Design, synthesis, and urease inhibition studies of a series of 4-amino-5-aryl-3H-1,2,4-triazole-3-thiones

Synthesis and biological evaluation of triazolones/oxadiazolones as novel urease inhibitors

Urease is the main virulence factor of infectious gastritis and gastric ulcers. Urease inhibitors are regarded as the first choice for the treatment of such diseases. Based on the triazolone/oxadiazolone skeleton, a urea-like fragment being able to specifically bind the urease activity pocket and prevent urea from hydrolysis, we designed and synthesized 45 triazolones/oxadiazolones as urease inhibitors. Eight compounds were proved to show excellent inhibitory activity against Helicobacter pylori urease, being more potency than the clinically used urease inhibitor acetohydroxamic acid. The most active inhibitor with IC50 value of 1.2 μM was over 20-fold higher potent than the positive control. Enzymatic kinetic assays showed that these novel inhibitors reversibly inhibited urease with a mixed competitive mechanism. Molecular dockings provided evidence for the observations in enzyme assays. Furthermore, these novel inhibitors were proved as drug-like compounds with very low cytotoxicity to mammalian cells and favorable water solubility. These results suggested that triazolone and oxadiazolone were promising scaffolds for the design and discovery of novel urease inhibitors, and were expected as good candidates for further drug development.

Synthesis and Biological Evaluation of New Schiff Bases Derived from 4-Amino-5-(3-fluorophenyl)-1,2,4-triazole-3-thione

The treatment of infectious diseases is a challenging issue faced by the medical community. The emergence of drug-resistant strains of bacteria and fungi is a major concern. Researchers and medical professionals are working to develop new and innovative treatments for infectious diseases. Schiff bases are one a promising class of compounds. In this work, new derivatives were obtained of the 4-amino-5-(3-fluorophenyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione reaction, with corresponding benzaldehydes with various substituents at position 4. The antibacterial and antifungal activities of all synthesized compounds were tested. Several new substances have shown moderate antifungal activity against Candida spp. The highest activity directed against C. albicans was shown by compound RO4, with a 4-methoxyphenyl moiety and an MIC value of 62.5 µg/mL. In order to check the toxicity of the synthesized compounds, their effect on cell lines was examined. Additionally, we tried to elucidate the mechanism of the antibacterial and antifungal activity of the tested compounds using molecular docking to topoisomerase IV, D-Alanyl-D-Alanine Ligase, and dihydrofolate reductase.

1,3,4-Thiadiazole and 1,2,4-triazole-5-thione derivatives bearing 2-pentyl-5-phenyl-2,4-dihydro-3H-1,2,4-triazole-3-one ring: Synthesis, molecular docking, urease inhibition, and crystal structure

Two series of 1,3,4-thiadiazole (40a-o) and 1,2,4-triazole-5-thione (41a-l) derivatives bearing a 2-pentyl-5-phenyl-1,2,4-triazole-3-one ring were synthesized and then studied for their urease inhibitory activities using thiourea as a standard drug. Among the two groups, the first group (40a-o) did not show good activity while the second group (41a-l) showed excellent activity. Compound 41j (1091.24 ± 14.02 µM) of the second series of compounds showed lower activity than thiourea, while the remaining 11 compounds (41a-i, k, and l) showed better activity than thiourea (183.92 ± 13.14 µM). Among the 11 compounds, 41b (15.96 ± 2.28 µM) having the 3-F group on the phenyl ring showed the highest inhibitory activity. Urease kinetic studies of 41b, which is the most active compound, determined it to have an un-competitive inhibition potential. Moreover, in silico analysis against urease from jack bean with 27 new heterocyclic compounds and the reference molecule was carried out to see the necessary interactions responsible for urease activity. The docking calculations of all compounds supported stronger binding to the receptor than the reference molecule, with high inhibition constants. In addition, compound 40m was characterized by single-crystal X-ray diffraction analysis. X-ray analysis reveals that the structures of the compound 40m crystallize in the monoclinic P21/c space group with the cell parameters: a = 10.2155(9) Å, b = 22.1709(18) Å, c = 21.4858(17) Å, β = 99.677(8)°, V = 4797.0(7) ų . X-ray diffraction analyses were also performed to gain insights into the role of weak intermolecular interactions and C-H…X (halogen) interactions in compound 40m that influence the crystal packing.

An overview on the synthetic urease inhibitors with structure-activity relationship and molecular docking

Urease is a kind of enzyme which could be found in various bacteria, fungi, plants, and algae, which can quickly catalyze the hydrolysis of urea into ammonia and carbon dioxide. With the ammonia concentration increasing, the activity of Helicobacter pylori has got an obvious enhancement and leads to mucosal damage in the stomach, gastroduodenal infection, peptic ulcers, and gastric cancer. The infectious diseases caused by Helicobacter pylori can be controlled to a certain extent by inhibiting urease activity with urease inhibitors. Hence, studies of urease inhibitors have attracted great attention all over the world and a variety of effective urease inhibitors have been synthesized in recent years. In this review, we will draw summaries for these inhibitors including urease inhibitory activity, inhibition kinetics, structure-activity relationship, and molecular docking. The collected information is expected to provide rational guidance and effective strategy to develop novel, potent, and safe urease inhibitors for better practical applications in the future.

Lead Molecules for Targeted Urease Inhibition: An Updated Review from 2010 -2018

The field of enzyme inhibition is a tremendous and quickly growing territory of research. Urease a nickel containing metalloenzyme found in bacteria, algae, fungi, and plants brings hydrolysis of urea and plays important role in environmental nitrogen cycle. Apart from this it was found to be responsible for many pathological conditions due to its presence in many microorganisms such as H. Pylori, a ureolytic bacteria having urease which elevates pH of gastric medium by hydrolyzing urea present in alimentary canal and help the bacteria to colonize and spread infection. Due to the infections caused by the various bacterial ureases such as Bacillus pasteurii, Brucella abortus, H. pylori, H. mustelae, Klebsiella aerogenes, Klebsiella tuberculosis, Mycobacterium tuberculosis, Pseudomonas putida, Sporosarcina pasteurii and Yersinia enterocolitica, it has been the current topic of today's research. About a wide range of compounds from the exhaustive literature survey has been discussed in this review which is enveloped into two expansive classes, as Inhibitors from synthetic origin and Inhibitors from natural origin. Moreover active site details of enzyme, mechanism of catalysis of substrate by enzyme, uses of plant urease and its pathogenic behavior has been included in the current review. So, overall, this review article diagrams the current landscape of the developments in the improvements in the thriving field of urease inhibitory movement in medicinal chemistry from year 2010 to 2018, with an emphasis on mechanism of action of inhibitors that may be used for more development of recent and strong urease inhibitors and open up new doors for assist examinations in a standout amongst the most lively and promising regions of research.

Regioselectivity of the alkylation of S-substituted 1,2,4-triazoles with dihaloalkanes

Background

1,2,4-Triazole3-thiones are good scaffolds for preparation of new lead compounds. Their derivatives attracted the attention of chemists due to their wide spectrum of biological activities. Alkylsulfanyl-1,2,4-triazoles have three nucleophilic sites (nitrogens) ready for reaction with electrophiles. Herein, new regioselective isomers were synthesized by the reaction of benzylsulfanyl-1,2,4-triazole with various dihaloalkanes. Regioselectivity was determined by X-ray crystallography and NMR.

Results

Coupling of 3-benzylsufanyl-5-(1H-indolyl)-1,2,4-triazole with dibromomethane, 1,2-dichloroethane, 1,3-dibromopropane and di(bromomethyl)quinoxaline was investigated in the presence of potassium carbonate in acetone. In the case of dibromomethane three different bis(triazolyl)methane isomers (–N¹–CH₂–N¹-4, –N¹–CH₂–N²-5, –N²–CH₂–N²-6) were formed in which the two bromide atoms were replaced by two triazole moieties. Among these isomers the reaction was regioselective towards the –N¹–CH₂–N²-5 isomer due to the steric effect. In the case of 1,3-dibromopropane two compounds were obtained due to the alkylation at N(2) to give 2-(3-bromopropyl)-triazole 8 and alkylation at N(1) was followed by cyclization at the indole nitrogen to form a condensed indolo-triazolo-diazepine 10. Upon alkylation of 3-benzylsufanyl-5-(1H-indolyl)-1,2,4-triazole with di(bromomethyl)quinoxaline, two bis(triazolyl-methyl)quinoxaline isomers were separated and characterized as (–N¹–CH₂–N¹–) 11 and (–N²–CH₂–N²–) 12. Single-crystal X-ray diffraction assisted the elucidation and confirmation of the structures of the isomers. An AM1 theoretical study explained the regioselectivity of the alkylation.

Conclusions

On reacting S-protected 1,2,4-triazoles with various alkylating agents, only N(1) and N(2) attack the electrophilic carbons. N(2) alkylated isomers are preferentially formed.

Electronic supplementary material

The online version of this article (doi:10.1186/s13065-016-0165-0) contains supplementary material, which is available to authorized users.

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.

Synthesis, characterization and antimicrobial evaluation of some new schiff, mannich and acetylenic Mannich bases incorporating a 1,2,4-triazole nucleus

A series of Schiff and Mannich bases derived from 4-amino-5-(3-fluoro-phenyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione were synthesized. The alkylation of 4-phenyl-5-(3-fluorophenyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione with propargyl bromide afforded the corresponding thiopropargylated derivative which upon treatment with the appropriate secondary amines in the presence of CuCl₂ furnished the desired acetylenic Mannich bases. The synthesized compounds were characterized on the basis of their spectral (IR, ¹H- and ¹³C-NMR) data and evaluated for their biological activities. Some of the compounds were found to exhibit significant antimicrobial activity.

4-Eth-oxy-benzohydrazide

The title compound, C₉H₁₂N₂O₂, is approximately planar (r.m.s. deviation = 0.13 Å for all non-H atoms). The carbonyl O atom is involved as acceptor in three different hydrogen-bond inter­actions. One N—H⋯O and the C—H⋯O(carbonyl) contact together with a weak C—H⋯O(eth­oxy) interaction link the mol­ecules into sheets parallel to (102). These are further linked into a three-dimensional network via the remaining C—H⋯O(carbon­yl) hydrogen bond and a C(methyl­ene)—H⋯π inter­action

Synthesis Using Microwave Irradiation, Characterisation and Antibacterial Activity of Novel Deoxycholic Acid-Triazole Conjugates

Novel deoxycholic acid 3α-triazole conjugates based on methyl 3α-chloroacetoxy-12α-hydroxy-cholanate have been synthesised. The synthesis is accelerated by microwave irradiation under solvent free conditions in the presence of K2CO3. Some of these compounds were tested for antibacterial activity against B.subtilis, P.aeruginosa and S.aureus. The preliminary results indicated that these deoxycholic acid-triazole conjugates have good inhibitory effect against B.subtilis. All of the compounds were characterised by 1H NMR, IR, ESI-MS spectra and elemental analyses.

Studies on the synthesis and antibacterial activity of 3,6-disubstituted 1,2,4-triazolo[3,4-b]1,3,4-thiadiazoles

Treating infections caused by drug-resistant bacterial strains constitutes one of the most essential challenges for medicine nowadays. A range of new derivatives of 1,2,4-triazolo[3,4-b]1,3,4-thiadiazole have been synthesized and evaluated for their in vitro antimicrobial activity. Compounds 1-8 indicated high activity towards Gram-positive bacteria, which was up to 16 times more than currently used antibiotics. To the best of our knowledge, the derivatives obtained by us are the most active among the 3-aryl-6-arylamino-1,2,4-triazolo[3,4-b]1,3,4-thiadiazoles known until now.

Synthesis of Novel Triazole Derivatives of Methyl 3-Oxocholanate Using Microwave Irradiation

An efficient rapid method for the synthesis of new triazole derivatives derived from methyl 3-oxocholanate under microwave irradiation has been developed. These new compounds were characterised by 1H NMR, IR, ESI-MS spectra and elemental analyses. Some of these triazoles were tested for antibacterial activity against Staphylococcus aureus, Candida albicans and Escherichia coli.

6-(Adamantan-1-yl)-3-(3-fluoro-phen-yl)-1,2,4-triazolo[3,4-b][1,3,4]thia-diazole

The title mol­ecule, C₁₉H₁₉FN₄S, displays C_s mol­ecular symmetry, in which the crystallographic mirror plane bis­ects the adamantan-1-yl unit while the 3-fluoro­phenyl triazole ring is located on the mirror plane. The F atom of the 3-fluoro­phenyl ring is positionally disordered [occupancy ratio 0.9:0.1]. In the crystal, π–π inter­actions between the triazole and phenyl rings occur [centroid–centroid distance = 3.5849 (7) Å] and weak C—H⋯F inter­actions form a ribbon propagating in [010].