%) and H⋯N/N⋯H (8.3%) inter­actions.

Novel unknown potentially biologically active 1-(1,2,3-thiadizolylcarbonyl)-4-(1,2,3-thiadiazolyl)-semicarbazides were synthesized by reactions of 1,2,3-thiadiazolylcarboxylic acid hydrazides with 1,2,3- thiadizolylcarbonyl azide in high yields. The structure of the synthesized compounds was studied by NMR and IR spectroscopy and X-ray diffraction analysis.

We developed and validated a method for the extraction, identification, and quantitation of four nitrofuran metabolites, 3-amino-2-oxazolidinone (AOZ), 3-amino-5-morpholinomethyl-2-oxazolidinone (AMOZ), semicarbazide (SC), and 1-aminohydantoin (AHD), as well as chloramphenicol and florfenicol in a variety of seafood commodities. Samples were extracted by liquid-liquid extraction techniques, analyzed by ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS), and quantitated using commercially sourced, derivatized nitrofuran metabolites, with their isotopically labeled internal standards in-solvent. We obtained recoveries of 90-100% at various fortification levels. The limit of detection (LOD) was set at 0.25 ng/g for AMOZ and AOZ, 1 ng/g for AHD and SC, and 0.1 ng/g for the phenicols. Various extraction methods, standard stability, derivatization efficiency, and improvements to conventional quantitation techniques were also investigated. We successfully applied this method to the identification and quantitation of nitrofuran metabolites and phenicols in 102 imported seafood products. Our results revealed that four of the samples contained residues from banned veterinary drugs.

Intramolecular cyclization of N-aryl-2-[(9-oxoacridin-10(9H)-yl)acetyl]hydrazinecarboxamides afforded new 10-(5-arylamino-1,3,4-oxadiazol-2-ylmethyl)acridin-9(10H)-ones. Some of the synthesized compounds showed a moderate antimicrobial activity against gram-positive and gram-negative bacteria. Keywords: acridone, hydrazide, semicarbazide, 1,3,4-oxadiazole, antibacterial activity

A series of substituted and fused heterocyclic derivatives 2–17 were synthesized using 3,5-bis(4-methoxybenzylidene)-1-propylpiperidin-4-one (1) as starting material. Treatment of 1 with malononitrile or semicarbazide afforded compounds 2 and 3, respectively. Condensation of 1 with ethyl cyanoacetate afforded naphthyridine-3-carbonitrile derivative 4, which reacted with phosphorus pentachloride and phosphoryl chloride to give chloro derivative 5. Treatment of 5 with thiosemicarbazide afforded compound 6. The reaction of 1 with malononitrile gave cyano aminopyrane derivative 7 which was condensed with pyromellitic dianhydride, phthalic anhydride, succinic anhydride, or morpholine in glacial acetic acid to obtain imide derivatives 8–11. Additionally, the reaction of 7 with aromatic aldehydes gave derivatives 12a–12c. Acetylation of 7 with acetic anhydride in boiling acetic acid gave N-acetyl derivative 13 which was cyclized to pyridine derivative 14 by refluxing in dioxane in the presence of triethylamine. Treatment of 7 with hydrazine hydrate gave pyrazolo derivative 15. Finally, the reaction of 7 with triethyl orthoformate in the presence of acetic anhydride gave formimidate 16 which was treated with hydrazine hydrate to form N-amino derivative 17. Some of the synthesized compounds were examined in vitro for their antitumor activity against HepG-2, PC-3, and HCT-116 human carcinoma cell lines using MTT assay.

To deepen the study on heptacoordinate transition metal coordination complexes, a novel seven-coordinated coordination compound [Cd(SCZ)3·H2O](HTNR)2(H2O)2 (1, SCZ = semicarbazide, H2TNR = styphnic...

A series of new copper(I) and mercury(II) complexes with 4-aminoantipyrine, semicarbazide, and thiosemicarbazide ligands [(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)carbonohydrazonoyl dicyanide (HL1), 2-cyano-N-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)-2-[(E)-(3-methylphenyl)-diazenyl]acetamide (H2L2), (Z)-2-cyano-N′-[(E)-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)-methylidene]-2-(2-phenylhydrazinylidene)acetohydrazide (HL3), 2-(anilinoacetyl)-N-phenylhydrazine-1-carbothioamide (H2L4), 2-(anilinoacetyl)-N-(3-methylphenyl)hydrazine-1-carbothioamide (H2L5), and 2-anilino-N′-[(E)-(2-hydroxyphenyl)methylidene]acetohydrazide (H2L6)] have been prepared and characterized by physical and spectral data, including microanalysis, IR and UV-visible spectra, conductivity measurements, and thermal analyses (DTG/TGA). The ligands H2L2 and HL3 produced dinuclear complexes. Thermal studies revealed that the copper(I) complexes are thermally more stable than mercury(II) complexes. The copper complexes exhibited potent inhibitory effect on the MCF7 human breast carcinoma cell line, as compared to mercury(II) complexes.

Deoxyribozymes can catalyze various types of reactions mostly with metal ions as their cofactors. Here we demonstrate that three copper compounds with thiosemicarbazide or semicarbazide ligands, are highly active cofactors of Cu2+-dependent deoxyribozymes without any additional reagents. The maximum catalytic rate constant of the deoxyribozyme with dichloro(di-thiosemicarbazide)copper as a cofactor is ∼25-fold faster than Cu2+ cofactor under the same reaction condition. Using a variety of spectroscopies, electrochemistry, and mutagenesis, we demonstrate that both the three-dimensional structure and redox potential of the copper center of the cofactors are essential to the catalysis of deoxyribozymes. The cofactor interacts with the enzyme-substrate complex forming a ternary enzyme-substrate-cofactor complex, which is confirmed by changing the structure of the enzyme-substrate complex through varying the temperature, or mutating the active site of the enzyme and conserved site of the substrate. The result suggests that Cu2+-dependent deoxyribozyme requires a well-defined active site to carry out the catalysis proficiently.

Synthesis of chalcones (1,3-diarylprop-2-en-1-ones) and 2-pyrazoline derivatives has been an active field of research due to their established pharmacological effects. In this study, a series of chalcones were prepared with methyl aryl ketones and substituted aldehydes in the presence of sodium hydroxide and methanol through Claisen-Schmidt condensation. 3,5-Disubstituted4,5-dihydro-1H-pyrazole-1-carbothioamides were synthesized by refluxing selected chalcones and thiosemicarbazide in alkaline medium. Similarly N-3,5-trisubstituted-4,5-dihydro-1H-pyrazole-1-carboxamides were synthesized by refluxing selected chalcones with N-(4-chlorophenyl) semicarbazide in alkaline medium. Structures of the synthesized compounds were confirmed by elemental analysis and spectral (UV, IR, H-1 NMR, C-13 NMR, and mass) data, which were in line with the proposed structures. All compounds were tested for their anticonvulsant activity using pentylenetetrazole induced seizure (PTZ) and maximal electroshock seizure (MES) tests in mice at a dose level of 50 mg/kg. Among the 2-pyrazoline-1-carbothioamide derivatives, 5-(2,6-dichlorophenyl)-3-(thiophen-2-yl)-4,5-dihydro-1H-pyrazole-1-carbothioamide (2e) reduced grade-5 seizure activity and also increased survival rate in PTZ test. In MES test, 5-(4-methoxyphenyl)-3-[4-(methylsulphonyl) phenyl]-4,5-dihydro-1H-pyrazole-1-carbothioamide(2g) has not only decreased seizure severity, but also increased survival rate. Among the 2-pyrazoline-1-carboxamide derivatives, 3-(5-bromothiophen-2-yl)-N-(4-chlorophenyl)-5-(2,6-dichlorophenyl)-4,5-dihydro-1H-pyrazole-1-carboxamide (3d) having 5-bromothiophen and 2,6-dichlorophenyl moieties and N-(4-chlorophenyl)-5-(2,6-dichloro-phenyl)-3-(5-chlorothiophen-2-yl)-4,5-dihydro-1H-pyrazole-1-carboxamide (3e) having 5-chlorothiophen and 2,6-dichlorophenyl moieties showed remarkable activities in PTZ test. Among all tested derivatives, compound 3d was found to be the most active one and reduced grade-5 seizure severity and also increased survival rate. (C) 2013 Production and hosting by Elsevier B.V. on behalf of King Saud University.

A novel nanocellulose/hydroxyapatite heterogeneous catalyst was used in the one-pot, two-component synthesis of triazolidine-3-one derivatives, produced from the cyclocondensation reaction between semicarbazide and an aromatic aldehyde. With the use of ethanol solvent, the products formed after a short reaction time (

The reactions of alkyl-3-nitroacrylates with semicarbazide as representative of polynitrogen nucleophiles proceeds at room temperature in a solution of glacial acetic acid and leads to aza-Michael adducts. Their structure was proved by 1H, 13C{1H} NMR and IR spectroscopy methods.

In this research, we have designed four isoniazid derivatives, i.e., isonicotinohydrazide (1-isonicotinoyl semicarbazide, 1-thiosemi isonicotinoyl carbazide, N '-(1, 3-dimethyl-1 h-pyrazole-5-carbonyl) isonicotino hydrazide, and N '-(1,2,3- 4-thiadiazole-carbonyl) isonicotinohydrazide. The docking and molecular dynamic have performed to them to study its interaction with Mycobacterium tuberculosis Enoyl-Acyl Carrier Protein Reductase (InhA). Based on this research, all of the compounds were predicted to have a stable interaction with Mycobacterium tuberculosis Enoyl-Acyl Carrier Protein Reductase (InhA) receptor so that they could be used as an anti-tuberculosis drug candidate

In this research work Semicarbazide, thiosemicarbazide derivatives 3 to 25 were synthesized by conventional methods with high percentage yield and reaction rate. 1H-NMR and EIMS spectroscopic techniques were used to elucidate the structure of the synthesized compounds. The effect of thiosemicarbazide and semicarbazide derivatives as an antioxidant agents were studied by DPPH free radical scavenging, ferric ion reducing, ferrous ion chelating assays. Higher DDPH radical scavenging activity exhibited by most of the compounds as compared to standard vitamin C. Excellent ferric ion reducing activity was indicated by compounds of theseriesas compared to standard vitamin C. However most of the compounds generally showed average ferrous ion chelating activity than standard EDTA.

The starting material 4-amino-4H-[1,2,4]triazino[5,6-b]indole-3-thiol 1 was synthesized by refluxing a mixture of isatin and thiocarbohydrazide in glacial acetic acid. Compound 1 reacted with various types of reagents including ammonia, hydrazine hydrate, semicarbazide HCl in various media to give triazino-[5,6-b]indole-3,4-diamine 2, 3-hydrazino-4H-[1,2,4]triazino[5,6-b]indol-4-amine 3 and 3,4-dihydro[1,2,4,5]-tetrazino[6',1':3,4][1,2,4]triazino[5,6-b]indole-2(1H)-one 5, respectively. Reactions of compounds 2 and 3 with ethyl chloroformate in boiling DMF led to 1H-[1,2,4]triazolo[5',1':3,4][1,2,4]triazino[5,6-b]indol-3(4H)-one 4 and compound 5, respectively. Microwave irradiation of compound 1 with maleic anhydride yielded 1-(3-mercapto-4H-[1,2,4]triazino[5,6-b]indol-4-yl)-1H-pyrrole-2,5-dione 6. Reactions of 1 with different aldehydes in EtOH-HCl gave the corresponding Schiff bases. Treatment of substrate 1 with NH4SCN in glacial AcOH yielded N-(3-mercapto-4H-[1,2,4]triazino[5,6-b]indol-4-yl)thiourea 9 and 1H-[1,2,4]triazolo[5',1':3,4][1,2,4]-triazino[5,6-b]indole-3(2H,4H)-thione 10, respectively. Reaction of substrate 1 with phenyl isothiocyanate in refluxing dioxan gave N-(3-mercapto-4H-[1,2,4]triazino[5,6-b]indol-4-yl)-N'-phenylthiourea 11. Its reaction with ethyl cyanoacetate upon refluxing in EtONa/EtOH afforded ethyl (4-amino-4H-[1,2,4]triazino[5,6-b]-indol-3-yl)(cyano)acetate 12, which upon boiling gave ethyl 2-amino-1H-pyrazolo[5',1':3,4][1,2,4]triazino-[5,6-b]indole-3-carboxylate 13. Structures of new compounds were confirmed by elemental analysis and spectroscopic data (IR, 1H and13C NMR). The newly synthesized compounds were subjected to the biological screening, which demonstrated promising results.

The compound, 5-(3, 4-Dimethoxyphenyl)-3-(thiophen-2-yl)-4, 5-dihydro-1H-pyrazole-1-carboxamide was synthesized by the reaction of 3-(3, 4-dimethoxyphenyl)-1-(thiophen-2-yl)prop-2-en-1-one and semicarbazide. The crystal structure was determined by the single crystal X-ray diffraction studies. It crystallizes in the triclinic crystal system with the space group P −1 and unit cell parameters, a = 8.941 (4) A, b = 9.838 (1) A, c = 10.663 (4) A; α = 72.2 (3)°, β = 84.9 (3)°, γ = 68.1 (2)° and Z = 2. The crystal and molecular structure of the title compound is stabilized by the N H⋯O and C H⋯O hydrogen bond interactions.

Nitrofurazone is an antibiotic with carcinogenic properties. Efforts by regulatory authorities to control nitrofurazone from agricultural foods are an important public health measure that have, to some extent, been undermined by widespread use amongst laboratories of the unreliable marker metabolite semicarbazide. This work confirms what has long been suspected, namely that powdered dairy products that are initially free of semicarbazide develop semicarbazide under storage conditions such as occur normally across commercial supply chains. The low ng g(-)(1) levels of semicarbazide formed in this way are insufficient to present any food safety hazard. That such development of a marker metabolite is demonstrated to occur by innocent means effectively invalidates the use of semicarbazide as a marker metabolite for powdered dairy products, and exacerbates the regulatory need for a more suitable analytical methodology. In milk, unlike meat, nitrofurazone is known to remain stable and thus available for analysis in the intact form, rather than necessitating any use of a metabolite or fragment. However, no previous methodology that was capable of achieving the stringent European minimum required performance limit of 1 ng g(-)(1) when using intact nitrofurazone had been described for milk. This work describes a specific methodology using LC-MS/MS for milk and milk powder; it achieves detection of intact nitrofurazone (as well as furazolidone, furaltadone and nitrofurantoin) to levels well below 1 ng g(-)(1). Laboratories will no longer need to use semicarbazide as an unreliable marker metabolite for the analysis of nitrofurazone in dairy products, paving the way for regulatory authorities to better control nitrofurazone abuse with greater confidence.

Semicarbazide functionalized with chlorosulfonic acid on the surface of silica-coated magnetic nanoparticles, {Fe3O4@SiO2@(CH2)3Semicarbazide-SO3H/HCl}, as a novel magnetic Bronsted acid catalyst according to the aims of green chemistry was synthesized and fully characterized using Fourier transform infrared, UV–visible and energy-dispersive X-ray spectroscopies, X-ray diffraction, scanning electron, transmission electron and atomic force microscopies and thermogravimetric analysis. The capability and excellent activity of this nanoparticle catalyst were exhibited in the synthesis of two series of compounds with important biological activities, namely 3,3′-(arylmethylene)bis(4-hydroxycoumarin) and 1-carbamato-alkyl-2-naphthol derivatives, under mild, green and solvent-free conditions. To the best of our knowledge, this is the first study of the synthesis and application of {Fe3O4@SiO2@(CH2)3Semicarbazide-SO3H/HCl} as Bronsted acid solid magnetic nanoparticles. Consequently the present study can open up a novel and promising intuition in the sequence of logical design, synthesis and applications of task-specific Bronsted acid magnetic nanoparticle catalyst with favourable properties as a full-fledged efficient material for sustainable approaches. Copyright © 2016 John Wiley & Sons, Ltd.

Semicarbazide (1) is a widespread genotoxic food contaminant originating as a metabolic byproduct of the antibiotic nitrofurazone used in fish farming or as a thermal degradation product of the common flour additive azodicarbonamide. The goal of this study is to develop a simple and sensitive high-performance liquid chromatography coupled with fluorescence detection (HPLC-FLD) method for the detection of compound 1 in food products. In comparison to existing methods for the determination of compound 1, the reported method combining online precolumn derivatization and HPLC-FLD is less labor-intensive, produces higher sample throughput, and does not require the use of expensive analytical instruments. After validation of accuracy and precision, this method was applied to determine the amount of compound 1 in fish and bread samples. Comparative studies using an established liquid chromatography coupled with tandem mass spectrometry method did not yield systematically different results, indicating that the developed HPLC-FLD method is accurate and suitable for the determination of compound 1 in fish and bread samples.

3-Aryl-6а-methyl-6-nitro-1-carbamoylhexahydrothieno[2,3-d]pyrazole-4,4-dioxides, novel original bicyclic species consisting of fused pyrazolidine and sulfolane rings, and 1,4-adducts were obtained by reacting 2-benzylidene-3-methyl-4-nitro-3-thiolene-1,1-dioxide and its derivatives with semicarbazide.

A straightforward and easy to handle two-step synthetic route for unsymmetric double Schiff-base ligands is presented. The isolated intermediate single Schiff-base precursor ligands H2sc-difo and H2tsc-difo were derived by condensation of 2,6-diformyl-4-methylphenol with semicarbazide and thiosemicarbazide, respectively. Further reaction of the precursor ligands with different amine components, including both aliphatic and aromatic examples, allows the synthesis of ditopic unsymmetric double Schiff-base ligands in high yields and purity. As aliphatic cases we used (2-aminoethyl)bis(2-pyridylmethyl)-amine (H2sc-hydra and H2tsc-hydra) and 2-(aminomethyl)-pyridine (H2sc-ampy and H2tsc-ampy), whereas 2-aminophenol was used as an aromatic sample (H3sc-amph and H3tsc-amph). The overall synthetic route allows for the preparation of the employed ligands in large scale. To explore the coordination capabilities of the reported ligand systems a mononuclear nickel(II) complex [Ni(tsc-difo)PPh3] and a homodinuclear zinc(II) complex [Zn2(tsc-hydra)(OAc)2] were synthesized with the single Schiff-base precursor ligand H2tsc-difo and the double Schiff-base ligands H2tsc-hydra, respectively. Both complexes crystallized in the monoclinic space group P21/n. For [Ni(tsc-difo)PPh3] a square-planar geometry is found for nickel(II) ion with H2tsc-difo acting as a tridentate ligand. Whereas the structure of complex [Zn2(tsc-hydra)(OAc)2] reveals two zinc(II) ions in distinctly different coordination geometry, one in distorted octahedral coordination located in the bispyridine based binding pocket with [N4O2] donor set and the other zinc(II) ion in a distorted square-pyramidal coordination given by the thiosemicarbazone based binding pocket with [NO3S] donor set.

New series of 2-(aryl or alkyl)-N-phenylhydrazine-1-carboxamides 1a–j were synthesized through one-pot reactions of aldehyde or ketones, hydrazine hydrate, and phenylisocyanate in MeOH. The structure of products was confirmed by Fourier transform infrared (FT-IR), proton nuclear magnetic resonance (1H NMR), and 13C NMR spectra. Minimum inhibitory concentration (MIC) of antibacterial activity of 1a–j was screened against five bacterial strains. Compound 1f showed antibacterial activity against Pseudomonas aeruginosa and Staphylococcus aureus.

This paper proposes a mechanism to explain the trace levels of natural semicarbazide occasionally observed in foods. The analytical derivative of semicarbazide, 2-nitrobenzaldehyde semicarbazone, is often measured as a metabolite marker to detect the widely banned antibiotic nitrofurazone. However, this marker is not specific as semicarbazide may be present in foods for several reasons other than exposure to nitrofurazone. In some cases, an entirely natural origin of semicarbazide is suspected, although up until now there was no explanation about how semicarbazide could occur naturally. In this work, semicarbazide is proposed as being generated from natural food compounds via an azine intermediate. Hydrazine, in the form of azines or hydrazones, may be generated in dilute aqueous solution from the natural food compounds ammonia, hydrogen peroxide and acetone, following known oxidation chemistry. When this mixture was prepared in the presence of ureas such as allantoin, urea, biuret or hydroxyurea, and then analysed by the standard method for the determination of semicarbazide, 2-nitrobenzaldehyde semicarbazone was detected. 2-Nitrobenzaldehyde aldazine was also found, and it may be a general marker for azines in foods. This proposal, that azine formation is central to semicarbazide development, provides a convergence of the published mechanisms for semicarbazide. The reaction starts with hydrogen peroxide, peracetic acid, atmospheric oxygen or hypochlorite; generates hydrazine either by an oxaziridine intermediate or via the chlorination of ammonia; and then either route may converge on azine formation, followed by reaction with a urea compound. Additionally, carbamate ion may speculatively generate semicarbazide by reaction with hydrazine, which might be a significant route in the case of the hypochlorite treatment of foods or food contact surfaces. Significantly, detection of 2-nitrobenzaldehyde semicarbazone may be somewhat artefactual because semicarbazide can form during the acid conditions of analysis, which can free hydrazine in the presence of urea compounds.