Synthesis and antimicrobial activities of some new 1-(5-phenylamino-[1,3,4]thiadiazol-2-yl)methyl-5-oxo-[1,2,4]triazole and 1-(4-phenyl-5-thioxo-[1,2,4]triazol-3-yl)methyl-5-oxo- [1,2,4]triazole derivatives

Use of Disubstituted Thiosemicarbazide in Synthesis of New Derivatives of 1,3,4-Thiadiazole, 1,2,4-Triazole and Pyrazole with Their Antimicrobial Evaluation

New derivatives of 1,3,4-thiadiazole, 1,2,4-triazole and pyrazole were obtained by cyclisation of the corresponding disubstituted thiosemicarbazide derivative. The newly synthesised derivatives were obtained in good yields and their structures were elucidated by spectral data and elemental analyses. The antimicrobial activity of some of the synthesised compounds is tested.

Amido/ureidosubstituted benzenesulfonamides-isatin conjugates as low nanomolar/subnanomolar inhibitors of the tumor-associated carbonic anhydrase isoform XII

By using a molecular hybridization approach, two series of amido/ureidosubstituted benzenesulfonamides incorporating substituted-isatin moieties were synthesized. The prepared derivatives were in vitro evaluated for their inhibitory activity against human carbonic anhydrase (hCA, EC 4.2.1.1) I, II (cytosolic) and IX, XII (transmembrane, tumor-associated) isoforms. All these isoforms were inhibited in variable degrees by the sulfonamides reported here. hCA I was inhibited with KIs in the range of 7.9-894 nM, hCA II in the range of 7.5-1645 nM (with one compound having a KI > 10 μM); hCA IX in the range of 5.0-240 nM, whereas hCA XII in the range of 0.47-2.83 nM. As all these isoforms are involved in various pathologies, in which their inhibition can be exploited therapeutically, the derivatives reported here may represent interesting extensions to the field of CA inhibitors of the sulfonamide type.

Synthesis, Crystal Structures and Xanthine Oxidase Inhibitory Activity of 2-(Benzylthio)-5-[1-(4-Fluorobenzyl)-3-Phenyl-1H-Pyrazol-5-Yl]-1,3,4-Oxadiazoles Derivatives

A synthetic route for the preparation of 2-(benzylthio)-5-[1-(4-fluorobenzyl)-3-phenyl-1H-pyrazol-5-yl]-1,3,4-oxadiazoles derivatives from ethyl 3-phenyl-1H-pyrazole-5-carboxylate has been developed. The configurations of the intermediate 1,3,4-oxadiazole-2-thione and 3-bromobenzylthio substituted 1,3,4-oxadiazole were determined by single crystal X-ray diffraction analysis. The in vitro xanthine oxidase inhibitory activity of these compounds was evaluated.

Regioselective Sequential Modification of Chitosan via Azide-Alkyne Click Reaction: Synthesis, Characterization, and Antimicrobial Activity of Chitosan Derivatives and Nanoparticles

Recently, the attention of researchers has been drawn toward the synthesis of chitosan derivatives and their nanoparticles with enhanced antimicrobial activities. In this study, chitosan derivatives with different azides and alkyne groups were synthesized using click chemistry, and these were further transformed into nanoparticles by using the ionotropic gelation method. A series of chitosan derivatives was successfully synthesized by regioselective modification of chitosan via an azide-alkyne click reaction. The amino moieties of chitosan were protected during derivatization by pthaloylation and subsequently unblocked at the end to restore their functionality. Nanoparticles of synthesized derivatives were fabricated by ionic gelation to form complexes of polyanionic penta-sodium tripolyphosphate (TPP) and cationic chitosan derivatives. Particle size analysis showed that nanoparticle size ranged from 181.03 ± 12.73 nm to 236.50 ± 14.32 nm and had narrow polydispersity index and positive surface charge. The derivatives and corresponding nanoparticles were evaluated in vitro for antibacterial and antifungal activities against three gram-positive and gram-negative bacteria and three fungal strains, respectively. The minimum inhibitory concentration (MIC) of all derivatives ranged from 31.3 to 250 µg/mL for bacteria and 188 to1500 µg/mL for fungi and was lower than that of native chitosan. The nanoparticles with MIC ranging from 1.56 to 25 µg/mLfor bacteria and 94 to 750 µg/mL for fungi exhibited higher activity than the chitosan derivatives. Chitosan O-(1-methylbenzene) triazolyl carbamate and chitosan O-(1-methyl phenyl sulfide) triazolyl carbamate were the most active against the tested bacterial and fungal strains. The hemolytic assay on erythrocytes and cell viability test on two different cell lines (Chinese hamster lung fibroblast cells V79 and Human hepatic cell line WRL68) demonstrated the safety; suggesting that these derivatives could be used in future medical applications. Chitosan derivatives with triazole functionality, synthesized by Huisgen 1,3-dipolar cycloaddition, and their nanoparticles showed significant enhancement in antibacterial and antifungal activities in comparison to those associated with native, non-altered chitosan.

Synthesis and evaluation of benzosuberone embedded with 1,3,4-oxadiazole, 1,3,4-thiadiazole and 1,2,4-triazole moieties as new potential anti proliferative agents

As an aspect of our ongoing research in search of new anti proliferative agents, a series of novel analogs of benzosuberone embedded with 1,3,4-oxadiazole, 1,3,4-thiadiazole and 1,2,4-triazole moieties were synthesized in excellent yields (82-93%). All the newly synthesized compounds were characterized by (1)H NMR, (13)C NMR, ESI/LC-MS, HRMS and evaluated for their in vitro anti proliferative activity against four human cancer cell lines (cervical, breast, pancreatic and alveolar). Among the synthesized compounds, 4b, 6a, 7d and 7l showed potent anti proliferative activity with GI50 values range of 0.079-0.957μM against four human cancer cell lines. However, it was revealed that the compound 7d have shown very close GI50 value 0.079μM as compared with positive control of colchicine against cervical cancer cell line.

Syntheses, spectroscopic characterization, thermal study, molecular modeling, and biological evaluation of novel Schiff's base benzil bis(5-amino-1,3,4-thiadiazole-2-thiol) with Ni(II), and Cu(II) metal complexes

Novel Schiff's base ligand, benzil bis(5-amino-1,3,4-thiadiazole-2-thiol) was synthesized by the condensation of benzil and 5-amino-1,3,4-thiadiazole-2-thiol in 1:2 ratio. The structure of ligand was determined on the basis of elemental analyses, IR, (1)H NMR, mass, and molecular modeling studies. Synthesized ligand behaved as tetradentate and coordinated to metal ion through sulfur atoms of thiol ring and nitrogen atoms of imine group. Ni(II), and Cu(II) complexes were synthesized with this nitrogen-sulfur donor (N2S2) ligand. Metal complexes were characterized by elemental analyses, molar conductance, magnetic susceptibility measurements, IR, electronic spectra, EPR, thermal, and molecular modeling studies. All the complexes showed molar conductance corresponding to non-electrolytic nature, expect [Ni(L)](NO3)2 complex, which was 1:2 electrolyte in nature. [Cu(L)(SO4)] complex may possessed square pyramidal geometry, [Ni(L)](NO3)2 complex tetrahedral and rest of the complexes six coordinated octahedral/tetragonal geometry. Newly synthesized ligand and its metal complexes were examined against the opportunistic pathogens. Results suggested that metal complexes were more biological sensitive than free ligand.

PEG-assisted two-component approach for the facile synthesis of 5-aryl-1,2,4-triazolidine-3-thiones under catalyst-free conditions

A straightforward and greener PEG-assisted protocol has been disclosed for the synthesis of 5-aryl-1,2,4-triazolidine-3-thiones via the reaction of aromatic aldehydes and thiosemicarbazides using very convenient neutral reaction conditions.

Organoiodine(iii) mediated intramolecular oxidative cyclization of 1-(3-arylisoquinolin-1-yl)-2-(arylmethylene)hydrazines to 5-aryl-3-(aryl)-[1,2,4]triazolo[3,4-a] isoquinolines

Intramolecular C–N bond formation is achieved through oxidative cyclization of 1-(3-arylisoquinolin-1-yl)-2-(arylmethylene)hydrazines, 3, in the presence of hypervalent iodine oxidant and dichloromethane at ambient temperature.

Recent advances bioactive 1,2,4-triazole-3-thiones

Triazoles are heterocyclic compounds which have a five-membered ring of two carbon atoms and three nitrogen atoms. These structures have been interest in the development of novel compounds with anticonvulsant, antidepressant, antioxidant, anti-inflammatory, analgesic, antinociceptive, antibacterial, antimycobacterial, antifungal, antiviral, anticancer, anti-parasitic, anti-urease and other activities. Therefore, many researchers have synthesized these compounds as target structures and evaluated their biological activities. This review contains various pharmacological activities of 1,2,4-triazole-3-thiones in one place and it is also the milestone for the new research towards this moiety.

Vibrational and quantum chemical investigation of cyclization of thiosemicarbazide group in 1-benzoyl-4-phenyl-3-thiosemicarbazide

1-Benzoyl-4-phenyl-3-thiosemicarbazide (H3bpt) was treated with acid - base in one sequence and base - acid in other sequence, both of which lead to ring formation of thiosemicarbazide group, giving N-phenyl-5-phenyl-1,3,4-thiadiazol-2-amine (Hppta) in the first case and 4,5-diphenyl-2,4-dihydro-1,2,4-triazole-3-thione (Hdptt) in the second case. The primary (H3bpt) as well as the resulting compounds (Hppta & Hdptt) has been characterized by elemental analyses, NMR, FTIR and Raman spectroscopic techniques. The quantum chemical calculations of the compounds are performed using DFT/B3LYP/6311G(d,p) method for geometry optimizations and also for prediction of the molecular properties. The cyclization is confirmed by disappearance of many bands belonging to the open chain subgroups of H3bpt such as; NH stretching, NH bending, CN stretching, NH puckering, CO stretching etc. The ring formation of 1-benzoyl-4-phenyl-3-thiosemicarbazide (H3bpt) has been further confirmed by the appearance of many bands belonging to the closed ring of thiosemicarbazide in the resulting compounds Hppta and Hdptt.

4-[(5-Bromo-2-hydroxybenzylidene)amino]-3-ethyl-1H-1,2,4-triazole-5(4H)-thione

The title compound, C₁₁H₁₁BrN₄OS, crystallized as a racemic twin with two symmetry-independent mol­ecules in the asymmetric unit. The dihedral angles between the benzene and triazole rings of the two independent mol­ecules are 56.41 (18) and 54.48 (18)°. An intra­molecular O—H⋯N hydrogen bond occurs in each mol­ecule. In the crystal, pairs of symmetry-independent mol­ecules are linked by pairs of almost linear N—H⋯S hydrogen bonds, forming cyclic dimers characterized by an R₂²(8) motif. There are weak π–π inter­actions between the benzene rings of symmetry-independent mol­ecules, with a centroid–centroid distance of 3.874 (3) Å.

Induction of intrinsic apoptosis pathway in colon cancer HCT-116 cells by novel 2-substituted-5,6,7,8-tetrahydronaphthalene derivatives

2-Acetyl tetralin (1) reacted with N,N-dimethylformamide dimethylacetal (DMF-DMA) to afford the enaminone 3. The reaction of 3 with piperidine and morpholine afforded the trans enaminone 5a,b, respectively. Compound 3 was treated with primary aromatic amines to give secondary enaminones 6a-e. The enaminone 3 reacted with acetylglycine and hippuric acid to yield pyranones 10a, b, respectively. The reaction of enaminone 3 with 1,4-benzoquinone and 1,4-naphthoquinone gave benzofuranyl tetralin derivatives 14a,b, respectively. Also, when 3 reacted with 5-amino-3-phenyl-1H-pyrazole 15a and 5-amino-1,2,3-triazole 15b, it afforded the new pyrazolo[1,5-a]pyrimidine 17a and 1,2,3-triazolo[1,5-a]pyrimidine 17b, respectively. While the reaction of 3 with pyrimidines 18a, b resulted in the formation of pyrido[2,3-d]pyrimidine derivatives 20a, b, respectively. Investigations of the cytotoxic effect of those compounds against different human cell lines indicated that some compounds showed high selective cytotoxicity against colon cancer HCT-116 cells. Some of these compounds led to DNA damaging and fragmentation that was associated with the induction of apoptosis via mitochondrial pathway. This pathway is initiated by the impairment of mitochondrial transmembrane potential (Δψm) and in response to that the mitochondria released cytochrome c increased, that in turn activated caspase-9 and caspase-3 and induced apoptosis. Compounds 17b and 20b were promising anti-cancer agents that induced intrinsic apoptosis pathway in colon cancer cells.

Efficient synthesis of Some Novel Symmetrical and Unsymmetrical Pyridine bis-1,2,4-triazoles and bis-1,3,4-thiadiazoles

A series of novel bis-1,2,4-triazoles and bis-1,3,4-thiadiazoles bearing pyridine rings was synthesised, by multistep reaction sequences, in good to high yields. Reaction of pyridine-2,5-bis- and pyridine-2,6-bis-carbohydrazides with alkyl- or aryl-isothiocyanates gave the corresponding bis(thiosemicarbazide) derivatives, which could be cyclised under strongly basic conditions to give novel pyridine bis(1,2,4-triazole-3-thiols). However, under strongly acidic conditions the corresponding bis(2-amino-1,3,4-thiadiazoles) were obtained. The synthetic routes and spectroscopic characterisation of the new compounds are reported.

Synthesis, photophysical and electrochemical properties of chiral and achiral thiadiazolophanes

One pot synthesis of chiral and achiral 2:2 oligomeric thiadiazolophane 1 and 3 and 3:3 oligomeric thiadiazolophane 2 and 4 with (S)-BINOL and methylene bis-naphthyl spacer unit has been achieved. The photophysical and electrochemical properties revealed higher degree of aggregation in 2:2 oligomor than 3:3 oligomer. Energy minimized calculations show that 3:3 oligomer has less heat of formation than 2:2 oligomer.

Synthesis, Crystal Structure, and Biological Activity ofcis/transAmide Rotomers of (Z)-N′-(2-Oxoindolin-3-ylidene)formohydrazide

(Z)-N′-(2-Oxoindolin-3-ylidene)formohydrazide (2) was synthesized by the reaction of (Z)-3-hydrazonoindolin-2-one (1) with formic acid under reflux. The structure of2was characterized by IR, Mass,1H NMR, and X-ray crystal structure determination. Interestingly, compound2appeared in DMSO-d6ascisandtransamide rotomers in 25% and 75%, respectively. The X-ray analysis showed theZgeometrical isomer of2around –C=N– forcisandtransamide rotomers. The crystal of2belongs to monoclinic, space groupP21/c, witha=4.5206(1) Å,b=22.4747(7) Å,c=17.3637(5) Å,β=103.752(1)°,Z=8,V=1713.57(8) Å3,Dc=1.467 Mg m−3,μ=0.11 mm−1,F(000)=784,R=0.047, andwR=0.123for 3798 observed reflections withI>2σ(I). Compound2exhibited a moderate activity in its antimicrobial evaluation againstE. coliandP. aeruginosaand a good activity againstS. aureusclose to that of the standard drug ciprofloxacin. Thein vitroanticancer activity of2was evaluated against two human tumor cell lines, namely, HepG2 hepatocellular carcinoma and MCF-7 breast cancer. HepG2 cancer cell line was more susceptible to compound2than MCF-7.