Identification of β-Amino alcohol grafted 1,4,5 trisubstituted 1,2,3-triazoles as potent antimalarial agents

Synthesis and Pharmacological Evaluation of Novel Triazole-Pyrimidine Hybrids as Potential Neuroprotective and Anti-neuroinflammatory Agents

OBJECTIVE

Neuroprotection is a precise target for the treatment of neurodegenerative diseases, ischemic stroke, and traumatic brain injury. Pyrimidine and its derivatives have been proven to use antiviral, anticancer, antioxidant, and antimicrobial activity prompting us to study the neuroprotection and anti-inflammatory activity of the triazole-pyrimidine hybrid on human microglia and neuronal cell model.

METHODS

A series of novel triazole-pyrimidine-based compounds were designed, synthesized and characterized by mass spectra, 1HNMR, 13CNMR, and a single X-Ray diffraction analysis. Further, the neuroprotective, anti-neuroinflammatory activity was evaluated by cell viability assay (MTT), Elisa, qRT-PCR, western blotting, and molecular docking.

RESULTS

The molecular results revealed that triazole-pyrimidine hybrid compounds have promising neuroprotective and anti-inflammatory properties. Among the 14 synthesized compounds, ZA3-ZA5, ZB2-ZB6, and intermediate S5 showed significant anti-neuroinflammatory properties through inhibition of nitric oxide (NO) and tumor necrosis factor-α (TNF-α) production in LPS-stimulated human microglia cells. From 14 compounds, six (ZA2 to ZA6 and intermediate S5) exhibited promising neuroprotective activity by reduced expression of the endoplasmic reticulum (ER) chaperone, BIP, and apoptosis marker cleaved caspase-3 in human neuronal cells. Also, a molecular docking study showed that lead compounds have favorable interaction with active residues of ATF4 and NF-kB proteins.

CONCLUSION

The possible mechanism of action was observed through the inhibition of ER stress, apoptosis, and the NF-kB inflammatory pathway. Thus, our study strongly indicates that the novel scaffolds of triazole-pyrimidine-based compounds can potentially be developed as neuroprotective and anti-neuroinflammatory agents.

Click Chemistry of Selenium Dihalides: Novel Bicyclic Organoselenium Compounds Based on Selenenylation/Bis-Functionalization Reactions and Evaluation of Glutathione Peroxidase-like Activity

A number of highly efficient methods for the preparation of novel derivatives of 9-selenabicyclo[3.3.1]nonane in high yields based on selenium dibromide and cis,cis-1,5-cyclooctadiene are reported. The one-pot syntheses of 2,6-diorganyloxy-9-selenabicyclo[3.3.1]nonanes using various O-nucleophiles including alkanols, phenols, benzyl, allyl, and propargyl alcohols were developed. New 2,6-bis(1,2,3-triazol-1-yl)-9-selenabicyclo[3.3.1]nonanes were obtained by the copper-catalyzed 1,3-dipolar cycloaddition of 2,6-diazido-9-selenabicyclo[3.3.1]nonane with unsubstituted gaseous acetylene and propargyl alcohol. The synthesis of 2,6-bis(vinylsulfanyl)-9-selenabicyclo[3.3.1]nonane, based on the generation of corresponding dithiolate anion from bis[amino(iminio)methylsulfanyl]-9-selenabicyclo[3.3.1]nonane dibromide, followed by the nucleophilic addition of the dithiolate anion to unsubstituted acetylene, was developed. The glutathione peroxidase-like activity of the obtained water-soluble products was estimated and compounds with high activity were found. Overall, 2,6-Diazido-9-selenabicyclo[3.3.1]nonane exhibits the highest activity among the obtained compounds.

Triple-Click Chemistry of Selenium Dihalides: Catalytic Regioselective and Highly Efficient Synthesis of Bis-1,2,3-Triazole Derivatives of 9-Selenabicyclo[3.3.1]nonane

The catalytic regioselective and highly efficient synthesis of bis-1,2,3-triazole derivatives of 9-selenabicyclo[3.3.1]nonane was developed. The 1,3-dipolar cycloaddition reaction of 2,6-diazido-9-selenabicyclo[3.3.1]nonane with a variety of terminal acetylenes catalyzed by a copper acetate/sodium ascorbate system proceeded in a regioselective fashion, affording 2,6-bis(4-organyl-1,2,3-triazole)-9-selenabicyclo[3.3.1]nonanes in high yields (93–98%). The reaction of 2,6-diazido-9-selenabicyclo[3.3.1]nonane with dimethyl and diethyl acetylenedicarboxylates was carried out as thermal 1,3-dipolar Huisgen cycloaddition giving the corresponding 4,5-disubstituted 1,2,3-triazole derivatives of 9-selenabicyclo[3.3.1]nonane in high yields. The obtained products are potentially bioactive compounds and first representatives of selenium heterocycles combined with two 1,2,3-triazole moieties. 2.6-Diazido-9-selenabicyclo[3.3.1]nonane was obtained in quantitative yield via the reaction of sodium azide with 2,6-dibromo-9-selenabicyclo[3.3.1]nonane at room temperature. The latter compound was synthesized by stereoselective transannular addition of selenium dibromide to cis, cis-1,5-cyclooctadiene.

Phthalimide analogs for antimalarial drug discovery

Malaria remains one of the world's most life-threatening diseases and, thus, it is a major public health concern all around the world. The disease can become devastating if not treated with proper medication in a timely manner. Currently, the number of viable treatment therapies is in continuous decline due to compromised effectiveness, probably owing to the complex life cycle of Plasmodium falciparum. The factors responsible for the unclear status of malaria eradication programmes include ever-developing parasite resistance to the most effective treatments used on the frontline (i.e., artemisinin derivatives) and the paucity of new effective therapeutics. Due to these circumstances, the development of novel effective drug candidates with unique modes of action is essential for overcoming the listed obstacles. As such, the discovery of novel chemical compounds based on validated pharmacophores remains an unmet need in the field of medicinal chemistry. In this area, functionalized phthalimide (Pht) analogs have been explored as potential candidates against various diseases, including malaria. Pht presents a promising bioactive scaffold that can be easily functionalized and thus utilized as a starting point for the development of new antimalarial candidates suitable for preclinical and clinical studies. In this short review, we highlight a wide range of Pht analogs that have been investigated for their activity against various strains of Plasmodium falciparum.

Molecular modeling and design of some β-amino alcohol grafted 1,4,5-trisubstituted 1,2,3-triazoles derivatives against chloroquine sensitive, 3D7 strain of Plasmodium falciparum

Resistance nature of Plasmodium falciparum (P. falciparum) to the most effective antimalarial drug, Artemisinin, intimidate the global goal of total eradication of malarial. In an attempt to overcome this challenge, the research was aimed at designing derivatives of β-amino alcohol grafted 1,4,5-trisubstituted 1,2,3-triazoles with improve activity against the P. falciparum through structural modifications of the most active compound (design template), and their activity determined using the developed theoretical predictive model. To achieve this, the geometries were optimized via density functional theory (DFT) using B3LYP/6-31G^∗ basis set to generate molecular descriptors for model development. Analysis of the developed model and the descriptors mean effect lead to the design of derivatives with improved activity. Five (5) theoretical models were developed, where the model {pIC₅₀ = 5.95067(SpMin5_Bhi) - 0.0323461(RDF45m) + 0.0203865 (RDF95e) + 0.0499285 (L1m) - 3.50822} with the highest coefficient of determination (R²) of 0.9367, cross-validated R² (Q²cv) of 0.8242, and the external validated R² (R²_pred) of 0.9462, selected as the best model. The mean effect analysis revealed descriptor SpMin5_Bhi as the most contributive. The descriptor encodes the first ionization potentials of the compounds and are influenced by electron-withdrawing/donating substituents. Hence, structural modifications of the compound with the highest activity (a design template) using electron-withdrawing substituents such as –NO₂, –SO₃H, -Br, –I, –CH₂CH₃, and –CH₃ was done at a different positions, to obtain five (5) hypothetical novel compounds. The statistical results, shows the robustness, excellent prediction power, and validity of the selected model. Descriptor analysis revealed the first ionization potential (SpMin5_Bhi) to play a significant role in the activity of β-amino alcohol grafted 1,4,5-trisubstituted 1,2,3-triazoles derivatives. The five design derivatives of β-amino alcohol grafted 1,4,5-trisubstituted 1,2,3-triazoles with higher activities revealed compound 21C to have an antimalarial activity of pIC₅₀ = 6.7573 higher than it co-designed compounds and even the standard drug. This claim could be verified through molecular docking to determine their interaction with the target protein.

A copper-catalyzed synthesis of aryloxy-tethered symmetrical 1,2,3-triazoles as potential antifungal agents targeting 14 α-demethylase

The search for potent therapeutic agents has prompted the design and synthesis of a library of twenty-six aryloxy-tethered and amide-linked symmetrical 1,2,3-triazoles (8a–z) using a copper(i)-catalyzed click chemistry approach.

An epigrammatic status of the 'azole'-based antimalarial drugs

The development of multidrug resistance in the malarial parasite has sabotaged majority of the eradication efforts by restraining the inhibition profile of first line as well as second line antimalarial drugs, thus necessitating the development of novel pharmaceutics constructed on appropriate scaffolds with superior potency against the drug-resistant and drug-susceptible Plasmodium parasite. Over the past decades, the infectious malarial parasite has developed resistance against most of the contemporary therapeutics, thus necessitating the rational development of novel approaches principally focused on MDR malaria. This review presents an epigrammatic collation of the epidemiology and the contemporary antimalarial therapeutics based on the 'azole' motif.

Regioselective Synthesis of Diverse Thio-, Seleno-substituted 1,2,3-Triazoles

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Thio-, seleno-substituted triazoles are useful scaffolds employed in the fields of organic synthesis, medicinal chemistry, and material science. A number of synthetic approaches to efficient formation of thio- and seleno-triazoles have been disclosed, including the interception of copper(I) triazolides generated in-situ, cycloaddition of internal alkynes (thio-, halo-, and metalated alkynes) to azides, and the coupling of azides and nonalkyne substrates. This mini-review intends to summarize the synthetic methods toward thio-, seleno-1,2,3-triazoles and the relative reaction mechanisms.

Recent Advances in the Discovery of Novel Antiprotozoal Agents

Parasitic diseases have serious health, social, and economic impacts, especially in the tropical regions of the world. Diseases caused by protozoan parasites are responsible for considerable mortality and morbidity, affecting more than 500 million people worldwide. Globally, the burden of protozoan diseases is increasing and is been exacerbated because of a lack of effective medication due to the drug resistance and toxicity of current antiprotozoal agents. These limitations have prompted many researchers to search for new drugs against protozoan parasites. In this review, we have compiled the latest information (2012-2017) on the structures and pharmacological activities of newly developed organic compounds against five major protozoan diseases, giardiasis, leishmaniasis, malaria, trichomoniasis, and trypanosomiasis, with the aim of showing recent advances in the discovery of new antiprotozoal drugs.

Triazole derivatives and their antiplasmodial and antimalarial activities

Malaria, caused by protozoan parasites of the genus Plasmodium especially by the most prevalent parasite Plasmodium falciparum, represents one of the most devastating and common infectious disease globally. Nearly half of the world population is under the risk of being infected, and more than 200 million new clinical cases with around half a million deaths occur annually. Drug therapy is the mainstay of antimalarial therapy, yet current drugs are threatened by the development of resistance, so it's imperative to develop new antimalarials with great potency against both drug-susceptible and drug-resistant malaria. Triazoles, bearing a five-membered heterocyclic ring with three nitrogen atoms, exhibit promising in vitro antiplasmodial and in vivo antimalarial activities. Moreover, several triazole-based drugs have already used in clinics for the treatment of various diseases, demonstrating the excellent pharmaceutical profiles. Therefore, triazole derivatives have the potential for clinical deployment in the control and eradication of malaria. This review covers the recent advances of triazole derivatives especially triazole hybrids as potential antimalarials. The structure-activity relationship is also discussed to provide an insight for rational designs of more efficient antimalarial candidates.

Design, Synthesis, and Biological Evaluation of New 1-(Aryl-1 H-pyrrolyl)(phenyl)methyl-1 H-imidazole Derivatives as Antiprotozoal Agents

We have designed and synthesized a series of new imidazole-based compounds structurally related to an antiprotozoal agent with nanomolar activity which we identified recently. The new analogues possess micromolar activities against Trypanosoma brucei rhodesiense and Leishmania donovani and nanomolar potency against Plasmodium falciparum. Most of the analogues displayed IC₅₀ within the low nanomolar range against Trypanosoma cruzi, with very high selectivity toward the parasite. Discussion of structure-activity relationships and in vitro biological data for the new compounds are provided against a number of different protozoa. The mechanism of action for the most potent derivatives (5i, 6a-c, and 8b) was assessed by a target-based assay using recombinant T. cruzi CYP51. Bioavailability and efficacy of selected hits were assessed in a T. cruzi mouse model, where 6a and 6b reduced parasitemia in animals >99% following intraperitoneal administration of 25 mg/kg/day dose for 4 consecutive days.

A review on diverse heterocyclic compounds as the privileged scaffolds in antimalarial drug discovery

The upward extend of malaria collectively with the emergence of resistance against predictable drugs has put enormous pressure on public health systems to introduce new malaria treatments. Heterocycles play an important role in the design and discovery of new malaria active compounds. Heterocyclic compounds have attracted significant attention for malaria treatment because of simplicity of parallelization and the examining power with regard to chemical space. Introduction of a variety of heterocyclic compounds have enabled to maintain the high levels of antimalarial potency observed for other more lipophilic analogues whilst improving the solubility and the oral bioavailability in pre-clinical species. In this review, we present an overview of recent literature to provide imminent into the applications of different heterocyclic scaffolds in fighting against malaria.

Design and synthesis of novel benzenesulfonamide containing 1,2,3-triazoles as potent human carbonic anhydrase isoforms I, II, IV and IX inhibitors

In a quest to discover new biologically active compounds, a series of twenty novel heterocyclic derivatives substituted at position 5 with -H (7a-7j) or -CF3 (8a-8j), bearing benzenesulfonamide at N-1 position and various aroyl groups at position 4 of the 1,2,3-triazole ring was synthesized and screened for their carbonic anhydrase (CA, EC 4.2.1.1) inhibition potential against four human (h) isoforms hCA I, II, IV and IX. All the compounds (7a-7j and 8a-8j) were synthesized via [3+2] cycloaddition reaction from 4-azidobenzenesulfonamide. Interestingly, compounds 7a-7j were prepared in one pot manner via enaminone intermediate using novel methodology. All the newly synthesized compounds (7a-7j &8a-8j) were found to be excellent inhibitors of edema related isoform hCA I with their inhibition constant (Ki) ranging from 30.1 to 86.8 nM as compared to standard drug acetazolamide (AAZ) with Ki = 250 nM. Further it was found that most of tested compounds were weaker inhibitors of isoform, hCA II although compounds 7b, 7d-7e, 8a, 8d-8f, 8i (mostly with electron withdrawing substituents) have shown better inhibition potential (Ki < 50 nM). Against glaucoma associated hCA IV, compound 7d was found to be better inhibitor (Ki = 52.4 nM) than AAZ (Ki = 74 nM) while against tumor associated hCA IX, all the compounds have shown moderate inhibition potential. Present study have added one more step in exploring the 1,2,3-triazlole moiety in the medicinal field.

Biological evaluation and structure-activity relationships of imidazole-based compounds as antiprotozoal agents

We discovered a series of azole antifungal compounds as effective antiprotozoal agents. They displayed promising inhibitory activities within the micromolar-submicromolar range against P. falciparum, L. donovani, and T. b. rhodesiense. Moreover, most of such compounds showed excellent nanomolar IC₅₀ against T. cruzi, showing also very low cytotoxicity. Discussion of structure-activity relationships and biological data for these compounds are provided against the different parasites. To assess the mechanism of action against T. cruzi we proved that the most potent compounds (3b, 3j-l) inhibited the T. cruzi CYP51. Moreover, the most active derivative 3j dramatically reduced parasitemia in T. cruzi mouse model without acute toxicity.

Design, synthesis, in silico and in vitro antimicrobial screenings of novel 1,2,4-triazoles carrying 1,2,3-triazole scaffold with lipophilic side chain tether

BACKGROUND

1,2,4-Triazoles and 1,2,3-triazoles have gained significant importance in medicinal chemistry.

RESULTS

This study describes a green, efficient and quick solvent free click synthesis of new 1,2,3-triazole-4,5-diesters carrying a lipophilic side chain via 1,3-dipolar cycloaddition of diethylacetylene dicarboxylate with different surfactant azides. Further structural modifications of the resulting 1,2,3-triazole diesters to their corresponding 1,2,4-triazole-3-thiones via multi-step synthesis has been also investigated. The structures of the newly designed triazoles have been elucidated based on their analytical and spectral data. These compounds were evaluated for their antimicrobial activities. Relative to the standard antimicrobial agents, derivatives of 1,2,3-triazole-bis-4-amino-1,2,4-triazole-3-thiones were the most potent antimicrobial agents with compound 7d demonstrating comparable antibacterial and antifungal activities against all tested microorganisms. Further, the selected compounds were studied for docking using the enzyme, Glucosamine-6-phosphate synthase.

CONCLUSIONS

The in silico study reveals that all the synthesized compounds had shown good binding energy toward the target protein ranging from - 10.49 to - 5.72 kJ mol-1 and have good affinity toward the active pocket, thus, they may be considered as good inhibitors of GlcN-6-P synthase.

Synergistic blending of high-valued heterocycles inhibits growth of Plasmodium falciparum in culture and P. berghei infection in mouse model

A series of phthalimide analogues, novelized with high-valued bioactive scaffolds was synthesized by means of click-chemistry under non-conventional microwave heating and evaluated as noteworthy growth inhibitors of Plasmodium falciparum (3D7 and W2) in culture. Analogues 6a, 6h and 6 u showed highest activity to inhibit the growth of the parasite with IC₅₀ values in submicromolar range. Structure-activity correlation indicated the necessity of unsubstituted triazoles and leucine linker to obtain maximal growth inhibition of the parasite. Notably, phthalimide 6a and 6u selectively inhibited the ring-stage growth and parasite maturation. On other hand, phthalimide 6h displayed selective schizonticidal activity. Besides, they displayed synergistic interactions with chloroquine and dihydroartemisinin against parasite. Additional in vivo experiments using P. berghei infected mice showed that administration of 6h and 6u alone, as well as in combination with dihydroartemisinin, substantially reduced the parasite load. The high antimalarial activity of 6h and 6u, coupled with low toxicity advocate their potential role as novel antimalarial agents, either as standalone or combination therapies.

Synthesis and antiplasmodial activity of novel indoleamide derivatives bearing sulfonamide and triazole pharmacophores

Due to the recent reports of growing parasite resistance to artemisinins and other antimalarial drugs, development of new antimalarial chemotypes is an urgent priority. Here in, we report a novel series of adamantyl/cycloheptyl indoleamide derivatives bearing sulfonamide and triazole pharmacophores adopting different chemical modifications and evaluated them for antiplasmodial activity in vitro. Among all the indoleamides, compounds 22, 24, 26 and 30 with sulfonamide pharmacophore showed promising activity with IC₅₀ of 1.87, 1.93, 2.00, 2.17 μM against CQ sensitive Pf3D7 strain and 1.69, 2.12, 1.60, 2.19 μM against CQ resistant PfK1 strain, respectively.

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.