Biological Evaluation of 4-(1H-triazol-1-yl)benzoic Acid Hybrids as Antioxidant Agents: In Vitro Screening and DFT Study

Fourteen triazole benzoic acid hybrids were previously characterized. This work aimed to screen their in vitro antioxidant activity using different assays, i.e., DPPH (1,1-diphenyl-1-picrylhydrazyl), reducing the power capability, FRAP (ferric reducing antioxidants power) and ABTS (2,2′-azino-bis(3-ethylben zothiazoline-6-sulfonate) radical scavenging. The 14 compounds showed antioxidant properties in relation to standard BHA (butylated hydroxylanisole) and Trolox (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid). Higher antioxidant activity was observed by the parent (1) at a concentration of 100 µg/mL (89.95 ± 0.34 and 88.59 ± 0.13%) when tested by DPPH and ABTS methods in relation to BHA at 100 µg/mL (95.02 ± 0.74 and 96.18 ± 0.33%). The parent (2) demonstrated remarkable scavenging activity when tested by ABTS (62.00 ± 0.24%), however, 3 was less active (29.98 ± 0.13%). Compounds 5, 6, 9, and 11 exhibited good scavenging activity compared to 1. DFT studies were performed using the B3LYP/6-311++g (2d,2p) level of theory to evaluate different antioxidant descriptors for the targets. Three antioxidant mechanisms, i.e., hydrogen atom transfer (HAT), sequential electron transfer proton transfer (SETPT) and sequential proton loss electron transfer (SPLET) were suggested to describe the antioxidant properties of 1–14. Out of the 14 triazole benzoic acid hybrids, 5, 9, 6, and 11 showed some good theoretical results, which were in agreement with some experimental outcomes. Based on the computed (PA and ETE) and (BDE and IP) values in (SPLET) and (HAT and SETPT) mechanisms, respectively, compound 9 emerged has having good antioxidant activity.

Investigation of 4-Hydrazinobenzoic Acid Derivatives for Their Antioxidant Activity: In Vitro Screening and DFT Study

Hydrazinobenzoic acid derivatives with isothiocyanate, benzylidene, and acid anhydride core units (1-13) were previously synthesized and fully characterized. Targets 1-13 were investigated for their antioxidant activities using different in vitro assays such as 1,1-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS), ferric reducing antioxidant power (FRAP), and reducing power capability. All derivatives showed antioxidant properties in relation to the standard butylated hydroxylanisole (BHA). Superior antioxidant activities was observed for compounds 3 and 5-9 at a concentration of 20 μg/mL (70-72%) when tested by the DPPH method in comparison to BHA (92%), and compounds 1-10 showed the highest free radical quenching activity (80-85%) when examined by ABTS at 20 μg/mL in relation to BHA (85%). Density function theory (DFT) studies were carried out using the B3LYP/6-311G(d,p) level of theory. Several antioxidant descriptors were calculated for targets 1-13 compared with BHA. Targets 1-13 were proposed to exhibit their antioxidant activities via the following three proposed antioxidant mechanisms: single electron transfer (SET), hydrogen atom transfer (HAT), and sequential proton loss electron transfer (SPLET). The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies and electron levels for 1-13 were also determined.

Transition-metal-free C-S, C-Se, and C-Te Bond Formation from Organoboron Compounds

The present review describes the successful application of organoboron compounds in transition-metal-free C-S, C-Se, and C-Te bond formations. We presented studies regarding these C-Chalcogen bond formations using organoboron reagents, such as boronic acids, boronic esters, borate anions, and several sources of chalcogen atoms/moieties. Moreover, a broad range of transition-metal-free approaches to synthesize sulfides, selenides, and tellurides were described using conventional heating methods, which are sometimes green since they use green solvents, safe reagents, among others. Furthermore, protocols using alternative energy sources, including ultrasound, microwave irradiation, photocatalysis, and electrolytic processes, were also shown to be suitable. These protocols were applied to prepare a broad scope of functionalized chalcogenides with high molecular diversity. These studies and their proposed mechanisms were also reported herein in addition to the reuse of reaction promoters.

Design, Synthesis, and Antimicrobial Activities of 1,2,3-Triazole Glycoside Clickamers

Bacterial resistance remains a significant threat and a leading cause of death worldwide, despite massive attempts to control infections. In an effort to develop biologically active antibacterial and antifungal agents, six novel aryl-substituted-1,2,3-triazoles linked to carbohydrate units were synthesized through the Cu(I)-catalyzed azide-alkyne cycloaddition CuAAC of substituted-arylazides with a selection of alkyne-functionalized sugars. The chemical structures of the new derivatives were verified using different spectroscopic techniques. The novel clicked 1,2,3-triazoles were evaluated for in vitro antibacterial activity against Gram-positive Staphylococcus aureus and Gram-negative Pseudomonas aeruginosa, and the obtained results were compared with the activity of the reference antibiotic "Ampicillin". Likewise, in vitro antifungal activity of the new 1,2,3-triazoles was investigated against Candida albicans and Aspergillus niger using "Nystatin" as a reference drug. The results of the biological evaluation pointed out that Staphylococcus aureus was more susceptible to all of the tested compounds than other examined microbes. In addition, some tested compounds exhibited promising antifungal activity.

Pharmacological and Cellular Significance of Triazole-Surrogated Compounds

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Heterocyclic compounds have been at the hierarchy position in academia, and industrial arena, particularly the compounds containing triazole-core are found to be potent with a broad range of biological activities. The resistance of triazole ring towards chemical (acid and base) hydrolysis, oxidative and reductive reaction conditions, metabolic degradation and its higher aromatic stabilization energy makes it a better heterocyclic core as therapeutic agents. These triazole-linked compounds are used for clinical purposes for antifungal, anti-mycobacterium, anticancer, anti-migraine and antidepressant drugs. Triazole scaffolds are also found to act as a spacer for the sake of covalent attachment of the high molecular weight bio-macromolecules with an experimental building blocks to explore structure-function relationships. Herein, several methods and strategies for the synthesis of compounds with 1,2,3-triazole moiety exploring Hüisgen, Meldal and Sharpless 1,3-dipolar cycloaddition reaction between azide and alkyne derivatives have been deliberated for a series of representative compounds. Moreover, this review article highlights in-depth applications of the [3+2]-cycloaddition reaction for the advances of triazole-containing antibacterial as well as metabolic labelling agents for the in vitro and in vivo studies on cellular level.

Tetrazoles via Multicomponent Reactions

Tetrazole derivatives are a prime class of heterocycles, very important to medicinal chemistry and drug design due to not only their bioisosterism to carboxylic acid and amide moieties but also to their metabolic stability and other beneficial physicochemical properties. Although more than 20 FDA-approved drugs contain 1 H- or 2 H-tetrazole substituents, their exact binding mode, structural biology, 3D conformations, and in general their chemical behavior is not fully understood. Importantly, multicomponent reaction (MCR) chemistry offers convergent access to multiple tetrazole scaffolds providing the three important elements of novelty, diversity, and complexity, yet MCR pathways to tetrazoles are far from completely explored. Here, we review the use of multicomponent reactions for the preparation of substituted tetrazole derivatives. We highlight specific applications and general trends holding therein and discuss synthetic approaches and their value by analyzing scope and limitations, and also enlighten their receptor binding mode. Finally, we estimated the prospects of further research in this field.

Synthesis of Amino Acid-Derived 1,2,3-Triazoles: Development of a Nontrivial Fluorescent Sensor in Solution for the Enantioselective Sensing of a Carbohydrate and Bovine Serum Albumin Interaction

A series of amino acid-derived 1,2,3-triazoles presenting the amino acid and the aromatic moieties connected by a triazole-4-carboxylate spacer is discussed in this work. These compounds were achieved in good yields by organocatalytic enamine-azide [3 + 2] cycloadditions. One of the molecules obtained, bearing a 7-chloroquinoline moiety, was photoactive in the UV-violet region and was successfully employed as a probe for substrate-specific enantiomeric sensing using d-(-)-arabinose and l-(+)-arabinose. The potential application as a fluorescent probe to detect protein in phosphate buffer solution was also explored using as model bovine serum albumin (BSA). The studied compounds presented both suppression and association behavior in the presence of BSA. In addition, theoretical calculations were performed at levels ωB97XD/cc-pVDZ and PBE1PBE/6-311+G(d,p) together with the polarizable continuum model to understand the interaction of the molecules with the enantiomers.

Copper Catalysis and Organocatalysis Showing the Way: Synthesis of Selenium-Containing Highly Functionalized 1,2,3-Triazoles

This article provides a comprehensive overview of reported methods - particularly copper- and organocatalyzed reactions - for the regioselective syntheses of selenium-containing 1,2,3-triazoles systems. These chemical entities are prevalent cores in biologically active compounds and functional materials. In view of their unique properties, substantial efforts have been paid for the design and development of practical approaches for the synthesis of these scaffolds.

Computational and biological evidences on the serotonergic involvement of SeTACN antidepressant-like effect in mice

A series of phenylselanyl-1H-1,2,3-triazole-4-carbonitriles with different substituents were screened for their binding affinity with serotonin transporter (SERT) and dopamine transporter (DAT) by docking molecular. 5-(4methoxyphenyl)-1-(2-(phenylselanyl)phenyl)-1H-1,2,3-triazole-4-carbonitrile (SeTACN) exhibited the best conformation with SERT even higher than fluoxetine and serotonin, suggesting a competitive inhibition. SeTACN demonstrated additional affinity to other serotonergic receptors involved in antidepressant effects: 5HT_1a, 5HT_2a and 5HT₃. In another set of experiments, SeTACN led to significant reductions in the immobility time of mice submitted to forced swimming test (FST) in the dose range of 0.1- 20mg/kg, suggesting an antidepressant-like effect. The possible mechanism of action was investigated using serotonergic and dopaminergic antagonists. The antidepressant-like effect of SeTACN (0.1mg/kg i.g.) was prevented by the pretreatment with WAY100635 (a selective 5HT_1a antagonist), ketanserin (a 5HT2_a/c antagonist) and ondansetron (a selective 5ht₃ antagonist), PCPA (an inhibitor of serotonin synthesis) but not with SCH23390 (dopaminergic D₁ antagonist) and sulpiride (D₂ antagonist). Sub-effective dose of fluoxetine was able to potentiate the effects of a sub-effective dose of SeTACN in FST. None of the treatments affected locomotor activity in open field test (OFT). These results together, suggest that the SeTACN antidepressant-like effect is mediate, at least in parts, by serotonergic system.

Ultrasound-promoted copper-catalyzed synthesis of bis-arylselanyl chrysin derivatives with boosted antioxidant and anticancer activities

Herein we report the use of ultrasonic irradiation (US) in the synthesis of six new semi-synthetic selenium-containing chrysin derivatives by a simple and effective methodology utilizing CuI as catalyst, in good to excellent yields (60-89%). It was observed that US accelerates the reaction compared to conventional heating with excellent selectivity for diselenylated products. Compounds were tested for their antioxidant and anticancer activities in vitro and it was observed that the presence of selenium in the A-ring of chrysin enhanced both antioxidant and anticancer properties. Semi-synthetic 6,8-bis(o-tolylselanyl)-chrysin 3b has the best radical scavenging activity of DPPH (I_max: 39.79µM) and ABTS⁺ (IC₅₀: 6.5µM) radicals. Similarly, in the Reactive Species (RS) assay, 3b showed high antioxidant activity in mice cortex (IC₅₀: 5.67µM), whereas 6,8-bis(p-anisoylselanyl)-chrysin 3c was the more active in the hippocampus (IC₅₀: 5.63µM). The Se-chrysins were effective in prevention of lipid peroxidation, highlighting 6,8-bis(p-fluorophenylselanyl)-chrysin 3d in cortex (IC₅₀: 0.54µM) and 3b in hippocampus (IC₅₀: 0.27µM). In addition, 3d was effective in inhibiting human lung adenocarcinoma (A549) cells growth, with a IC₅₀ of 19.9µM after 72h of treatment, while 6,8-bis(p-anisoylselanyl)-chrysin 3c presented the higher antiproliferative activity after 48h of treatment (IC₅₀ of 41.4µM).

Ultrasound-promoted organocatalytic enamine-azide [3 + 2] cycloaddition reactions for the synthesis of ((arylselanyl)phenyl-1H-1,2,3-triazol-4-yl)ketones

The use of sonochemistry is described in the organocatalytic enamine-azide [3 + 2] cycloaddition between 1,3-diketones and aryl azidophenyl selenides. These sonochemically promoted reactions were found to be amenable to a range of 1,3-diketones or aryl azidophenyl selenides, providing an efficient access to new ((arylselanyl)phenyl-1H-1,2,3-triazol-4-yl)ketones in good to excellent yields and short reaction times. In addition, this protocol was extended to β-keto esters, β-keto amides and α-cyano ketones. Selanyltriazoyl carboxylates, carboxamides and carbonitriles were synthesized in high yields at short times of reaction under very mild reaction conditions.

Combinatorial synthesis, in silico, molecular and biochemical studies of tetrazole-derived organic selenides with increased selectivity against hepatocellular carcinoma

Novel tetrazole-based diselenides and selenoquinones were synthesized via azido-Ugi and sequential nucleophilic substitution (SN) strategy. Molecular docking study into mammalian TrxR1 was used to predict the anticancer potential of the newly synthesized compounds. The cytotoxic activity of the compounds was evaluated using hepatocellular carcinoma (HepG2) and breast adenocarcinoma (MCF-7) cancer cells and compared with their cytotoxicity in normal fibroblast (WI-38) cells. The corresponding redox properties of the synthesized compounds were assessed employing 2,2-diphenyl-1-picrylhydrazyl (DPPH), glutathione peroxidase (GPx)-like activity and bleomycin dependent DNA damage. In general, diselenides showed preferential cytotoxicity to HepG2 compared to MCF-7 cells. These compounds exhibited also good GPx catalytic activity compared to ebselen (up to 5 fold). Selenoquinones 18, 21, 22 and 23 were selected to monitor the expression levels of caspase-8, Bcl-2 and Ki-67 molecular biomarkers. Interestingly, these compounds downregulated the Bcl-2 and Ki-67 expression levels and activated the expression of caspase-8 in HepG2 cells compared to untreated cells. These results indicate that some of the newly synthesized compounds possess anti-HepG2 activity.