Synthesis and antiprotozoal activity of cationic 1,4-diphenyl-1H-1,2,3-triazoles

A copper(ii) metal-organic hydrogel as a multifunctional precatalyst for CuAAC reactions and chemical fixation of CO2 under solvent free conditions

A copper(ii) metal-organic hydrogel has been synthesised and characterised. This hydrogel is an efficient, reusable precatalyst for CuAAC reactions and chemical fixation of CO₂ under solvent free conditions.

In Vitro and In Vivo Studies of the Trypanocidal Effect of Novel Quinolines

Therapies for human African trypanosomiasis and Chagas disease, caused by Trypanosoma brucei and Trypanosoma cruzi, respectively, are limited, providing minimal therapeutic options for the millions of individuals living in very poor communities. Here the effects of 10 novel quinolines are evaluated in silico and by phenotypic studies using in vitro and in vivo models. Absorption, distribution, metabolism, excretion, and toxicity (ADMET) properties revealed that most molecules did not infringe on Lipinski's rules, which is a prediction of good oral absorption. These quinolines showed high probabilities of Caco2 permeability and human intestinal absorption and low probabilities of mutagenicity and of hERG1 inhibition. In vitro screens against bloodstream forms of T. cruzi demonstrated that all quinolines were more active than the reference drug (benznidazole [Bz]), except for DB2171 and DB2192, with five (DB2187, DB2131, DB2186, DB2191, and DB2217) displaying 50% effective concentrations (EC₅₀s) of <3 μM (4-fold lower than that of Bz). Nine quinolines were more effective than Bz (2.7 μM) against amastigotes, showing EC₅₀s ranging from 0.6 to 0.1 μM. All quinolines were also highly active in vitro against African trypanosomes, showing EC₅₀s of ≤0.25 μM. The most potent and highly selective candidates for each parasite species were tested in in vivo models. Results for DB2186 were promising in mice with T. cruzi and T. brucei infections, reaching a 70% reduction of the parasitemia load for T. cruzi, and it cured 2 out of 4 mice infected with T. brucei DB2217 was also active in vivo and cured all 4 mice (100% cure rate) with T. brucei infection.

Hetero-Diels-Alder reactions of novel 3-triazolyl-nitrosoalkenes as an approach to functionalized 1,2,3-triazoles with antibacterial profile

The generation and reactivity of 3-triazolyl-nitrosoalkenes are reported for the first time. The study showed that hetero-Diels-Alder reaction of these heterodienes is an interesting synthetic strategy to functionalized 1,2,3-triazoles, including 1,2,3-triazolyl-pyrroles, 1,2,3-triazolyl-dipyrromethanes and 1,2,3-triazolyl-indoles. The evaluation of the antibacterial profile against Gram-positive and Gram-negative strains revealed the new 5,5'-diethyldipyrromethane bearing a side chain incorporating a triazole and oxime moieties. The antibacterial profile detected was within the Clinical and Laboratory Standard Institute (CLSI) range and against important Staphylococcus species including Methicillin-resistant strain (S. aureus ATCC 25923, S. epidermidis ATCC 12228 and S. simulans ATCC 27851 and MRSA). Interestingly, this new 1,2,3-triazole presented hemocompatibility and low in silico toxicity profile similar to antibiotics current in use. It also has an usual antibiofilm activity against MRSA, which reinforced its potential as a new antibacterial prototype.

Synthesis of Novel Glycerol-Derived 1,2,3-Triazoles and Evaluation of Their Fungicide, Phytotoxic and Cytotoxic Activities

The synthesis of a series of 1,2,3-triazoles using glycerol as starting material is described. The key step in the preparation of these triazolic derivatives is the copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC), also known as click reaction, between 4-(azidomethyl)-2,2-dimethyl-1,3-dioxolane (3) and different terminal alkynes. The eight prepared derivatives were evaluated with regard to their fungicide, phytotoxic and cytotoxic activities. The fungicidal activity was assessed in vitro against Colletotrichum gloeosporioides, the causative agent of papaya anthracnose. It was found that the compounds 1-(1-((2,2-dimethyl-1,3-dioxolan-4-yl)methyl)-1H-1,2,3-triazol-4-yl)-cyclo-hexanol (4g) and 2-(1-((2,2-dimethyl-1,3-dioxolan-4-yl)methyl)-1H-1,2,3-triazol-4-yl)propan-2-ol (4h) demonstrated high efficiency in controlling C. gloeosporioides when compared to the commercial fungicide tebuconazole. The triazoles did not present any phytotoxic effect when evaluated against Lactuca sativa. However, five derivatives were mitodepressive, inducing cell death detected by the presence of condensed nuclei and acted as aneugenic agents in the cell cycle of L. sativa. It is believed that glycerol derivatives bearing 1,2,3-triazole functionalities may represent a promising scaffold to be explored for the development of new agents to control C. gloeosporioides.

Copper-Catalyzed Cross-Dehydrogenative N2-Coupling of NH-1,2,3-Triazoles with N,N -Dialkylamides: N-Amidoalkylation of NH-1,2,3-Triazoles

An efficient copper-catalyzed C-N bond formation by N-H/C-H cross-dehydrogenative coupling (CDC) between NH-1,2,3-triazoles and N,N-dialkylamides has been developed. The method provided N-amidoalkylated 1,2,3-triazoles with moderate to high yields, and the reactions showed high N²-selectivities when 4,5-disubstituted NH-1,2,3-triazoles served as the substrates.

Exploration of DAPI analogues: Synthesis, antitrypanosomal activity, DNA binding and fluorescence properties

The DAPI structure has been modified by replacing the phenyl group with substituted phenyl or heteroaryl rings. Twelve amidines were synthesized and their DNA binding, fluorescence properties, in vitro and in vivo activities were evaluated. These compounds are shown to bind in the DNA minor groove with high affinity, and exhibit superior in vitro antitrypanosomal activity to that of DAPI. Six new diamidines (5b, 5c, 5d, 5e, 5f and 5j) exhibit superior in vivo activity to that of DAPI and four of these compounds provide 100% animal cure at a low dose of 4 × 5 mg/kg i.p. in T. b. rhodesiense infected mice. Generally, the fluorescence properties of the new analogues are inferior to that of DAPI with the exception of compound 5i which shows a moderate increase in efficacy while compound 5k is comparable to DAPI.

Medicinal attributes of 1,2,3-triazoles: Current developments

1,2,3-Triazoles are important five-membered heterocyclic scaffold due to their extensive biological activities. This framework can be readily obtained in good to excellent yields on the multigram scale through click chemistry via reaction of aryl/alkyl halides, alkynes and NaN₃ under ambient conditions. It has been an emerging area of interest for many researchers throughout the globe owing to its immense pharmacological scope. The present work aims to summarize the current approaches adopted for the synthesis of the 1,2,3-triazole and medicinal significance of these architectures as a lead structure for the discovery of drug molecules such as COX-1/COX-2 inhibitors (celecoxib, pyrazofurin), HIV protease inhibitors, CB1 cannabinoid receptor antagonist and much more which are in the pipeline of clinical trials. The emphasis has been given on the major advancements in the medicinal prospectus of this pharmacophore for the period during 2008-2016.

Ultrasound promoted facile one pot synthesis of triazole derivatives catalyzed by functionalized graphene oxide Cu(I) complex under mild conditions

A facile one pot three component reaction of alkyl halides, sodium azide with terminal alkynes can be catalyzed by functionalized graphene oxide copper (I) complex under ultrasonic irradiation at room temperature. In this protocol, the 1,4-disubstituted 1,2,3-triazoles were afforded as target pure products in excellent yields and short reaction times. The prepared catalyst has been characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction spectroscopy (XRD), Energy Dispersive X-ray (EDX) and field emission scanning electron microscopy (FE-SEM) techniques. Also, the catalyst is chemoselective and stable and can be reused several times without any appreciable loss of its catalytic activity.

Synthesis, DNA binding and antitrypanosomal activity of benzimidazole analogues of DAPI

A series of novel benzimidazole diamidines were prepared from the corresponding dicyano analogues either by applying Pinner methodology (5a-c, 10 and 13a) or by making amidoximes intermediates that were reduced to the corresponding amidines (15a-c). The new amidines were evaluated in vitro against the protozoan parasite Trypanosoma brucei rhodesiense (T. b. r.). The thiophene analogue 5b and the N-methyl compound 15a showed superior antitrypanosomal activity compared to that of the parent I.

Synthesis of Novel Symmetrical 1,4-Disubstituted 1,2,3-Bistriazole Derivatives via 'Click Chemistry' and Their Biological Evaluation

A series of symmetric bis-1,2,3-triazole compounds 2-5(a-f) were synthesized as potential antioxidant agents via click chemistry. Their structures were confirmed by ¹H-NMR and (13)C-NMR. All of the synthesized compounds were subjected to antioxidant and antimicrobial assays. The antioxidant activity of these compounds (AChE inhibition, DPPH and SOD activities) was evaluated. Compound 2f was found to show the highest AChE inhibition activity of all compounds, while compound 3b showed a strong inhibitory effect on DPPH radical and compound 2a was the most effective of all compounds for SOD activity. All synthesized compounds were found to possess moderate antibacterial activity against the bacteria E. coli and Y.pseudotuberculosis.

Synthesis, photophysical properties and anticancer activity of micro-environment sensitive amphiphilic bile acid dendrimers

Porphyrin-cored bile acid dendrimers containing deoxymethyl cholate and methyl cholate units at the periphery, have been synthesized by convergent methodology using a click chemistry approach and characterized by ¹H and ¹³C NMR and MALDI-TOF MS data.

Cysteine-based silver nanoparticles as dual colorimetric sensors for cations and anions

The synthesis of amide–triazole-based Ag NPs and their sensing ability towards anions and cations in aqueous solution were investigated. The importance of amide–triazole as a binding motif, in conjunction with Ag NPs, and the mode of the sensing ability of these amide–triazole Ag NPs as dual colorimetric sensors have been studied in detail.

Discovery of a selective, safe and novel anti-malarial compound with activity against chloroquine resistant strain of Plasmodium falciparum

In recent years the DNA minor groove has attracted much attention for the development of anti-malarial agents. In view of this we have attempted to discover novel DNA minor groove binders through in-silico and in-vitro workflow. A rigorously validated pharmacophore model comprising of two positive ionizable (PI), one hydrophobic (HY) and one ring aromatic (RA) features was used to mine NCI chemical compound database. This led to retrieval of many hits which were screened on the basis of estimated activity, fit value and Lipinski's violation. Finally two compounds NSC639017 and NSC371488 were evaluated for their in-vitro anti-malarial activities against Plasmodium falciparum 3D7 (CQ sensitive) and K1 (CQ resistant) strains by SYBR green-I based fluorescence assay. The results revealed that out of two, NSC639017 posses excellent anti-malarial activity particularly against chloroquine resistant strain and moreover NSC639017 also appeared to be safe (CC50 126.04 μg/ml) and selective during cytotoxicity evaluation.

One-pot sequential alkynylation and cycloaddition: regioselective construction and biological evaluation of novel benzoxazole-triazole derivatives

Individually, benzoxazole and triazole moieties are of significant biological interest owing to their importance in drugs and pharmaceuticals. To assess their combined biological impact when woven into one molecule, we designed a novel, regioselective, multicomponent, one-pot (MCOP) approach for the construction of benzoxazole-linked triazoles. The synthesis has been achieved in two sequential steps involving copper-catalyzed alkynylation of benzoxazole followed by a 1,3-dipolar cycloaddition reaction. By combination of these two bioactive units into one core, a series of new benzoxazole-triazole scaffolds has been synthesized and subjected to in vitro antibacterial and anticancer evaluation. Tests against clinical isolates of Staphylococcus aureus and Escherichia coli showed potent Gram-negative activity for compounds 4{1,1,1}, 4{1,1,4}, and 4{1,2,1}. The cytotoxicity of the synthesized library was determined against three cancer cell lines: HeLa, SKBr3, and Hep G2. Compound 4{2,2,2} showed significant cytotoxicity against all the cell lines. These preliminary bioassay evaluations strongly suggest the promise and scope of these novel molecules as therapeutic agents in medical science.

A polymer supported ascorbate functionalized task specific ionic liquid: an efficient reusable catalyst for 1,3-dipolar cycloaddition

In situ coalescence of copper on polymer supported ascorbate functionalized task specific ionic liquid, acts as an efficient catalyst for Huisgen 1,3 dipolar cycloaddition.

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.

Copper-loaded polymeric magnetic nanocatalysts as retrievable and robust heterogeneous catalysts for click reactions

A novel heterogeneous copper catalyst based on poly(ionic liquid)-coated magnetic nanoparticles was prepared by the polymerization of 3-carboxymethyl-1-vinylimidazolium in the presence of surface-modified magnetic nanoparticles, followed by the coordination of the carboxylate units in the polymer chains with copper sulfate.

Nano magnetite supported metal ions as robust, efficient and recyclable catalysts for green synthesis of propargylamines and 1,4-disubstituted 1,2,3-triazoles in water

Superparamagnetic supported metals complex catalysts have been synthesized and applied for the synthesis of propargylamines and 1,2,3-triazoles.

Synthesis and antifungal activity of benzamidine derivatives carrying 1,2,3-triazole moieties

Eighteen novel benzamidine derivatives containing 1,2,3-triazole moieties were synthesized. The in vitro and in vivo fungicidal acitivities of the title compounds and the arylamidine intermediates against Colletotrichum lagenarium and Botrytis cinerea were tested. The synthesized benzamidines exhibited weak antifungal activities in vitro against the tested fungi, but some of the compounds showed excellent activities in vivo to the same strains. Among the compounds tested, 9b showed 79% efficacy in vivo against C. lagenarium at a concentration of 200 μg/mL, and the efficacy of compound 16d (90%) toward the same strain was even superior than that of the commercial fungicide carbendazim (85%).

Bioassay-guided isolation of a sesquiterpene lactone of deoxyelephantopin from Elephantopus scaber Linn. active on Trypanosome brucei rhodesience

Methanolic extracts of 70 Malaysia plants were screened for their in vitro antitrypanosomal activity using Trypanosome brucei rhodesience, strain STIB 900 and mouse skeletal cell (L-6) in cytotoxicity activity assay. Results indicated that methanol extract from Elephantopus scaber Linn. (E. scaber) possessed the highest value of antitrypanosomal activity with good selectivity index (antitrypanosomal IC50 of 0.22±0.02 μg/ml, SI value of 204.55). Based on these results, E. scaber was chosen for further study by applying bioassay guided fractionation to isolate its antiprotozoal principle. The antiprotozoal principle was isolated from the ethyl acetate partition through solvent fractionation and crystallization process. The isolated active compound 1 was identified as deoxyelephantopin on the basis of its spectral analysis (FTIR, MS, 1D and 2D NMR).

Synthesis of β-hydroxy-1,4-disubstituted-1,2,3-triazoles catalyzed by copper ferrite nanoparticles in tap water using click chemistry

A novel one pot synthesis of β-hydroxy-1,4-disubstituted-1,2,3-triazoles has been developed by using CuFe₂O₄ nanoparticles. This protocol involves easily recyclable catalyst in water and avoids the handling of azides as they are generated in situ.